The first sphinctozoan-bearing reef from an Ordovician back-arc basin - Li, Qijian; Li, Yue; Kießling, Wolfgang (Facies, 2015)
Although sphinctozoans, multi-chambered hypercalcified sponges, can be traced from the Cambrian, their reef-building capacity in the Early Paleozoic appears limited. The oldest sphinctozoan-coral-microbial reef‏ is documented here, from the Upper Sanqushan Formation (Late Katian) of southeast China. This is also the first report of Ordovician sphinctozoans from South China. The sponges occur in a >120-m-thick reef that is mainly constructed by calcimicrobes (Kordephyton, Renalcis, and Epiphyton) with a low abundance of in situ metazoans, predominantly sphinctozoan sponges (Corymbospongia) and rugose corals (mostly Palaeophyllum and Streptelasma). Tetradium is the only tabulate coral preserved in growth position. Crinoids and brachiopods are common reef dwellers. Dasycladacean algae are rare and probably transported and stromatactis is abundant. Bio- and litho-facies in this area as well as the characteristics of the microbialite suggest that the reef developed in a deeper subtidal setting that was unfavorable for most metazoan reef builders. In contrast to the high-energy stromatolite-sphinctozoan reefs from the Late Silurian, this case represents a low-energy community, indicating that the first reef-building sphinctozoans might have originated in a relatively deep-water environment on seamounts of a back-arc basin during the Late Ordovician.
UnivIS-Import:2015-10-26:Pub.2015.nat.dgeo.IGM.LP.thefir
Keywords: Back-arc basin; Late Katian; Microbialites; South China; Sphinctozoans; Stromatactis

The fish assemblage from the Pennsylvanian Buckhorn Asphalt Quarry Lagerstätte (Oklahoma, USA) - Ivanov, Alexander; Seuß, Barbara; Nützel, Alexander (Palaeontologische Zeitschrift, 2017)

The formation of a giant post-collision porphyry copper system: A case study of the Jiama deposit, Tibet - Sun, Miao; Tang, Ju Xing; Klemd, Reiner; Lin, Bin; Tang, Pan; Zhang, Ze bin; Chen, Wei; Li, Fa Qiao; Qi, Jing; Chen, Han; Gu, Feng hua (Geological Society of America Bulletin, 2024)
The large magma reservoirs underlying world-class porphyry deposits are one of the key factors in their formation, which thus led to the present study focusing on the unmineralized intrusive rocks underlying the porphyry molybdenum-copper orebody of the post-collisional Jiama porphyry-skarn copper-polymetallic deposit in southern Tibet. The Jiama porphyry intrusion comprises intermediate-silica quartz diorite, monzogranite, and granodiorite porphyries, as well a high-silica granite porphyry. The intrusive rocks suite exhibits similar whole-rock Sr-Nd isotopic compositions [εNd(t) = −3.9 to −0.8], suggesting a common, non-radiogenic magma source. Yet, these rocks have distinct geochemical characteristics. The intermediate- silica rocks are relatively enriched in Ba and Sr with minor Eu anomalies, and show adakite-like geochemical characteristics. In contrast, the high-silica granite porphyry is strongly depleted in Ba, Sr, and Eu, and lacks adakite-like geochemical characteristics. We propose that the high-silica granite porphyry represents highly fractionated melt extracted from a silicic mush reservoir (crystallinity of ∼40%–65%), and that the monzogranite and granodiorite porphyries constitute the complementary residual silicic cumulates. High crystallinity facilitates the formation of connected fluid pathways, allowing the efficient removal of volatiles from the remaining silicic melt and a rapid flux of the ore-forming fluids toward the apical parts of the large magma reservoir. Less-evolved mafic melt is believed to have repeatedly intruded the base of the magma reservoir, thereby releasing volatiles and water into the silicic mush systems. The volatiles migrated upward through the fluid channels and accumulated in the apical part of the magma reservoir, subsequently, as a result of the overpressure in the roof zone, ore-forming fluids and successive batches of magma were expelled together, thereby forming the Jiama porphyry-skarn deposit.
CRIS-Team Scopus Importer:2024-03-29

The formation of micritic limestones and the development of limestone-marl alternations in the Silurian of Gotland, Sweden - Munnecke, Axel; Samtleben, Christian (Facies, 1996)
Micritic Iimestone-mari alternations make up the major part of the Silurian strata on Gotland (Sweden). Their position on the stable Baltic Shield protectcd them from deep burial and tectonic stress and allowed the preservation of early stages of burial diagenesis, incl uding lilhification. In the micritic Iimestones certain characteristics have been preserved (e.g., pitted microspar crystals, sharp bot;ndaries between microspar and components, Iack of deformation phenomena) that offcr insights into lheir formation. We suppose thc formation of lhese micritic Iimestones and Iimestone-mari alternations to be based on a rhylhmic diagenesis within an aragonite solution zone (ASZ) close below the sediment surface. The micritic Iimestones are the product of a poikilotopic cementation of carbonate muds which consisted of varying portions of aragonitic, calcitic and terrigenaus matter. Their microspar crystals show the primary size and shape of the cements lithifying the original carbonate mud. Dissolution of aragonite in the marls provided the carbonate for the lithification of the limestones. By cementation, lhe Iimestone beds evaded further compaclion. The marls, which already underwent a volume decrease by aragonite depletion, lacked cement and became more and more compacted due to increasing se overburden. Allhough field Observationsshow lhat primary differences in material influence lhe development of Iimestone-mari alternations lhey are notrequired for lheir formatio
Keywords: Iimestone; marl; micritic; carbonate

The formation of microbial-metazoan bioherms and biostromes following the latest Permian mass extinction - Heindel, Katrin; Foster, William J.; Richoz, Sylvain; Birgel, Daniel; Roden, Vanessa; Baud, Aymon; Brandner, Rainer; Krystyn, Leopold; Mohtat, Tayebeh; Koşun, Erdal; Twitchett, Richard J.; Reitner, Joachim; et al. (Gondwana Research, 2018)
Keywords: Microbial mat; Lipid biomarker; Keratose sponges; Early Triassic; Paleoecology; Cyanobacteria

The formation of shoshonitic magma and its relationship to porphyry-type mineralisation: the Maronia pluton in NE Greece - Schaarschmidt, Anna; Klemd, Reiner; Regelous, Marcel; Voudouris, Panagiotis C.; Melfos, Vasilios; Haase, Karsten (Lithos, 2021)
The Oligocene shoshonitic Maronia pluton in NE Greece is part of an age-progressive belt of calc-alkaline intrusions and associated with a porphyry Cu-Mo±Re±Au mineralisation. We present new data on mineral and whole rock compositions as well as Sr, Nd and Pb isotopes of the monzodioritic to granitic rocks from Maronia, including the mineralised microgranite, which crosscuts the main intrusion. The age progression of the plutons in NE Greece follows the southward-directed trench retreat implying that the magmas formed during subduction of continental lithosphere after the closure of the Pindos ocean. The shoshonitic magmas of Maronia were generated by hydrous melting of a phlogopite-bearing mantle that was enriched by 3-5% of slab-derived sediment melts. A lower degree of melting controls the higher K, LILE and incompatible element contents of the shoshonitic magmas in comparison to the neighbouring calc-alkaline magmas. The mafic shoshonitic rocks in NE Greece contain much higher P2O5 contents than the associated calc-alkaline magmas, which probably reflects subducted phosphate-rich sediments in their source. Constant Sr- and Nd-isotopes with increasing SiO2 contents imply minimal crustal assimilation and that felsic magmas including the mineralised porphyritic granite were generated by fractional crystallisation of mafic magmas. Amphibole and apatite analyses provide evidence for the intrusion of S-poor, Cl-rich magmas at 5 to 6 km depths, followed by rapid uplift and exsolution of magmatic fluids. Late granitic dikes at Maronia indicate that volatiles, sulphur and metals became enriched during the late stages of the magma evolution.
CRIS-Team Scopus Importer:2020-12-25
Keywords: Magmatic sulphur; Metal budget; Porphyry copper deposits; Sediment subduction; Shoshonitic magmatism

The fossilised desert: recent developments in our understanding of the Lower Cretaceous deposits in the Huab Basin, NW Namibia. - Jerram, Dougal A.; Mountney, Nigel; Howell, John; Stollhofen, Harald (Communications - Geological Survey of Namibia, 2000)
The Lower Cretaceous deposits in the Huab Basin, NW Namibia, comprise fluvial and aeolian sandstones, lava flows and associated intrusions of the Etendeka Group. The sandstones formed part of a major aeolian sand sea (erg) system that was active across large tracts of the Paraná-Huab Basin during Lower Cretaceous times (133-132 Ma). This erg system was progressively engulfed and subsequently preserved beneath and between lava flows of the Paraná-Etendeka Flood Basalt Province. Burial of this erg by flood basalts has resulted in the preservation of a variety of intact aeolian bed forms. Preserved bed forms vary in type and scale from 1 km wavelength compound transverse draa to isolated barchan dunes with downwind wavelengths of < 100 m. Due to the present-day preferential erosion of the lava flows, preserved aeolian dunes are now exposed in 3-D in the position in which they were migrating 133 Ma ago. A relatively non-destructive eruption style of inflated pahoehoe flows preserved the bed form geomorphology. These first pahoehoe flow fields, comprising olivine-phyric Tafelkop lavas, define a shallow shield-like volcanic feature. This volcanic feature centres around the Doros igneous centre marking this as the likely source for the lavas. Early lava flows followed low topography between dune build-ups, ponding in the interdune areas. Striations left on the sand surface by the lavas indicate the localised flow directions of the lava. Numerous sediment interlayers, preserved between the lava flows, record a change in palaeowind direction during volcanism. This change in climate may have been driven by the ongoing break-up of the West-Gondwana supercontinent or may be a direct result of the widespread volcanism.
UnivIS-Import:2015-03-09:Pub.2000.nat.dgeo.IGM.LG.thefos

The Fossil Record of Parasitism: Its Extent and Taphonomic Constraints - de Baets, Kenneth; Huntley, John Warren; Klompmaker, Adiël A.; Schiffbauer, James D.; Muscente, A. D. (The Evolution and Fossil Record of Parasitism, 2021)
The fossil record of parasites is limited thus far. A survey of the fossil record shows that some modes of preservation show a higher potential for the preservation of parasitic remains or parasite–host associations than generally recognized. A better understanding of the taphonomy of parasites is critical to better predict their preservation potential and, together with new techniques like computed tomography, can open the door for systematic screening of parasite sources in deep time. Phosphatization seems particularly fruitful to characterize anatomical details for microscopic parasites or pathogens. Amber deposits are rich in terrestrial parasitic ecdysozoans and their pathogens, but their extent does not bracket a single mass extinction. For particular parasite–host associations, preservation of direct evidence is unlikely, but traces they leave in skeletons and other host remains can be used to trace them back to the Mesozoic or even the Paleozoic. Vertebrate coprolites have yielded remains of endoparasites as far back as the Carboniferous, but a more systematic screening of coprolites is necessary to make them a successful source of parasitic remains as for the Quaternary. Parasites with preservable hard parts and/or characteristic pathologies have the best potential to track changes in marine disease prevalence in high resolution across extinction or environmental perturbations in deep time, but more studies need to report their sample sizes and prevalences.
Keywords: Parasite–host interactions; Evolution; Ecology; Pathogens; Taphonomy

The FossilSimShiny app for simulating under the fossilized birth-death process and plotting the results - Chambe, Titouan; Warnock, Rachel; Barido-Sottani, Joëlle (Paleobiology, 2024)
Phylogenetic inferences using combined datasets of both extant and extinct species have grown increasingly popular, in part thanks to the development of the fossilized birth-death (FBD) process. The FBD process provides a powerful model for the evolution of past and present lineages and can be used for both inference and simulation. Simulations in particular are very helpful for new users to gain better understanding of the model and its different components. In this work, we present FossilSimShiny, a visual application for simulating phylogenies, fossil samples, and fossil taxonomies under the FBD process. The app integrates a wide range of simulation models and presents the simulation results in clear, customizable figures. As a teaching tool, FossilSimShiny allows lecturers to create illustration plots and students to directly experiment with the model. For research applications, the app can help researchers save time and effort by testing and calibrating simulation setups before running them on a large scale.
CRIS-Team Scopus Importer:2024-11-29

The Franconian Basin thermal anomaly, SE Germany revised: New thermal conductivity and uniformly corrected temperature data - Kämmlein, Marion; Bauer, Wolfgang; Stollhofen, Harald (Zeitschrift der Deutschen Gesellschaft für Geowissenschaften, 2020)
Exploration activities for hydrocarbons and thermal waters between the 1960s and 1980s consolidated the assumption of a positive temperature anomaly in the Franconian Basin of SE Germany. However, the geological causes of the temperature high are not known yet. In addition, an up-to-date compilation of temperature data from deep wells and thermal conductivity data of the Permo-Triassic section and of the basement rocks is lacking. In this study, we present a homogenised dataset of uniformly corrected temperature readings from 18 deep wells and new thermal conductivity data of the key strata of the Franconian Basin to constrain the geometry of the anomaly and to calculate reliable conductive surface heat flow densities. We further apply a vertical Péclet number analysis on equilibrated temperature logs for quantifying convective and conductive components in heat transfer. The isotherms of calculated equilibrium temperature gradients >30.0 - 48.9 °C km-1 constrain the presence of elevated temperatures in the Franconian Basin within an area of 100 x 65 km2. The elevated temperatures in the centre of the anomaly presumably originate in the basement but rapidly decrease away from the centre. The geothermal potential of the area is locally high, with surface heat flows exceeding 100 mW m-2 and reaching a maximum of 134(±16) mW m-2 in the central part of the anomaly. The NW-SE elongated shape of the anomaly implies that the strike of the major regional fault system has a significant control on the present-day temperature field. A Péclet number analysis and the correlation of T-log breaks with the new thermal conductivity data prove a predominantly conductive heat transfer regime. However, signatures of convective heat transfer have been proven for the aquifers of the Buntsandstein, Muschelkalk and Keuper groups. The study also reveals significant data gaps in the Franconian Basin, which strongly limit a reliable three-dimensional representation of the temperature field and a further limitation of possible cause(s) of the temperature anomaly. Namely, these are missing temperature data of the basement and a generally low density and the partially low depth level of available temperature dat
Keywords: temperature correction; temperature gradient; temperature anomaly; geothermal energy; heat flow density; Germany

The Franconian Basin thermal anomaly: testing its origin by conceptual 2‑D models of deep‑seated heat sources covered by low thermal conductivity sediments - Kämmlein, Marion; Dietl, Carlo; Stollhofen, Harald (International Journal of Energy and Environmental Engineering, 2019)
This study presents conceptual 2-D models for coupled fluid flow and heat transport simulations of the Franconian Basin in SE Germany to verify the plausibility of different hypothesis on the origin of a local temperature anomaly. The simulated geothermal systems consist of a deep-seated heat source within an impermeable basement (heat-producing granite or enhanced background heat flow), covered by low thermal conductivity sediments. Solely conductive or additional convective heat transport including the presence of a permeable fault was applied. We found that heat transfer in the model setups is strongly controlled by (1) the volume of the heat-producing granite, (2) the amount of the background heat flow, (3) the permeability of the basement rocks, (4) the thermal conductivity contrasts between the sedimentary cover and the basement, and (5) the type of heat transport. If there is no reliable information on these model parameters, a high degree of uncertainty with regard to quantitative statements on the heat transfer in the specific geothermal system can be expected. An equilibrium temperature log from the study area could only be reproduced by (1) an enhanced background heat flow of 0.115 W m2, in combination with a permeable fault zone of permeability 1.0 × 10−13 m2 or (2) a heat-producing granite of large cross-sectional area (300 km2) in combination with an average background heat flow of 0.070 W m2. Moreover, high temperatures were only achieved in the presence of a low conductive, insulating cover above the heat source.<br
Keywords: Thermo-hydraulic modelling; Heat-producing granite; Temperature anomaly; Enhanced heat flow; Fault; Fault permeability

The function of Li carbonate and tartaric acid in the hydration of mixtures of calcium aluminate cement (CAC) with calcium sulfate hemihydrate - Götz-Neunhoeffer, Friedlinde (Cement International, 2007)
X-ray diffraction patterns of hydrating pastes made of calcium aluminate cement with α-calcium sulfate hemihydrate were evaluated to clarify the phase development and its effect on workability. Binder mixtures of this type are used in filler compounds and plasters. The behaviour pattern of the phase formation at 23 °C can be documented in situ with XRD analysis. The results of the normalized quantitative phase analysis of the pastes with a water/solids ratio W/S = 0.5 in combination with the time-dependent data from the heat flow calorimetry have made it possible to develop models for the hydration of calcium aluminate cement in the presence of calcium sulfate, Li2CO3 and tartaric acid. The quantitative phase analysis of the hydration of calcium aluminate cement with calcium sulfate hemihydrate showed that monocalcium aluminate (CA) and calcium sulfate hemihydrate are dissolved and that ettringite and also gypsum can be detected as new formations. The behaviour pattern of the hydration of calcium aluminate cement-calcium sulfate hemihydrate-mixtures is altered by the addition of Li2CO3 solutions as CA accelerators. The rate of reaction of ettringite formation is significantly dependent on the concentration of the Li+. As with pure calcium aluminate cement the formation of an impermeable Al hydroxohydrate layer around the particles of CA in calcium aluminate cement-calcium sulfate hemihydrate-mixtures is also hindered by the effect of Li+ and the availability of aluminium is increased via the lithium aluminium hydrate intermediate compound (LA2H10 where L = Li2O). LA2H10 is a compound of the hydrotalcite type and consists of a main layer [Li2Al4(OH) 12]2+ and an intermediate layer [(OH) 2•3H2O] 2- but anions, such as CO32-, 2Cl- or 2(NO3-), can also be incorporated in the intermediate layer in place of the hydroxide. The function of the Li2CO3 is confined to the dissolving of the CA and has no influence on the dissolving of the calcium sulfate hemihydrate. The tartaric acid can lead to precipitation of Ca tartrate, which affects the Ca2+ from the dissolving of the CA and of the calcium sulfate hemihydrate and it can also coat the reactive surfaces of the CA and calcium sulfate hemihydrate.
UnivIS-Import:2015-03-09:Pub.2007.nat.dgeo.IGM.LM.thefun

The Gai-As lake system, Northern Namibia and Brazil. - Stollhofen, Harald; Stanistreet, Ian G.; Rohn, Rosemarie; Holzförster, Frank; Wanke, Ansgar (Lake basins through space and time, 2000)
UnivIS-Import:2015-03-09:Pub.2000.nat.dgeo.IGM.LG.thegai

The gastropods from the Pennsylvanian Buckhorn Asphalt Deposit (Oklahoma, USA) – an unique mollusc Lagerstätte - Nützel, Alexander; Seuß, Barbara (88. Jahrestagung der Paläontologischen Gesellschaft, 2017)

The general dynamic model of island biogeography revisited at the level of major flowering plant families - Lenzner, Bernd; Weigelt, Patrick; Kreft, Holger; Beierkuhnlein, Carl; Steinbauer, Manuel (Journal of Biogeography, 2017)
Aim: The general dynamic model (GDM) proposed by Whittaker et al. (2008) has become a widely accepted theoretical framework in island biogeography. In this study, we explore whether GDM predictions hold when overall plant diversity is deconstructed into major plant families.   Location: 101 islands from 14 oceanic archipelagos world-wide.   Methods: Occurrence data for all species of nine large, cosmopolitan flowering plant families were used to test predictions derived from the GDM. We analysed the effects of island area and age on species richness as well as number and percentage of single-island endemic species per family using mixed-effect models.   Results: Total species and endemic richness as well as the percentage of endemic species showed the predicted hump-shaped relationship with island age. The overall pattern was mainly driven by few species-rich plant families. Varying patterns were found for individual families, some of them opposing the general trend. In most cases, native and endemic species richness peaked much earlier in the island life cycle than suggested by the GDM. The contribution of area to the explained variation of all dependent variables was much higher than that of island age.   Main conclusions: The results suggest that biodiversity-age relationships reported for large taxonomic groups like plants are driven by only a few species-rich clades. The way these families influence the overall patterns of species richness and endemism is related to family-specific properties, such as evolutionary history or dispersal strategies. Deviances from the GDM predictions can hence largely be explained by family characteristics and considering taxon-specific traits may help to further improve the explanatory power of the GDM. Families not following the expectations, like Orchidaceae, may be particularly valuable candidates to unveil so far neglected drivers of island biogeographical patterns.
Keywords: general dynamic model; island biogeographical theory; island endemism; mixed-effect models; oceanic islands; scale effect

The geochemical stratigraphy of lavas from the Troodos Ophiolite - Wölki, Dominic; Regelous, Marcel; Haase, Karsten; Beier, Christoph (Goldschmidt 2017 Paris, 2017)
The Troodos ophiolite on Cyprus formed in a ‘supra-subduction zone’ environment, but the precise tectonic setting is still debated. The presence of a sheeted dyke complex, overlain by pillow lavas and underlain by gabbros and mantle rocks, indicates formation at a former spreading centre. On the other hand, the enrichment in fluid-soluble elements relative to REE and HFSE in Troodos lavas compared to MORB indicates formation above a former subduction zone. The presence of boninites may indicate formation in a fore-arc location, during subduction initiation. We will present the results of an ongoing study to construct a 3D geochemical stratigraphy of the Troodos lava pile, based on major and trace element and isotope analyses of fresh volcanic glasses, from representative sections throughout the ophiolite. Fresh glasses allow us to avoid the geochemical effects of alteration, and carefully located sampling to determine the geographical chemical variation can reveal the geodynamic setting of formation and the geochemical evolution of magmatism. Troodos glasses range from boninitic, to tholeiitic picrite-basalt-andesite-dacite, with true boninitic glasses apparently most abundant in the upper parts of the stratigraphy on the southern margin, where they are interbedded with tholeiites. Boninite glasses have depleted MREE-HREE ratios, coupled with enrichments in Pb, U, LILE and to a lesser extent Nb and the LREE. These trace element systematics indicate extreme source depletion, with later re-enrichment by both melts and fluids. Tholeiites from the northern and southern sections were derived from a less depleted source, with moderate enrichment in fluid-soluble elements, and have trace element compositions intermediate between those of the boninites and basalts from active back-arc basins. The higher Pb/Ce and more radiogenic Pb isotope compositions of the boninites indicates a larger contribution from subducted sediments. The presence of ‘fore-arc’ boninites and primitive, depleted tholeiites on the southern margin of the lava pile, and arc – back-arc type andesites and dacites in the north indicates the former subduction zone lay closer to the present-day southern margin of Troodos.

The geochemistry of continental hydrothermal systems - Hurwitz, Shaul; Stefánsson, Andri; Shock, Everett L.; Kleine-Marshall, Barbara (Treatise on Geochemistry, 2025)
Hydrothermal systems on the continents are of great significance because they are primary sources of economically important metals and geothermal energy, they are tourist attractions, they support bathing and health resorts, and they host extreme life forms. Research on hot springs and their deposits provide clues to early life on Earth and possibly on Mars and have led to major breakthroughs in biotechnology. Aqueous and gas-rich hydrothermal fluids also contribute to a range of volcanic hazards including the destabilization of volcanic edifices, acting as propellant in steam-driven hydrothermal explosions, reducing effective stresses in mudflows (lahars), emitting toxic and potentially lethal gases, and transporting toxic metals to watersheds. The main goals of this review are to summarize the state of knowledge on the chemistry of continental hydrothermal systems and highlight the myriad processes that operate under a wide range of temperatures, pressures, chemical compositions, and oxidation state

The geochronology and significance of ash-fall tuffs in the glaciogenic Carboniferous-Permian Dwyka Group of Namibia and South Africa - Stollhofen, Harald; Bangert, Berthold; Lorenz, Volker; Armstrong, Richard A. (Journal of African Earth Sciences, 1999)
Centimetre thick, laterally extensive tuff horizons occur within dark, marine mudstones of the Carboniferous-Permian Dwyka Group (Karoo Supergroup) in southern Namibia and South Africa. These pyroclastic deposits preserve the earliest evidence of volcanism in Karoo-equivalent strata of southern Africa. Four deglaciation sequences (DS I-IV) recorded in the Dwyka Group of Namibia and South Africa are capped by mudstone units such as the 45 m thick marine fossil-bearing Ganigobis Shale Member in Namibia in which 24 thin ash-fall horizons are preserved. Ion microprobe analyses (SHRIMP) of juvenile, magmatic zircons from the tuff horizons were used to determine their age. They permit a new radiometric age calibration of the top of deglaciation sequence II and of the Dwyka/Ecca Group boundary in southern Africa. Juvenile zircons of two tuff horizons near Ganigobis (southern Namibia) give *06’Pb/238U ages of 302.Ok3.0 Ma and 299.2 f 3.2 Ma (latest Kasimovian) for the top of DS II. Juvenile zircons from two tuff horizons of the basal Prince Albert Formation, sampled north of Klaarstroom and south of Laingsburg in the Western Cape (South Africa), were dated at 288.O t3.0 and 289.6k3.8 Ma (earliest Asselian). According to these age determinations, the deposition of Dwyka Group sediments in southern Africa started by the latest at about 302 Ma and ended at about the Carboniferousl Permian boundary, 290 Ma before present.
UnivIS-Import:2015-03-05:Pub.1999.nat.dgeo.IGM.LG.thegeo

The geodynamics of plume-influenced mid-ocean ridges: insights from the Foundation Segment of the Pacific-Antarctic Ridge - Brandl, Philipp A.; Beier, Christoph; Haase, Karsten; Genske, Felix S.; Hauff, Folkmar; Regelous, Marcel; Devey, Colin W.; Rüpke, Lars H. (Frontiers in Earth Science, 2024)
The intersection of the Foundation Plume with the Pacific-Antarctic Ridge is a key location in global geodynamics where a mantle plume is approached by and interacting with a fast-spreading mid-ocean ridge. Here, we discuss a comprehensive major and trace element and Sr-Nd-Pb isotope dataset of new and existing samples from the young Foundation Seamount Chain (<5 Ma) and adjacent section of the Pacific-Antarctic Ridge. We use the geochemistry of axial, off-axis and intraplate lavas to map the spatial extent of plume dispersal underneath the ridge as well as the internal zonation of the upwelling plume. We show that the unusual length, increased crustal thickness and occurrence of silicic rocks on the axis of the Foundation Segment are the direct result of plume being tapped by the axial melting zone. We demonstrate that the plume is not homogeneous but shows a HIMU-like (high time-integrated 238U/204Pb) OIB (Ocean Island Basalt) component characterized by 206Pb/204Pb of up to 20.5 in its center and a more EM1-like (Enriched Mantle one) OIB component characterized by low U/Pb and 206Pb/204Pb but high Rb/Nb and 87Sr/86Sr towards its edges. Plume entrainment leads to a high magma supply rate that fosters the formation of silicic rocks and triggers the lengthening of the segment over time. However, plume dispersal is not symmetric as the geochemical tracers for the OIB component are extending <100 km northwards but >300 km southwards. We relate this to the current plate tectonic framework in which the obliquity between the migrating ridge and the absolute plate motions induces a sub-axial asthenospheric flow that preferentially channels plume material southwards.
CRIS-Team Scopus Importer:2024-10-25
Keywords: Foundation; geochemistry; intraplate; mid-ocean ridge; Pacific-Antarctic Ridge; plume-ridge interaction; ridge segmentation

The Geoheritage of Madeira: Implications for Natural Heritage and Geotourism - Sotiriou, Paul; Nunes, Pedro (Geoheritage, 2024)
The island of Madeira forms part of the Madeira Archipelago, an Autonomous Region of Portugal, in the NE Atlantic Ocean. The Madeira Archipelago was built on 140-million-year-old oceanic crust. The exposed geology of Madeira is comprised of the Miocene (> 5.6 million years old) Basal (Inferior), Pleistocene-Miocene (1.8–5.6 million years old) Intermediate Volcanic, Pleistocene (0.7–1.8 million years old) Upper (Superior) Volcanic, and Holocene-Pleistocene (0.007-0.7 million years old) Upper (Superior) Volcanic complexes, generating the landforms and landscapes for which the island is renowned. There are at least 17 geosites on Madeira, including those in the Ponta de São Lourenço, Porto da Cruz, São Vicente Valley, Pico Ruivo, and Ponta da Cruz areas. Geotourism is not as well developed as cultural or biodiversity tourism on Madeira, however, it represents another way for tourists to explore the island’s natural heritage if done in a sustainable manner. Future studies are required to better delineate and set up georoutes on Madeira, particularly in the Ponta de São Lourenço, Porto da Cruz, and São Vicente Valley areas. It is envisaged that the aforementioned geosites could be linked by a single georoute around Madeira, the Madeira Georoute. Further investigation of the geosites identified by this study is required to ensure that these sites are managed and conserved, thereby protecting the geoheritage of Madeira. Geoconservation, sustainable tourism and the cooperation between the public and government authorities (including geologists) are required to improve geotourism on Madeira. The application of the Inventario Español de Lugares de Interés Geológico (IELIG) and Geosite Assessment (GA) models are required to assess and manage threats to Madeira’s geoheritage sites. Such threats include coastal erosion and human activities, such as mass tourism and urban expansion. It is proposed that the government of the Autonomous Region of Madeira in consultation with local and regional stakeholders should submit an application to create a UNESCO Global Geopark on the island of Madeira. This territorial sustainable development approach should be implemented based on the principles of geotourism, geoconservation, and geoeducation.
CRIS-Team Scopus Importer:2024-07-12
Keywords: Geoconservation; Geoheritage; Geotourism; Madeira; Natural heritage

The geological record of ocean acidification - Hoenisch, Baerbel; Ridgwell, Andy; Schmidt, Daniela N.; Thomas, Ellen; Gibbs, Samantha J.; Sluijs, Appy; Zeebe, Richard; Kump, Lee; Martindale, Rowan C.; Greene, Sarah E.; Kießling, Wolfgang; Ries, Justin; et al. (Science, 2012)
Ocean acidification may have severe consequences for marine ecosystems; however, assessing its future impact is difficult because laboratory experiments and field observations are limited by their reduced ecologic complexity and sample period, respectively. In contrast, the geological record contains long-term evidence for a variety of global environmental perturbations, including ocean acidification plus their associated biotic responses. We review events exhibiting evidence for elevated atmospheric CO2, global warming, and ocean acidification over the past ∼300 million years of Earth's history, some with contemporaneous extinction or evolutionary turnover among marine calcifiers. Although similarities exist, no past event perfectly parallels future projections in terms of disrupting the balance of ocean carbonate chemistry - a consequence of the unprecedented rapidity of CO 2 release currently taking place.
UnivIS-Import:2015-03-09:Pub.2012.nat.dgeo.IGM.LP.thegeo

The Geoscience Collections of the Göttingen University - Reich, Mike; Reitner, Joachim; Roden, Vanessa; Stegemann, Tanja R. (2013)

The Geoscientific Collections of the Göttingen University - Reich, Mike; Reitner, Joachim; Roden, Vanessa; Stegemann, Tanja R. (2009)

The Great Ordovician Biodiversification Event (GOBE): The palaeoecological dimension - Servais, Thomas; Owen, Alan W.; Harper, David A.T.; Kröger, Björn; Munnecke, Axel (Palaeogeography, Palaeoclimatology, Palaeoecology, 2010)
The 'Great Ordovician Biodiversification Event' (GOBE) saw a spectacular increase in marine biodiversity at all taxonomic levels largely within the phyla established much earlier during the so-called 'Cambrian Explosion'. The diversification was probably the result of a combination of several geological and biological processes and the positive feedbacks resulting from them. The present paper reviews the palaeoecological dimension of the GOBE. It involved major increases in α, ß and γ biodiversity largely associated with the rise of the Paleozoic Evolutionary Fauna dominated by suspension feeders and involving a greater occupation of ecospace and more complex ecological structures in the Ecological Evolutionary Units P1 and P2. In the benthos, these include more complex food webs than those of the Cambrian, greater tiering, especially above the sediment-water interface, and the development of guild structures indicating increased competition between taxa for particular resources. The Ordovician is characterized by a profound change in reef composition, with a switch from microbial-dominated reefs in the Early and Middle Ordovician to metazoan-dominated reefs in the Late Ordovician. Increases in complexity of deep-water trace fossil assemblages began in the Early Ordovician and mark the increasing exploitation in that environment and the development of hardgrounds permitted bioerosion and encrusting strategies together with the appearance of cryptic communities.Within the water column, the GOBE involved a significant increase in the diversity of the phytoplankton and the development of a diverse zooplankton (including planktotrophic larvae from a range of invertebrate clades). This revolution in the plankton enabled the establishment of a diverse fauna of pelagic vertebrates, molluscs and arthropods and promoted the rise of suspension feeders in the benthos. An escalation amongst predators and thus community evolution may also have been a major driver of biodiversification. © 2010 Elsevier B.
Keywords: Biodiversification; Ordovician; Palaeoecology; Palaeoenvironment

The Greidaloch near Murnau in the northern Estergebirge in the Bavarian Alps Das Greidaloch bei Murnau im nördlichen Estergebirge, Bayerische Alpen - Wolf, Andreas; López Correa, Matthias; al-Fudhaili, Najat; Rupp, Hildegard; Mayr, Christoph; Pasda, Kerstin (Mitteilungen des Verbandes der Deutschen Höhlen- und Karstforscher, 2021)
The 38 m deep and 55 m long pit cave Greidaloch (1272/05) has been discovered in 1994 in the northwestern part of the Estergebirge in the Bavarian Alps. The entrance at 1431 m a.s.l. is located 3 km SE of Murnau on the southern slope of the Buchrain and is developed along local NNE-SSW striking faults within folded carbonates of the Triassic Plattenkalk unit. Here, the survey of the cave is given together with a detailed description. At the deepest point, the bones of an adult male red deer (Cervus elaphus) have been found, along with bones of other vertebrates, notably the skull of a European Woodcock (Scolopax rusticola), and rests of a Common Hazelhen (Tetrastes bonasia). 14C-dating revealed an early Holocene age for the deer at 10.3 calibrated kiloyears before present (ka cal BP).
CRIS-Team Scopus Importer:2024-12-16

The H2020 project GEO4CIVHIC (Most Easy, Efficient and Low Cost Geothermal Systems for Retrofitting Civil and Historical Buildings) - de Carli, Michele; Galgaro, Antonio; Cadelano, Gianluca; Cicolin, Francesco; Bobbo, Sergio; Urchueguía, Javier; Mezzasalma, Giulia; Pasquali, Riccardo; Poletto, Fabio; Castelruiz Aguirre, Amaia; Romanowsky, Arno; Poletto, Davide; et al. (REHVA 13th World Congress CLIMA, 2019)
The market of Ground Source Heat Pumps needs to be increased and one of the barriers is represented by the use of this technology in the retrofit of buildings in urban environments. For this purpose,the H2020 project GEO4CIVHIC has been funded and is currently running. The project develops several solutions for shallow geothermal energy in the retrofit environment, based on the building type, climate and the geological conditions of the underground and considers all aspects of the geothermal system (drilling methodology, ground heat exchangers, grouting, heat pumps).The main objectives are: identify and where missing develop modular solutions in drilling (machines and methods)and installing (narrow and reduced spaces), heat exchangers types, heat pumps and other renewable energy/storage technologies, heating and cooling terminals with the focus on each type of built environment (civil and historical); generate and demonstrate the easiest to install and cost-effective geothermal energy solutions using and improving existing and new tools. Demonstrate the environmental respect and the reduction of CO2emissions in the atmosphere More efficient ground heat exchangers and cheaper drilling methodologies/machines adapted to the built also narrow environment like the historical centers will be realised. This approach will bring to an easy applicability in thebuilding refurbishment presenting different constraints, to reduce the overall drilling cost in the given geological conditions, to fit in different levels of retrofit (partial or deep). For better meeting the different needs of the retrofitted buildings 6 prototypes of heat pumps will be developed and built up, from high temperature heat pumps (when heating terminals are maintained) up to plug & play solutions (for deep retrofit), thus reducing the retrofit costs.The association of the innovations with different tools like aDecision Support System will enable to find the best solution for each combination of building type/climate/geology to be chosen. Moreover, the design tools will reduce overall engineering costs, avoid design mistakes and form the basis for a major dissemination effort. Application tools will help the users for different practical aspects.The new solutions in the project will be demonstrated in 3 pilot facilities, in 4 real demonstration sites (warm, mild warm, mild cold and cold climates) and in 12 virtual sites. Demonstrations go from partial to deep renovations and include historical buildings.The H2020 project started in April 2018, lasts 4 years with an overall budget of 8.36 M€, accounting 19 partners from 10 coun
Keywords: Shallow geothermal

The high-K calc-alkaline to shoshonitic volcanism of Limnos, Greece: implications for the geodynamic evolution of the northern Aegean - Glaser, Leon; Grosche, Anna; Voudouris, Panagiotis C.; Haase, Karsten (Contributions To Mineralogy and Petrology, 2022)
Genetic models for the formation of K-rich magmas in subduction-related settings range from partial melting of subduction-affected mantle sources to melting of crustal rocks depending on the local tectonic framework. The Miocene high-K calc-alkaline to shoshonitic rocks of Limnos Island reflect the magmatic activity in the northern Aegean, which migrated southwards in response to trench retreat and the collision of continental terranes in the Hellenic subduction system. New whole rock and mineral data of basaltic andesites, dacites and monzonites from Limnos indicate that the magmas underwent fractional crystallization of olivine, clinopyroxene, amphibole, apatite, and Fe-Ti oxides at 1100 to 700 degrees C and 0.5 to 0.1 GPa without significant assimilation of crustal rocks during the magma evolution. The strong enrichment of large ion lithophile elements and light rare-earth elements relative to depleted heavy rare earth and high-field strength elements points towards a mantle source that has been extensively hybridized by subducted sedimentary material. New Sr-Nd-Pb isotope data reveal a distinct isotopic composition of the Limnos rocks with high Pb-207/Pb-204 at low Pb-206/Pb-204 and Nd-143/Nd-144 ratios that is likely related to the subduction of the continental crustal succession of the Apulian block which was subducted prior to the onset of magmatism on Limnos. Partial melting models assuming a hybridized mantle source suggest that the primary melts of Limnos formed by melting of a phlogopite pyroxenite at melting degrees of 5 to 10%. Compositional differences between high-K calc-alkaline and shoshonitic magmas are explained by variable melting degrees and varying amounts of sediment supply to the mantle. The magmatic and tectonic evolution of Limnos island is typical for the Oligocene and Miocene volcanic centres of the migrating western Aegean arc front.
CRIS-Team WoS Importer:2022-07-29

The history of the "Virgin with Child" sculpture (Ottaviano, Naples, southern Italy): hypotheses from archaeometric multi-technique investigations. - Balassone, Giuseppina; Toscano, Maria; Cavazzini, Giancarlo; De Bonis, Alberto; D'Orazio, Loredana; Joachimski, Michael; Weihe, Hogni; Prochaska, Walter; Mondillo, Nicola; Mormone, Angela; Petti, Carmela; Solpietro, Antonia (Journal of Cultural Heritage, 2014)
A life-size whitish marble statue of a "Virgin with Child" has been recently rediscovered in the St.Rosario church located in Ottaviano, a small town near Naples (southern Italy). This artwork shows stylistic features of the Tuscan-Roman school of the 16th century, and is framed in an intriguing historical context. Historical documents testify that the sculpture was a property of the cadet branch of noble Tuscan family of the Medici, the Medici of Ottaviano. A multianalytical approach has been used to try to indicate the supply area of the white marble of the studied sculpture. Considering the whole mineralogical, petrographic and geochemical data, the source rock can be possibly limited to the main classical white marbles of the Mediterranean district, as the classical marble of Aphrodisias. A reuse practice of a former artwork can be also hypothesized. © 2013 Elsevier Masson SAS.
UnivIS-Import:2015-03-09:Pub.2014.nat.dgeo.IGM.LG.thehis
Keywords: Italian cultural heritage; Marble sculpture; Multi-methodological approach; Provenance

The Hitchhiker's guide to island endemism: Biodiversity and endemic perennial plant species in roadside and surrounding vegetation - Irl, Severin; Steinbauer, Manuel; Epperlein, Lilith; Harter, David; Jentsch, Anke; Pätz, Susanne; Wohlfart, Christian; Beierkuhnlein, Carl (Biodiversity and Conservation, 2014)
Roadsides are habitats with very specific environmental conditions, often substantially differing from their natural surroundings. However, roads can have a positive effect on local vascular plant species richness. Endemic species on oceanic islands are considered to be less disturbance-adapted than native non-endemics and thus should be negatively affected by roads. Islands provide optimal conditions for testing this, as they possess a large share of clearly defined endemic species. This study focuses on a comparison of endemic plant species in roadside and surrounding communities and the interacting effects of elevation, vegetation type and trade wind-induced precipitation differences. We applied 96 circular plots with 50 m radius along two elevational gradients on the eastern (humid) and western (dry) slope of La Palma, Canary Islands, ranging from 100 to 2,400 m. Interestingly, we found roads to have a significant positive effect on endemic richness and the percentage of endemics as well as the same tendency for plant species richness after correcting for elevation and precipitation. Endemic species turnover was relatively high. The opening of cliffs during construction and, not to be overlooked, the protection from disturbances such as fire and omnipresent introduced herbivores (mainly rabbits or goats) probably leads to a positive effect of roads on endemics. In addition, many endemics might profit from species-specific dispersal capabilities well suited for roadside conditions. However, we do not argue for the use or even construction of roads for nature conservation but suggest protecting existing endemic populations because natural areas have a higher conservation value.
Keywords: Canary Islands; Disturbance; Elevational gradient; Endemic richness; Road ecology; Vascular plant species

The Homerian carbon isotope excursion (Silurian) within graptolitic successions on the Midland Platform (Avalonia), UK: implications for regional and global comparisons and correlations - Fry, Charlotte R.; Ray, David C.; Wheeley, James R.; Boomer, Ian; Jarochowska, Emilia; Loydell, David K. (GFF, 2017)

The hydration of alite: a time-resolved quantitative X-ray diffraction approach using the G-factor method compared with heat release - Jansen, Daniel; Bergold, Sebastian; Götz-Neunhoeffer, Friedlinde; Neubauer, Jürgen (Journal of Applied Crystallography, 2011)
The classical external-standard method derived from the work of OConnor & Raven [Powder Diffr. (1988), 3, 2-6] was used to examine the hydration of the major phase, alite, of ordinary Portland cements at different temperatures and different water/alite ratios. In order to estimate the accuracy of the method, heat-flow curves were calculated from the alite dissolution curves obtained from X-ray diffraction in situ experiments. The heat-flow curves calculated in this way were compared with heat-flow curves recorded using a calorimeter. It is shown that the calculated curves agree well with the curves obtained from heat-flow experiments. © 2011 International Union of Crystallography.
UnivIS-Import:2015-03-09:Pub.2011.nat.dgeo.IGM.LM.thehyd
Keywords: alite hydration; G-factor method; heat-flow calorimetry; in situ X-ray diffraction analysis

The hydration of nearly pure ye'elimite with a sulfate carrier in a stoichiometric ettringite binder system. Implications for the hydration process based on in-situ XRD, 1H-TD-NMR, pore solution analysis, and thermodynamic modeling - Jansen, Daniel; Wolf, Julian; Fobbe, Nicholas (Cement and Concrete Research, 2020)
The hydration of synthetic ye'elimite was studied with sulfate carriers in a stoichiometric ettringite binder system. Heat flow calorimetry, in-situ XRD, 1H-TD-NMR and pore solution analysis were applied in order to gain a deeper understanding of the hydration kinetics of the system. Additionally, thermodynamic modeling was used in order to show the evolution of the pore solution in the system Ca-Al-S-H2O. The experiments showed that a first ettringite generation might be formed in a regime where CAH10, monosulfate, ettringite and AHamorphous are stable while at later points in time the ettringite is formed in a regime where AHmicrocrystalline and ettringite is stable. The different shoulders in the heat flow curve seem to arise from the recrystallization of AHmicrocrystalline and the final adjustment of the water content of the aluminum hydroxide towards AH3.
CRIS-Team Scopus Importer:2019-11-19

The hydration of synthetic brownmillerite in presence of low Ca-sulfate content and calcite monitored by quantitative in-situ-XRD and heat flow calorimetry - Ectors, Dominique; Neubauer, Jürgen; Götz-Neunhoeffer, Friedlinde; Götz-Neunhoeffer, Friedlinde; Neubauer, Jürgen (Cement and Concrete Research, 2013)
We present here experimental data of the hydration of C4AF in a Portland cement environment with low sulfate content. Calorimetric data indicate a distinct two-step main reaction of C4AF, which was successfully deconvoluted by laboratory scale in-situ-XRD in combination with the G-factor method and a quantitative approach by mass balance estimation with normalized peak areas of hydrate phases. The presented data here suggest a rapid unhindered dissolution of C4AF after depletion of sulfate in the pore solution, which is then rapidly leading to an oversaturation with respect to sulfate-AFm-16 (C4AH16). Since the sulfate content of the mixture is low, a second acceleration of C4AF dissolution, due to precipitation of hydroxy-AFm-19 (C4AH19) was observable after the decline in ettringite (C6A 3H32) content and the subsequent conversion to sulfate-AFm-16 (C4AH16). © 2013 Elsevier Ltd.
UnivIS-Import:2015-03-09:Pub.2013.nat.dgeo.IGM.LM.thehyd
Keywords: Calcium aluminoferrite (D); Calorimetry (A); Hydration (A); Reaction (A); X-ray diffraction (B)

The impact of Etendeka flood basalts on the diagenesis of the fluvio-aeolian Jurassic Etjo Formation, Namibia - Salomon, Eric; Caracciolo, Luca; Stollhofen, Harald; Bonnell, Linda; Lander, Robert H.; Kittel, Mario (The impacts of volcanism on sedimentary basins and their energy resources, 2022)
The rapid effusion of volcanic rocks of large igneous provinces results in a relatively rapid burial of underlying rocks. In such settings, siliciclastic deposits and potential reservoir rock may on the one hand experience a high degree of mechanical compaction prior to the onset of significant chemical compaction, while on the other hand an increased geothermal gradient or hydrothermal activity may speed up cementation processes. To assess such impact, we present the results of a study on the diagenesis of the aeolian upper unit of the Jurassic Etjo Formation in Namibia, that was subject to burial related to the emplacement of the voluminous Lower Cretaceous Etendeka flood basalts that reached presumed thicknesses of up to c. 2-5 km, and is today again exposed at the Earth’s surface. We have studied the Etjo Formation at three key localities, namely Waterberg, Mt. Etjo, and Gamsberg, that lie >100 km apart from each other. At all locations, the sandstone is texturally mature and quartzose with very low quantities of feldspars and lithic grains. However, petrographic analysis shows that the Etjo Formation has experienced a very different diagenesis at each location with respect to intergranular volume (IGV) and quartz cementation (Fig. 1). Average IGV and quartz cement values are 23.7 % and 6.5 % (Waterberg), 19.7 % and 15.4 % (Mt. Etjo), and 30.7 % and 24.3 % (Gamsberg). Porosity values, based on buoyancy measurements, are on average 21.0 w.t.% (Waterberg), 8.1 w.t.% (Mt. Etjo), and 5.2 w.t.% (Gamsberg). Also permeability, based on air permeameter measurements, varies between the locations with highest values at Waterberg (15 – 2819 mD), intermediate values at Mt. Etjo (14 – 132 mD), and lowest values at Gamsberg (2 – 82 mD). We attribute the differences of IGV and quartz cement to spatial thickness variations of the overlying volcanic rock column. Higher compaction and cementation values at Mt. Etjo compared to Waterberg are likely related to the proximity of Mt. Etjo to the presumed center of Etendeka volcanism. Gamsberg is the only location where a first generation of quartz overgrowth formed prior to Etendeka burial, as evidenced by cathodoluminescence imagery, which likely has stabilized the grain framework to prevent further mechanical compaction during this burial. These interpretations are supported by TouchstoneTM numerical modeling for sandstone diagenesis. Permeability appears to be linked to the summed up quantity of quartz cement and eogenetic infiltrated clay. Our study demonstrates the variability in diagenetic properties that a sandstone formation can attain depending on its location under a massive sheet of flood volcanic rocks. <br

The Impact of Field Courses on Undergraduate Knowledge, Affect, Behavior, and Skills: A Scoping Review - Shinbrot, Xoco A.; Treibergs, Kira; Hernandez, Lina M. Arcila; Esparza, David; Ghezzi-Kopel, Kate; Goebel, Marc; Graham, Olivia J.; Heim, Ashley B.; Smith, Jansen; Smith, Michelle K. (Bioscience, 2022)
Field courses provide transformative learning experiences that support success and improve persistence for science, technology, engineering, and mathematics majors. But field courses have not increased proportionally with the number of students in the natural sciences. We conducted a scoping review to investigate the factors influencing undergraduate participation in and the outcomes from field courses in the United States. Our search yielded 61 articles, from which we classified the knowledge, affect, behavior, and skill-based outcomes resulting from field course participation. We found consistent reporting on course design but little reporting on demographics, which limits our understanding of who takes field courses. Cost was the most commonly reported barrier to student participation, and knowledge gains were the most commonly reported outcome. This scoping review underscores the need for more rigorous and evidence-based investigations of student outcomes in field courses. Understanding how field courses support or hinder student engagement is necessary to make them more accessible to all students.
CRIS-Team WoS Importer:2022-09-02

The impact of the Pliensbachian–Toarcian crisis on belemnite assemblages and size distribution - de Baets, Kenneth; Nätscher, Paulina; Rita, Patricia; Fara, Emmanuel; Neige, Pascal; Bardin, Jérémie; Dera, Guillaume; Duarte, Luís Vítor; Hughes, Zoe; Laschinger, Peter; Carlos Garcia-Ramos, Jose; Pinuela, Laura; et al. (Swiss Journal of Palaeontology, 2021)
The second-order Pliensbachian–Toarcian crisis affected major groups of marine organisms. While its impact has been intensively studied for ammonites, the response of belemnites is only currently emerging through quantitative studies. Novel overall and regional diversity analyses suggest that belemnite richness in the NW-Tethys drops at the Pliensbachian–Toarcian boundary, while overall diversity slightly increases in NW-Tethys assemblages during the Toarcian Oceanic Anoxic event (T-OAE), mostly driven by NW European assemblages (e.g., Yorkshire). The T-OAE coincides with marked taxonomic turnover within individual basins, which is associated with an increase in median rostrum size of specimens in taxa at most localities. The changes in median body size across the Pliensbachian–Toarcian boundary are less consistent and driven by changes in body size within individual lineages crossing the boundary. However, our analyses also illustrate differences in sampling across the Pliensbachian–Toarcian crisis, which needs to be considered in further studies.
Keywords: Cephalopoda; Belemnitida; Rarefraction; Rostrum size; Paleoecology; Sampling

The Importance of Fossils in Understanding the Evolution of Parasites and Their Vectors - de Baets, Kenneth; Littlewood, D. Timothy J. (Advances in Parasitology, 2015)
Knowledge concerning the diversity of parasitism and its reach across our current understanding of the tree of life has benefitted considerably from novel molecular phylogenetic methods. However, the timing of events and the resolution of the nature of the intimate relationships between parasites and their hosts in deep time remain problematic. Despite its vagaries, the fossil record provides the only direct evidence of parasites and parasitism in the fossil record of extant and extinct lineages. Here, we demonstrate the potential of the fossil record and other lines of geological evidence to calibrate the origin and evolution of parasitism by combining different kinds of dating evidence with novel molecular clock methodologies. Other novel methods promise to provide additional evidence for the presence or the life habit of pathogens and their vectors, including the discovery and analysis of ancient DNA and other biomolecules, as well as computed tomographic methods.

The influence of bioerosion on taphonomy - a case stuy using Nautilus macromphalus - Seuß, Barbara; Hembree, Daniel I.; Wisshak, Max; Mapes, Royal H. (GSA Annual meeting, 2017)
Bioerosion, i.e., chemical and mechanical degradation of largely carbonate skeletal material, was studied in detail in shells of Nautilus for the first time. Nautilus typically lives along slopes of coral reefs in water depths between 300-400 m, with a range of 100-700 m and occurs in the Indo-Pacific Ocean exclusively. After death of the animal its conch will either float (up to hundreds of km until it sinks or is washed onto the beach) or it will rapidly sink to the seafloor close to where Nautilus has lived and died. Two sets of N. macromphalus shells from New Caledonia are included in this study: 1) Backshore collected (from two beaches on Lifou (Loyalty Islands)) and 2) Deep-sea dredged (395 m: halfway from Grand Terre and the Isle of Pines; 589 m: western edge of the Lansdowne Bank west of Grand Terre). After preparing synthetic resin casts these were analyzed with the SEM and ichnotaxa were categorized semi-quantitatively in the plan view. In total, 30 ichnotaxa were identified, some of them are new. Seven ichnotaxa were produced by cyanobacteria and five traces by chlorophytes. Further traces were produced by sponges, fungi, foraminifers, and by rhodophytes. Six traces were produced by some unknown heterotroph and two have an unknown affinity so far. The 23 ichnotaxa occurring in the backshore ichnocoenosis contain eleven traces that are produced by phototrophic and ten by heterotrophic organisms; two forms are of unknown origin. The 15 traces from the 395 m sample contain both, traces of photoautotroph producers and those of heterotrophs. All of the eight taxa recorded from 589 m water depth are of heterotrophic origin. Interpretation of the results is largely based on the ichnobathymetrical scheme combining the key ichnospecies and the mode of penetration: 1) Backshore: Shallow euphotic zone III to the deep euphotic zone; key ichnotaxa of the intertidal are present as well reflecting transport from nearshore to backshore. 2) 398 m: Transport must have taken place from the deep euphotic zone down into the aphotic zone. 3) 589 m: The shell had rapidly sunk to the seafloor after death of the specimen into aphotic conditions and had likely stayed close to the living site of the anima

The influence of calcium formate on the hydration of calcium sulfate hemihydrate - Fobbe, Nicholas; Götz-Neunhoeffer, Friedlinde; Jansen, Daniel (Materials and Structures, 2023)
In this study, the influence of calcium formate (CF) on the hydration of a synthesized calcium sulfate hemihydrate (HH) powder was investigated. Isothermal calorimetry measurements showed that CF retards the hydration reaction of HH. This was confirmed by XRD of stored samples and pore solution analysis. Two retardation mechanisms were identified. The combination of pore solution and laser granulometric experiments revealed that firstly, the initial dissolution of hemihydrate decelerates because of high Ca2+ ion concentrations, donated by the faster dissolving CF. Secondly, the HCOO- species of CF adsorb on surfaces of the gypsum crystals, as further pore solution measurements showed. This impedes their formation kinetic. The gypsum crystals exhibited anisotropic peak narrowing in XRD measurements when CF was added. This was caused by a morphology change, which could be verified using the anisotropic domain size morphology approach during Rietveld refinement analysis and SEM images. Gypsum crystals exhibit a blockier shape with CF addition compared to the usual acicular shape in pure water.
CRIS-Team WoS Importer:2023-05-26

The influence of fly ash on the hydration of OPC within the first 44 h - A quantitative in situ XRD and heat flow calorimetry study - Dittrich, Sebastian; Neubauer, Jürgen; Götz-Neunhoeffer, Friedlinde (Cement and Concrete Research, 2014)
We used in-situ XRD and heat flow calorimetry to investigate the first 44 h of hydration of Ordinary Portland Cement (OPC) blended with siliceous fly ash (FA). By recalculating the heat flow using XRD data it was possible to establish the direct influence of FA on the silicate and aluminate reaction of the OPC hydration in combination with absolute phase quantities. A retarding effect of FA on the silicate reaction was detected, probably induced by the adsorption of Ca2 + ions on the FA surface. The aluminate reaction proved to be influenced by FA. Thereby the filler effect produces an acceleration of the reaction by providing additional nucleation sites. Additionally the reaction itself is very sensitive to the chemical composition of FA. Readily available SO3 seems to be the factor responsible for retarding the aluminate reaction. The increasing of the effective w/s-ratio seems to have only a slight influence on the hydration behavior. © 2013 Elsevier Ltd.
UnivIS-Import:2015-03-09:Pub.2014.nat.dgeo.IGM.LM.theinf
Keywords: Calorimetry (A); Early hydration; Fly ash (D); Portland cement (D); X-ray diffraction (B)

The influence of low calcium sulfate contents on early calcium aluminate cement–calcite hydration kinetics and pore solution chemistry - Rost, Pauline; Neubauer, Jürgen; Götz-Neunhoeffer, Friedlinde (Cement and Concrete Research, 2024)
A binder mix consisting of CAC, calcite and H2O was investigated to clarify the influence of the addition of low amounts of calcium sulfate in the form of gypsum, hemihydrate or anhydrite on the hydration at 23 °C. Based on experimental data, a model for the hydration of CAC + calcite in the presence of sulfate ions could be developed. Using heat flow calorimetry at 23 °C, it was shown that hydration is accelerated depending on the solubility rates of the different sulfates. In addition, early hydration is characterized by a sequential reaction in which the calcium sulfate must be consumed completely from the pore solution by the precipitation of ettringite before the already known course of CAC + Cc hydration can occur. Monocarbonate and AH3 precipitate as the stable dominant hydrate phases during the main reaction, but conversion-sensitive hydrate phases such as CAH10 are not stable.
Created from Fastlane, Scopus look-up
Keywords: Calcium aluminate cement (D); Calcium sulfate (D); Ettringite (D); Hydration (A); Pore solution analysis (B); X-ray diffraction (B)

The Influence of Structural Inheritance and Multiphase Extension on Rift Development, the NorthernNorth Sea - Phillips, Thomas; Fazlikhani, Hamed; Gawthorpe, Rob L.; Fossen, Haakon; Jackson, Christopher A-L; Bell, Rebecca E.; Faleide, Jan; Rotevatn, Atle (Tectonics, 2019)
The northern North Sea rift evolved through multiple rift phases within a highly heterogeneous crystalline basement. The geometry and evolution of syn-rift depocenters during this multiphase evolution and the mechanisms and extent to which they were influenced by preexisting structural heterogeneities remain elusive, particularly at the regional scale. Using an extensive database of borehole-constrained 2D seismic reflection data, we examine how the physiography of the northern North Sea rift evolved throughout late Permian-Early Triassic (RP1) and Late Jurassic-Early Cretaceous (RP2) rift phases, and assess the influence of basement structures related to the Caledonian orogeny and subsequent Devonian extension. During RP1, the location of major depocenters, the Stord and East Shetland basins, was controlled by favorably oriented Devonian shear zones. RP2 shows a diminished influence from structural heterogeneities, activity localizes along the Viking-Sogn graben system and the East Shetland Basin, with negligible activity in the Stord Basin and Horda Platform. The Utsira High and the Devonian Lomre Shear Zone form the eastern barrier to rift activity during RP2. Toward the end of RP2, rift activity migrated northward as extension related to opening of the proto-North Atlantic becomes the dominant regional stress as rift activity in the northern North Sea decreases. Through documenting the evolving syn-rift depocenters of the northern North Sea rift, we show how structural heterogeneities and prior rift phases influence regional rift physiography and kinematics, controlling the segmentation of depocenters, as well as the locations, styles, and magnitude of fault activity and reactivation during subsequent events.
CRIS-Team WoS Importer:2019-12-13

The influence of the bridgehead in Saalfrank-type cryptands: prediction of ion selectivity by quantum chemical calculations XII - Balović, Jelena; Ćoćić, Dušan; Puchta, Ralph; Scheurer, Andreas; van Eldik, Rudi (Journal of Coordination Chemistry, 2020)
We examined the cation selectivity of the Saalfrank-type 2-metallocryptands [Ga2R3] and [Fe2R3] (R: 1,1'-(pyridine-2,6-diyl)bis(2-(1H-tetrazol-5-yl)ethan-1-one)) with alkaline and earth alkaline metal ions by means of DFT calculations (B3LYP/LANL2DZp) to obtain a better insight into the influence of the bridge head metal ions responsible for the cryptands ion selectivity. Based on our DFT calculations, notably the application of model equations and geometric features regarding the flexibility of the 2-metallocryptands, we identified K+, Sr2+ and Ba2+ as the best fitting ions. While [Fe2R3] has a cavity a bit larger than [Ga2R3], it prefers the Ba2+ cation, whereas [Ga2R3] selects the smaller Sr2+ cation. The good flexibility of the investigated hosts is provided by the oxygen-donor moieties of the 2-metallocryptands.
CRIS-Team Scopus Importer:2020-07-24
Keywords: cryptand; DFT-study; Selective ion complexation

The influence of the glass transition temperature (T g) of polymers on early OPC hydration: a complete study of the heat flow, phase evolution, and pore solution chemistry - Jansen, Daniel; Lu, Z.; Kong, X. M.; Pakusch, J.; Jahns, E.; Deschner, F.; Schmidtke, Ch (Materials and Structures, 2019)
The impact of two different dialyzed styrene-acrylate polymer dispersions on the early hydration of OPC was studied. The polymer particles of both dispersions show a similar particle size distribution and high charge due to carboxylic groups on the surface of the particles. Both dispersions also show similar adsorption behavior. The hydration of the OPC was studied at a polymer concentration below the initial adsorption in order to evaluate possible reasons for the interaction of the polymer particles with cement hydration. It can be shown that the polymer particle with the lower glass transition temperature Tg shows a stronger impact on cement hydration, which cannot be explained by any influence on the pore solution composition or the initial dissolution of cement phases. Hence, the adsorption mechanism seems to be the most likely cause of the interaction of the polymers with hydrating cement.
CRIS-Team Scopus Importer:2019-12-24
Keywords: Cement hydration; Glass transition temperature; Polymers; Pore solution; Retardation

The integrated project AquaTerra of the EU sixth framework lays foundations for better understanding of river-sediment-soil-groundwater systems - Barth, Johannes; et al. (Journal of Environmental Management, 2007)

The interaction of strike-slip deformation, sedimentation and magmatism: The Permo-Carboniferous Saar-Nahe-Basin (SW-Germany). - Stollhofen, Harald (18th IAS Regional European Meeting of Sedimentology, Heidelberg, September 2-4, 1997. Field Trip Guide Book, 1997)
UnivIS-Import:2015-03-05:Pub.1997.nat.dgeo.IGM.LG.theint

The Ireviken Event in the lower Silurian of Gotland, Sweden - Relation to similar Palaeozoic and Proterozoic events - Munnecke, Axel; Samtleben, Christian; Bickert, Torsten; Munnecke, Axel; Munnecke, Axel (Palaeogeography, Palaeoclimatology, Palaeoecology, 2003)
For a long time, the Silurian was thought to represent a time of stable environmental conditions in the greenhouse period that followed the Late Ordovician glaciation. During the past decade, knowledge about the Silurian has increased markedly and today it is known that the conditions in the Silurian were much more variable than previously assumed. Detailed isotopic investigations have revealed several distinct positive excursions in both carbon and oxygen isotope values. In low latitudes, these periods of high C- and O-isotope values are in many cases characterised by the growth of reefs and the formation of extended carbonate platforms. The sediments deposited during these excursions contain impoverished fossil assemblages, especially with respect to conodonts, graptolites, and trilobites. A conspicuous isotope excursion coincident with facies changes and a marked mass extinction is observed near the Llandovery/Wenlock boundary. This event is called the 'Ireviken Event' after its type locality on the island of Gotland, Sweden (Jeppsson, L., 1987. In: Palaeobiology of Conodonts. Ellis Horwood Ltd., Chichester, pp. 129-145). Here, isotope data from nine sections at the NW coast of Gotland are presented that cover the time interval of the Ireviken Event. The δC mean values rise from +1.4‰ to +4.5‰, and the δO values increase from -5.6‰ to -5.0‰. The relative timing of stable isotope development, extinctions, and facies development is discussed. It is shown that first extinctions precede the isotope excursion. This indicates that extinction events and stable isotope development are only indirectly connected but might reflect the same causes. Other events characterised by similar relationships between positive isotope excursions, mass extinctions, and facies development are found in younger parts of the Silurian (late Wenlock and Ludlow), in the late Ordovician, the late Cambrian, and, with some reservations, in the Proterozoic. The similarities between these events indicate analogous controlling mechanisms. For the Silurian, climatic changes between humid and arid conditions in low latitudes were postulated in an earlier study of the authors. A palaeoceanographic/climatic model was postulated which is consistent with most of the sedimentological, palaeontological, and geochemical data. Here we demonstrate that this model may be applicable also for the older events. © 2003 Elsevier Science B.V. All rights reserve
Keywords: Bioevents; Cambrian; Mass extinction; Ordovician; Silurian; Stable isotope

The Jabali nonsilfide Zn-Pb-Ag deposit, Western Yemen. - Mondillo, N.; Boni, Maria; Balassone, G.; Joachimski, Michael; Mormone, A. (Ore Geology Reviews, 2014)
UnivIS-Import:2015-03-09:Pub.2014.nat.dgeo.IGM.LG.thejab

The karst-hosted mina grande nonsulfide zinc deposit, Bongará District (Amazonas Region, Peru) - Arfè, G.; Mondillo, N.; Boni, M.; Balassone, G.; Joachimski, Michael; Mormone, A.; Di Palma, T. (Economic Geology, 2017)

The KTB superdeep borehole: petrography and structure of a 9-km-deep crustal section - de Wall, Helga; et al. (Geologische Rundschau, 1997)
The KTB boreholes that were drilled from 1989 to 1994 near Windischeschenbach, NE Bavaria, penetrated rocks of the Zone Erbendorf-Vohenstrauss (ZEV). The upper and lower sections of the 9101-m-deep profile are mainly composed of gneiss units and variegated units. Metabasic units constitute mainly the middle section. Geochemical data suggest their derivation from oceanic crust. All rocks are probably pre- to early Ordovician in protolith age. They underwent early Devonian MP metamorphism. Relics of preceding HP metamorphism are preserved in metagabbros. In contrast to the conditions of the Mesozoic (mainly Cretaceous/Tertiary) faulting the P-T conditions of MP metamorphism, the cooling ages and the late-Variscan graphite-bearing prehnite-actinolite facies mineralization show no significant depth-dependent gradients. This can be explained by Mesozoic supracrustal stacking.
UnivIS-Import:2015-03-05:Pub.1997.nat.dgeo.IGM.c3tekt.thektb

The Ladinian-Carnian conodont fauna at Yize, Yunnan, southwestern China, with implications for conodont palaeoecology and palaeogeography - Zhang, Zaitian; Sun, Yadong (Geological Magazine, 2023)
Subdivisions of Ladinian-Carnian boundary beds and the lower Carnian strata in South China are challenging owing to a paucity of west Tethyan ammonoids. We investigated a conodont fauna in a continuous section at Yize in eastern Yunnan Province to provide a biostratigraphic solution. Five genera and 24 conodont species are recognized, and five conodont zones are established. The zones are, in ascending order, the Paragondolella inclinata Zone, the Quadralella polygnathiformis Zone, the Quadralella praelindae Zone, the Quadralella auriformis Zone and the Quadralella robusta Zone. The Ladinian-Carnian boundary is provisionally defined by the first occurrences of Quadralella polygnathiformis and Quadralella intermedia in the cherty limestone member of the Zhuganpo Formation. Regional correlations via conodont biostratigraphy indicate that the Zhuganpo Formation is probably diachronous, with a maximal range spanning the upper Ladinian to the lower Carnian. Amongst all common late Ladinian - early Carnian conodont genera, Paragondolella, Quadralella and Mazzaella are probably cosmopolitan. Budurovignathus was restricted to a few basins and probably preferred offshore or deep-water environments.
CRIS-Team WoS Importer:2023-02-24

The Late Paleozoic Ice Age (LPIA) – Turnover rates during a phase of major climatic changes - Seuß, Barbara; Roden, Vanessa; Kocsis, Ádám; Kießling, Wolfgang (Jahrestagung der Paläontologischen Gesellschaft in München, 2019)

The Loss of a Unique Palaeobotanical Site in Terceira Island Within the Azores UNESCO Global Geopark (Portugal) - Góis-Marques, Carlos A.; Elias, Rui B.; Steinbauer, Manuel; de Nascimento, Lea; Fernández-Palacios, José María; de Sequeira, Miguel Menezes; Madeira, José (Geoheritage, 2019)
Terceira Island (Azores archipelago, central Atlantic Ocean) presents a unique but poorly studied Quaternary palaeobotanical record. Among the sites referenced in the literature, Fanal Bay, within Angra do Heroísmo city, is known at least since the 1940s. Field prospection in the summer of 2016 revealed two layers of leaf fossils with an unexpected fossil abundance. The preliminary results showed that these represented autochthonous or para-autochthonous (T0) fossil assemblages, preserved by the emplacement of ash or lapilli layers by volcanic events, in a leaf litter of a laurel palaeoforest. Unfortunately, in 2018, the site was destroyed due to development works to consolidate and requalify the Fanal Bay cliff from further sea erosion. This prevented a detailed study and the ex situ preservation of an important palaeontological site, within the Azores UNESCO Global Geopark. With this work, we hope to call the attention to the need of implementing geoconservation strategies in order to prevent the destruction of important geoheritage within the Azores Islands and to transpose this warning to other geoconservationists in oceanic islands worldwide.
CRIS-Team Scopus Importer:2019-09-03
Keywords: Anthropic impact; Azores Islands; Geoconservation; Macaronesia; Palaeobotany

The magmatic evolution of young island arc crust observed in gabbroic to tonalitic xenoliths from Raoul Island, Kermadec Island Arc - Haase, Karsten; Lima, Selma; Krumm, Stefan; Garbe-Schönberg, Dieter (Lithos, 2014)
We provide new geochemical and O isotope data for minerals and whole rocks of a suite of gabbroic to tonalitic xenoliths from Raoul Island in the Kermadec island arc. The plagioclase, olivine and clinopyroxene compositions are similar to those observed in the Raoul Island lavas supporting a close relationship of the plutonic and volcanic rocks by crystal fractionation. Plagioclase in gabbros is significantly more An-rich than in similar rocks from oceanic spreading axes reflecting higher water contents in the island arc magmas. Incompatible element and O isotope data suggest that the gabbroic rocks formed from accumulation of minerals of the ascending magmas whereas the tonalites represent highly evolved magmas after extreme fractional crystallization. Temperatures of the magmas calculated from O isotope equilibria and pyroxene thermometers range from about 1200. °C in the mafic to 800. °C in felsic rocks. Barometry of the rocks suggests that gabbros formed between 12 and 18. km depth and tonalites shallower which is in agreement with seismic models of island arc crustal layering. The xenolith data from Raoul Island support seismic studies indicating that some portions of the Tonga-Kermadec island arc show similar layering of felsic and mafic rocks to the Izu-Bonin and the fossil Talkeetna island arcs.
Keywords: Crust formation; Fractional crystallization; Magma differentiation; O isotopes

The marble horizon from Auerbach/Odenwald: Phase relations and PT evolution - Schmädicke, Esther; et al. (Mineralogy and Petrology, 2001)
UnivIS-Import:2017-03-24:Pub.2001.nat.dgeo.IGM.profes_1.themar

The metamorphosed mafic-ultramafic complex of Mokuro, Ilesha Schist Belt, southwestern Nigeria - Schmädicke, Esther; et al. (Journal of African Earth Sciences, 1998)
In the Proterozoic Schist Belt of Nigeria, lenticular bodies of metabasites and meta-ultramafics are frequently intercalated within staurolite bearing metapelitic schists. Such a metamorphosed mafic-ultramafic complex is particularly well exposed in the Mokuro riverbed between the towns of Ife and Ilesha. These outcrops display contact relationships with the surrounding metasediments, as well as between the individual mafic and ultramafic rock types. The most common mafic rocks are indistinctly layered amphibolites, accompanied by apatite rich amphibolites and massive amphibolites, in part rich in ilmenite and pyrrhotite. Among the generally massive ultramafic rocks, nearly monomineralic amphibole rocks predominate, while chlorite-amphibole, talc-chlorite-amphibole and talc bearing olivine-chlorite-amphibole rocks occur in subordinate amounts. Field, textural and geochemical evidence suggest that mafic-ultramafic complex derived from a thick, structurally differentiated basaltic sill that contained doleritic portions in its interior. Slow cooling rates in these inner parts enabled crystal settling with the formation of ultramafic cumulates. Due to the enrichment of volatiles during the crystallization process, higher amounts of apatite and sulphides, as well as late magmatic amphibole, were formed in parts of the mafic-ultramafic body. Mineral assemblages in the mafic-ultramafic complex testify to a metamorphic overprint under amphibolite-facies conditions. Thermodynamic modelling in the system CMFASH leads to an estimated P-T range of 1.5-3 kbar and 550-620°C for the metamorphic peak assemblage talc-olivine-chlorite-Ca amphibole-orthoamphibole.
UnivIS-Import:2017-03-24:Pub.1998.nat.dgeo.IGM.profes_1.themet

The Mid-Ludfordian (late Silurian) Glaciation: a link with global changes in ocean chemistry and ecosystem overturns - Frýda, Jiři; Lehnert, Oliver; Joachimski, Michael; Männik, Peep; Kubajko, Michal; Mergl, Michal; Farkaš, Juraj; Frýdová, Barbora (Earth-Science Reviews, 2021)
The present study reviews the main geochemical, sedimentological, and paleontological events associated with one of the largest perturbations in the Phanerozoic carbon cycle, the Mid-Ludfordian Carbon Isotope Excursion (MLCIE), which is globally documented in Late Silurian marine successions. Climate changes associated with the MLCIE are not yet well documented in contrast to most other Silurian CIEs. We report sea-water surface temperature changes across the entire MLCIE using δ18Oapatite records of conodonts originating from different regions located in temperate as well as tropical paleolatitudes. Significant positive δ18Oapatite excursions (up to 3.8‰) measured in temperate-water areas of the Prague Basin and Carnic Alps (peri-Gondwana) as well as in the tropical areas of Baltica (Laurussia) and Australia (Gondwana) provide evidence for significant global cooling during the MLCIE. The marked cooling of sea surface temperatures, coupled with a significant eustatic sea-level fall recorded on all corresponding paleocontinents, point to a major glaciation in polar and subpolar Gondwana which is denominated here as the “Mid-Ludfordian Glaciation”. The onset of rapid cooling in the Prague Basin (peri-Gondwana) is associated with the deposition of shales enriched in redox-sensitive trace metals suggesting that anoxic/euxinic waters expanded on the deeper carbonate shelf just before the MLCIE. The coincidence of the anoxic event with the Lau/Kozlowskii extinction events is documented for the first time outside of the Laurussian epeiric basins. Widespread oxygen-deficient conditions are interpreted to have been stressful to shelfal ecosystems and may have been a major cause of the extinctions. The Mid-Ludfordian glacio-eustatic sea-level fall caused a reduction of shelf habitats culminating in a lower faunal diversity and a change in the structure of faunal communities. The observed positive δ18Oapatite excursion is tightly coupled to δ13C and δ34S anomalies documented from temperate (peri-Gondwana) as well as tropical (Laurussia) paleolatitudes. The δ18Oapatite data complete the Silurian seawater temperature curve and show evidence that one of the largest positive carbon isotope anomalies (MLCIE) of the Phanerozoic was preceded by a widespread anoxic event and tightly linked with climate cooling event as documented as well for most other Silurian CIEs.<br
Keywords: Silurian; climate change; Ludfordian Glaciation; anoxic event; extinction; Lau/Kozlowskii Bioevent

The moral and legal imperative to return illegally exported fossils - Cisneros, Juan; Ghilardi, Aline Marcele; Raja Schoob, Nussaibah Begum; Stewens, Paul (Nature Ecology & Evolution, 2021)

The nature of Ordovician limestone-marl alternations in the Oslo-Asker District (Norway): Witnesses of primary glacio-eustasy or diagenetic rhythms? - Amberg, Chloé E. A.; Collart, Tim; Salenbien, Wout; Egger, Lisa Marie; Munnecke, Axel; Nielsen, Arne Thorshøj; Monnet, Claude; Hammer, Øyvind; Vandenbroucke, Thijs R.A. (Scientific Reports, 2016)
Ordovician limestone-marl alternations in the Oslo-Asker District have been interpreted as signaling glacio-eustatic lowstands, which would support a prolonged â €œ Early Palaeozoic Icehouseâ €. However, these rhythmites could alternatively reflect differential diagenesis, without sedimentary trigger. Here, we test both hypotheses through one Darriwilian and three Katian sections. Our methodology consists of a bed-by-bed analysis of palynological (chitinozoan) and geochemical (XRF) data, to evaluate whether the limestone/marl couplets reflect an original cyclic signal. The results reveal similar palynomorph assemblages in limestones and marls. Exceptions, which could be interpreted as reflecting palaeoclimatological fluctuations, exist at the species level: Ancyrochitina bornholmensis seems to be more abundant in the marl samples from the lower Frognerkilen Formation on Nakkholmen Island. However, these rare cases where chitinozoans differ between limestone/marl facies are deemed insufficient for the identification of original cyclicity. The geochemical data show a near-perfect correlation between insoluble elements in the limestone and the marls, which indicates a similar composition of the potential precursor sediment, also in the Frognerkilen Formation. This is consistent with the palynological data. Although an original cyclic pattern could still be recorded by other, uninvestigated parameters, our palaeontological and geochemical data combined do not support the presence of such a signa

The Occurrence Birth-Death Process for Combined-Evidence Analysis in Macroevolution and Epidemiology - Andreoletti, Jeremy; Zwaans, Antoine; Warnock, Rachel; Aguirre-Fernandez, Gabriel; Barido-Sottani, Joelle; Gupta, Ankit; Stadler, Tanja; Manceau, Marc (Systematic Biology, 2022)
Phylodynamic models generally aim at jointly inferring phylogenetic relationships, model parameters, and more recently, the number of lineages through time, based on molecular sequence data. In the fields of epidemiology and macroevolution, these models can be used to estimate, respectively, the past number of infected individuals (prevalence) or the past number of species (paleodiversity) through time. Recent years have seen the development of "total-evidence" analyses, which combine molecular and morphological data from extant and past sampled individuals in a unified Bayesian inference framework. Even sampled individuals characterized only by their sampling time, that is, lacking morphological and molecular data, which we call occurrences, provide invaluable information to estimate the past number of lineages. Here, we present new methodological developments around the fossilized birth-death process enabling us to (i) incorporate occurrence data in the likelihood function; (ii) consider piecewise-constant birth, death, and sampling rates; and (iii) estimate the past number of lineages, with or without knowledge of the underlying tree. We implement our method in the RevBayes software environment, enabling its use along with a large set of models of molecular and morphological evolution, and validate the inference workflow using simulations under a wide range of conditions. We finally illustrate our new implementation using two empirical data sets stemming from the fields of epidemiology and macroevolution. In epidemiology, we infer the prevalence of the coronavirus disease 2019 outbreak on the Diamond Princess ship, by taking into account jointly the case count record (occurrences) along with viral sequences for a fraction of infected individuals. In macroevolution, we infer the diversity trajectory of cetaceans using molecular and morphological data from extant taxa, morphological data from fossils, as well as numerous fossil occurrences. The joint modeling of occurrences and trees holds the promise to further bridge the gap between traditional epidemiology and pathogen genomics, as well as paleontology and molecular phylogenetics. [Birth-death model; epidemiology; fossils; macroevolution; occurrences; phylogenetics; skyline.]
CRIS-Team WoS Importer:2022-06-24

The offshore East African Rift System: Structural framework at the toe of a juvenile rift - Franke, Dieter; Jokat, Wilfried; Ladage, Stefan; Stollhofen, Harald; Klimke, Jennifer; Lutz, Ruediger; Mahanjane, Estevao Stefane; Ehrhardt, Axel; Schreckenberger, Bernd (Tectonics, 2015)
The Cenozoic East African Rift System (EARS) extends from the Red Sea to Mozambique. Here we use seismic reflection and bathymetric data to investigate the tectonic evolution of the offshore branch of the EARS. The data indicate multiple and time transgressive neotectonic deformations along 800 km of the continental margin of northern Mozambique. We observe a transition from a mature rift basin in the north to a juvenile fault zone in the south. The respective timing of deformation is derived from detailed seismic stratigraphy. In the north, a 30 km wide and more than 150 km long, N-S striking symmetric graben initiated as half-graben in the late Miocene. Extension accelerated in the Pliocene, causing a continuous conjugate border fault and symmetric rift graben. Coevally, the rift started to propagate southward, which resulted in a present-day 30 km wide half-graben, approximately 200 km farther south. Since the Pleistocene, the rift has continued to propagate another 300 km, where the incipient rift is reflected by subrecent small-scale normal faulting. Estimates of the overall brittle extension of the matured rift range between 5 and 12 km, with an along-strike southward decrease of the extension rate. The offshore portion of the EARS evolves magma poor, similar to the onshore western branch. The structural evolution of the offshore EARS is suggested to be related to and controlled by differing inherited lithospheric fabrics. Preexisting fabrics may not only guide and focus extension but also control rift architecture.
Keywords: East African Rift; Mozambique; reflection seismic; rifting; seafloor bathymetry; structure

The oldest deep-boring bivalves? Evidence from the Silurian of Gotland (Sweden) - Claußen, Anna Lene; Munnecke, Axel; Wilson, Mark A.; Oswald, Irina (Facies, 2019)
Compared to modern counterparts, bioerosion is rare in Paleozoic reefs, especially macro-bioerosion. The unique and enigmatic Silurian reefs from Gotland (Sweden), composed of bryozoans and microbial laminates, show evidence of a large amount of bioerosion. The samples contain Trypanites trace fossils, as well as a large number of undescribed macroborings. Small articulated bivalve shells are preserved in some of these macroborings, identified from thin-sections. Three-dimensional images from micro-computed tomography (microCT) reveal an additional bivalve, which is occupying a bioerosion trace. This specimen is possibly contained in a different boring that can be classified as possibly clavate-shaped. Furthermore, evidence of nestling, such as a subsequent modification of the ichnofossils, the presence of bivalves that are much smaller than the trace, or the presence of additional specimens, is missing; therefore, it is most likely that the bivalves made the borings. This is evidence for the existence of deep-boring bivalves in the Silurian.
CRIS-Team Scopus Importer:2019-05-03
Keywords: Bioerosion; Bryozoans; Endolithic bivalves; Paleozoic; Reefs; Tofta Formation

The oldest labechiid stromatoporoids from intraskeletal crypts in lithistid sponge Calathium reefs - Li, Qijian; Li, Yue; Kießling, Wolfgang (Lethaia, 2017)
UnivIS-Import:2017-03-24:Pub.2017.nat.dgeo.IGM.LP.theold
Keywords: Calathium; intraskeletal crypts; keratose sponges; labechiid stromatoporoids; reefs

The Olduvai Gorge Coring Project: Drilling high resolution palaeoclimatic and palaeoenvironmental archives to constrain hominin evolution - Njau, Jackson K.; Toth, Nicholas; Schick, Kathy; Stanistreet, Ian G.; McHenry, Lindsay J.; Stollhofen, Harald (Palaeogeography, Palaeoclimatology, Palaeoecology, 2021)
Volcano-sedimentary cores recovered from Pleistocene Palaeolake Olduvai by the Olduvai Gorge Coring Project (OGCP) provide a high-resolution record for reconstructing climatic and environmental contexts of hominin evolution. Approximately 612 m were recovered from four cores from three drill sites across the basin depocentre through scientific drilling, and these have yielded unprecedented data that substantially extend the Olduvai record both temporally and spatially. Results from multiproxy analyses based on sedimentological, mineralogical, isotopic, and geochemical measurements, along with analysis of organic matter and microfossils, backed up by new 40Ar/39Ar dating, palaeomagnetic reversal analysis and tuff fingerprinting, provide detailed palaeoecological and palaeoenvironmental data, and stratigraphic resolution adequate to provide context for the palaeoanthropological records from outcrops. In this Special Issue we present the first phase reporting of the core results, which establishes a new stratigraphic and palaeogeographic framework upon which palaeoenvironmental and palaeoanthropological data can be contextualized. The cores revealed thick intercalated lakebeds below the Bed I Basalt and the even older Naabi Ignimbrite, more than doubling the thickness of the known Olduvai stratigraphy. Seismic studies suggest that the sedimentary sequence contained in the lake's depositional sump extends even further back in time, perhaps back to 2.5 Ma, nearly 500 kyr older than the deepest strata exposed in outcrop. From stratal characteristics, we deduce that the palaeolake was deeper, more permanent, and longer-lived within the lake sump than previously thought, at least until the Masek Beds (before 0.82 Ma), although frequent phases of total or nearly total lake emptying/drying were detected, and the lake depocentre was at times filled by volcaniclastic fan progradation during periods of intense volcanic activity in the neighboring Ngorongoro Volcanic Highlands. Furthermore, biogeochemical evidence supports our interpretation of the lake history, and documents abrupt transitions in terrestrial vegetation, aquatic biota, and lake dynamics on a Milankovitch and sub-Milankovitch scale, which potentially exerted complex influences on hominin-exploited palaeolandscapes. This work revises the longstanding view of the basin history and transforms the scientific debate about the environmental conditions under which hominins evolved in the Olduvai Basin.<br
Keywords: Eastern Africa palaeolakes; Magnetostratigraphy; 40Ar/39Ar; Biomarkers; Tanzania; Tephrostratigraphy; Palaeoanthropology; Scientific Drilling

The onset of the 'Ordovician Plankton Revolution' in the late Cambrian - Servais, Thomas; Perrier, Vincent; Danelian, Taniel; Klug, Christian; Martin, Ronald E.; Munnecke, Axel; Nowak, Hendrik; Nützel, Alexander; Vandenbroucke, Thijs R.A.; Williams, Mark; Rasmussen, Christian Mac Ørum (Palaeogeography, Palaeoclimatology, Palaeoecology, 2016)
The ‘Great Ordovician Biodiversification Event’ comprises the rapid diversification of marine organisms during the Ordovician Period. It is now clear that this adaptive radiation started for some organisms already in the Cambrian and continued for others beyond the end of the Ordovician, making the ‘Great Ordovician Biodiversification Event’ part of a long-term late Proterozoic and Early Palaeozoic radiation, that in part is expressed by the fossil record as the ‘Cambrian Explosion.’ A significant diversification of different groups of the plankton is observed in the late Cambrian–Early Ordovician interval, leading to the subsequent ‘Ordovician Plankton Revolution.’ The possible causes of this ‘plankton revolution’ are currently debated. They include changes in palaeoclimate, palaeogeography or tectonic and volcanic activity, as well as a modified nutrient supply. In this context, the Steptoean Positive Carbon Isotope Excursion δ13Ccarb (SPICE) event in the late Cambrian (Paibian Stage, Furongian Series) has been related to a major increase in atmospheric O2 (from 10–18% to some 20 – 29%) and to increased oceanic nutrient availability. Here we analyze the diversification of the planktonic groups during the late Cambrian and Early Ordovician, in particular in relation to the SPICE event. Our analyses include the changing diversities of the phytoplankton (acritarchs), diverse groups of zooplankton (e.g., radiolarians, graptolites, chitinozoans) and the switch to a planktonic mode of life of fossil groups (e.g., arthropods, molluscs) that were part of the Cambrian benthos and that later occupied pelagic niches. In addition, we focus also on data indicating evidence for a late Cambrian to Ordovician origin of planktotrophy in invertebrate larvae. It can be concluded that none of the diversifications of the different planktonic organisms can be related directly to the SPICE event. However, a long term (10–20 million years) oxygenation pulse related to the SPICE event might have fuelled the explosion of phytoplankton diversity observed in the latest Cambrian–Early Ordovician that led to completely modified trophic structures permitting an increase in diversity and abundance of plankton-feeding groups during the Ordovicia
Keywords: Plankton; SPICE; Late Cambrian; Early Ordovician; Ordovician Plankton Revolution

The onset of the permo-carboniferous glaciation: Reconciling global stratigraphic evidence with biogenic apatite δ 18 O records in the late visean - Barham, Milo; Murray, J.; Joachimski, Michael; Williams, D. (Journal of the Geological Society, 2012)
The δ O values of phosphatic microfossils recovered from NW Ireland are used to determine the timing and magnitude of cooling associated with the onset of the Carboniferous glaciation. icrofossil fish δ Oapatite demonstrates a +2.4‰ (V-SMOW) shift, which, once corrected for δ O changes owing to evolving ice volumes, equates to an approximate 4.5 °C reduction in equatorial sea surface temperature between the earliest Asbian and the mid- Brigantian (late Visean). Both conodont and microfossil fish δ O indicate stabilization of an 'icehouse' climate during the Brigantian and into the Serpukhovian. Substantial late Visean cooling identified herein is in good agreement with global glacioeustatic records.
UnivIS-Import:2015-03-09:Pub.2012.nat.dgeo.IGM.LG.theons

The Ordovician Biodiversification: revolution in the oceanic trophic chain - Servais, Thomas; Lehnert, Oliver; Li, Jun; Mullins, Gary L.; Munnecke, Axel; Nützel, Alexander; Vecoli, Marco (Lethaia, 2008)
The Early Palaeozoic phytoplankton (acritarch) radiation paralleled a long-term increase in sea level between the Early Cambrian and the Late Ordovician. In the Late Cambrian, after the SPICE δ13C carb excursion, acritarchs underwent a major change in morphological disparity and their taxonomical diversity increased to reach highest values during the Middle Ordovician (Darriwilian). This highest phytoplankton diversity of the Palaeozoic was possibly the result of palaeogeography (greatest continental dispersal) and major orogenic and volcanic activity, which provided maximum ecospace and large amounts of nutrients. With its warm climate and high atmospheric CO2 levels, the Ordovician was similar to the Cretaceous: a period when phytoplankton diversity was at its maximum during the Mesozoic. With increased phytoplankton availability in the Late Cambrian and Ordovician a radiation of zooplanktonic organisms took place at the same time as a major diversification of suspension feeders. In addition, planktotrophy originated in invertebrate larvae during the Late Cambrian-Early Ordovician. These important changes in the trophic chain can be considered as a major palaeoecological revolution (part of the rise of the Palaeozoic Evolutionary Fauna of Sepkoski). There is now sufficient evidence that this trophic chain revolution was related to the diversification of the phytoplankton, of which the organic-walled fraction is partly preserved. © 2008 The Authors, Journal compilation © 2008 The Lethaia Foundatio
UnivIS-Import:2015-03-09:Pub.2008.nat.dgeo.IGM.LG.theord
Keywords: Acritarchs; Evolutionary radiation; Ordovician; Palaeoecology; Phytoplankton; Trophic chain

The origin and crustal evolution of microcontinents in the Beishan orogen of the southern Central Asian Orogenic Belt - He, Zhenyu; Klemd, Reiner; Yan, Lili; Zhang, Zeming (Earth-Science Reviews, 2018)
Microcontinents with Precambrian basement have played an important role in the accretionary and amalgamation history of the Central Asian Orogenic Belt (CAOB). However, their geological evolution is only poorly constrained due to restricted exposure of the Precambrian rocks, which were extensively overprinted mainly by Paleozoic tectonic, metamorphic and magmatic events. In the present study, in situ zircon U–Pb age and Hf isotopic data of 64 Paleozoic and early Mesozoic (from 499 to 217 Ma) as well as 14 Mesoproterozoic and Neoproterozoic (from 1555 to 871 Ma) granitic samples from four major arc terranes of the Beishan orogen (southernmost CAOB) were compiled in order to assess the nature of their crustal basement as well as the subsequent Paleozoic tectonic evolution. Zircon εHf(t) values and calculated Hf model ages are similar for all arc terranes with Hf model age peaks at approximately 1.0–0.8 Ga and 2.0–1.8 Ga. We suggest that all of these Paleozoic arc terranes formed on a single, uniform Precambrian continental terrane. Furthermore, this continental terrane shows typical characteristics of Mesoproterozoic ( 1.4 Ga) juvenile crustal growth, which may have been part of an extensive Mesoproterozoic continental terrane, now tectonically fragmented and located over a distance of more than a thousand kilometers in the southern CAOB. Among the cratons bordering the CAOB, Balticadisplays most similarities with this continental terrane, while a Mesoproterozoic correlation with the Tarim Craton is rather questionable.<br
Keywords: Zircon Hf–O isotope; Mesoproterozoic crustal growth; Beishan orogen; Southern Central Asian Orogenic Belt; Granitoids

The origin of evolved volcanic rocks in Methana, Greece - Schönhofen, Milena; Wölki, Dominic; Haase, Karsten; Beier, Christoph (Goldschmidt 2017, 2017)
The formation of evolved andesite to dacite magmas at subduction zones is an important process on Earth. The Aegean arc has one of the highest rates of sediment subduction globally that impacts on the composition of the erupted melts. Methana peninsula is located at the western margin of the Aegean arc and consists of numerous effusive andesitic to dacitic eruptions. These evolved lavas frequently contain basaltic to basaltic-andesitic enclaves. An origin of the Methana andesites as a result of melting of mantle hybridized by sediment melts can be excluded from the occurrence of basaltic enclaves. Petrological and geochemical data suggest shallow crustal processes playing a crucial role in the formation of these rocks. The major element patterns (e.g. FeO*, Al2O3 or TiO2 vs. MgO) show evidence for fractional crystallization. Mineral compositions display oscillatory zonings, disequilibrium textures, secondary rim overgrowths and different mineral populations indicating complex mixing of magmas. Plagioclase generations can mainly be distinguished by their size and phenocrysts display anortithe contents from 43 to 88, while amphiboles show evidence for polybaric fractionation. Thermobarometric calculations using amphibole-plagioclase assemblages imply that magma mixing occurs in the shallow crust (9-15km) feeding the volcanic eruptions. We develop a model of a deep-reaching magma system reaching to the crust-mantle boundary. This can explain continuous magma mixing along a range of depths. Fe-Ti oxide thermometry yields partly higher temperatures than the plagioclase-amphibole thermometer and possibly resulting from rapid magma ascent. Explosive volcanism dominates the central and eastern Aegean islands, e.g., Santorini or Kos [1], while Methana displays extensive effusive volcanism with lava domes and flows. We interpret this to result from pre-eruptive re-heating [2] by recharge of more primitive and hotter magma from the crust-mantle boundary. The larger crustal thickness in the western Aegean may influence the eruptive mechanism by intensive degassing covering a higher distance during magma ascent than in other parts of the arc. [1] Druitt et al. (2016), Journal of Petrology 57(3), 461- 494; [2] Ruprecht & Bachmann (2010), Geology, 38(10), 919-922.
Keywords: Aegean arc; Andesites; Dacites; Plagioclase; magma mixing

The origins and transformation of carbonate mud during early marine burial diagenesis and the fate of aragonite: A stratigraphic sedimentological perspective - Munnecke, Axel; Wright, V. Paul; Nohl, Theresa (Earth-Science Reviews, 2023)
The current understanding of the origins of modern carbonate muds and their early stages of transformations are reviewed. The fine-grained nature of such sediments makes them susceptible to intensive structural and chemical alteration at relatively shallow burial depths driven especially by mineral instability under microbially mediated reactions within the sediment associated with the decay of organic matter. Whereas the transformation of high Mg calcite (HMC) to low magnesian calcite (LMC) generally takes place incongruently and in situ, that of aragonite is predominantly via congruent dissolution. The loss of aragonite produces a huge potential flux of carbonate which is translocated within the sediment. Parallel to studies on Quaternary sediments, investigations in the stratigraphic record have shown that in low-energy settings the transformation of the aragonite component leads to the formation of diagenetic bedding (such as limestone-marl-alternations or LMAs), and related bipartite lithologies, some types of hardgrounds, secondary carbonate mudrocks, and to the significant modification of the original skeletal biota. There are uncertainties such as the exact sources for the precursor aragonite, where the released carbonates reprecipitate in the shallow sediment column, how much carbonate (and hence carbon) is back-fluxed to the water column, how this affects palaeoenvironmental proxies, and the environmental distributions of these processes. The evidence from the stratigraphic record, from settings where organic matter was able to accumulate promoting these transformations, is that these changes in carbonate-rich sediments took place very early, at shallow (decametre or less) burial depths, affecting what we now see from the micron to the outcrop scale. The complexity and inter-relationships of these fundamental processes has received more attention in recent years, though their implications still seem remarkably undervalued.
CRIS-Team Scopus Importer:2023-03-17
Keywords: Bacterial decay of organic matter; Diagenetic bedding; Marine carbonate flux; Micrite; Microspar; Shallow burial marine diagenesis

The overlooked realities of sampling bias - Raja, Nussaïbah Begum; Dunne, Emma; Khan, Tasnuva; Nätscher, Paulina (GSA Annual Meeting 2020, 2020)
Analyses of past global biodiversity are severely hindered by sampling biases and gaps in the fossil record. These have previously been attributed to several geological and biological factors such as rock outcrop area, taxonomic definitions, fossil abundance, among others. In many cases, inferred so-called global diversity curves only reflect regional diversity of well-sampled localities. However, global compilations of fossil occurrences, such as from the Paleobiology Database (PBDB), not only reflect the physical aspects of the fossil record, but also document the historical compilation of this data over more than two centuries. In this study, we find that socioeconomic factors such as wealth, language and security may help to explain spatial variation in the compiled data of the PBDB. Countries with high per capita gross domestic product (GDP; implying greater access to research funds), a population with high English proficiency, and greater political stability were generally found to be the countries from which higher number of collections originated and documented in the PBDB. Similarly, we found that these countries also contributed to a majority of the compiled literature from which the data was extracted. The factors identified in this study influence fossil data collection, access and availability by determining who has access to specimens and the ability to do research. As such, efforts towards achieving an understanding of the “real” past global diversity will benefit from investing in scientific education, and more research and collaborations in countries at a disadvantage, with a focus on improving local geological and paleontological knowledg

The pace of shifting climate in marine and terrestrial ecosystems - Burrows, Michael T.; Schoeman, David S.; Buckley, Lauren B.; Moore, Pippa; Poloczanska, Elvira S.; Brander, Keith M.; Brown, Chris; Bruno, John F.; Duarte, Carlos M.; Halpern, Benjamin S.; Holding, Johnna; Kappel, Carrie V.; et al. (Science, 2011)
Climate change challenges organisms to adapt or move to track changes in environments in space and time. We used two measures of thermal shifts from analyses of global temperatures over the past 50 years to describe the pace of climate change that species should track: the velocity of climate change (geographic shifts of isotherms over time) and the shift in seasonal timing of temperatures. Both measures are higher in the ocean than on land at some latitudes, despite slower ocean warming. These indices give a complex mosaic of predicted range shifts and phenology changes that deviate from simple poleward migration and earlier springs or later falls. They also emphasize potential conservation concerns, because areas of high marine biodiversity often have greater velocities of climate change and seasonal shift
UnivIS-Import:2015-03-09:Pub.2011.nat.dgeo.IGM.LP.thepac

The Paleozoic evolution of the gastropod larval shell: larval armor and tight coiling as results of predation-driven heterochronic character displacement - Seuß, Barbara; Nützel, Alexander; Scholz, Henning; Frýda, Jiři (Evolution & Development, 2012)
Early and middle Paleozoic gastropod protoconchs generally differ strongly from their corresponding adult morphologies, that is, most known protoconchs are smooth and openly coiled, whereas the majority of adult shells are ornamented and tightly coiled. In contrast, larval and adult shells of late Paleozoic gastropods with planktotrophic larval development (Caenogastropoda, Neritimorpha) commonly resemble each other in shape and principle ornamentation. This is surprising because habitat and mode of life of planktonic larvae and benthic adults differ strongly from each other. Generally, late Paleozoic to Recent protoconchs are tightly coiled. This modern type of larval shell resembles the adult shell morphology and was obviously predisplaced onto the larval stage during the middle Paleozoic. The oldest known planktonic-armored (strongly ornamented) larval shells are known from the late Paleozoic. However, smooth larval shells are also common among the studied late Paleozoic gastropods. The appearance of larval armor at the beginning of the late Paleozoic could reflect an increase of predation pressure in the plankton. Although there are counter examples in which larval and adult shell morphology differ strongly from each other, there is statistical evidence for a heterochronic predisplacement of adult characters onto the larval stage. Larval and adult shells are built in the same way, by accretionary secretion at the mantle edge. It is likely that the same underlying gene expression is responsible for that. If so, similarities of larval and adult shell may be explained by gene sharing, whereas differences may be due to different (planktic vs. benthic life) epigenetic patterns. © 2012 Wiley Periodicals, Inc
UnivIS-Import:2015-03-09:Pub.2012.nat.dgeo.IGM.LP.thepal

The Paleozoic-Mesozoic transition in South China: Oceanic environments and life from Late Permian to Late Triassic - Chen, Zhong-Qiang; Algeo, Thomas J.; Sun, Yadong; Schoepfer, Shane D. (Palaeogeography, Palaeoclimatology, Palaeoecology, 2017)

The Paleozoic problematica Wetheredella and Allonema are two aspects of the same organism - Jarochowska, Emilia; Munnecke, Axel (Facies, 2014)
Wetheredella is a calcareous encrusting microproblematicum known only from its two-dimensional expression in thin-sections. It occurs in Cambrian through Permian rocks, often in association with Rothpletzella and Girvanella, probable calcifying cyanobacteria. We show that Wetheredella can be produced by sectioning of the Paleozoic incertae sedis sclerobiont Allonema, which has until now been recognized based on its surface, 3D aspect. Therefore, we propose that Wetheredella should be regarded as a junior synonym of Allonema. Structures resembling Wetheredella have also been obtained in thin-sections through another encrusting microproblematicum, Ascodictyon, which, however, differs in the ultrastructure of its wall, which consists of parallel calcite crystals in contrast to radial crystals in Allonema. Allonema specimens used in the study were extracted from the Middle Silurian Mulde Brick-clay Member (Gotland, Sweden), representing an off-platform environment below the photic zone. This, together with the primary calcitic, radial wall structure of Allonema argues against a cyanobacterial or algal affinity, which had been considered for Wetheredella. The taxonomic position of Allonema remains unresolved, but the sclerobiont shares many common characteristics with some Paleozoic encrusting foraminifers. Combining the occurrence data on Allonema in its surface aspect and the "Wetheredella" aspect recognized in thin-sections may shed more light on its affinity and paleoecological functions, particularly its association with cyanobacteria and its role as a framework-builder in Paleozoic reefs. © 2014 Springer-Verlag Berlin Heidelberg.
UnivIS-Import:2015-04-14:Pub.2014.nat.dgeo.IGM.LP.thepal
Keywords: Ascodictyon; Cyanobacteria; Pseudo-bryozoans; Ptychocladiidae; Rothpletzella; Tuberitinidae

The peculiar geochemical signatures of São Miguel (Azores) lavas: metasomatised or recycled mantle sources? - Beier, Christoph; Stracke, Andreas; Haase, Karsten (Earth and Planetary Science Letters, 2007)
The island of São Miguel, Azores consists of four large volcanic systems that exhibit a large systematic intra-island Sr-Nd-Pb-Hf isotope and trace element variability. The westernmost Sete Cidades volcano has moderately enriched Sr-Nd-Pb-Hf isotope ratios. In contrast, lavas from the easternmost Nordeste volcano have unusually high Sr and Pb and low Nd and Hf isotope ratios suggesting a long-term evolution with high Rb/Sr, U/Pb, Th/Pb, Th/U and low Sm/Nd and Lu/Hf parent-daughter ratios. They have trace element concentrations similar to those of the HIMU islands, with the exception of notably higher alkali element (Cs, Rb, K, Ba) and Th concentrations. The time-integrated parent-daughter element evolution of both the Sete Cidades and Nordeste source matches the incompatibility sequence commonly observed during mantle melting and consequently suggests that the mantle source enrichment is caused by a basaltic melt, either as a metasomatic agent or as recycled oceanic crust. Our calculations show that a metasomatic model involving a small degree basaltic melt is able to explain the isotopic enrichment but, invariably, produces far too enriched trace element signatures. We therefore favour a simple recycling model. The trace element and isotopic signatures of the Sete Cidades lavas are consistent with the presence of ancient recycled oceanic crust that has experienced some Pb loss during sub-arc alteration. The coherent correlation of the parent-daughter ratios (e.g. Rb/Sr, Th/U, U/Pb) and incompatible element ratios (e.g. Nb/Zr, Ba/Rb, La/Nb) with the isotope ratios in lavas from the entire island suggest that the Sete Cidades and Nordeste source share a similar genetic origin. The more enriched trace element and isotopic variations of Nordeste can be reproduced by recycled oceanic crust in the Nordeste source that contains small amounts of evolved lavas (∼ 1-2%), possibly from a subducted seamount. The rare occurrence of enriched source signatures comparable to Nordeste may be taken as circumstantial evidence that stirring processes in the Earth's mantle are not able to homogenise material within the size of seamounts over timescales of mantle recycling. © 2007 Elsevier B.V. All rights reserved.
UnivIS-Import:2015-03-09:Pub.2007.nat.dgeo.IGM.legeo.thepec
Keywords: enriched mantle; incompatible elements; Ocean Island Basalts; radiogenic isotopes; recycling; subduction

The performance of geothermal passive heating and cooling for asphalt and concrete pavement - Baumgärtel, Sebastian; Schweighofer, Julian; Rohn, Joachim; Luo, Jin (Developments in the Built Environment, 2021)
Hydronic pavement heating and cooling applications have been well established to provide road safety over the past two decades. However, most of the systems run on asphalt, only a few are tested with concrete, and there rarely is a comparison between those two common materials in their heating and cooling performance. In this work, a field study was carried out using asphalt and concrete as pavement material for pavement heating and cooling under the climatic conditions of the city Erlangen, Germany. Both heating performance in winter and cooling performance in summer were tested with similar setups and a low inlet temperature of 10 degrees C. The results indicate that asphalt's heating performance is worse than that of concrete, showing slightly lower surface temperatures and limited snow melting capabilities. During heavy snowfall, concrete's surface remained snow-free, while asphalt's surface was covered under a thin layer of snow, indicating that snow is melted not fast enough. However, in summer, asphalt, due to its lower albedo, had a significantly higher energy output of 450 W/m(2) compared to 290 W/m(2) of concrete. Therefore, asphalt showed good cooling perfomance, compared to concrete. Thus, it is concluded that both materials have advantages and disadvantages in geothermal passive heating and cooling, which leave the decision on appropriate material to match the specific planned parameters and environmental requirements.
CRIS-Team WoS Importer:2021-08-13

The Permian-Triassic boundary interval as a model for forcing marine ecosystem collapse by long-term atmospheric oxygen drop - Kießling, Wolfgang; et al. (Geology, 2003)
Ecological traits of reefs across the Permian-Triassic boundary interval coincide with a modeled decline of atmospheric oxygen throughout the Permian Period. Selective extinction and recovery patterns within the reef system are observed both at the end of the middle Permian (end-Guadalupian) and at the Permian-Triassic boundary. The end-Guadalupian event selectively affected corals and broke down the cool-water carbonate factory. Sponges, however, were largely unaffected and bloomed in reefs toward the end of the Permian. The end-Permian total destruction of the metazoan reef system only left behind poorly diverse microbial communities. The temporal reef patterns are thus similar to spatial patterns of modern benthic communities approaching oxygen minimum zones. This observation suggests that a decline in oxygen concentrations was at least partly involved in the destruction of reefs, even where there is no direct evidence of oceanic anoxia.
UnivIS-Import:2015-03-09:Pub.2003.nat.dgeo.IGM.LP.permia
Keywords: Anoxia; Mass extinction; Permian; Recovery; Reefs; Triassic

The petrology and geochemistry of lavas from the western azores islands of flores and corvo - Genske, Felix; Turner, Simon P.; Beier, Christoph; Schaefer, Bruce (Journal of Petrology, 2012)
The islands of Flores and Corvo in the Azores archipelago are the only two of nine subaerial volcanic edifices lying west of the Mid-Atlantic Ridge (MAR). This makes them important for constraining the evolution of this young (<40 Ma) oceanic plateau. The alkalic basalt suites from Flores and Corvo lie on a single liquid line of descent. Ankaramitic cumulates, with MgO contents up to 18 wt %, result from clinopyroxene-dominated polybaric crystallization. The parental magmas (MgO 11 wt %) are inferred to be low-degree partial melts (F = 3-5%) of enriched peridotite generated at depths of 80-90 km. These primary magmas commenced crystallizing at the lithosphere-asthenosphere boundary and this continued in conduits over a pressure range of 0·;6-1·;2 GPa. Only lavas with MgO < 3 wt % fractionated at shallow crustal levels. Nd and Sr isotope data reveal variations in the source of both magmatic systems, suggesting variable contributions from both enriched (E-) and depleted (D-) mid-ocean ridge basalt (MORB)-source mantle components. This is supported by the greater variability of incompatible trace-element ratios within the Flores lavas (e.g. Ba/Nd, La/Sm, Th/Nd), whereas those from Corvo exhibit a good correlation between key trace-element ratios [e.g. (La/Sm) , Th/Nd] and Sr isotope ratios. Lavas from Flores display a greater variability in Sr and Nd isotope compositions and define a mixing array between an E-MORB source and a common Azores mantle source. The latter signature is restricted to lava suites from the north and east of Flores. We concur with the generally accepted notion that Flores and Corvo are derived from the same mantle plume as is responsible for the eastern Azores islands. However, there is evidence (different Nb/Zr, Ta/Hf and La/Sm, but homogeneous Sr and Nd isotopic composition) that these two islands are dominated by a source component that is not as evident in the eastern archipelago. © The Author 2012. Published by Oxford University Press. All rights reserved.
Keywords: Azores plateau; Magmatic differentiation; Oceanic lithosphere; OIB; Polybaric fractionation

The petrology and geochemistry of Vesteris Seamount, Greenland Basin: An intraplate alkaline volcano of non-plume origin. - Haase, Karsten; Devey, Colin (Journal of Petrology, 1994)
Vesteris Seamount is a solitary alkaline volcano in the Greenland Basin some 280 km NW of Jan Mayen. Topographic and geophysical studies have shown no sign of an associated plume trace. Evidence from ash layers in sediment cores around the volcano and dating of dredged samples show that it has been active in Quaternary times. The lavas from Vesteris studied here consist of basanites, tephrites, mugearite, and alkali basalts. Crystal fractionation models are consistent with the generation of the tephrites and mugearite from a basanitic parent. Extensive kaersutite fractionation is required late in the fractionation sequence to produce the extreme mugearite composition. Na-Al-Fe-rich green cores to many clinopyroxene phenocrysts at Vesteris suggest a fractionation history beginning at high pressure in the mantle. Differences between Vesteris and Jan Mayen in the ratios of highly incompatible trace elements such as Ce/Pb and Rb/Cs, which will not normally be fractionated from one another during mantle melting, suggest that the two are not derived from the same source. Relatively unradiogenic Sr isotope ratios (compared with Bulk Earth), and highly incompatible trace element patterns similar to those for St. Helena, suggest that Vesteris magmas are derived from a depleted, asthenospheric source. We propose that the Vesteris basanites are very low degree partial melts (̃1%) of this source, most probably those which give rise to the seismic low-velocity zone (LVZ). Such small-degree melts may preferentially tap small-scale heterogeneities in the asthenosphere. Vesteris lies at the intersection of two major structural trends in the Greenland Basin-(1) a zone of major reorientation of spreading direction on the Mohns Ridge north of Jan Mayen and (2) the extension of the Kolbeinsey Ridge axis. We propose that a combination of the extensional stress fields related to these two lineaments produces sufficient dilation of the lithosphere at Vesteris to allow magmas from the LVZ to reach the surface. © 1994 Oxford University Press.
UnivIS-Import:2015-03-05:Pub.1994.nat.dgeo.IGM.legeo.thepet

The PONKCS method applied for time resolved XRD quantification of supplementary cementitious material reactivity in hydrating mixtures with ordinary Portland cement - Naber, Christoph; Stegmeyer, Samuel; Jansen, Daniel; Götz-Neunhoeffer, Friedlinde; Neubauer, Jürgen (Construction and Building Materials, 2019)
A method is presented to determine the reactivity of supplementary cementitious materials (SCMs) in blended cement systems. To this end, hydration of ordinary Portland cement (OPC) and of OPC blended with the SCMs microsilica and metakaolin has been measured by X-ray diffraction (XRD) and heat flow calorimetry. The quantities of the SCMs in the hydrating mixtures, although of very low crystallinity, could be directly determined by Rietveld refinement employing a method for partially or not known crystal structures (PONKCS method). Considerable amounts of microsilica and metakaolin already react during the first day of hydration in addition to an increased reaction of the cement phases due to the filler effect. The phase assemblage in the hydrated samples is influenced by the SCM present.
CRIS-Team Scopus Importer:2019-05-02
Keywords: Amorphous phases; Blended cement; Hydration; Metakaolin; Microsilica; X-ray diffraction

The potential of carbonate ramps to record C-isotope shifts: insights from the upper Miocene of the Central Mediterranean area - Cornacchia, Irene; Munnecke, Axel; Brandano, Marco (Lethaia, 2020)
The late Miocene is a crucial interval for global climate evolution as well as for the regional geodynamic evolution of the Central Mediterranean area. It spans the transition from the warm Mid Miocene Climatic Optimum, associated with the major Monterey Carbon Isotope Excursion, to the cooler Pliocene, characterized by a bipolar glaciation. Within this climatic transition, during the early Tortonian, a positive carbon isotope excursion related to a global carbon cycle perturbation is recorded, named Carbon Maximum 7 (CM7). In this study, two upper Serravallian–lower Tortonian carbonate ramps of the Central Mediterranean have been analysed: the Latium-Abruzzi and the Apula ramps (Central Apennines, Central Italy). Carbon isotope ratios have been coupled with facies and microfacies analyses with the aims: (1) to identify the CM7 in the Central Mediterranean carbonate ramp successions; (2) to evaluate potential carbonate factory changes or demises related to the CM7; and (3) to discriminate the role of global vs regional factors in affecting the Mediterranean carbonate ramps. The two studied ramps show different evolutions due to regional geodynamics causes. The Latium-Abruzzi ramp drowns in the Tortonian, while the Apula shows a regressive trend, with upper Tortonian middle ramp facies overlying the lower Tortonian outer ramp. Despite the complex geodynamic setting, a positive carbon isotope shift has been identified in both ramps and correlated with the CM7. This positive carbon isotope shift may be linked to the strengthening of the global ocean circulation during the late Miocene cooling. This strengthening of the circulation enhanced the coastal upwelling, bringing nutrient-rich waters to the surface and triggering an enhanced primary productivity consistent with the CM7.
CRIS-Team Scopus Importer:2020-05-22
Keywords: Apennines; C-isotopes; carbonate ramps; late Miocene; Mediterranean

The potential of coralline algae as SST proxy and for climate model evaluation: A New Zealand case study - Kropac, Elena; Mölg, Thomas; Teichert, Sebastian (EGU General Assembly 2022, 2022)
General circulation models (GCMs) are currently the most important tools for obtaining projections about future climate. In addition, they provide data input for regional atmospheric models that translate global climate change to regional and local scales where humans and environments face the impacts. To ensure the accurateness of their simulations, GCMs need to be evaluated as thoroughly as possible against past climate records, where one focus is on the so-called "historical period" (1850–present). However, the evaluation task is difficult for the period before World War II and earlier due to a frequent lack of reliable observations. This problem is exacerbated for the Southern Hemisphere, which has been notoriously understudied in comparison to the climate of the Northern Hemisphere. In New Zealand, variations in sea surface temperature (SST) are reflected on a variety of spatial and temporal scales and are statistically detectable through to temperature anomalies and glacier mass balance changes in the high mountains of the Southern Alps. The correct simulation of SST by GCMs is therefore crucial, especially when investigating the physical mechanisms that transform large-scale SST signals into local climate anomalies by using regional atmospheric modeling. In the project “NZ-PROXY”, we utilize crustose coralline algae (CCA) – a rather recently discovered proxy archive – to extend the observational time series of SST in the New Zealand region back to 1850. The SST reconstruction is then employed in GCM evaluation to reveal their skill in representing the large-scale climate of New Zealand. Finally, high-resolution sensitivity simulations are obtained from a regional atmospheric model to investigate the added value of the advanced GCM selection for regional climate modelin

The power of hydropeaking: Trade-offs between flexible hydropower and river ecosystem services in Europe - Venus, Terese E.; Ola, Oreoluwa; Alp, Maria; Bätz, Nico; Bejarano, Maria Dolores; Boavida, Isabel; Bruno, Maria Cristina; Casas-Mulet, Roser; Carolli, Mauro; Chiogna, Gabriele; Gosselin, Marie Pierre; Halleraker, Jo H.; et al. (Ecological Economics, 2025)
The operational practice of “hydropeaking” allows hydropower plants to cover peaks and deficits in energy demand, but it also impacts river ecosystems. The assessment of hydropeaking impacts plays an important role in safeguarding ecosystem services, but is challenging due to the relative importance of impacts at different sites. To compare impacts in hydropeaking rivers, we elicit expert judgment on the relative impacts of hydropeaking on river ecosystem services. Using the best-worst scaling (BWS) method, we compare the impact on the three categories of river ecosystem services (provisioning, regulating and cultural). Our respondents include 98 hydropower experts. Our analysis accounted for individual heterogeneity to assess how perceptions vary across regions, attitudes and representative river characteristics. We find trade-offs between provisioning and regulating services at the regional and local levels, which represents a key issue in dealing with climate change and ecosystem degradation. The best-affected services were water for power generation, raw materials, water for industrial activities and water for irrigation. The worst-affected services were fisheries and aquaculture, maintenance of population and habitat, and wild animals. Our results have implications for the safeguarding of river ecosystem services and the design of regulatory and incentive schemes for mitigation.
CRIS-Team Scopus Importer:2025-03-28
Keywords: Best-worst scaling; Biodiversity; Choice experiment; Ecological compensation; Ecosystem services; Hydropower

The P-T evolution of ultra high temperature garnet-bearing ultramafic rocks from the Saxonian Granulitgebirge Core Complex, Bohemian Massif - Schmädicke, Esther; Gose, Jürgen; Will, T. M. (Journal of Metamorphic Geology, 2010)
Keywords: Bohemian Massif; Garnet pyroxenite; Garnet peridotite; Ultra high temperature metamorphism; Saxonian Granulitgebirge

The radiogenic isotope composition of the high-latitude North Atlantic mantle. - Mertz, Dieter; Haase, Karsten (Geology, 1997)
New Sr, Nd, and Pb isotope data on North Atlantic high-latitude (about 69°30′N to 76°30′N) intraplate and ridge volcanic rocks, together with published data, are used to evaluate the mantle sources contributing to Iceland and the surrounding ridges. Considerable overlap between Icelandic lavas and depth-filtered North Atlantic mid-oceanic-ridge basalts (MORBs) in all isotope plots confirm that a MORB asthenosphere-plume mixing model can explain the ranges of isotope compositions found on Iceland. Regional isotope patterns north of lat 53°N show two distinct mantle domains. Lavas forming a low-radiogenic-Pb, high-radiogenic-Sr array occur north of central Iceland, whereas volcanic rocks forming a high-radiogenic-Pb, low-radiogenic-Sr array mainly erupt on and south of Iceland. The depleted end members of each array most likely represent MORB source material. The enriched end member of the high-radiogenic-Pb, low-radiogenic-Sr array appears to reside in the Iceland plume. The other enriched end member also occurs in on-axis and mainly intraplate magmas north of about lat 71°N.
UnivIS-Import:2015-03-05:Pub.1997.nat.dgeo.IGM.legeo.therad

The raw material preferences for producing picture stones on Gotland - Hänsel, Patrick; Oehrl, Sigmund; Widerström, Per; Ideström, Lena; Munnecke, Axel (Fornvännen. Journal of Swedish Antiquarian Research, 2024)
The picture stones on Gotland are monuments from the late Scandinavian Iron Age, which are important for the archaeological research about the North Germanic culture. Their imagery is also a valuable source for the pre-Christian religion in Scandinavia. Most of them are produced of Silurian limestones which are dated 423 to 433 million years. The Gotlandic picture stones were produced of thickly bedded limestones which are exposed in the vicinity of fossil reefs and carbonate platforms. Archaeologically, the picture stones can be classified into five groups (A to E stones), and an informal sixth group (so-called blind C/D/E stones). Geologically, the picture stone raw materials can be sorted into six different types based on visual facies analysis. The purpose of our paper is to investigate the raw material preferences for single picture stone types. According to our results, coarse and fine reef debris limestones were the most frequently used rock types. For the B stones, crinoidal limestone was preferentially used because of its sparkling effect of the crinoid remains in sunlight. However, the availability of nearby thickly bedded limestones was the most important prerequisite to produce most of the picture stone
Keywords: crinoidal limestone; Gotland; picture stones; raw material preferences; reef debris limestone

The record of climate-driven morphological changes in 376 Ma old Devonian fossils - Balter, Vincent; Renaud, Sabrina; Girard, Catherine; Joachimski, Michael (Geology, 2008)
UnivIS-Import:2015-03-09:Pub.2008.nat.dgeo.IGM.LG.therec

The record of early Silurian climate changes from South China and Baltica based on integrated conodont biostratigraphy and isotope chemostratigraphy - Yan, Guanzhou; Lehnert, Oliver; Männik, Peep; Calner, Mikael; Luan, Xiaocong; Gong, Fangyi; Li, Lixia; Wei, Xin; Wang, Guangxu; Zhan, Renbin; Wu, Rongchang (Palaeogeography, Palaeoclimatology, Palaeoecology, 2022)
New conodont and stable isotope data are presented from the classical Baizitian section in the Yanbian County of Sichuan Province, South China. The Telychian to Sheinwoodian strata were sampled and studied for carbon isotope stratigraphy and conodont biostratigraphy. The paired δ13Ccarb and δ13Corg data reveal a pronounced positive excursion, the Manitowoc carbon isotope excursion (Manitowoc CIE, ‘Manitowoc Excursion’) spanning the upper Pterospathodus eopennatus Zone and the lower Pterospathodus amorphognathoides amorphognathoides Superzone, with an increase of ca. 2‰ in δ13Ccarb and ca. 5‰ in δ13Corg. Well-bracketed by conodont biostratigraphy, the Manitowoc CIE is an essential tie-point for correlation between the Baizitian succession and the Telychian strata of Baltica and Laurentia. Our new δ13Ccarb and δ13Corg data imply that the carbon isotope excursion previously recognized as the ‘Ireviken Excursion’ (Early Sheinwoodian Carbon Isotope Excursion) at Baizitian should be revised as being the Manitowoc CIE. The Δ13C data presented in this study further suggest a slight concurrent drop of atmospheric CO2, and thus add evidence for a perturbation of the global carbon cycle during the middle Telychian. Based on the combined information from the conodont apatite oxygen isotope records from Estonia and the significant stratigraphic gaps recognized at the Baizitian section, we propose that the latter stratigraphic gaps should correlate with the Telychian Valgu and the early Sheinwoodian glaciation.
CRIS-Team Scopus Importer:2022-10-07
Keywords: Conodont biostratigraphy; Manitowoc Icehouse; Sheinwoodian glaciation; Silurian climate; Stable isotope chemostratigraphy; Valgu glaciation

The reefs of the Arctic - photoautotrophic ecosystem engineers endangered by microplastic and climate change? - Teichert, Sebastian; Löder, Martin; Laforsch, Christian; Pyko, Ines Anna; Schulbert, Christian; Wisshak, Max (The Arctic Biodiversity Congress, 2018)
Large areas of the Svalbard shelf are covered by rhodoliths, coralline red algal structures which form a rigid framework of magnesium calcite. They act as ecosystem engineers, comparable to corals in tropical regions. Additionally, many rhodoliths are gouged by boring mussels and become hollow ecospheres which are intensely colonised by benthic organisms. The existence of both, solid and hollow rhodoliths has a significant impact on local biodiversity. However, this special ecosystem is threatened by the contamination with microplastic. We detected eight different types of microplastic within the bodies of the boring mussels, whereof polystyrene is the most common. If the particles are harmful to the mussels, their future role as niche providers is endangered and the consistency of the whole community is doubtful. Furthermore, we could show that the rhodoliths themselves are endangered by climate change in terms of increased glacial runoff, as coverage with sediments and reduced transparency of the water column are significantly impairing the growth conditions of the rhodoliths. This twofold environmental deterioration will have unpredictable consequences for the associated organisms. This special but extensive ecosystem plays a crucial role on Svalbard’s shelf biodiversity and should be included in future policy recommendations and strategic plans for biodiversity.<br

The relationship between the age of the lithosphere and the composition of oceanic magmas: Constraints on partial melting, mantle sources and the thermal structure of the plates. - Haase, Karsten (Earth and Planetary Science Letters, 1996)
On the basis of different proportions and chemical compositions of shield and post-shield magmas, three types of oceanic intraplate volcanism appear to exist. The average SiO2 contents of primitive melts of most Pacific and Atlantic intraplate lavas show a regular decrease with increasing age of the lithosphere up to 70 Ma. The average pressures of melting of most magmas lie beneath the thermal boundary layer defined by the 1300°C isotherm, in accordance with geophysical models. The average melting pressures of shield tholeiites erupting at the largest hotspots on Earth suggest that erosion of the plate is restricted to strong plumes. Increasing average ratios of (Ce/Yb)N(=chondrite-normalized) and (Tb/Yb)N with increasing age of the lithosphere imply that residual garnet has an increasing influence on the melting of most magmas. An influence of MORB material in intraplate magmas is observed in volcanoes erupting on lithosphere younger than 15 Ma. Correlations between SiO2 and the rare earth element ratios suggest that the rare earth elements are more strongly influenced by the pressure of melting than by differences in source composition. Lavas with extremely low 143Nd/144Nd (e.g. Gough-Tristan da Cunha) have high (Nd/Sm)N for a given SiO2, in accordance with a long-term enriched mantle source. After a correction for the fractionation occurring at high melting pressures (a recalculation of all averages to 50% SiO2,) the (Nd/Sm)N of most lavas can be modeled by 3-15% melting of depleted mantle sources.
UnivIS-Import:2015-03-05:Pub.1996.nat.dgeo.IGM.legeo.therel
Keywords: Hot spots; Lithosphere; Partial melting; Rare earth elements; Silica

The relationship between the landslide frequency and hydrogeological aspects: a case study from a hilly region in Northern Bavaria (Germany) - Wiedenmann, Johannes; Moser, Michael; Rohn, Joachim (Environmental Earth Sciences, 2016)
Keywords: Bavaria; Ground truth; Hydrogeological aspects; Landslides

The relationship between the spectral diversity of satellite imagery, habitat heterogeneity, and plant species richness - Warren, Steven D.; Alt, Martin; Olson, Keith D.; Irl, Severin D. H.; Steinbauer, Manuel; Jentsch, Anke (Ecological Informatics, 2014)
Keywords: Biodiversity; Heterogeneous disturbance; IKONOS; Plant diversity; Remote sensing

The relationships between volcanism, tectonism, and hydrothermal activity on the Southern Equatorial Mid-Atlantic Ridge - Devey, Colin; German, Christopher; Haase, Karsten; Lackschewitz, Klas; Melchert, Bernd; Connelly, Douglas (Diversity of Hydrothermal Systems on Slow Spreading Ocean Ridges, 2010)
The Mid-Atlantic Ridge south of the equator is a key region for many aspects of spreading axis studies, from biogeography to ridge-hotspot interaction. Despite this, the ridge axis had, until 2004, seen little systematic study. Repeated trips to the area since then have mapped and explored some 900 km of ridge length, from 2° to 14°S. The result is complete bathymetric and side-scan coverage of the axialregion and the discovery and characterization of the first hydrothermal vents southof the equator. Such multisegment detailed and interdisciplinary coverage allows us to formulate a general model for the interplay between volcanism, tectonics,and hydrothermalism on a slow spreading ridge. The model defines three basic types of ridge morphology with specific hydrothermal characteristics: (a) a deep,tectonically dominated rift valley where hydrothermalism is seldom associatedwith volcanism and much more likely confined to long-lived bounding faults; (b)a shallower, segment-center bulge where a combination of repeated magmatic activity and tectonism results in repeated, possibly temporally overlapping periodsof hydrothermal activity on the ridge axis; and (c) a very shallow axis beneathwhich temperatures in all but the uppermost crust are so high that deformation is ductile, inhibiting the formation of high-porosity deep fractures and severely depressing hydrothermal circulation. This model is used together with satellite- derived predicted bathymetry to provide forecasts of the best places to look for hydrothermal sites in the remaining unexplored regions of the South Atlantic.
UnivIS-Import:2015-03-09:Pub.2009.nat.dgeo.IGM.legeo.therel

The Relationships Between Volcanism, Tectonism, and Hydrothermal Activity on the Southern Equatorial Mid-Atlantic Ridge - Devey, Colin; German, Chris; Haase, Karsten; Lackschewitz, Klas; Melcher, Bernd; Connelly, Douglas (wiley, 2013)
The Mid-Atlantic Ridge south of the equator is a key region for many aspects of spreading axis studies, from biogeography to ridge-hotspot interaction. Despite this, the ridge axis had, until 2004, seen little systematic study. Repeated trips to the area since then have mapped and explored some 900 km of ridge length, from 2° to 14°S. The result is complete bathymetric and side-scan coverage of the axial region and the discovery and characterization of the first hydrothermal vents south of the equator. Such multisegment detailed and interdisciplinary coverage allows us to formulate a general model for the interplay between volcanism, tectonics, and hydrothermalism on a slow spreading ridge. The model defines three basic types of ridge morphology with specific hydrothermal characteristics: (a) a deep, tectonically dominated rift valley where hydrothermalism is seldom associated with volcanism and much more likely confined to long-lived bounding faults; (b) a shallower, segment-center bulge where a combination of repeated magmatic activity and tectonism results in repeated, possibly temporally overlapping periods of hydrothermal activity on the ridge axis; and (c) a very shallow axis beneath which temperatures in all but the uppermost crust are so high that deformation is ductile, inhibiting the formation of high-porosity deep fractures and severely depressing hydrothermal circulation. This model is used together with satellitederived predicted bathymetry to provide forecasts of the best places to look for hydrothermal sites in the remaining unexplored regions of the South Atlantic.
Keywords: Atlantic; Chemical oceanography; Hydrothermal deposits; Hydrothermal vents; Hydrothermalism; Sea-floor spreading; Spreading; Tectonics; Volcanism

The remarkable record of mustelids from Hunas (Bavaria, Germany) Le remarquable signalement des mustélidés de Hunas (Bavière, Allemagne) - Marciszak, Adrian; Hilpert, Brigitte; Ambros, Dieta Carola (Comptes Rendus Palevol, 2024)
The mustelid assemblage from Hunas is represented by seven species: Gulo gulo gulo (Linnaeus, 1758), Meles meles (Linnaeus, 1758), Lutra lutra groissii Heller, 1983, Martes martes (Linnaeus, 1758), Mustela putorius Linnaeus, 1758, Mustela erminea Linnaeus, 1758 and Mustela nivalis Linnaeus, 1766. Most species have been found in the G1-G3 complex, while their remains in other layers are rare. The guild is dominated by remains of Mustela nivalis, for which well-preserved and stratified material shows a large, robust weasel, with a notable predominance of males. The morphology of Mustela nivalis, together with the occurrence of Lutra lutra (Linnaeus, 1758), allowed us to estimate the age of the horizon at MIS 7.
CRIS-Team Scopus Importer:2024-09-27
Keywords: assemblage; biochronology; Morphology; paleobiology

The retarding effect of phosphoric acid during CAC hydration - Manninger, Tanja; Jansen, Daniel; Neubauer, Jürgen; Götz-Neunhoeffer, Friedlinde (Cement and Concrete Research, 2019)
The hydration of CA-cement under the influence of low concentrations of phosphoric acid was investigated. The research was focused on the developing phase content and phase equilibria by QXRD and pore water analysis. To obtain a quantitative phase content the G-Factor method was employed, which was established and applied in the last years for different cementitious systems. Pore water extraction was enforced through centrifugation of cement paste and by high pressure squeezing of cement stone. Data could be obtained up to 48 h. The overall heat flow during this time was also recorded by heat flow calorimetry. We found strong influence of phosphoric acid on the pore water composition and thus determining the initially and later formed hydrate phases. The theoretical data of oversaturated phases from thermodynamic point of view were compared to the actual phases detected by QXRD.
CRIS-Team Scopus Importer:2019-05-16
Keywords: Calcium aluminate cement (D); Pore solution (B); Retardation (A); Thermodynamic calculations (B); X-ray diffraction (B)

The Return of Fossils Removed Under Colonial Rule - Dunne, Emma; Raja Schoob, Nussaibah Begum; Stewens, Paul (2022)
Debates on the restitution of colonial loot usually focus on art, antiquities, religious artefacts, and similar objects. Many fossils of considerable scientific and cultural value were also removed under colonial rule, yet they rarely feature in these discussions despite being classified as cultural objects. This article seeks to shed light on the colonial removal of fossils and explore potential avenues for their return under public international law. Instead of focusing on the (il-)legality of colonial takings, we argue that the right to access culture has developed from the right to participate in cultural life in Article 15(1)(a) of the International Covenant on Economic, Social and Cultural Rights (ICESCR), which provides, if not a solid legal basis, a valuable set of arguments for former colonies requesting the return of fossils looted from their countries/territories of origin. The case study of the negotiations on the return of the Broken Hill skull before the UNESCO Intergovernmental Committee for Promoting the Return of Cultural Property to its Countries of Origin or its Restitution in Case of Illicit Appropriation (ICPRCP) highlights the potential of this mechanism of dispute resolution with respect to fossils. <br

The Rhodope Zone as a primary sediment source of the southern Thrace basin (NE Greece and NW Turkey): evidence from detrital heavy minerals and implications for central-eastern Mediterranean palaeogeography - Caracciolo, Luca; et al. (International Journal of Earth Sciences, 2015)
Keywords: Biga Peninsula; Circum-Rhodope Belt; Cr-spinel geochemistry; Detrital heavy minerals; Sediment provenance; Thrace basin

The Rio Sassito sedimentary succession (Ordovician): A pinpoint in the geodynamic evolution of the Argentine Precordillera - Keller, Martin; Lehnert, Oliver (Geologische Rundschau, 1998)
Keywords: Argentine Precordillera; Ordovician; Conodont biostratigraphy; Temperate-water carbonates; Paleogeography

Thermal and Thermomechanical Performance of Energy Piles with Double U-Loop and Spiral Loop Heat Exchangers - Luo, Jin; Zhang, Qi; Zhao, Haifeng; Gui, Shuqiang; Xiang, Wei; Rohn, Joachim; Soga, Kenichi (Journal of Geotechnical and Geoenvironmental Engineering, 2019)
This study investigates the thermal and thermomechanical behavior of two energy piles with either double U-loop or spiral loop heat exchanger configurations. The piles were installed in a sandstone formation, and a heating-recovery-cooling-recovery cycle was applied to the piles. In both piles, the shaft resistance evaluated from the measured axial-strain distributions was greater in the heating mode than that in the cooling mode. In the heating model, radial expansion was detected. The radial stress at the pile-soil interface increased due to the high stiffness of the sandstone, which in turn increased the shaft friction. In the cooling stage, the radial contraction of the pile was measured, which in turn decreased the radial stress at the pile-soil interface. The amount of pile contraction was similar to the thermally induced free contraction, and consequently large pile settlement was measured at the top of the pile during cooling. The normalized heat-transfer rate shows similar thermal efficiency between heating and cooling, indicating the heat transfer was not much affected by the radial expansion and contract of the piles.
CRIS-Team Scopus Importer:2019-10-08
Keywords: Energy piles; Expansion and contraction; Heat-transfer performance; Heating and cooling stages; Thermally induced deformation

Thermal efficiency comparison of borehole heat exchangers with different drillhole diameters - Luo, Jin; Bayer, Manfred; Prieß, Anna; Rohn, Joachim (Energies, 2013)
Keywords: Borehole Heat Exchanger; Drillhole Diameter; Ground Source Heat Pump System; Thermal Efficiency

Thermal Efficiency Optimization of a Ground Source Heat Pump System by Assistant Preheating/Precooling: A Case Study on a Heating-Load Dominated Building - Luo Jin,; Zhang Qi,; Prieß, Anna; Rohn, Joachim (Journal of Thermal Science, 2022)
Operation strategies of Ground Source Heat Pump System (GSHPS) such as continuous or intermittent approaches have been extensively studied. In this work, a novel strategy was proposed to maximize the energy efficiency of GSHPS. In this approach, the buildings was first air-conditioned by the preheating/precooling mode and the rest thermal load was covered by the heat pump (HP) mode. The system performance can then be optimized by considering the combination of these two operating modes. A case study was made to examine the thermal performance of a GSHPS installed in Nuremberg, Germany. Thermal performance of the HP and the preheating/precooling operating modes was examined. The system was optimized by deploying the assistant preheating/precooling approach and over one-year period monitoring showed that the seasonal Coefficient of Performance (COP) of the GSHPS was 4.12 in winter and 5.01 in summer. These COP values are higher than that of the conventional GSHPS. Thus, this proposed strategy could be an efficient way to improve the thermal performance of GSHPS.
CRIS-Team WoS Importer:2022-09-09

Thermal maturity of Cambrian to Devonian rocks of northeastern Ellesmere Island - Harrison, J. C.; Nowlan, Godfrey; Lehnert, Oliver (Bulletin of the Geological Survey of Canada, 2008)

Thermal performance and economic evaluation of double U-tube borehole heat exchanger with three different borehole diameters - Luo, Jin; Bayer, Manfred; Prieß, Anna; Rohn, Joachim (Energy and Buildings, 2013)
Keywords: Borehole diameter; Borehole heat exchanger; Economic profitability; Ground source heat pump system; Saving-to-investment ratio (SIR); Thermal performance

Thermal plume dispersion induced by shallow geothermal applications: the case study of Villaverla (Italy) - Galgaro, Antonio; Cultrera, Matteo; Boaga, Jacopo; Dalla Santa, Giorgia; Di Sipio, Eloisa (EGC 2016- European Geothermal Congress Proceedings, 2016)
Keywords: thermal plume; shallow geothermal energy; thermal conductivity; heat flow; Electrical Resistivity Tomography; FEM modelling; Distributed Temperature Sensing

Thermal Response Testing Results of Different Types of Borehole Heat Exchangers: An Analysis and Comparison of Interpretation Methods - Zarrella, Angelo; Emmi, Giuseppe; Graci, Samantha; de Carli, Michele; Cultrera, Matteo; Dalla Santa, Giorgia; Galgaro, Antonio; Bertermann, David; Müller, Johannes; Pockelé, Luc; Mezzasalma, Giulia; Righini, Davide; et al. (Energies, 2017)
Keywords: Geologie; erneuerbare Energiequelle

Thermal Soil Clustering - Mapping variations of thermal conductivity for high-voltage underground power lines - Bertermann, David; Schwarz, Hans; Müller, Johannes; Iancu, Viktor; Stegner, Johannes (Geophysical Research Abstracts Vol. 20, 2018)
Germany has set itself the ambitious objective that until 2050 at least 80% of the national power supply should be fed by renewable energies. Thus, a profound instauration of the country’s power grid is obligatory and new power lines have to be constructed. Due to decisive heat emission of the live wire exigent requirements concerning characteristics of the surrounding soil need to be modeled and documented. Heat transport mechanisms in soils are, among the influence of bulk density, mineral and organic constituents and their temperature, tightly coupled to their water content. This natural water content depends strongly i.a. on the characteristic water retention, which is a function of a location’s soil type and climatic conditions. This investigation has to be performed along potential corridors for the construction of new power lines. To serve this purpose, an extensive GIS database was elaborated, incorporating various climate and soil parameters from the affected federal states’ agencies for an area of approximately 3100 km². In general, the systemically important parameters are extracted from soil maps and drilling protocols. For incorporating the federal system’s mostly inhomogeneous data, manual synchronization of the data for the expanse of the proposed corridors is necessary. Within GIS all gathered basic digital data has to be incorporated in various processes for deriving formula inlet parameters like bulk density, water content, thermal conductivity or climate water budget. Aim of the project is to generate relevant soil parameters such as thermal conductivity, susceptibility to compaction and diggability throughout the whole corridor area. Subsequently, the acquired data has to be modeled and mapped, which enables a proper soil assessment along the corridors. As a result, well-founded derived information for assistance during the planning and construction phase concerning locally adequate constructional aspects ought to be provided. This includes soil conserving construction measures, required cable diameters, as well as trench shoring systems or need for imported backfill material. Based on the project’s aim an extensive pedological transect, included and processed within a GIS architecture, is generated. <br

Thermite Reactions within Liquid Gallium/Iron Oxide Supraparticles Triggered Via Induction Heating - Raczka, Theodor; Groppe, Philipp; Hurle, Katrin; Moritz, Michael; Papp, Christian; Mandel, Karl; Wintzheimer, Susanne (ACS Applied Nano Materials, 2025)
Thermite reactions are well-known for mixtures of aluminum and iron oxide. However, other reactive metals, such as gallium, were not studied in this application, and the use of induction as an external trigger for the thermite reaction has not been established. In this work, supraparticles of gallium and iron oxide nanoparticles were synthesized to combine a low melting point with inductive heating properties. The enabled thermite-like redox reactions generate temperatures up to 900 °C within seconds in an alternating magnetic field, tunable by the material’s gallium content. Induction heating profiles are thus significantly expanded and could be applied for targeted heat-on-demand.
CRIS-Team Scopus Importer:2025-05-23
Keywords: gallium nanoparticles; induction heating; iron oxide nanoparticles; spray-drying; supraparticles; thermite

Thermochemical anomalies in the upper mantle control Gakkel Ridge accretion - O'Connor, John; Jokat, Wilfried; Michael, Peter J.; Schmidt-Aursch, Mechita C.; Miggins, Daniel P.; Koppers, Anthony A. P. (Nature Communications, 2021)
Despite progress in understanding seafloor accretion at ultraslow spreading ridges, the ultimate driving force is still unknown. Here we use 40Ar/39Ar isotopic dating of mid-ocean ridge basalts recovered at variable distances from the axis of the Gakkel Ridge to provide new constraints on the spatial and temporal distribution of volcanic eruptions at various sections of an ultraslow spreading ridge. Our age data show that magmatic-dominated sections of the Gakkel Ridge spread at a steady rate of 11.1 ± 0.9 mm/yr whereas amagmatic sections have a more widely distributed melt supply yielding ambiguous spreading rate information. These variations in spreading rate and crustal accretion correlate with locations of hotter thermochemical anomalies in the asthenosphere beneath the ridge. We conclude therefore that seafloor generation in ultra-slow spreading centres broadly reflects the distribution of thermochemical anomalies in the upper mantle.
CRIS-Team Scopus Importer:2021-12-10

Thermodynamic prediction of complex hydration processes and verification by experiments for the Ca-Al-C (CA, calcite, water) and Ca-Al-S (ye'elimite, gypsum, water) systems - Jansen, Daniel; Lothenbach, Barbara (Cement and Concrete Research, 2023)
The solubility of relevant phases in the calcium aluminate cements with limestone and in calcium sulfoaluminate cements with gypsum indicate several potential phase assemblages which might be formed during hydration. Thermodynamic calculations and pore solution data indicate that initially the solution is oversaturated with respect to several phases and thermodynamically metastable phase combinations may form. Some initially formed metastable phase assemblages contain more phases than predicted by the Gibbs phase rule and gain less Gibbs free energy than the stable phase assemblage. Solubility curves are used to define potential phase assemblages, the associated potential Gibbs free energy gain, to plot possible kinetic paths and to evaluate their respective probability. If different kinetic paths are conceivable, the reaction occurs along the solubility of the initially formed stable phases, namely monocarbonate in the calcium aluminate and ettringite in calcium sulfoaluminate system.
CRIS-Team Scopus Importer:2024-12-16
Keywords: Calcium aluminate; Calcium sulfoaluminate; Hydration; Solubilities; Thermodynamics

Thermo-economic analysis of borehole heat exchangers (BHE) grouted using drilling cuttings in a dolomite area - Luo, Jin; Xue, Wei; Hu, Tao; Xiang, Wei; Rohn, Joachim (Applied Thermal Engineering, 2019)
One major barrier to the application of ground source heat pump (GSHP) systems is linked to the high installation costs of borehole heat exchanger (BHE). Therefore, it is of crucial importance to reduce the costs of BHEs by maintaining high thermal efficiency. In this paper, thermo-economic performance of BHEs grouted using drilling cuttings mixtures in a dolomite area is studied. Thermal conductivity for the drilling cuttings with bentonite and cement mixtures was measured and the mixture ratio was optimized. Four thermal response tests (TRTs) were implemented in the field to determine the borehole thermal properties. Results show that the BHEs grouted using drilling cuttings reach the same heat transfer efficiency than those BHEs grouted by silicate sand or concrete. Furthermore, a case study is made to evaluate the economic performance of 566 BHEs with different grouting alternatives of a GSHP system. Compared to the materials of concrete and bentonite-quartz mixtures, 14.87% and 17.16% of BHE installation costs can be saved using the dolomite drilling cuttings. Thus, drilling cuttings grouted BHEs have a high thermo-economic performance for GSHP systems application in dolomite areas.
CRIS-Team WoS Importer:2019-04-12

Thermo-economic analysis of four different types of ground heat exchangers in energy piles - Luo, Jin; Zhao, Haifeng; Gui, Shuqiang; Xiang, Wei; Blum, Philipp; Rohn, Joachim (Applied Thermal Engineering, 2016)
Keywords: Economic performance; Energy piles; Ground heat exchanger; Thermal efficiency

The role of climate on the emergence of giant caimanines (Crocodylia, Alligatoroidea) from the Miocene western Amazonian region - Paiva, Ana Laura S.; Godoy, Pedro L.; Dunne, Emma; Farnsworth, Alexander; Valdes, Paul J.; Lunt, Daniel J.; Klein, Wilfried; Langer, Max C.; Hsiou, Annie S. (Palaeogeography, Palaeoclimatology, Palaeoecology, 2024)
Extant caimanines include the six modern species of caimans, which occur predominantly in South and Central America and are mostly medium-sized crocodylians. Nevertheless, the fossil record of the group reveals a significantly higher diversity, with remarkable body size variation. In particular, the giants Purussaurus and Mourasuchus, from the Miocene western Amazonian region, are two of the most prominent representatives. Previous work has demonstrated a correlation between the body size of crocodylians and abiotic factors throughout the Cenozoic; however, this relationship is poorly understood, particularly within the Caimaninae lineage. Here, we explore evolutionary body size patterns within Caimaninae, investigating the potential influence of climatic factors. Using a phylogenetically-informed method, we estimated the body size of 33 caimanine specimens, coupled with climatic variables from a General Circulation Model to reconstruct deep-time patterns. Our results indicate that giant Miocene caimanines are restricted to warmer conditions, with significantly less seasonal temperature variation. This suggests that the unmatching climatic conditions of the Miocene western Amazonian region possibly allowed the emergence of unique palaeoecosystems, favouring the sustenance of these very large crocodylians.
CRIS-Team Scopus Importer:2024-11-15
Keywords: Ancestral states; Body size evolution; Climate reconstruction; Crocodylia; Gigantism

The role of diagenesis and depositional facies on pore system evolution in a Triassic outcrop analogue (SE Spain) - Caracciolo, Luca; et al. (Marine and Petroleum Geology, 2014)
Keywords: Diagenesis; Fluvial facies; Outcrop analogue; Pore system; TAGI; Triassic

The role of extinction in large-scale diversity-stability relationships - Simpson, Carl; Kießling, Wolfgang (Proceedings of the Royal Society of London, Series B: Biological Sciences, 2010)
More-diverse communities are thought to be ecologically stable because a greater number of ecological interactions among members allows for the increases in robustness and resilience. Diversity - stability relationships have mostly been studied on short ecological time scales but one study has identified such patterns over million-year time scales in reef communities. Here we propose and test a hypothesis for the mechanism of large-scale diversity - stability relationships in reefs. The extinction of community members destabilizes the community as a whole, unless there is sufficient diversity to buffer the community from the stochastic loss of members, thereby preventing collapse. If genera have high extinction rates, any variation in diversity among communities will result in a diversity-stability relationship. Conversely, in the absence of other mechanisms, the stability of low extinction communities is expected to be independent of diversity. We compare the extinction rates of six reef-building metazoan taxa to patterns of reef community stability and reef volume. We find that extinction of reef-builders occurs independent of reef volume, and that the strength of the diversity-stability relationship varies positively with extinction rate. © 2009 The Royal Society.
UnivIS-Import:2015-03-09:Pub.2010.nat.dgeo.IGM.LP.therol
Keywords: Coloniality; Corals; Diversity-stability relationship; Extinction; Reefs

The role of groundwater in CO2 production and carbon storage in Mediterranean peatlands: An isotope geochemistry approach - Santoni, S.; Garel, E.; Gillon, M.; Babic, M.; Spangenberg, J. E.; Bomou, B.; Sebag, D.; Adatte, T.; van Geldern, Robert; Pasqualini, V.; Mattei, A.; Huneau, F. (Science of the Total Environment, 2023)
Peatlands are permanent wetlands recognized for ecosystem services such as biodiversity conservation and carbon storage capacity. Little information is available about their response to global change, the reason why most Earth system climate models consider a linear increase in the release of greenhouse gases (GHG), such as CO2, with increasing temperatures. Nevertheless, numerous studies suggest that an increase in the temperature may not imply a decrease in photosynthesis and carbon storage rates if water availability is sufficient, the latter being under the control of local hydrology mechanisms. Mediterranean peatlands well illustrate this fact. Since they are groundwater-dependent, they are hydrologically resilient to the strong seasonality of hydroclimatic conditions, especially during the summer drought. In the present study, we demonstrate that, even if such peatlands release CO2 into the atmosphere, they can maintain a carbon storage capacity. To this end, a geochemical study disentangles the origin and fate of carbon within a Mediterranean peatland at the watershed scale. Field parameters, major ions, dissolved organic and inorganic carbon content and associated δ13C values allow for characterizing the seasonality of hydrochemical mechanisms and carbon input from an alluvial aquifer (where rain, river, shallow, and deep groundwater flows are mixing) to the peatland. The inorganic and organic content of peat soil and δ13C values of total organic matter and CO2 complete the dataset, making it possible to provide arguments in favour of lower organic matter oxidation compared to primary production. Overall, this study highlights the groundwater role in the fluxes of CO2 at the peatland-atmosphere interface, and more broadly the need to understand the interactions between the water and carbon cycles to build better models of the future evolution of the global climate.
CRIS-Team Scopus Importer:2023-01-20
Keywords: Groundwater-dependent ecosystem; Origin of carbon; Peatland-atmosphere interface; Peatland‑carbon-water system; Sources and sinks of carbon

The role of liberation lagerstätten as windows into past biodiversity - Roden, Vanessa; Hausmann, Imelda M.; Nützel, Alexander; Seuß, Barbara; Reich, Mike; Urlichs, Max; Hagdorn, Hans; Kießling, Wolfgang (PaleoBios 36 (Supplement 1), 2019)

The role of siliciclastics in carbonate fabric diversity and preservation: A case study from the Neoproterozoic carbonate – siliciclastic Horse Thief Springs Formation, Death Valley - Smrzka, Daniel; Kuzel, K.; Chiarella, D.; Joachimski, Michael; Vandyk, T.; Kettler, C.; Le Heron, D. P. (Sedimentology, 2022)
The sedimentary record of the Pahrump Group in Death Valley comprises well-exposed successions of mixed carbonate and siliciclastic deposits. Despite the abundance of studies focussing on the depositional dynamics of mixed carbonate – siliciclastic deposition in the Phanerozoic, the record of similar Proterozoic examples is comparatively sparse. Using high-resolution stratigraphy and microfacies analyses, this study investigates the Tonian Horse Thief Springs Formation within the Pahrump Group of Death Valley, California, in order to propose first-order constraints on the interplay between carbonate and siliciclastic deposition in the early Neoproterozoic. The mixed successions are unlike many previously studied examples interpreted as being caused by glacio-eustatic sea-level changes, thus arguing for a more relevant tectonic influence on siliciclastic deposition. This interpretation is supported by detailed microfacies analyses of siliciclastic-rich dolostones, which show abundant soft-sediment deformation features suggesting sudden pulses of sandstone deposition onto a shallow marine carbonate shelf. The Tonian carbonate factory recovered quickly after being smothered by siliciclastics, particularly due to abundant stromatolite growth. A new relationship between siliciclastic input, carbonate fabric diversity, and carbonate preservation is established based on microfacies analyses, putting forward that siliciclastic deposition had a significant impact on the formation and preservation of later-stage diagenetic dolomite cements, as well as on stromatolite morphology and carbonate fabric diversity within the microbialites. This study shows how repeated siliciclastic incursions had a significant impact on the Proterozoic carbonate factory of the Horse Thief Springs Formation, as well as on diagenetic modification and preservation of shallow marine carbonates, and establishes previously unexplored relationships between carbonate and siliciclastic strata in the Proterozoic.<br

The r package divDyn for quantifying diversity dynamics using fossil sampling data - Kocsis, Ádám; Reddin, Carl James; Alroy, John; Kießling, Wolfgang (Methods in Ecology and Evolution, 2019)
Unbiased time series of diversity dynamics are vital for quantifying the grand history of life. Applications include identifying ancient mass extinctions and inferring both biotic and abiotic controls on diversification rates. We introduce divDyn, a new r package that facilitates the calculation of taxonomic richness, extinction and origination rates from time-binned fossil data. State-of-the-art counting protocols, and sampling standardization functions permit the reconstruction of biologically meaningful time series. Additional functions permit the partitioning of turnover rates by environmental affinity. Using divDyn, we display Phanerozoic-scale diversity dynamics of marine invertebrates. With the help of the core function and standard subsampling options, we revisit the hypothesis of declining taxonomic rates over time, mass extinctions and equilibrial diversity dynamics and assess their methodological dependency. Our results suggest that rates declined only over the early Phanerozoic, only three mass extinctions stand out clearly, and evidence of equilibrial dynamics is dependent on the used methods. The modular and fast implementation of published methods ensures traceability, reproducibility and comparability of future studies.
CRIS-Team Scopus Importer:2019-05-02
Keywords: diversity dynamics; extinction; fossil record; origination; Palaeobiology Database; subsampling

The scaling law of climate change and its relevance to assessing (palaeo)biological responses - Kießling, Wolfgang; Eichenseer, Kilian (EGU General Assembly Conference Abstracts, 2014)
It is often argued that current rates of climate change are unprecedented in the geological past. At the same time,the magnitudes of change were often much greater in deep time than they are in history. The most severe globalwarming in the Phanerozoic, with dramatic consequences for life, probably occurred across the Permian-Triassic (P-T) boundary when an increase of tropical water temperatures of 15 ̊C has been observed to occur over a timespan 0.8 myr (Sun et al. 2012), whereas global ocean warming over the last 50 years was 0.35 ̊C (Burrows et al. 2011). When transforming these data into rates of change the P-T rate was roughly 370 times smaller than the currentrate. We argue that the smaller rates of change inferred from geological proxy records are due to a scaling effect,that is, rates of climate change generally decrease with timespan of observation. We compiled from the published literature data on measured or inferred temperature changes and the timespansover which these changes were assessed. Our compilation currently comprises 120 values and covers timespansfrom 20 to 107years. A log-log plot of timespan versus rate of temperature change depicts a highly significantcorrelation (r2= 0.95) of a power-law relationship with an exponent of -0.87. Warming trends show a slightlylower exponent (-0.84) than cooling trends (-0.89) but the explained variance is better for the scaling of warmingtrends. Importantly, the scaled warming trend across the P-T boundary is higher than the current rates of warming. Similar scaling effects are well explored for sediment accumulation rates (Sadler 1981) and evolutionary rates(Gingerich 1993). These have been interpreted as being due to breaks in sedimentation and periods of stasis ortransient reversals, respectively. In case of climate change, transient reversals in general trends are the most likelyexplanation for the scaling relationship. Even relatively rapid intervals of warming, such as the Pleistocene inter-glacials, are not monotonic, but punctuated by short-term cooling intervals. The fossil record tells us that biodiversity responded dramatically to ancient intervals of climate warming. We cannow see that the apparently slower rates of change in some mass extinctions (Permian-Triassic, Triassic-Jurassic)were greater than today when the scaling law is considered. This reassures us that studying deep time patterns oforganismic response to climate change is a worthwhile endeavor that is relevant for predicting the future. References Burrows, M. T., Schoeman, D. S., Buckley, L. B., Moore, P., Poloczanska, E. S., Brander, K. M., Brown, C., Bruno,J. F., Duarte, C. M., Halpern, B. S., Holding, J., Kappel, C. V., Kiessling, W., O’Connor, M. I., Pandolfi, J. M.,Parmesan, C., Schwing, F. B., Sydeman, W. J., and Richardson, A. J.: The pace of shifting climate in marine andterrestrial ecosystems, Science, 334, 652-655, 2011. Gingerich, P. D.: Quantification and comparison of evolutionary rates, American Journal of Science, 293A, 453-478, 1993. Sadler, P. M.: Sediment accumulation rates and the completeness of stratigraphic sections, Journal of Geology, 89,569-584, 1981. Sun, Y., Joachimski, M. M., Wignall, P. B., Yan, C., Chen, Y., Jiang, H., Wang, L., and Lai, X.: Lethally hottemperatures during the Early Triassic greenhouse, Science, 338, 366-370, 201

The sedimentary and structural evolution of the Argentine Precordillera - the key of the history of an exotic terrane. - Buggisch, Werner; Bordonaro, Oswaldo; Cañas, Fernando; von Gosen, Werner; Keller, Martin; Krumm, Stefan; Lehnert, Oliver; Loske, Werner (Zeitschrift für Angewandte Geologie, 2000)
UnivIS-Import:2015-03-09:Pub.2000.nat.dgeo.IGM.LG.thesed_2

The sediment composition and predictive mapping of facies on the Propeller Mound-A cold-water coral mound (Porcupine Seabight, NE Atlantic) - Heindel, Katrin; Titschack, Jürgen; Dorschel, Boris; Huvenne, Veerle A.I.; Freiwald, André (Palaeogeography, Palaeoclimatology, Palaeoecology, 2017)
Here we provide a detailed qualitative and quantitative insight on recent sediment composition and facies distribution of a cold-water coral (CWC) mound using the example of the Propeller Mound on the Irish continental margin (Hovland Mound Province, Porcupine Seabight). Five facies types on Propeller Mound are defined: (1) living coral framework, (2) coral rubble, (3) dropstone, (4) hardground, representing the on-mound facies, and (5) hemipelagic sediment facies, which describes the off-mound area. This facies definition is based on already published video-data recorded by Remotely Operated Vehicle (ROV), photo-data of gravity cores, box cores, and dredges from sediment surfaces as well as on the composition of the sediment fraction coarser than 125 μm, which has been analyzed on five selected box cores. Sediment compositions of the living coral framework and coral rubble facies are rather similar. Both sediment types are mainly produced by corals (34 and 35 wt%, respectively), planktonic foraminifers (22 and 29 wt%, respectively), benthic foraminifers (both 7 wt%), and molluscs (21 and 10 wt%, respectively), whereas the living coral framework characteristically features additional brachiopods (6 wt%). Hardgrounds are well-lithified coral rudstones rich in coral fragments (>30 surf%), foraminifers, echinoderms, and bivalves. The dropstone facies and the hemipelagic sediment typically carry high amounts of lithoclasts (36 and 53 wt%, respectively) and planktonic foraminifers (35 and 32 wt%, respectively); however, their faunal diversity is low compared with the coral-dominated facies (12 and <2 wt% coral fragments, 7 and 6 wt% benthic foraminifers, and 4 and 0 wt% balanids). Using the maximum likelihood algorithm within ArcGIS 9.2, spatial prediction maps of the previously described mound facies are calculated over Propeller Mound and are based on mound morphology parameters, ground-truthed with the sedimentary and faunal information from box cores, photographs, and video-data. This method is tested for the first time for CWC ecosystems and provides areal estimates of the predicted facies, as well as suggests further occurrences of living coral frameworks, coral rubble, and dropstones, which are not discovered in the area yet. Thus, sediment composition analysis combined with facies prediction mapping might provide a potential new tool to estimate living CWC occurrences and sediment/facies distributions on CWC mounds, which is an important prerequisite for budget calculations and definition of marine protected areas, and which will improve our understanding of CWC mound formation.

The Silurian of Gotland - Part I: Review of the stratigraphic framework, event stratigraphy, and stable carbon and oxygen isotope development - Calner, Michael; Jeppsson, Lennart; Munnecke, Axel (Erlanger geologische Abhandlungen, Sonderband 5, 2004)
Keywords: Silurian; Gotland; Carbon isotopes; Oxygen isotopes; stratigraphy

The Silurian transgression of a palaeo-shoreline: the area between Old Radnor and Presteigne, Welsh Borderlands - Ray, David C.; Jarochowska, Emilia; Hughes, Helen E.; Claußen, Anna Lene; Tingley, Arthur C.; Moseley, John; Bremer, Oskar (Lithosphere, 2021)
Quarries between Old Radnor and Presteigne, Welsh Borderlands, expose a Silurian nearshore succession, which onlaps a rocky palaeotopography of Neoproterozoic basement that had been uplifted along the Church Stretton Fault Zone. The succession documents the Aeronian to Sheinwoodian transgression of an island or islands, with the following sequence of events: deposition of shallow-marine sandstones (Folly Sandstone Formation); regional uplift; the preservation of a rocky-shoreline and associated deposits (Dolyhir Rudite Member); deposition of limestones characterised by a profusion of coralline algae and the abundant remains of reefs (Dolyhir and Nash Scar Limestone Formation); and finally the deposition of trilobitic silty-mudstones (basal Coalbrookdale Formation). Facies analysis, carbon isotope (δ13Ccarb) values, sequence stratigraphy and collections of bryozoans, conodonts, thelodonts and trilobites, have been used here as a means of refining our stratigraphic understanding of this unique succession. The revised stratigraphy demonstrates many similarities with the adjoining Midland Platform and the wider Silurian world. Notable features include the globally recognised early Sheinwoodian carbon isotope excursion, and sea-level changes of regional and global extent. As one of the best examples of its kind, the palaeo-shoreline and nearshore succession of Old Radnor and Presteigne acts as a depositional model for ancient rocky shores worldwid

The source of stone building materials from the Pompeii archaeological area and its surroundings. - Kastenmeier, Pia; Di Maio, Giovanni; Balassone, Giuseppina; Boni, Maria; Joachimski, Michael; Mondillo, Nicola (Periodico Di Mineralogia, 2010)
This work is part of a large-scale survey carried out by the Deutsches Archäologisches Institut (DAI) of Berlin, which aim to locate the sources of raw building materials employed throughout various archaeological sites on the Sarno River plain (Pompeii, Nuceria, Stabiae, Longola, etc.) while also reconstructing the paleo-environments of this area during the Olocene. The present paper reports the preliminary results of a multidisciplinary project on the ancient stones used for construction in the town of Pompeii and other archaeological areas nearby (6th century B.C.-A.D.79). The building stones used in these areas (volcanic and sedimentary carbonate rocks) have been analysed for their geological, mineralogical, petrographic and geochemical features and have been compared to rocks cropping out on the Sarno River plain - the possible provenances for these building material. Our data indicate that most of the stones employed for the edifices in Pompeii and other related archaeological sites between 6th century B.C. and A.D. 79 originate from local quarries, mainly situated in several localities on the Sarno River plain itself and in surrounding areas.
UnivIS-Import:2015-03-09:Pub.2010.nat.dgeo.IGM.LG.thesou
Keywords: Ancient Pompeii; Building stones; Limestone; Paleo-environment; Provenances; Sarno River plain; Travertine; Volcanic rocks

The sources for hotspot volcanism in the South Pacific Ocean. - Devey, Colin; Haase, Karsten (Oceanic Hotspots: Intraplate submarine magmatism and tectonism., 2004)
UnivIS-Import:2015-04-20:Pub.2004.nat.dgeo.IGM.legeo.thesou

The Southwest Indian Ocean Bathymetric Compilation (swIOBC) - Dorschel, B.; Jensen, L.; Arndt, J. E.; Brummer, G. J.; de Haas, H.; Fielies, A.; Franke, D.; Jokat, W.; Krocker, R.; Kroon, D.; Pätzold, J.; Schneider, R. R.; et al. (Geochemistry Geophysics Geosystems, 2018)
We present a comprehensive regional bathymetric data compilation for the southwest Indian Ocean (swIOBC) covering the area from 4°S to 40°S and 20°E to 45°E with a spatial resolution of 250 m. For this, we used multibeam and singlebeam data as well as data from global bathymetric data compilations. We generated the swIOBC using an iterative approach of manual data cleaning and gridding, accounting for different data qualities and seamless integration of all different kinds of data. In comparison to existing bathymetric charts of this region, the new swIOBC benefits from nearly four times as many data-constrained grid cells and a higher resolution, and thus reveals formerly unseen seabed features. In the central Mozambique Basin a surprising variety of landscapes were discovered. They document a deep reaching influence of the Mozambique Current eddies. Details of the N-S trending Zambezi Channel could be imaged in the central Mozambique Basin.
Keywords: Bathymetry; Digital bathymetric model; Seafloor; Southwest Indian Ocean

The stability of coastal benthic biogeography over the last 10 million years - Kocsis, Ádám; Reddin, Carl James; Kießling, Wolfgang (Global Ecology and Biogeography, 2018)
Aim We demarcate marine benthic global bioregions based on fossil and recent occurrence data. Our main goal is to compare past and present biogeography and to extract major abiotic drivers of biogeographical patterns. We specifically test the hypothesis that global biogeography has changed markedly after the climatic fluctuations of the past 10 Myr. Location Worldwide. Time period Recent; late Miocene?Pleistocene interval. Major taxa studied Benthic taxa with a rich fossil record: Bivalvia, Brachiopoda, Bryozoa, Gastropoda, Echinodermata, Decapoda and reef corals. Methods We use occurrence data from the Ocean Biogeographic Information System (OBIS) and the Paleobiology Database to construct compositional networks and outline objective marine bioregions of benthic marine invertebrates using the 'infomap' community detection algorithm. We assess the association of modern bioregions with a variety of environmental parameters by applying multivariate statistical analyses, such as principal components analysis, random forests and multiple logistic regressions. Results Recent first-order bioregions for the coastal ocean are, in general, consistent across all taxa. Seawater temperature surpasses nutrients, primary production and salinity as a predictor of modern bioregion distributions. Despite substantial climatic variations, late Cenozoic biogeographical patterns recorded in fossils are very similar to modern ones. Main conclusions Biogeographical boundaries within oceans are strongly controlled by temperature gradients, but open oceanic and continental barriers determine the global biogeographical structure. The joint structure of a landmass distribution, deep ocean basins and the latitudinal temperature gradient defines bioregionalization of the benthic marine habitat, which did not change substantially over the past 10 Myr.
Keywords: global; invertebrates; marine; networks; palaeobiogeography; recent biogeography; temperature

The stratigraphic record of the Argentine Precordillera and its plate-tectonic background - Keller, Martin; Buggisch, Werner; Lehnert, Oliver; et al. (The Proto-Andean Margin of Gondwana, 1998)
UnivIS-Import:2015-04-20:Pub.1998.nat.dgeo.IGM.LG.thestr
Keywords: Argentinien; Präkordillere; Stratigraphie. Terrane

The submarine Azores Plateau: Evidence for a waning mantle plume? - Beier, Christoph; Genske, Felix; Huebscher, Christian; Haase, Karsten; Bach, Wolfgang; Nomikou, Paraskevi (Marine Geology, 2022)
The submarine Azores Plateau in the Central Northern Atlantic has generally been considered to represent a large igneous plateau formed some 10 Ma by widespread volcanism, however a lack of age progression amongst the younger submarine and subaerial volcanism, an irregular distribution of platform-related magmas east and west of the Mid-Atlantic Ridge, a strong tectonic stress regime, and a lack of abundant tholeiitic compositions that reflect initial, high degrees of melting is not easily explainable in the framework of a classic, long-lived mantle plume model. Here, we present new bathymetric and seismic data from the submarine Azores Plateau obtained during cruises M113/1 and M128 with the German R/V Meteor. Our new data combined with prior geochemical and petrological studies indicate that the majority of the western Azores Plateau may indeed have formed during the arrival of a short-lived mantle melting anomaly at 10 Ma. However, our new data also indicate that volcanism <2 Ma is extremely localized and along structural features that result from plate reorganisation in the vicinity of the diffuse triple junction of the Eurasian, Nubian and North American plates, and that much of the easternmost Azores Plateau is magmatically inactive. Our model implies not only that the actual flood basalt province of the Azores is only some 30% of what has been previously estimated but may not have formed from a typical large-scale, long-lived mantle plume. Instead, excess melting as evident from the anomalously shallow water depth and the presence of islands in the Azores may be the result of a volumetrically small-scale melting anomaly in the upper mantle which is in its waning stages as evident from the localised distribution of magmatic activity at <1 Ma. Our model also solves the conundrum of a potential asymmetry of the recent submarine and subaerial volcanism both east and west of the Mid-Atlantic Ridge which instead is the result of an interacting upper mantle anomaly and the complex plate tectonic domain in the vicinity of the triple junction of the Eurasian, Nubian and North American plates.
CRIS-Team Scopus Importer:2022-08-05
Keywords: Azores Plateau; Large igneous provinces; North Atlantic Ocean; Plate tectonics

The tectonic evolution of the Irtysh tectonic belt: New zircon U–Pb ages of arc-related and collisional granitoids in the Kalaxiangar tectonic belt, NW China - Hong, Tao; Klemd, Reiner; Gao, Jun; Xiang, Peng; Xu, Xing-Wang; You, Jun; Wang, Xin-Shui; Wu, Chu; Li, Hao; Ke, Qiang (Lithos, 2017)
Precise geochronological constraints of the Irtysh tectonic belt situated between the Saur Island Arc and the Altay Terrane are crucial to a better understanding of the tectonic evolution of the Central Asian Orogenic Belt (CAOB). Recently, we discovered repeatedly deformed arc-related and collisional granitoids in the Kalaxiangar tectonic belt (KTB), which is located in the eastern part of the Irtysh tectonic belt. In this study, we report new whole-rock geochemical, zircon U–Pb and Hf isotopic data of the arc-related and collisional granitoids. Our data reveal that 1) arc-related granodioritic porphyries formed at ca. 382–374 Ma. Recrystallized zircon grains from a (ultra-)mylonitic granodiorite of the Laoshankou zone in the southern KTB display a U–Pb age of ca. 360 Ma; 2) syn-collisional granodioritic porphyries, which distribute along faults and parallel to the cleavage, were emplaced at ca. 367–356 Ma, with εHf(t) values varying from + 7.8 to + 14.2 and Hf model ages from 873 to 459 Ma; 3) a post-collisional A-type granodioritic porphyry, which crosscuts the NW-NNW trending schistosity of the metasedimentary country rocks at a low angle, has an age of ca. 324–320 Ma, while the εHf(t)values range from + 7.6 to + 14.4 with Hf model ages from 850 to 416 Ma; 4) post-collisional strike-slip A-type granite dykes, exposed along strike-slip faults, gave ages between 287 and 279 Ma, whereas the εHf(t) values range from + 4.9 to + 12.7 and the Hf model ages from 995 to 500 Ma; and 5) A-type biotite granite dykes, which intruded along conjugate tension joints, have ages of 274–271 Ma, and εHf(t) values from + 1.5 to + 13.2 with Hf model ages from 1196 to 454 Ma. Consequently, we propose that the collision between the Saur Island Arc and the Altay Terrane occurred in the Early Carboniferous (ca. 367–356 Ma) and the subsequent post-collisional tectonic process continued to the Late Carboniferous (ca. 324–320 Ma). It is further suggested that the Irtysh tectonic belt underwent large-scale strike-slip deformation during the mid-Permian between 287 and 279 Ma. The termination of the Irtysh tectonic belt orogeny is thought to have also occurred during the mid-Permian between 274 and 271 Ma.
Keywords: Zircon U–Pb age; Arc-related and collisional granitoids; Tectonic evolution; Irtysh tectonic belt

The timescales of magma evolution at mid-ocean ridges - Brandl, Philipp A.; Regelous, Marcel; Beier, Christoph; O'Neill, Hugh St C.; Nebel, Oliver; Haase, Karsten (Lithos, 2016)
Oceanic crust is continuously created at mid-ocean ridges by decompression melting of the upper mantle as it upwells due to plate separation. Decades of research on active spreading ridges have led to a growing understanding of the complex magmatic, tectonic and hydrothermal processes linked to the formation of new oceanic igneous crust. However, less is known about the timescales of magmatic processes at mid-ocean ridges, including melting in and melt extraction from the mantle, fractional crystallisation, crustal assimilation and/or magma mixing. In this paper, we review the timescales of magmatic processes by integrating radiometric dating, chemical and petrological observations of mid-ocean ridge basalts (MORBs) and geophysical models. These different lines of evidence suggest that melt extraction and migration, and crystallisation and mixing processes occur over timescales of 1 to 10,000 a. High-resolution geochemical stratigraphic profiles of the oceanic crust using drill-core samples further show that at fast-spreading ridges, adjacent flow units may differ in age by only a few 100 a. We use existing chemical data and new major- and trace-element analyses of fresh MORB glasses from drill-cores in ancient Atlantic and Pacific crust, together with model stratigraphic ages to investigate how lava chemistry changes over 10 to 100 ka periods, the timescale of crustal accretion at spreading ridges which is recorded in the basalt stratigraphy in drilled sections through the oceanic crust. We show that drilled MORBs have compositions that are similar to those of young MORB glasses dredged from active spreading ridges (lavas that will eventually be preserved in the lowermost part of the extrusive section covered by younger flows), showing that the dredged samples are indeed representative of the bulk oceanic crust. Model stratigraphic ages calculated for individual flows in boreholes, together with the geochemical stratigraphy of the drilled sections, show that at fast-spreading ridges, magma compositions vary over < 100 to 1000 a, likely due to variations in the relative rates of crystallisation and melt recharge. However, on longer timescales of 10 to 100 ka, variations in the composition of the primitive melt feeding the ridge lead to chemical variations in the erupted lavas, likely as a function of thermal and/or chemical heterogeneity of the mantle source. The further understanding of these temporal variations in magma composition, especially at shorter timescales of less than a few centuries, is a promising area for future research.
Keywords: Crystallisation; Magma evolution; MORB; Ocean drilling; Oceanic crust; Timescales

The timing of metamorphism in the Odenwald–Spessart basement, Mid-German Crystalline Zone - Will, T. M.; Schulz, Bernhard; Schmädicke, Esther (International Journal of Earth Sciences, 2017)
Keywords: In situ monazite age dating; 40Ar/39Ar age data; Odenwald–Spessart basement; Mid-German Crystalline Zone; Terrane boundary; Paired metamorphic belt

The transition from diagenesis to Low Grade Metamorphism in the Argentine Precordillera: An application of the Conodont Colour Alteration Index. - Keller, Martin; Lehnert, Oliver; Buggisch, Werner (Actas, v.1, 1993)
UnivIS-Import:2015-04-16:Pub.1993.nat.dgeo.IGM.LG.thetra

The unexpected species richness of Arctic rhodolith beds - Pyko, Ines Anna; Wisshak, Max; Knebelsberger, Thomas; Halfar, Jochen; Hetzinger, Steffen; Teichert, Sebastian (56. European Marine Biology Symposium, 2023)
Rhodolith beds are an important benthic habitat created by so-called ecosystem engineers. Rhodoliths are free-living, photoautotrophic structures of calcium carbonate (CaCO3) formed by different species of crustose coralline algae (CCA). This particular group of red algae precipitate CaCO3 within their cell walls to form a stable skeleton and next to rhodoliths, they also form crusts of varying thickness on fixed substrates. The shelfs around the high Arctic Svalbard archipelago (Norway) are intensely covered by such rhodolith beds and cm-thick crusts of CCA in shallow waters. The beds occur in water depths of about 10 to 50 m and the algae can live for more than 100 years. Quantitative biodiversity analyses of samples collected by dredge and manned submersible indicate that rhodolith beds form coral reef like structures at higher latitudes and thus represent an important ecological resource. However, research methods outlined above only allow for a snapshot on biodiversity with a focus on the benthic fauna associated with rhodoliths. Furthermore, there are no studies in relation to biodiversity and the CCA crusts. We performed a multi-marker eDNA metabarcoding survey (COX1, rbCL, 16S, ITS) to assess the entire spectrum of potentially occurring species within the Arctic rhodolith beds as well as within the CCA crusts. First results indicate about 650 potentially occurring different taxa (species and genus level). This survey is a step forward in order to estimate the impact of CCA on Svalbard’s shelf biodiversity and provides a background for their inclusion in future policy recommendations and strategic plans for biodiversity conservatio

The Unitary Association method in biochronology and its potential stratigraphic power between benthic and planktic organisms: A case study on foraminifers from Paleocene–Eocene strata of southern Egypt - Abdelhady, Ahmed; Seuß, Barbara; El-Dawy, Mostafa; Obaidalla, Nageh; Hussien, Samar; Mahfouzd, Kamel (Geobios, 2018)
Although foraminifers have been extensively used for biochronology, no quantitative evaluation of the quality of their application is available. In this work we apply a quantitative approach – the Unitary Association (UA) method – to evaluate the relative quality of planktic and benthic foraminifers in biostratigraphy. Based on 12,321 specimens belonging to 65 planktic and 132 benthic foraminifer species in 117 samples from the Paleocene–Eocene strata of the Kharga-Baris Oases (Western Desert, Egypt), the potential stratigraphic resolution power of benthic foraminifers is quantitatively assessed and compared to planktic foraminifers. The UA method accounts for superpositional contradictions between sets of coexisting taxa and generates unitary associations, which are conceptually similar to Oppel zones. The analysis produced fifteen unitary associations for the Paleocene–Eocene benthic Foraminifera of the studied sections, instead of three classical zones; most of these unitary associations are easily identified by the restricted occurrence of a single species. Although planktic Foraminifera have a higher seriation reality leading to a more robust biozonation, benthic Foraminifera have a higher stratigraphic resolution, at least at such regional scale. Furthermore, there was a significant positive correlation between the number of unitary associations and the number of species (R = 0.78 for planktic and 0.70 for benthic foraminifers; both with p < 0.001). These results corroborate that quantitative techniques may lead to a higher resolution in biochronology, even when applied to poor biochronological markers. Moreover, in contrast to simple spatiotemporal analyses, the Unitary Association method can accurately assess the stratigraphic potential of a given taxonomic group.

The use of field dependence of magnetic susceptibility for monitoring variations in titanomagnetite composition - A case study on basanites from the Vogelsberg 1996 Drillhole, Germany - de Wall, Helga; et al. (Studia Geophysica Et Geodaetica, 2004)
Keywords: Field amplitude; Magnetic susceptibility logging; Vogels berg volcanic complex

The use of low and high k(T)-curves for the characterization of magneto-mineralogical changes during metamorphism - de Wall, Helga; Kontny, Agnes (Physics and Chemistry of the Earth, 2000)
UnivIS-Import:2015-03-09:Pub.2000.nat.dgeo.IGM.c3tekt.theuse

The Valanginian isotope event: A complex suite of palaeoenvironmental perturbations.- - Greselle, Benjamin; Pittet, Bernard; Mattioli, Emanuela; Joachimski, Michael; Barbarin, Nicolas; Riquier, Laurent; Reboulet, Stephane; Puceat, Emmanuelle (Palaeogeography, Palaeoclimatology, Palaeoecology, 2011)
The Valanginian records a severe crisis of carbonate systems, both on platforms and in the pelagic realm. This crisis is roughly concomitant with the Weissert Event, characterized by a positive δ13C excursion of about 2‰ in marine carbonates. However, it is unclear if the response of these two carbonate systems to the global perturbations is contemporaneous, or if they react differently. For this purpose, accumulation rates of pelagic carbonates produced by nannofossils and of platform-derived carbonates have been quantified in a hemipelagic environment (the Vocontian Basin, SE France) that has the potential to record the reaction of both shallow-water and pelagic carbonate production to a major perturbation of the carbon cycle, testified by the isotope excursion. Also, changes through time of clay input have been measured in order to evaluate variations in continental weathering rates, and thus in continent-derived nutrient input and climatic conditions in terms of humidity/aridity. Accumulation rates of pelagic carbonates, of platform-derived carbonates and of clays were calculated on the basis of nannofossil absolute abundance and species-specific masses, of weight percent carbonate content of rocks, and a high-resolution timescale given by cyclostratigraphy. The onset of the positive δ13C excursion and the demise of the platforms testify for a synchronous, but inverse response of the shallow-water and pelagic carbonate systems to an increase in nutrient influx to marine waters. As carbonate production by nannofossils decreased during the Late Valanginian in time of still low platform production, the low temperature of marine waters coeval to a still high nutrient input recorded in the latest Late Valanginian possibly could explain that both platform and pelagic carbonate production contemporaneously decreased. © 2011 Elsevier B.V.
UnivIS-Import:2015-03-09:Pub.2011.nat.dgeo.IGM.LG.theval
Keywords: δ13C weissert Event; Accumulation rates; Carbonate production crisis; Climate change; Valanginian

The youngest ophiocistioid: a first Palaeozoic-type echinoderm group representative from the Mesozoic - Reich, Mike; Stegemann, Tanja R.; Hausmann, Imelda M.; Roden, Vanessa; Nützel, Alexander (Palaeontology, 2018)
Keywords: Carnian; echinoderms; Permian/Triassic fossil record; Italy; ophiocistioids

Thixotropy of superplasticized cement pastes – Underlying mechanisms considering the polycarboxylate molecular structure, interparticle interactions and hydration kinetics - Nicia, David; Jakob, Cordula; Jansen, Daniel; Ivanov, Dimitri; Mazanec, Oliver; Dengler, Joachim; Neubauer, Jürgen; Lowke, Dirk (Cement and Concrete Research, 2023)
This paper deals with the decisive mechanisms of thixotropic structural build-up in superplasticized cement-based suspensions related to the PCE molecular structure. We investigate the effect of the side chain length and anionic charge ratio of tailored PCE superplasticizers on thixotropic structural build-up under quantitative consideration of colloidal and contact interactions as well as very early hydration kinetics. The thixotropic structural build-up of superplasticized cement pastes with systematically varying the PCE molecular structure was investigated at constant workability, i.e. dynamic yield stress, by adjusting the individual PCE dosage. Thixotropy was quantified using plate-plate rheometry, while at the same time superplasticizer adsorption, specific surface area, granulometric measurements and quantitative XRD analysis provided an experimental basis for the identification of the respective contribution to the structural build-up. Our results show that the thixotropic structural build-up increases with decreasing PCE side chain length and increasing anionic charge ratio. This is due to accelerated very early hydration kinetics, causing an increase in the specific surface area. The latter is primarily attributed to ettringite, modifying the particle size distribution of the hydrated cement paste. Our approach of separating the colloidal and contact interactions indicates that the PCE-induced change in particle size distribution due to accelerated ettringite formation as well as the change in the average effective layer thickness are the dominant mechanisms for the thixotropic structural build-up in this context.
CRIS-Team Scopus Importer:2023-08-18
Keywords: Hydration kinetics; Interparticle interactions; Polycarboxylate superplasticizers PCE; Rheology of cement-based suspensions; Thixotropic structural build-up

Three episodes of Precambrian mafic magmatism in the southern Central Tianshan Block (NW China): Insight into an evolving geodynamic model - Wang, Xin Shui; Klemd, Reiner; Gao, Jun; Jiang, Tuo (Precambrian Research, 2020)
Precambrian microcontinents are an essential component in the tectonic evolution and architecture of the Central Asian Orogenic Belt (CAOB). However, the early crustal evolution and origin of Precambrian microcontinents remain poorly constrained due to the scarcity of early Precambrian rocks. The Chinese Central Tianshan Block (CTB) constitutes a microcontinent in the western CAOB with Precambrian basement rocks along its southern margin. The basement rocks, comprising amphibolite-facies supracrustal assemblages of possible volcano-sedimentary origin, are exposed in the Wuwamen Complex, which occurs as tectonic slivers in the late Paleozoic Wuwamen ophiolitic mélange. Here we present in situ zircon U–Pb and Lu–Hf isotopic data and the whole-rock geochemistry of three suites of (meta-)mafic rocks from the Wuwamen Complex and an associated Neoproterozoic gabbro body. The zircon dating revealed that the Wuwamen Complex contains two suites of meta-mafic rocks with protolith formation at ca. 2.55 Ga and 2.21 Ga followed by an amphibolite-facies metamorphic overprint at ca. 1.83 Ga. In addition, an individual gabbro body adjacent to the Wuwamen Complex yielded an emplacement age of ca. 0.69 Ga, reflecting a mid-Neoproterozoic mafic magmatic event in the CTB. Furthermore, zircon U–Pb dating of a crosscutting diorite dyke and a gneissic diorite sourced from a composite batholith in the CTB yielded weighted mean intrusive ages of ca. 320 Ma and 454 Ma, respectively. In conjunction with the field observation, the emplacement ages suggest that the Wuwamen Complex represents a part of the continental arc basement of the CTB. The three suites of (meta-)mafic rocks show geochemical characteristics similar to typical arc-related basalts. Along with the evolved zircon Hf isotopic compositions, it is suggested that these rocks originated from partial melting of a metasomatized sub-continental lithospheric mantle during different events. In conjunction with previous studies, the here presented new data further suggest that the CTB and other microcontinents in the western CAOB record similar Precambrian magmatic and metamorphic episodes, which are comparable to those of the northern Tarim during Proterozoic times. The here outlined new model indicates that the microcontinents of the western CAOB and the Tarim Craton may have shared a common geodynamic evolution.
CRIS-Team Scopus Importer:2020-11-06
Keywords: Accretionary processes; CAOB; Central Tianshan; Mafic magmatism; Microcontinent

Thresholds and the species-area relationship: A synthetic analysis of habitat island datasets - Matthews, Thomas; Steinbauer, Manuel; Tzirkalli, Elli; Triantis, Kostas; Whittaker, Robert (Journal of Biogeography, 2014)
Aim: The application of island biogeography theory in habitat fragmentation research assumes a simple relationship between species richness and fragment area. However, previous work has suggested that in some cases thresholds can be detected, at which the form of the island species–area relationship (ISAR) changes abruptly. Piecewise regression has been advocated as a suitable statistical technique to model such thresholds. Here we first provide a comparative analysis of piecewise regression models to determine the prevalence and type of thresholds in habitat island ISARs. Second, we evaluate piecewise regression as a method for locating thresholds in the ISAR, with particular emphasis on the implications of data transformation. Location: World-wide. Methods: Seventy-six habitat island datasets were sourced from the literature. An information theoretic approach was employed to compare linear regression ISAR models with piecewise regression models. The models were applied to untransformed (species–area), semi-log (species–log area) and log–log (log species–log area) data. Three types of piecewise regression models were evaluated: continuous, discontinuous and zero slope. Model performance was compared using the Akaike information criterion. We also examined the influence on model performance of taxon, number of habitat islands, and area of smallest island. Results: Linear regression models performed best, although piecewise models were preferred in a number of cases. Cases in which no model was significant were most prevalent in untransformed space relative to the semi-log and log–log transformations. Piecewise fits were more prevalent in datasets with a larger numbers of islands. Main conclusions: Data transformation is a key part of model selection and needs to be explicitly considered, especially in terms of drawing inferences from models. Piecewise models, even if selected as the favoured model in our analyses, were often ecologically unintelligible in relation to area alone. When detected, breakpoint values ranged over five orders of magnitude, although with one exception all were under 50 ha. Our findings highlight the limitations of using individual threshold values to inform conservation practice.
Keywords: Breakpoint values; Conservation biogeography; Habitat islands; Island biogeography; Piecewise regression; Scale dependency; Small island effect; Species-area relationship; Thresholds

Tidal versus fluvial point bars: Key features from the integration of outcrop, core and wireline log information of Triassic examples - Yeste, Luis Miguel; Gil-Ortiz, Marc; García-García, Fernando; Viseras, César; Mcdougall, Neil David; Cabello, Patricia; Caracciolo, Luca (Depositional Record, 2024)
The Triassic red beds of the Tabular Cover of the Iberian Meseta are an excellent reservoir outcrop analogue, a direct consequence of high-quality exposures, which offer exceptional three-dimensional outcrops, as well as a wide variability of depositional environments. Fluvial and transitional with tide-influenced and wave-influenced settings are recognised. Three point bar geobodies of similar scale, but influenced by different processes, were selected from this succession. Point bar geobody 1 was influenced by purely fluvial processes while geobodies 2 and 3 were tide-influenced. Both types of geobody were developed as point bar deposits in sinuous channels. A fully integrated study was carried out on these geobodies, utilising both outcrop and subsurface-based approaches, to characterise the key differences between fluvial and tidal point bars in the sedimentary record. The outcrop-based component involved traditional field data collection methods alongside digital techniques and data capture, including the use of digital outcrop models. Additionally, subsurface-based methods were employed, utilising core and wireline logs obtained from wells drilled in close proximity to the outcrop. The integration of these approaches aims to accurately differentiate the depositional settings of the three different geobodies, which while apparently very similar in many key respects also exhibit considerable differences when considered from the perspective of subsurface management of potentially similar geobodies. This study also emphasises the need to clearly distinguish high-sinuosity deposits based on their depositional sub-environment in order to properly evaluate their potential for subsurface management. Additionally, it highlights the presence and importance of internal baffles that may well influence fluid migration and indeed even compartmentalise geobodies. Three point bar geobodies of similar scale, but influenced by different processes, have been selected in this succession. A fully integrated study was carried out on these geobodies, utilising both outcrop-based and subsurface-based approaches, to characterise the key differences between fluvial and tidal point bars in the sedimentary record.
CRIS-Team Scopus Importer:2024-05-24
Keywords: fluvial point bar; outcrop analogue; outcrop/behind-outcrop characterisation; TIBEM; tidal point bar; Triassic

Ti distribution in quartz across a heterogeneous shear zone within a granodiorite: The effect of deformation mechanism and strain on Ti resetting - Bestmann, Michel; Pennacchioni, Giorgio (Lithos, 2015)
The study of a heterogeneous ductile shear zone that developed at . 500. °C and 0.2. GPa during post-magmatic cooling of a granodiorite has allowed the effect of strain and recrystallization on Ti re-equilibration of quartz to be assessed. Understanding this effect is critical for applying Ti-in-quartz thermobarometry to mylonites. Differently strained quartz across the shear zone shows a heterogeneous distribution of Ti concentrations ([Ti]) (measured by Secondary Ion Mass Spectrometry, SIMS) ranging between 2 and 45. ppm. Quartz cathodoluminescence (CL) is proven by spectral analysis to be correlated with [Ti], allowing CL images to be calibrated as Ti maps using SIMS measurements. Coarse-grained weakly deformed domains consist of magmatic quartz extensively recrystallized by grain boundary migration (GBM) and mostly (65-75% area) contain 20-38. ppm Ti. Resetting to lower [Ti] occurred locally: (i) in haloes surrounding titanite and biotite inclusions ([Ti] as low as 6. ppm); (ii) along grain boundaries; and (iii) towards the interface of quartz domains with other mineral domains. With increasing strain, quartz underwent progressive grain size reduction and developed a bimodal microstructure with elongate grains (>. 100's μm long) surrounded by mantles of new grains (10-30. μm in size) recrystallized by subgrain rotation (SGR). Dynamic recrystallization by SGR, associated with prism. <. a. >. slip, became increasingly dominant over GBM as strain increased towards the shear zone core. Significant resetting of Ti in quartz only occurred in high strain domains (at shear strain γ probably >>. 10) in the shear zone core where fine recrystallization amounts to 50-60% by area and coarser cores are strongly sub-structured. These domains are not compositionally homogeneous and still show a range of [Ti] mostly between 2 and 10. ppm. In all strain facies of the shear zone quartz-filled pressure shadows associated with feldspar show an almost constant [Ti] of . 2. ppm. The pristine Ti content of the magmatic quartz mylonitized in the shear zone core is therefore significantly reset and converges "asymptotically" towards the "equilibrium" 2. ppm [Ti] shown by new quartz precipitated in pressure shadows. It is inferred that extensive recrystallization by SGR and repeated cycles of dislocation creep and rearrangement provided fluid access to quartz grain interiors, promoting chemical buffering and leading to partial re-equilibration to low [Ti]. These observations imply limitations on the use of the Ti-in-quartz thermobarometry to constrain ambient conditions of ductile deformation.
UnivIS-Import:2015-07-08:Pub.2015.nat.dgeo.IGM.c3tekt.tidist
Keywords: Cathodoluminescence; Ductile shear zone; Dynamic recrystallization; Quartz microstructure; SIMS; Ti in quartz thermobarometry

Tiefenaufgelöste Phasenanalyse von selbstnivellierenden Bodenspachtelmassen mit dem GADDS - Seifert, Severin; Motzet, Hubert; Götz-Neunhoeffer, Friedlinde; Neubauer, Jürgen (GDCh-Monographie, 2007)
UnivIS-Import:2015-04-16:Pub.2007.nat.dgeo.IGM.LM.tiefen

Timing and duration of discrete tectono-metamorphic events of the polymetamorphic high-grade Central zone of the Limpopo Belt (South Africa): Insight from in situ geochronology of monazite and zircon - Zhou, Tian; Klemd, Reiner; Brandt, Sönke; Liu, Yu; Li, Qiu Li (Precambrian Research, 2022)
The Central Zone of the Limpopo Belt in southern Africa is a complex polymetamorphic terrane that has experienced three metamorphic events, at 3.22 Ga (M1), 2.71–2.56 Ga (M2) and 2.02 Ga (M3). On the basis of a previous detailed petrological and geothermobarometrical study of a newly discovered supracrustal enclave within the Bulai Pluton (ca. 2.61 Ga granitoid gneiss in the Central Zone), we conducted a geochronological in situ study of texturally and chemically different monazite and zircon grains, which occur respectively as inclusions in garnet, in decompressional cordierite coronas around garnet and as matrix grains in polymetamorphic granulite-facies metapelites. Secondary-ion mass spectrometry (SIMS) in situ analyses of the monazite and zircon grains in thin sections, complemented by analyses of separated zircon grains, allowed the texturally-controlled direct determination of U-Pb and 207Pb/206Pb ages at a scale of < 10 μm. A concordant age of ca. 2.71 Ga derived from zircon included in garnet is interpreted to reflect the age of initial garnet growth during the prograde M2 metamorphism. Zircons in the cordierite coronas around garnet revealed a slightly younger concordant age of ca. 2.56 Ga. Zircon growth in the coronas is related to the retrograde breakdown of garnet (Zr-bearing) through to the decompression reaction garnet + sillimanite + quartz → cordierite + zircon and hence the ca. 2.56 Ga zircon age is interpreted to reflect the timing of post-peak decompressional uplift. The zircon ages constrain the duration of M2 metamorphism to approximately 145 Myr. A concordant 2.71 Ga age of large monazite inclusions in garnet cores corroborates the 2.71 Ga zircon age of initial garnet growth during the prograde M2 metamorphism. Core domains of the largest monazite in cordierite corona revealed ages between 2.5 and 2.0 Ga that are interpreted to reflect (multiple) Pb-loss during the M3 granulite-facies metamorphism. Other monazites in cordierite coronas and matrix showed an age of ca. 2.0 Ga, reflecting complete re-equilibration or new growth during M3 overprinting. Owing to the preservation of the original micro-textures related to the growth of zircon and monazite we were able to link the age data with the P-T record, and refine the timing and duration of the M2 granulite-facies metamorphism (approximately 2.71–2.56 Ga) in the Limpopo Belt that was previously dated at ca. 2.62 Ga by zircon separation techniques. The ca. 145 Ma duration of granulite-facies metamorphism is consistent with a tectonic model of long-lasting asthenosphere upwelling and subsequent continent–continent collision in the late Neoarchean. Decompression triggered by post-collisional extension occurred at 2.56 Ga. Paleoproterozoic M3 granulite-facies metamorphism at ca. 2.0 Ga caused the widespread re-setting of the U-Pb and Pb-Pb data that also affected most zircon and monazite grains. This study reveals that precise dating of the timing and duration of distinct tectono-metamorphic events by texturally-controlled in situ geochronology allows a much better insight into the complex geodynamic evolution of high-grade polymetamorphic terranes.
CRIS-Team Scopus Importer:2022-01-21
Keywords: Duration of metamorphic events; Limpopo Belt; Monazite; Polymetamorphism; Secondary ion mass spectrometry; U-Pb dating; Zircon

Toarctocera (Gastropoda, Aporrhaidae): a new genus from the Jurassic (Toarcian/Aalenian) of South Germany and the early evolutionary history of the family Aporrhaidae - Gründel, Joachim; Nützel, Alexander; Schulbert, Christian (Palaeontologische Zeitschrift, 2009)
Toarctocera, a new gastropod genus of the family Aporrhaidae (Stromboidea) is described for Rostellaria subpunctata. It occurs in Central Europe (S Germany, N Switzerland, and France) and is commonly one of the most abundant gastropods in Late Toarcian/Early Aalenian soft bottom faunas. Toarctocera subpunctata has extremely elongated apertural spines; this has been interpreted as an adaptation to extremely soft-bottom conditions (snowshoe strategy). The new genus represents one of the earliest certain aporrhaids (Stromboidea). Aporrhaids are probably as old as Late Triassic, and possible Triassic and Early Jurassic species are discussed. Spiniloma is proposed as a nomen novum in order to replace the homonym Spinigera and consequently the family Spinilomatinae replaces the Spinigeridae. The sister group of Stromboidea still needs to be identified. A previously suggested sister group relationship with the Heteropoda is seen as unlikely. © Springer-Verlag 2009.
UnivIS-Import:2015-03-09:Pub.2009.nat.dgeo.IGM.LP.toarct
Keywords: Aporrhaidae; Gastropoda; Jurassic; Phylogeny; Stromboidea; Taxonomy

Tonian and Silurian magmatism in Nordaustlandet: Svalbard's place in the Caledonian orogen - Mcclelland, William C.; von Gosen, Werner; Piepjohn, Karsten (Circum-Arctic Structural Events: Tectonic Evolution of the Arctic Margins and Trans-Arctic Links with Adjacent Orogens, 2019)
The Nordaustlandet terrane of Svalbard plays a critical role in evaluating strike-slip displacements in the Caledonian orogen. Comparison of Silurian and Tonian magmatism in Nordaustlandet, East Greenland, and the Pearya terrane on Ellesmere Island provides a means to evaluate models of large-scale versus minimal displacements. Augen gneiss with an emplacement age of 972 +/- 5 Ma demonstrates that the Tonian granite suite is coeval with the calc-alkaline Kap Hansteen volcanic rocks. Zircon from Silurian leucosomes, leucogranites, and granites is dominated by xeno-crystic components, making it analytically difficult to isolate magmatic versus inherited age domains. Zircon systematics from a relatively undeformed Silurian granite (431 +/- 5 Ma) resemble those of similar granites interpreted to be Tonian in age (e.g., Kontaktberget granite). Assuming less deformed granites of Nordaustlandet are Silurian, synemplacement or syntectonic deformation of Tonian augen gneiss and volcanic rocks is no longer required. Tonian magmatic rocks of Svalbard share a common origin with basement rocks of the Pearya terrane within a continental arc system, but are distinctly older than Tonian igneous and metamorphic rocks of East Greenland. Migmatite complexes and granite intrusions in Nordaustlandet, with ages ranging from 440 to 425 Ma, are coeval with granites in East Greenland that record the combined effects of subduction beneath Laurentia and mid-crustal melting. Migmatites in East Greenland are juxtaposed with low grade rocks by syn-contraction normal faults whereas migmatites show gradational contacts into lower grade rocks on Nordaustlandet. These differences in basement age and structural setting preclude proximity of the Nordaustlandet terrane with East Greenland during the 440-400 Ma continent-continent collision phase (Scandian) of the Caledonian orogen. Similarly, differences in depositional, magmatic, and metamorphic history between the Pearya terrane basement and Nordaustlandet terrane argue against simple offset of crustal fragments. The Pearya and Nordaustlandet terranes likely were not involved in the main phase of crustal thickening directly related to collision of Baltica and Laurentia, but rather resided on a convergent boundary north of the Scandian continent-continent collision zone, consistent with models of Gee and Teben'kov (2004) and Johansson et al. (2005).
CRIS-Team WoS Importer:2019-11-15

Tonian evolution of an active continental margin - a model for Neoproterozoic NW India-SE Pakistan–E Oman linkage - de Wall, Helga; Regelous, Anette; Tomaschek, Frank; Bestmann, Michel; Hahn, Gregor; Sharma, Kamal Kant (Precambrian Research, 2022)
Here we introduce a new model for a Tonian active continental margin in the Neoproterozoic western foreland of the Delhi Fold Belt of NW India. This study gives indication for a transition from continental crust into an active arc setting prior to emplacement of the volcano-plutonic Malani Igneous Suite. Erinpura Granites (890 to 860 Ma) are exposed in a large area west of the Delhi Fold Belt in NW India. The Erinpura Granites are S-type (εNd −10 to −3) whereas granites, granodiorites and gabbros exposed in the westernmost basement outcrops (Bhinmal, Harsani) are I-type granitoids and show positive Nd ratios (εNd + 4 to + 6). These intrusions are derived from crustal melting with a lithospheric component and affinity to a subduction setting, as can also be inferred from trace element ratios. Our study places the Bhinmal granite as youngest intrusion in this setting (U-Pb analyses of zircon 794 ± 17 Ma and titanite 793 ± 19 Ma). High temperature linear solid-state fabrics in the granites indicate intrusion and deformation during crustal extension. After uplift and exhumation bimodal dykes and granites of the Malani Igneous Suite (770–750 Ma) intruded into this older crust (pre-Malani basement). An evolutionary model for a Tonian active continent margin is established by integrating data from Nagar Parkar in East Pakistan and Neoproterozoic basement inliers in East Oman. The data indicate 130 Myr of ongoing subduction (900 to 770 Ma) along the continental margin. Magmatic activity is identified as episodic with three major pulses starting at ca. 840 Ma, ca. 825 Ma and ca. 770 Ma. High temperature melting constitutes the last Tonian magmatic pulse (Malani Igneous Suite) attributed to roll-back of the subducting slab. The implications for Neoproterozoic plate tectonic reconstructions are discussed.
CRIS-Team Scopus Importer:2022-09-30
Keywords: Geochemistry; Geochronology; Neoproterozoic; NW India; Sr-Nd isotope

Topography-driven isolation, speciation and a global increase of endemism with elevation - Steinbauer, Manuel; Field, Richard; Grytnes, John-Arvid; Trigas, Panayiotis; Ah-Peng, Claudine; Attorre, Fabio; Birks, H. John B.; Borges, Paulo A. V.; Cardoso, Pedro; Chou, Chang-Hung; De Sanctis, Michele; De Sequeira, Miguel M.; et al. (Global Ecology and Biogeography, 2016)
Keywords: Altitude; biogeographical processes; diversity; ecological mechanisms; endemism; global relationship; isolation; latitudinal gradient; mixed-effects models; sky islands

Toughening by revitrification of Li2SiO3 crystals in Obsidian® dental glass-ceramic - Lubauer, Julia; Hurle, Katrin; Cicconi, Maria Rita; Petschelt, Anselm; Peterlik, Herwig; Lohbauer, Ulrich; Belli, Renan (Journal of the Mechanical Behavior of Biomedical Materials, 2021)
As a predominantly lithium-metasilicate-containing glass-ceramic, Obsidian® (Glidewell Laboratories, USA) has a peculiar composition and microstructure among other dental lithium silicates, warranting an evaluation of the crystallization process to establish relationships between microstructural evolution and mechanical properties. Blocks of the pre-crystallized material were processed into slices measuring 12 × 12 × 1.5 mm3 and subjected to the mandatory crystallization firing by interruption the heating ramp at temperatures between 700 °C and 820 °C (dwell time between 0 min and 10 min). The crystallization peaks of the base and the pre-crystallized glass were obtained by differential scanning calorimetry (DSC). The coefficient of thermal expansion and the glass transition temperature were derived from differential thermal analysis (DTA). X-ray diffraction (XRD) was performed to quantify and characterize the crystal phase fraction, whose microstructural changes were visualised using FE-SEM. The ball-on-three-balls surface crack in flexure method was used to track the evolution of fracture toughness. The microstructural evolution during crystallization firing was characterized by two regimes of growth: (i) the progressive revitrification (dissolution) of the 5 μm-sized Li2SiO3 polycrystals manifested at the boundaries of nanometric single coherent scattering domains (CSDs); (ii) the non-isothermal period is marked by an Ostwald ripening process characterized by the growth of the single crystalline structures into 0.5 μm polycrystals. The decrease in the crystal fraction of Li2SiO3 crystals from 41 vol.% to 37 vol.% is accompanied by the formation of a small amount of Li3PO4 (6 vol.%), maintaining the total crystal phase fraction mostly constant. The KIc accompanied the reverse trend of crystallinity, departing from 1.63 ± 0.02 MPa√m at the pre-crystallized stage to 1.84 ± 0.06 MPa√m after 10 min at 820 °C in a linear trend. Toughening appeared counter-intuitive in view of the decreasing crystal fraction and size, to rather relate to the relaxation of the residual stresses in the interstitial glass due to the spheroidization of the initially anisotropic, elongated Li2SiO3 crystals into round, nearly equiaxed particles, as let suggest from the disappearance of the extensive microcracking.
CRIS-Team Scopus Importer:2021-09-10
Keywords: Crystallization; Dental; Fracture toughness; Glass-ceramic; Mechanical properties; X-ray Diffraction

Towards a further understanding of cement hydration in the presence of triethanolamine - Lu, Zichen; Kong, Xiangming; Jansen, Daniel; Zhang, Chaoyang; Wang, Jian; Pang, Xiaofan; Yin, Jianhao (Cement and Concrete Research, 2020)
The acting mechanism of triethanolamine (TEA) on cement hydration was studied by combination of techniques including calorimetry, in-situ XRD and pore solution analysis. Results show that, a high dosage of TEA (0.5%) results in accelerated aluminate reaction and retarded silicate reaction during hydration of ordinary Portland cement (OPC). The initial dissolutions of C3S, C3A, C4AF and gypsum are greatly facilitated by TEA. The secondary fast reactions of C4AF and C3A triggered by the earlier sulfate-depletion produce a new exothermic peak before the main hydration peak of C3S that usually presents as a shoulder after the main hydration peak in the reference sample. TEA retards the hydration of pure C3S, but much more severely delays the silicate reaction in OPC system, attributed to the negative interference of aluminate reaction on silicate reaction. The new insights into the interaction between TEA and OPC contribute to the theoretical base for regulating cement hydration.
CRIS-Team Scopus Importer:2020-03-27
Keywords: Cement hydration; Complexation; Triethanolamine (TEA)

Towards an assessment of true diversity in fossil ecosystems - Roden, Vanessa; Hausmann, Imelda M.; Nützel, Alexander; Reich, Mike; Kießling, Wolfgang (1st Palaeontological Virtual Congress. Book of abstracts. Palaeontology in a virtual era, 2018)

Towards a new paleotemperature proxy from reef coral occurrences - Lauchstedt, Andreas; Pandolfi, John; Kießling, Wolfgang (Scientific Reports, 2017)
Global mean temperature is thought to have exceeded that of today during the last interglacial episode (LIG, similar to 125,000 yrs b.p.) but robust paleoclimate data are still rare in low latitudes. Occurrence data of tropical reef corals may provide new proxies of low latitude sea-surface temperatures. Using modern reef coral distributions we developed a geographically explicit model of sea surface temperatures. Applying this model to coral occurrence data of the LIG provides a latitudinal U-shaped pattern of temperature anomalies with cooler than modern temperatures around the equator and warmer subtropical climes. Our results agree with previously published estimates of LIG temperatures and suggest a poleward broadening of the habitable zone for reef corals during the LIG.

Towards an improved discrimination and correlation of Permian-Lower Triassic sediments in Central Europe: A chemostratigraphic approach - Ravidà, Domenico; Caracciolo, Luca; Heins, William A.; Stollhofen, Harald (Sedimentary Geology, 2023)
The stratigraphic classification and correlation of Permian-Lower Triassic clastic beds in the Central European Basin System traditionally rely on geophysical, bio-, and lithostratigraphic methods. However, in basin margin areas, the accuracy of these tools is diminished due to the heterogeneous distribution of stratigraphic markers, lack of index fossils, and greater climatic and tectonic disturbance. To overcome these limitations, this study introduces a more versatile, multifaceted and chemostratigraphy-based approach. By integrating results from bulk X-ray fluorescence analysis, sandstone petrography, Raman heavy mineral analysis, lithofacies characterisation and borehole gamma-ray logs, we produce robust multi-stratigraphic schemes for selected sequences in the Franconian Basin (SE Central European Basin System). Hierarchical chemostratigraphic zones, comprising five chemozones and sixteen subzones, were designed using key elemental ratios (Ga/Rb, Rb/K, Na/K, Ca/Mg, Cr/Ti, Th/Ti, Nb/Th, Ti/Nb, P/Ti, Zr/P, Zr/Y), whose changes through time reflect modifications in the mineralogical composition of sedimentary rocks. To ensure precise interpretations of geochemical data, we established links between mineralogical and chemical components through statistical processing and direct comparison with mineralogical assemblages. Our results demonstrate that chemostratigraphic boundaries can identify major changes in palaeo-depositional environments and sediment sources induced by eustatic, tectonic and climatic disturbances. For example, changes in the P/Ti and Zr/P ratios across the CP3-CT1 document the increased abundance in apatite-rich granitic detritus, resulting from the exposure of new source lithologies in the catchment area due to Early Triassic synsedimentary tectonism. Since these perturbations had a regional impact on sedimentation, their geochemical fingerprints are correlated across the basin, regardless of lithofacies variability or distance between sections. Moreover, integrating characteristic geochemical signals into multi-stratigraphic schemes enables more precise placement of stratigraphic boundaries, identification of locally deposited/preserved stratigraphic markers, and overall refinement of outdated classification schemes. The chemostratigraphic approach introduced in this study offers a solution to the limitations of conventional stratigraphic tools, allowing robust characterisations and correlations of Permian-Triassic sequences in the marginal regions of the Central European Basin System. In addition, the multi-analytical workflow for processing geochemical data, refining stratigraphic schemes and attributing geochemical anomalies to environmental perturbations represents a further step towards more precise applications of chemostratigraphy to the depositional record.
CRIS-Team Scopus Importer:2023-09-01
Keywords: Basin-scale correlation; Central European Basin System; Chemostratigraphy; Clastic sediments; External forcing controls; Permo-Triassic boundary

Towards an unbiased estimate of fluctuations in reef abundance and volume during the Phanerozoic - Kießling, Wolfgang (Biogeosciences, 2006)
The globally preserved number and volume of ancient biogenic reefs is strongly biased by two factors: geological history and research intensity. These biases are sufficiently strong to cast doubts on the biological meaning of the recorded raw pattern. Without adjustment, it is hard to reliably identify factors potentially controlling the waxing and waning of this important ecosystem through time. Although it is currently impossible to completely compensate for the biases, I demonstrate here, based on a comprehensive database of ancient reefs, that spatiotemporal heterogeneities of the biases can largely be evened out by: (1) omitting oceanic reef sites and reef sites only known from subsurface exploration; (2) standardizing for economic factors known to affect research intensity; and (3) adjusting for sedimentary cycling processes. The resulting curves of fossil reef abundance and volume appear quite different from the original ones but the patterns of waxing and waning of the time series are not significantly altered and the overall volatility is not reduced. This suggests that both the raw curves and the adjusted curves correctly depict the basic timing of major reef blooms and declines. Nevertheless, the general pattern of the new curves (maximum proliferation in the middle Paleozoic, decline thereafter) is more in line with patterns of global cratonic carbonate sedimentation than the original curves. The adjusted curves should thus be preferred over the original ones for future tests of potential extrinsic controls of Phanerozoic reef development.
UnivIS-Import:2015-03-09:Pub.2006.nat.dgeo.IGM.LP.toward

Trace Element and In Situ O–Nd Isotope Signatures of Apatite from the Bilihe Porphyry Au-Only Deposit: Magmatic Constraints on Au Mineralization - Hong, Jingxin; Zhai, Degao; Keith, Manuel; Zhao, Qingqing; Liu, Jiajun (Journal of Petrology, 2024)
The magmatic controls on the formation of porphyry Au-only deposits are still poorly understood. The Bilihe deposit (> 30 t at 2.7 g/t Au) located at the northern margin of the North China Craton is such an example, where apatite chemistry from a causative granodiorite intrusion constrains the physicochemical conditions and ore-forming potential of the porphyry-related magmas. Apatite can be subdivided by distinct CL intensities into early CL-bright and late CL-gray/dark sub-types both occurring in fresh (Ap-f), as well as in potassic (Ap-k) and phyllic (Ap-p) altered granodiorite. The mostly euhedral CL-bright apatite shows a homogeneous texture and is enriched in LREE and depleted in Fe, Mg, Mn, Y, and U compared to CL-gray/dark apatite, which develops patchy or oscillatory zoning. The CL-gray/dark apatite exhibits decreasing Fe and Mg contents, as well as δ18O values from Ap-f to Ap-k and Ap-p due to consecutive fluid alteration during porphyry evolution, which was generally not observed in CL-bright apatite. We thus conclude that all types of CL-bright apatite but only CL-gray/dark Ap-f inherit the original magma composition. Binary O–Nd isotope mixing simulations suggest that both magmatic CL-bright apatite and CL-gray/dark Ap-f were influenced by crustal sediment assimilation. Our results further indicate that the magma parental to the Bilihe porphyry Au-only deposit was H2O-poor (< 2 wt %), causing plagioclase fractionation in the absence of hornblende, as evidenced by relatively low Sr/Y (< 0.1) and significantly negative Eu anomalies in magmatic apatite. Pressure estimates by magmatic biotite that record the late crystallization stage yielded 48.9 ± 8.4 MPa, indicating a shallow final emplacement depth of 1.85 ± 0.32 km. The studied apatites formed under volatile-saturated conditions from S-deficient magmas at relatively reduced conditions (ΔFMQ +0.5) compared to porphyry Cu deposits. We thus conclude that these physicochemical parameters together with the low-pressure conditions result in a fertile magmatic-hydrothermal environment for the formation of Au-only porphyry deposits.
CRIS-Team Scopus Importer:2024-11-29
Keywords: apatite; Bilihe porphyry Au-only deposit; in situ O and Nd isotopes; parental magma; trace elements

Trace element and isotope geochemistry of the Northern and Central Tongan Islands with an emphasis on the genesis of High Nb/Ta signatures at the Northern Volcanoes of Tafahi and Niuatoputapu - Beier, Christoph; Turner, Simon P.; Haase, Karsten; Pearce, Julian; Münker, Carsten; Regelous, Marcel (Journal of Petrology, 2017)
Keywords: High field strength elements; Island arc magmatism; Louisville seamounts; Partial melting; Slab components; Tonga arc

Trace Element and Isotope Systematics in Vent Fluids and Sulphides From Maka Volcano, North Eastern Lau Spreading Centre: Insights Into Three-Component Fluid Mixing - Klose, Lukas; Keith, Manuel; Hafermaas, Daniel; Kleint, Charlotte; Bach, Wolfgang; Diehl, Alexander; Wilckens, Frederike; Peters, Christian; Strauss, Harald; Klemd, Reiner; van Geldern, Robert; Haase, Karsten; et al. (Frontiers in Earth Science, 2021)
Back-arc spreading centres and related volcanic structures are known for their intense hydrothermal activity. The axial volcanic edifice of Maka at the North Eastern Lau Spreading Centre is such an example, where fluids of distinct composition are emitted at the Maka hydrothermal field (HF) and at Maka South in 1,525–1,543 m water depth. At Maka HF black smoker-type fluids are actively discharged at temperatures of 329°C and are characterized by low pH values (2.79–3.03) and a depletion in Mg (5.5 mmol/kg) and SO4 (0.5 mmol/L) relative to seawater. High metal (e.g., Fe up to ∼6 mmol/kg) and rare Earth element (REE) contents in the fluids, are indicative for a rock-buffered hydrothermal system at low water/rock ratios (2–3). At Maka South, venting of white smoke with temperatures up to 301°C occurs at chimneys and flanges. Measured pH values range from 4.53 to 5.42 and Mg (31.0 mmol/kg), SO4 (8.2 mmol/L), Cl (309 mmol/kg), Br (0.50 mmol/kg) and Na (230 mmol/kg) are depleted compared to seawater, whereas metals like Li and Mn are typically enriched together with H2S. We propose a three-component mixing model with respect to the fluid composition at Maka South including seawater, a boiling-induced low-Cl vapour and a black smoker-type fluid similar to that of Maka HF, which is also preserved by the trace element signature of hydrothermal pyrite. At Maka South, high As/Co (>10–100) and Sb/Pb (>0.1) in pyrite are suggested to be related to a boiling-induced element fractionation between vapour (As, Sb) and liquid (Co, Pb). By contrast, lower As/Co (<100) and a tendency to higher Co/Ni values in pyrite from Maka HF likely reflect the black smoker-type fluid. The Se/Ge ratio in pyrite provides evidence for fluid-seawater mixing, where lower values (<10) are the result of a seawater contribution at the seafloor or during fluid upflow. Sulphur and Pb isotopes in hydrothermal sulphides indicate a common metal (loid) source at the two vent sites by host rock leaching in the reaction zone, as also reflected by the REE patterns in the vent fluids.
Keywords: hydrothermal systems in back-arc basins; three-component fluid mixing; vent fluids; hydrothermal sulphides; Northeast Lau basin; trace elements; isotopes

Trace element and oxygen isotope study of eclogites and associated rocks from the Münchberg Massif (Germany) with implications on the protolith origin and fluid-rock interactions - Pohlner, Johannes E.; El Korh, Afifé; Klemd, Reiner; Grobéty, Bernard; Pettke, Thomas; Chiaradia, Massimo (Chemical Geology, 2021)
Eclogites, metagabbros, and paragneisses from the Variscan Münchberg Massif record a complex succession of igneous, hydrothermal and metamorphic processes. The geodynamic setting related to the protolith formation and the impact of different types of fluid-rock interactions have been uncertain up to now. We use major and trace element chemistry as well as oxygen isotopes to disentangle the geochemical signatures related to the different stages of the rocks' history. In the Münchberg Massif, dark eclogites (kyanite-free; Fe-Ti-MORB signature) are distinguished from light eclogites (kyanite-bearing; higher Mg#, Al2O3, and Cr; lower incompatible element contents; positive Eu anomalies; MORB to arc basalt signature). The δ18O values for both types (+5.0 to +10.8‰) are equal to, or higher than those of MORB. Amphibolite facies metagabbros have a more enriched, almost OIB-like trace element signature and high δ18O values (+9.4 to +10.3‰). Good linear correlations between fluid-immobile elements throughout the eclogite types confirm their derivation from a common, N-MORB to E-MORB-like parental magma. We interpret the light eclogites as former plagioclase-rich cumulates and the dark eclogites as their complementary differentiates. This relationship is partly obscured by variable degrees of magma contamination by sediments, which also affected the metagabbros. However, the metagabbros originated from a more enriched mantle source than the eclogites. Following intrusion, the eclogites were subjected to hydrothermal alteration under the influence of seawater, as indicated by positive correlations between Li, B, Sb, and δ18O. Metamorphic fluid-rock interactions appear to be mostly of limited extent, probably due to the lack of lawsonite dehydration as a fluid source. Nevertheless, the contents at least of some fluid-mobile elements, such as LILE, Li, and Pb, were probably modified during the subduction-exhumation cycle of the eclogites. The crustal contamination of the protolith magmas argues against derivation of the eclogites and metagabbros from typical oceanic crust. Instead, a rift-drift transition setting related to the opening of the Rheic or Saxothuringian Ocean seems most likely. The eclogites and metagabbros, alongside with similar rocks in the Mariánské Lázně complex and other resembling high-pressure massifs, may record different stages of this rift-drift transition.
CRIS-Team Scopus Importer:2021-06-11
Keywords: Eclogites; Fluid-rock interactions; Subduction; Variscan Orogeny

Trace element and stable isotope geochemistry of secondary carbonates in alkaline volcanic rocks of the Rhoen, Germany. - Joachimski, Michael; et al. (Chemie Der Erde-Geochemistry, 1999)
Carbonates occurring as accessory phases within volcanic rocks are often interpreted as being of meteoric water origin. Contary to this model, trace element studies in chloroacetic acid leachates from rocks of the tertiary intracontinental alkaline volcanic field of the Rhoen (Germany) give evidence that the precipitation of the carbonates was imprinted by highly evolved late magmatic fluids. High concentrations of F, Sr, Ba, and the REE indicate that the volcanic rocks were affected by magmatogenic carbonate rich fluids. δ13C covers a range from -2.9 to -14.2‰ PDB and the δ18O values lie between 26.9 and 34.2‰ SMOW. The carbon isotopes have primary magmatic character with a shift to isotopic light carbon. The oxygen isotopes indicate equilibration with fluids of a meteoric-hydrothermal system at low temperatures. Based on these data, a two-step model is proposed for the genesis including a first late magmatic stage and a later secondary low temperature alteration.
UnivIS-Import:2015-03-05:Pub.1999.nat.dgeo.IGM.LG.tracee

Trace-element composition of minerals and rocks in the Belaya Zima carbonatite complex (Russia): Implications for the mechanisms of magma evolution and carbonatite formation - Doroshkevich, Anna G.; Veksler, Ilya V.; Klemd, Reiner; Khromova, Elena A.; Izbrodin, Ivan A. (Lithos, 2017)
The nature of petrogenetic links between carbonatites and associated silicaterocks is a matter of discussion for several decades and still remains controversial among igneous petrologists. The Belaya Zima plutonic complex in southern Siberia is a typical intrusion, in which carbonatites are spatially and temporally associated with the ijolite series rocks and nepheline syenites. In this study we use whole-rock compositions and trace element characteristics of the major and accessory minerals for reconstructing the magmatic evolution of the complex and clarifying the origin of carbonatites. We conclude that the observed gradual increase of Zr, Nb and REE concentrations in the magma is consistent with the process of extensive fractional crystallization and gradual transition from silicate rocks to carbonatites, and inconsistent with the formation of carbonatites by liquid immiscibility. Magma differentiation by fractional crystallization continued during the carbonatite formation. The textural and analytical evidence indicates that the early calcitic carbonatites evolved to dolomitic and ankeritic carbonatites. In addition, maximum Nb and Zr concentrations occur in the calcitic carbonatite, whereas the REE content increases in the dolomitic and ankeritic facies.<br
Keywords: REE and Nb; Carbonatites; Alkaline silicate rocks; Evolution

Trace Element Emissions Vary With Lava Flow Age and Thermal Evolution During the Fagradalsfjall 2021–2023 Eruptions, Iceland - Wainman, L.; Ilyinskaya, Evgenia; Pfeffer, Melissa Anne; Mandon, Céline L.; Bali, E.; Edwards, Brock A.; Kleine-Marshall, Barbara; Gudjonsdottir, S. R.; Cotterill, Adam; Scott, Samuel W.; Wieser, P; Stefansson, Andri; et al. (Geochemistry Geophysics Geosystems, 2024)
Basaltic fissure eruptions emit volatile and environmentally reactive gases and particulate matter (PM) into the lower troposphere (e.g., SO2, HCl, and HF in the gas phase; Se, As, Pb as complexes in the PM phase). Lava flows from fissure eruptions can be spatially extensive, but the composition and fluxes of their emissions are poorly characterized compared to those from main vent(s). Using uncrewed aircraft systems-mounted (drone) samplers and ground-based remote Fourier Transform Infrared Spectroscopy, we investigated the down-flow compositional evolution of emissions from active lava flows during the Fagradalsfjall 2021–2023 eruptions. The calculated fluxes of volatile trace metals from lava flows are considerable relative to both main vent degassing and anthropogenic fluxes in Iceland. We demonstrate a fractionation in major gas emissions with decreasing S/halogen ratio down-flow. This S-Cl fractionation is reflected in the trace element degassing profile, where the abundance of predominantly sulfur-complexing elements (e.g., Se, Te, As, Pb) decreases more rapidly in down-flow emissions relative to elements complexing as chlorides (e.g., Cu, Rb, Cs), oxides (e.g., La, Ce) and hydroxides (e.g., Fe, Mg, Al, Ti). Using thermochemical modeling, we explain this relationship through temperature and composition dependent element speciation as the lava flow ages and cools. As a result, some chloride-complexing elements (such as Cu) become relatively more abundant in emissions further down-flow, compared to emissions from the main vent or more proximal lava flows. This variability in down-flow element fluxes suggests that the output of metals to the environment may change depending on lava flow age and thermal evolutio

Trace element fractionation and precipitation in submarine back-arc hydrothermal systems, Nifonea caldera, New Hebrides subduction zone - Keith, Manuel; Haase, Karsten; Häckel, Florian; Schwarz-Schampera, Ulrich; Klemd, Reiner; Hannington, Mark; Strauss, Harald; McConachy, Timothy; Anderson, Melissa (Ore Geology Reviews, 2021)
Hydrothermal activity is abundant at volcanic structures in subduction zones, including those associated with young volcanism in back-arc regions. Fluid boiling is a common process in these environments, but its fractionation and precipitation effects on trace metals and metalloids are still poorly constrained. The submarine back-arc hydrothermal system of Nifonea caldera hosts two recently discovered active vent sites with sulphide-sulphate chimneys showing a diverse mineralogy and chemistry. The focused discharge of fluids with temperatures (up to 368 °C) near the seawater boiling curve at 1860 m water depth and “jets of steam” emitted from the chimney structures suggest fluid boiling. Fluid processes, as well as metal and metalloid deposition vary on a relatively small spatial-scale (<0.5 km2) and coincide with changes in sulphide-sulphate mineralogy and texture between different chimneys with zoning and dendritic intergrowths, indicating temperature gradients and fluid boiling. Boiling-induced precipitation, together with seawater mixing in the sub-seafloor led to a depletion of Zn, Ga, Ge, Ag, Cd, Sb, Au and Pb in the discharging fluids and their precipitates at the main compared to the northern vent site, also resulting in a depleted trace element signature with respect to most other back-arc hydrothermal systems in the Pacific Ocean. A magmatic-hydrothermal signature (high ) in some of the discharging fluids propose a weak magmatic volatile influx to the Nifonea caldera hydrothermal system. However, S isotope data provides no evidence for a magmatic volatile component and rather suggests, in combination with the sulphide-sulphate (Zn, Ge, Se, Ag, Cd, Sb, Ba, Au and Pb) and fluid data (high K) that the Nifonea caldera hydrothermal system is dominantly controlled by a combination of boiling, mixing and water–rock interaction.<br

Trace elements and textures of hydrothermal sphalerite and pyrite in Upper Permian (Zechstein) carbonates of the North German Basin - Knorsch, Manuel; Nadoll, Patrick; Klemd, Reiner (Journal of Geochemical Exploration, 2020)
Deeply buried Upper Permian (Zechstein) carbonates in the southwestern North German Basin host widespread Zn-Fe-Pb sulfide mineralization. The spatial extent of the sediment-hosted mineralization, the geochemical formation conditions, and the number of mineralizing events that are manifested in the Permian sedimentary rocks are an ongoing matter of debate and interest for mineral exploration efforts in the North German Basin. We present detailed petrographic and geochemical data of ore minerals from drill core samples from the Lower Saxony Basin that forms the southwestern part of the North German Basin. Based on these data, we propose and discuss a genetic model for the ore-forming processes. Of particular interest are the sources of metals and sulfur and the timing and temperature at which the sulfides formed. The main sulfide minerals are sphalerite, pyrite, and galena, which commonly occupy mm- to m-scale open space fillings and fractures. Petrographic observations further suggest hydrothermal replacement of the Zechstein Ca2 carbonates, by sulfides, secondary calcite, and anhydrite. Early diagenetic pyrite occurs disseminated in the Zechstein Ca2 carbonates. Scanning electron microscopy, electron microprobe, laser ablation ICP-MS, and sulfur isotope analyses were used to collect petrographic and compositional data on the sphalerite and pyrite. Hydrothermal sphalerite displays cyclical growth patterns and sectoral zoning characterized by colors varying from colorless to black and corresponding indicative variations in their minor and trace element concentrations, e.g., Fe concentrations ranging between below the limit of detection (7.7 ppm) to a maximum of 2.8 wt%. A detailed LA-ICP-MS multielement map illustrates the observed growth patterns and reveals that Mn, Co, Fe, Cu, Ge, Ag, Cd, Hg, Tl, and Pb are the elements that control the distinct color variations. Sectoral zoning is reflected in comparatively high Cu, Ag, and Pb contents, whereas the cyclical growth banding can be retraced by variations in Fe, Co, Cd, Hg, and Tl contents. Calculated temperatures from the trace element signatures using the GGIMFis geothermometer indicate a formation temperature of 148 ± 55 °C for sphalerite. Although the investigated mineralization bears many trademarks of a Mississippi Valley-type (MVT) deposit, the elevated temperatures, a burial depth of around 3.2 km, low concentrations of common strategic elements such as Ga, Ge, and In (< median of 1.3 ppm in sphalerite), as well as the abundance of pyrite represent the unique nature of the Ca2-hosted mineralization. The observed epigenetic ore zones are therefore best described as carbonate replacement mineralization and present an intriguing case study of geochemical exploration in a deeply covered terrane.
CRIS-Team Scopus Importer:2019-11-29
Keywords: Ca2 Zechstein carbonate; LA-ICP-MS; Lower Saxony Basin; North German Basin; Pyrite; Sphalerite

Trace Element Signatures in Pyrite and Marcasite From Shallow Marine Island Arc-Related Hydrothermal Vents, Calypso Vents, New Zealand, and Paleochori Bay, Greece - Nestmeyer, Mark; Keith, Manuel; Haase, Karsten; Klemd, Reiner; Voudouris, Panagiotis; Schwarz-Schampera, Ulrich; Strauss, Harald; Kati, Marianna; Magganas, Andreas (Frontiers in Earth Science, 2021)
Fluid conditions of shallow marine hydrothermal vent sites (<200 mbsl) in island arcs resemble those of subaerial epithermal systems. This leads to a distinct mineralization-style compared to deeper arc/back-arc (>200 mbsl) and mid-ocean ridge-related environments (>2000 mbsl). At Calypso Vents in the Bay of Plenty and Paleochori Bay at the coast of Milos Island, fluids with temperatures <200°C are emitted through volcaniclastic sediments in water depths <200 mbsl. The hydrothermal mineralization from these fluids is dominated by pyrite and marcasite showing diverse textures, including colloform alternations, semi-massive occurrences surrounding detrital grains, vein-type pyrite, and disseminated fine-grained assemblages. Pyrite and marcasite from Calypso SE show elevated concentrations of volatile elements (e.g., As, Sb, Tl, Hg) implying a vapor-rich fluid phase. By contrast, elements like Zn, Ag, and Pb are enriched in hydrothermal pyrite and marcasite from Calypso SW, indicating a high-Cl liquid-dominated fluid discharge. Hence, vapor-liquid element fractionation induced by fluid boiling is preserved in the seafloor mineralization at Calypso Vents. Hydrothermal mineralization at very shallow vent sites (<10 mbsl), like Paleochori Bay, are affected by wave action causing a seasonal migration of the seawater-fluid interface in the sediment cover. The δ34S composition of native S crusts and crystalline S (0.7–6.7‰) is indicative for host rock leaching and thermochemical reduction of seawater sulphate. By contrast, the highly negative δ34S signature of native S globules in sediments (−7.6 to −9.1‰) is related to microbial sulphate reduction or a subordinate magmatic fluid influx. Alunite-jarosite alteration (Paleochori Bay) and a mineral assemblage consisting of orpiment, realgar, and native S (Calypso Vents) may also suggest a contribution by an oxidised (sulphate-rich) low pH fluid of potential magmatic origin. However, fluid boiling is pervasive at Calypso Vents and Paleochori Bay, and the condensation of vapor-rich fluids in a steam-heated environment may produce a similar alteration and mineralization assemblage without a significant magmatic fluid influx, as known from some subaerial epithermal systems.<br

Trace elements in magnetite from the pagoni rachi porphyry prospect, NE Greece: Implications for ore genesis and exploration - Mavrogonatos, Constantinos; Voudouris, Panagiotis; Berndt, Jasper; Klemme, Stephan; Zaccarini, Federica; Spry, Paul G.; Melfos, Vasilios; Tarantola, Alexandre; Keith, Manuel; Klemd, Reiner; Haase, Karsten (Minerals, 2019)
Magnetite is a common accessory phase in various types of ore deposits. Its trace element content has proven to have critical implications regarding petrogenesis and as guides in the exploration for ore deposits in general. In this study we use LA-ICP-MS (laser ablation-inductively coupled plasma-mass spectrometry) analyses of trace elements to chemically characterize magnetite from the Pagoni Rachi Cu–Mo–Re–Au porphyry-style prospect, Thrace, northern Greece. Igneous magnetite mostly occurs as euhedral grains, which are commonly replaced by hematite in fresh to propylitic-altered granodiorite porphyry, whereas, hydrothermal magnetite forms narrow veinlets or is disseminated in sodic/potassic-calcic altered (albite + K-feldspar + actinolite + biotite + chlorite) granodiorite porphyry. Magnetite is commonly associated with chalcopyrite and pyrite and locally exhibits martitization. Laser ablation ICP-MS analyses of hydrothermal magnetite yielded elevated concentrations in several trace elements (e.g., V, Pb, W, Mo, Ta, Zn, Cu, and Nb) whereas Ti, Cr, Ni, and Sn display higher concentration in its magmatic counterpart. A noteworthy enrichment in Mo, Pb, and Zn is an unusual feature of hydrothermal magnetite from Pagoni Rachi. High Si, Al, and Ca values in a few analyses of hydrothermal magnetite imply the presence of submicroscopic or nano-inclusions (e.g., chlorite, and titanite). The trace element patterns of the hydrothermal magnetite and especially the decrease in its Ti content reflect an evolution from the magmatic towards the hydrothermal conditions under decreasing temperatures, which is consistent with findings from analogous porphyry-style deposits elsewhere.
CRIS-Team Scopus Importer:2019-12-03
Keywords: Exploration; Hydrothermal; LA-ICP-MS; Magmatic; Magnetite; Porphyry; Trace elements

Trace element systematics and ore-forming processes in mafic VMS deposits: Evidence from the Troodos ophiolite, Cyprus - Martin, Andrew J.; Keith, Manuel; Mcdonald, Iain; Haase, Karsten; Mcfall, Katie A.; Klemd, Reiner; Macleod, Christopher J. (Ore Geology Reviews, 2019)
The volcanogenic massive sulfide (VMS) deposits in the Troodos ophiolite (Cyprus) are ancient analogues for modern day seafloor massive sulfide mineralisation formed in a supra-subduction zone environment. In this study we present the first detailed in situ study of trace elements in sulfides from twenty VMS deposits hosted in the Troodos ophiolite to better understand factors that influence the distribution, enrichment and incorporation of trace elements in different sulfide minerals.
CRIS-Team WoS Importer:2019-04-09

Trace element systematics of pyrite from submarine hydrothermal vents - Keith, Manuel; Häckel, Florian; Haase, Karsten; Schwarz-Schampera, Ulrich; Klemd, Reiner (Ore Geology Reviews, 2016)
Submarine hydrothermal sulfide ores occur at mid-ocean ridges, intra-oceanic arcs and in back-arc basins associated with host rocks of highly variable composition. Pyrite is the dominant sulfide mineral in most samples presented within this study, and thus the trace element composition of pyrite may reflect the different metal sources and precipitation processes. Here, we report on a systematic study of minor and trace element contents in pyrite from active and inactive submarine hydrothermal vent fields at different plate-tectonic settings including the Indian and Mid-Atlantic Ridges, the Tonga-Kermadec intra-oceanic arc, the Lau back-arc and the central Okinawa Trough. Our results show that the trace element contents of pyrite from different locations vary significantly but for most elements without any systematic correlation to the concentration in the magmatic host rocks. Only As appears to be depleted in pyrite from ultramafic-hosted vent systems that are affected by serpentinization. These As depleted pyrites preferentially host Au micro- or nano-particles. Bismuth is enriched in pyrite from hydrothermal systems that contain a sedimentary component and micro-inclusions of sphalerite are either due to fluid-sediment interaction or phase-separated fluid venting. Pyrites from individual locations have highly variable concentrations of elements like Au, Co, Cu, Se, Mo, Ag and Sb that are most likely related to fluid evolution and changes in fluid composition. Sub-seafloor hydrothermal fluid-seawater mixing influences the distribution of Au, Co, Cu, Se and Mo in pyrite. Elements like Au, Ag, Sb and Pb often have a characteristic affinity to As, while Cd correlates closely with Zn. A magmatic volatile contribution to the Hine Hina hydrothermal system may result in the precipitation of Cu-enriched pyrite. Our results show that the concentrations of most trace metals in pyrite are a function of the physicochemical parameters of the fluid phase rather than a reflection of the magmatic host rock compositio
Keywords: Hydrothermal sulfides; Laser ablation ICP-MS; Pyrite; Trace elements; VHMS

Trace Fossil Evidence of Trematode-Bivalve Parasite-Host Interactions in Deep Time. - Huntley, John Warren; de Baets, Kenneth (Advances in Parasitology, 2015)
Parasitism is one of the most pervasive phenomena amongst modern eukaryotic life and yet, relative to other biotic interactions, almost nothing is known about its history in deep time. Digenean trematodes (Platyhelminthes) are complex life cycle parasites, which have practically no body fossil record, but induce the growth of characteristic malformations in the shells of their bivalve hosts. These malformations are readily preserved in the fossil record, but, until recently, have largely been overlooked by students of the fossil record. In this review, we present the various malformations induced by trematodes in bivalves, evaluate their distribution through deep time in the phylogenetic and ecological contexts of their bivalve hosts and explore how various taphonomic processes have likely biased our understanding of trematodes in deep time. Trematodes are known to negatively affect their bivalve hosts in a number of ways including castration, modifying growth rates, causing immobilization and, in some cases, altering host behaviour making the host more susceptible to their own predators. Digeneans are expected to be significant agents of natural selection. To that end, we discuss how bivalves may have adapted to their parasites via heterochrony and suggest a practical methodology for testing such hypotheses in deep tim
Keywords: Bivalve; Fossil; Mollusca; Paleoecology; Paleopathology; Parasitism; Trematode

Tracing mantle components and the effect of subduction processes beneath the northern Antarctic Peninsula - Anderson, D. W.; Saal, A. E.; Lee, J. I.; Mallick, S.; Riley, T. R.; Keller, R. A.; Haase, Karsten (Geochimica Et Cosmochimica Acta, 2023)
Understanding subduction processes is critical in assessing the long-term evolution of the upper mantle and continental crust. We present new geochemical data on glassy submarine lavas from the Bransfield Strait, the Phoenix and West Scotia ridges, and previously unpublished data of marine sediments from atop the Phoenix Plate. We combined new and published geochemical data from across the northern sector of the Antarctic Peninsula to unravel both large-scale mantle composition and flow across the region. The geochemistry of Phoenix and West Scotia Ridge basalts supports the hypothesis that both ridges are underlain by Pacific MORB mantle, brought into the region through the eastward expansion of the Scotia Plate. Comparisons among lavas from the Phoenix/West Scotia ridges, the South Shetland Islands volcanic arc, and the Bransfield Strait/Prince Gustav Rift back-arc region reveal that the Pacific upper mantle flowed into the mantle wedge and was subsequently modified by subduction processes. The compositions of Bransfield Strait lavas range from strongly subduction-influenced near the strait's center to akin to Phoenix Ridge MORB toward the strait's edges. This suggests that the Phoenix MORB mantle has flowed around the slab edges into the mantle wedge, diluting the subduction signal and focusing the subduction-modified mantle towards the center of the strait. Monte Carlo simulations indicate that mixing of Phoenix MORB mantle with 0 to 3 % subduction component having a fluid/sediment ratio of ∼1 can explain the compositional range in the Bransfield Strait. Furthermore, our modeling suggests the presence of a more depleted Phoenix MORB mantle beneath the South Shetland Islands modified by the addition of ∼3 % subduction component with a fluid/sediment ratio ranging from ∼0.18 to 4. The increase in fluid/sediment ratios in the South Shetland Island lavas corresponds to a spatiotemporal progression of volcanism from the southwest (40–140 Ma) to the northeast (30–60 Ma). Finally, we have identified a set of lavas with unique trace element and isotope compositions typical of alkaline volcanism found across other parts of the Antarctic Peninsula. Surprisingly, we find occurrences of these lavas on both sides of the South Shetland Trench, suggesting the presence of a distinct enriched source in the upper mantle throughout the region.
CRIS-Team Scopus Importer:2023-02-17
Keywords: Back-arc basin; Bransfield Strait; Geochemistry; Phoenix Ridge; Subduction

Tracing the Sveconorwegian orogen into the Caledonides of West Norway: Geochronological and isotopic studies on magmatism and migmatization - Wang, Cheng Cheng; Wiest, Johannes; Jacobs, Joachim; Bingen, Bernard; Whitehouse, Martin J.; Elburg, Marlina A.; Sørstrand, Thea S.; Mikkelsen, Lise; Hestnes, Åse (Precambrian Research, 2021)
The Sveconorwegian orogen represents a branch of Grenville-age ( 1250–950 Ma) orogenic belts that formed during the construction of the supercontinent Rodinia. This study traces the Sveconorwegian records from its type-area in the Baltic Shield of South Norway into basement windows underneath Caledonian nappes, by combining zircon U–Pb geochronology and Hf–O isotopes. Samples along a N-S trending transect reveal multiple magmatic episodes during Gothian (ca. 1650 Ma), Telemarkian (ca. 1500 Ma) and Sveconorwegian (1050–1020 Ma vs. 980–930 Ma) orogenesis as well as Sveconorwegian migmatization (1050–950 Ma). Newly documented 1050–1020 Ma magmatism and migmatization extend the Sirdal Magmatic Belt to a 300 km-long, NNW-SSE trending crustal domain, with the northern boundary corresponding to the gradual transition from Telemarkian to Gothian crust. These Precambrian crustal heterogeneities largely controlled the development of Caledonian shear zones. The ca. 1050–1040 Ma granitic and mafic magmas show similar isotopic signatures with slightly negative or positive εHf(t) and moderate δ18O values (6–7‰), which indicates that crustal reworking was more dominant than juvenile inputs during their genesis. The generation of leucosomes and leucogranites at ca. 1030–1020 Ma, which have a more evolved Hf isotopic composition, probably reflects an even higher degree of remelting of older crust. The Hf–O isotopic patterns show that Sveconorwegian magmas differ from typical arc magmas by lower involvement of sedimentary components and juvenile material. This makes the 1050–930 Ma magmatism incompatible with a long-term subduction setting. The ca. 1650–1500 Ma samples, in contrast, generally have juvenile Hf isotopic compositions associated with varying δ18O values of 4.5–9‰, consistent with subduction-accretion processes involving significant sedimentary recycling. This accretionary margin was most likely transformed into the Sveconorwegian orogen through collisional interactions of Baltica, Laurentia and Amazonia in the context of Rodinia amalgamation.
CRIS-Team Scopus Importer:2021-08-13
Keywords: Baltica; Collisional orogen; Hf–O isotopes; Mesoproterozoic; Rodinia; Zircon U–Pb geochronology

Tracking crystal-melt segregation and magma recharge using zircon trace element data - Yan, Li Li; He, Zhen Yu; Klemd, Reiner; Beier, Christoph; Xu, Xi Sheng (Chemical Geology, 2020)
The Cretaceous Yunshan caldera complex in SE China consists of an unusual coexisting assemblage of peraluminous and peralkaline rhyolites and a resurgent intra-caldera porphyritic quartz monzonite. In this study, we use zircon trace element data to study the compositional differences of zircons from cogenetic magmas and to track the evolution of the entire magmatic system. Our results indicate that the zircons from the peraluminous and peralkaline rhyolites formed from highly evolved compositions with high Hf concentrations and low Ti contents, and low Th/U and Zr/Hf ratios, which are distinct from those of the intrusive porphyritic quartz monzonite. Zircons from the peraluminous and peralkaline rhyolites display overlapping Zr/Hf and Hf, but the zircons from the peralkaline rhyolites have extremely low Eu/Eu* ratios (<0.1) and Ti contents (2.26–13.3 ppm). The lack of overlapping zircon trace element compositions between the volcanic and intrusive caldera units is interpreted to represent crystal–melt segregation processes. In addition, zircon grains from the porphyritic quartz monzonite and a few zircon grains from the peraluminous rhyolite display distinctly bright rims and whole grains in cathodoluminescence imaging, which have high Ti, Zr/Hf, and Eu/Eu*, and are similar to those of zircons from the mafic microgranular enclave within the porphyritic quartz monzonite. We interpret these signatures to reflect crystallization from a relatively hot and less evolved magma indicating a magma chamber recharge event. We further developed a model in which the magmas of the peraluminous and peralkaline rhyolites were successively extracted from a primitive crystal mush by crystal–melt segregation with a rejuvenation of the crystal mush after the extraction of the peraluminous rhyolitic melt, leaving behind residual mushes solidified as porphyritic quartz monzonite. Our study shows that trace element analyses of zircons can effectively be used to pinpoint multiple crystal–melt segregation and melt extraction events as well as magma recharge processes in silicic magmatic systems.
CRIS-Team Scopus Importer:2020-04-07
Keywords: Crystal–melt segregation; Magma differentiation; Magma recharge; SE China; Yunshan caldera complex

Traits to live or traits to die? Tracing the development of functional diversity in trees during Cenozoic climate change - Wilkens, Vincent; Walentowitz, Anna; Teichert, Sebastian; Beierkuhnlein, Carl (Macroecology and Biogeography meeting, 2023)

Trajectories of Late Permian Jurassic radiolarian extinction rates: no evidence for an end-Triassic mass extinction - Kießling, Wolfgang; Danelian, Taniel (Fossil Record, 2011)
The hypothesis that ocean acidification was a proximate trigger of the marine end-Triassic mass extinction rests on the assumption that taxa that strongly invest in the secretion of calcium-carbonate skeletons were significantly more affected by the crisis than other taxa. An argument against this hypothesis is the great extinction toll of radiolarians that has been reported from work on local sections. Radiolarians have siliceous tests and thus should be less affected by ocean acidification. We compiled taxonomically vetted occurrences of late Permian and Mesozoic radiolarians and analyzed extinction dynamics of radiolarian genera. Although extinction rates were high at the end of the Triassic, there is no evidence for a mass extinction in radiolarians but rather significantly higher background extinction in the Triassic than in the Jurassic. Although the causes for this decline in background extinction levels remain unclear, the lack of a major evolutionary response to the end-Triassic event, gives support for the hypothesis that ocean acidification was involved in the dramatic extinctions of many calcifying taxa. © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
UnivIS-Import:2015-03-09:Pub.2011.nat.dgeo.IGM.LP.trajec
Keywords: Ocean acidification; Radiolarians; Sampling standardization; Triassic

Transfer and transformations of oxygen in rivers as catchment reflectors of continental landscapes: A review - Piatka, David; Wild, Romy; Hartmann, Jens; Kaule, Robin; Kaule, Lisa; Gilfedder, Benjamin; Peiffer, Stefan; Geist, Juergen; Beierkuhnlein, Carl; Barth, Johannes (Earth-Science Reviews, 2021)
Oxygen is one of the most crucial elements on earth and equally affects life and inorganic redox processes. After its transition to water with moderate solubility and slow diffusion rates, most aquatic organisms depend on permanent renewal of dissolved oxygen (DO). Recharge of this pivotal aqueous gas may become hampered by anthropogenic and climatic influences with so far unknown consequences for surface freshwater systems and entire ecosystems. Because rivers integrate biogeochemical information of catchments, their oxygen dynamics may also reflect ecosystem and landscape health. Here we summarize the most important sources and sinks of DO and its role in river systems. These considerations also extend to associated water compartments and fluxes including lakes, reservoirs, soils, groundwater and the hyporheic zone. In addition, for continental-scale considerations, we analysed the GLObal RIver CHemistry (GLORICH) database with 170,369 DO measurements. These analyses revealed that DO in rivers relates to water temperature, pH and nutrient availability. On larger scales, it is also influenced by catchment area, slope, ratios of forests to managed land and population density. Our review also highlights important links between physical and biological influences on DO transfer as well as its sources and sinks in streams and rivers. We conclude that DO monitoring should be combined with novel interdisciplinary tracing techniques such as stable isotope ratios, radon gas and biological analyses. Such combined analyses have the potential to improve our understanding of transfer and transformations of oxygen in rivers as essential integrators of landscapes.
CRIS-Team Scopus Importer:2021-09-10
Keywords: Anthropogenic pressure; Climate change; Dissolved oxygen; GLObal RIver CHemistry database; Rivers; Transformation; Turnover

Transfer of pollutants in soils, sediments and water systems: From small to large scale - Finkel, Michael; Grathwohl, P.; Barth, Johannes; Barcelo, Damia; Charlet, L. (Journal of Hydrology, 2009)

Transferring and implementing the general dynamic model of oceanic island biogeography at the scale of island fragments: The roles of geological age and topography in plant diversification in the Canaries - Otto, Ruediger; Whittaker, Robert J.; Von Gaisberg, Markus; Stierstorfer, Christian; Naranjo-Cigala, Agustin; Steinbauer, Manuel; Borregaard, Michael K.; Ramon Arevalo, Jose; Garzon-Machado, Victor; Del Arco, Marcelino; Maria Fernandez-Palacios, Jose (Journal of Biogeography, 2016)
Aim: The general dynamic model (GDM) of oceanic island biogeography integrates rates of immigration, speciation and extinction in relation to a humped trajectory of island area, species carrying capacity and topographic complexity through time, based on a simplified island ontogeny. In practice, many islands have more complex ontogenies, featuring surfaces of varying age. Here, we extend the GDM to apply at a local scale within islands, and test the predictions analytically within individual islands. Location: El Hierro, La Palma and Tenerife (Canary Islands). Methods: Following the GDM logic, we derive predictions for the distributions and richness of single island endemics (SIEs) across island landscapes of different age. We test these predictions by means of generalized linear models and binominal tests using gridded species occurrence data for vascular plant SIE species and a set of climatic, topographic and terrain age variables. We also examined phylogenetic divergence times for a subset of endemic lineages. Results: Geological age, in interaction with slope, and topographic variables, best explained SIE richness at the landscape scale. About 70% of SIEs had ranges strongly biased to, or largely restricted to old terrain. Available phylogenetic divergence times of SIEs of radiated plant lineages suggested an origin on the older parts of the islands. Metrics of anthropogenic disturbance and habitat availability were unrelated to the observed SIE pattern. Main conclusions: Our findings support the hypothesis that SIEs have evolved and accumulated on older and topographically complex terrain, while colonization processes predominate on the youngest parts. These results imply that evolutionary processes shape species distributions at the landscape scale within islands. This opens the perspective of extending the GDM framework to understand processes at a local scale within individual islands.
Keywords: Canary Islands; Endemic plants; Environmental heterogeneity; General dynamic model; Island biogeography; Island evolution; Landscape diversity; Oceanic islands; Spatial autocorrelation; Species richness patterns

Trend analysis of annual precipitation of Mauritius for the period 1981–2010 - Raja, Nussaïbah Begum; Aydin, Olgu (Meteorology and Atmospheric Physics, 2019)
This study researched the precipitation variability across 53 meteorological stations in Mauritius and different subregions of the island, over a 30-year study period (1981–2010). Time series was investigated for each 5-year interval and also for the whole study period. Non-parametric Mann–Kendall and Spearman’s rho statistical tests were used to detect trends in annual precipitation. A mix of positive (increasing) and negative (decreasing) trends was highlighted for the 5-year interval analysis. The statistical tests nevertheless agreed on the overall trend for Mauritius and the subregions. Most regions showed a decrease in precipitation during the period 1996–2000. This is attributed to the 1998–2000 drought period which was brought about by a moderate La Niña event. In general, an increase in precipitation levels was observed across the country during the study period. This increase is the result of an increase in extreme precipitation events in the region. On the other hand, two subregions, both located in the highlands, experienced a decline in precipitation levels. Since most of the reservoirs in Mauritius are located in these two subregions, this implies serious consequences for water availability in the country if existing storage capacities are kept.
CRIS-Team Scopus Importer:2019-07-19

Trias-Exkursion I. Buntsandstein zwischen Hannover und Würzburg. - Röhling, Heinz-Gerd; Stollhofen, Harald; Tietze, Klaus-Werner (GEO 2002-Planet Erde: Vergangenheit, Entwicklung, Zukunft. Programm und Kurzfassungen der Tagung vom 1. bis 5. Oktober 2002 in Würzburg, 2002)
UnivIS-Import:2015-04-20:Pub.2002.nat.dgeo.IGM.LG.triase

Triassic-Jurassic carbonates from the Hochfelln Mountain (Northern Calcareous Alps) - Its facies, silicified fauna and implications for the end-Triassic biotic crisis - Seuß, Barbara; Höfling, Richard; Nützel, Alexander (Facies, 2005)
A suite of Early Mesozoic (Late Triassic, Norian to Early Jurassic) calcareous beds was studied from the Hochfelln Mountain in the Northern Calcareous Alps (NCA, South Germany). The Hauptdolomit Group consists of thick peritidal deposits and is overlain by basin deposits of the Rhaetian Kössen Formation and Rhaetian reefoidal limestone with corals. Unlike many other sections in the Tethys realm, coral growth seems to continue into the Jurassic or starts again relatively early within the Early Jurassic. Silicified corals and other marine invertebrates are present in the calcareous, micritic Hochfelln Beds. A re-examination of previously collected ammonite material indicates the presence of Coroniceras sp. which suggests an Early Sinemurian age for the Hochfelln Beds. Abundant sponge spicules (spiculites) suggest that sponges were the source for the silicification. The site produced one of the most diverse Early Jurassic (Sinemurian) gastropod faunas of the NCA (25-30 species, some undescribed). The relatively diverse Early Sinemurian gastropod fauna and coral growth indicate rapid recovery from the end-Triassic biotic crisis. © Springer-Verlag 2005.
UnivIS-Import:2015-03-09:Pub.2005.nat.dgeo.IGM.profes.triass
Keywords: Corals; End-Triassic mass extinction; Gastropods; Hochfelln; Northern Calcareous Alps; Silicification; Triassic/Jurassic transition

Triassic Reefs of the Tethys - Flügel, Erik; Senowbari-Daryan, Baba (The History and Sedimentology of Ancient Reef Systems, 2001)
The evolution of Triassic reefs started with a long-lasting global crisis of the metazoan reef ecosystem after the Permian—Triassic mass extinction (about 12 Ma), followed by a relatively rapid recovery during the Middle Triassic. Reef systems were differentiated during the Upper Triassic but were severely affected by a global crisis at the Triassic—Jurasic boundary. The present contribution is focused on the biological controls of Triassic reefs, particularly in the Tethyan realm, and on the major changes in reef ecosystems recorded by differences in reef types and reef biota. The term “reef” as used in this chapter refers to bioconstructions characterized by (1) biological control during the formation of the structure (predominantly by sessile benthic organisms), (2) a laterally restricted topographic relief, and (3) (inferred) rigidity of the structure.
UnivIS-Import:2017-11-07:Pub.2001.nat.dgeo.IGM.LP.triass
Keywords: Middle Triassic; Northern Calcareous; Microbial Crust; Reef Mound; Triassic Reef

Trilobite extinctions, facies changes and the ROECE carbon isotope excursion at the Cambrian Series 2–3 boundary, Great Basin, western USA - Faggetter, Luke E.; Wignall, Paul B.; Pruss, Sara B.; Newton, Robert J.; Sun, Yadong; Crowley, Stephen F. (Palaeogeography, Palaeoclimatology, Palaeoecology, 2017)
Keywords: C-Shale Member; Carrara Formation; Olenellid extinction; Pioche Formation; Pyramid Shale Member

Trilobites as Hosts for Parasites: From Paleopathologies to Etiologies - de Baets, Kenneth; Budil, Petr; Fatka, Oldřich; Geyer, Gerd (The Evolution and Fossil Record of Parasitism, 2021)
Extant marine arthropods are afflicted by a variety of parasitic diseases making it plausible that extinct trilobites also had a variety of parasites. Direct evidence in the form of preserved parasite body fossils is lacking to date, which is not surprising considering the poor preservation potential of soft tissues of parasites and their hosts. Some of these interactions might leave traces and pathologies in their exoskeletons, which can be traced in deep time. Knowledge of the parasitic causes of pathologies in modern arthropods such as crustaceans and horseshoe crabs might, therefore, help to better interpret past afflictions and their potential culprits. Our review shows that a variety of structures have been attributed to parasitism—some more confidently than others. The restriction of these structures to particular trilobite lineages might indicate the influence of phylogeny, anatomy, and potential role of ecology (feeding, mode of life) on infestation risks. However, preservation and research biases might also contribute to differences between time intervals and individual trilobite lineages. Other interactions such as epizoa, bioerosion, as well as other structures, which have been confused with parasitic causes are briefly discussed. The culprits of many of these structures remain elusive.
Keywords: Paleopathology; Borings; Neoplasia; Shell disease syndrome; Parasitic infestations; Helminths Bacteria

Trilobites from the Red Fauna (latest Emsian, Devonian) of Hamar Laghdad, Morocco and their biodiversity - Crônier, Catherine; Oudot, Morgane; Klug, Christian; de Baets, Kenneth (Neues Jahrbuch für Geologie und Paläontologie-Abhandlungen, 2018)
Trilobites are widespread in Early Devonian deposits of north Gondwana; some of the most emblematic ones were collected from the famous latest Emsian (Early Devonian) mudmound locality Hamar Laghdad in south-eastern Morocco. This locality is famous for its trilobites, especially for the conspicuous red-coloured remains of phacopid trilobites with often greenish eyes. Here, we present a taxonomic revision of the previously described trilobites from the so-called Red Fauna of Hamar Laghdad. We introduce the new taxa Harpes hamarlaghdadensis n. sp. and Morocops davidbrutoni n. sp. Phacopids dominate the trilobite assemblage from the Red Cliff at Hamar Laghdad in terms of the number of specimens (represented by Morocops) as a whole. Additionally, we focus on the description of trilobite diversity of this interval compared to Algerian assemblages.<br

Tritium as a hydrological tracer in Mediterranean precipitation events - Juhlke, Tobias; Sültenfuß, Jürgen; Trachte, Katja; Huneau, Frédéric; Garel, Emilie; Santoni, Sébastien; Barth, Johannes; van Geldern, Robert (Atmospheric Chemistry and Physics, 2020)
Climate models are in need of improved constraints for water vapor transport in the atmosphere, and tritium can serve as a powerful tracer in the hydrological cycle. Although the general principles of tritium distribution and transfer processes within and between the various hydrological compartments are known, variation on short timescales and aspects of altitude dependence are still under debate. To address questions regarding tritium sources, sinks, and transfer processes, the sampling of individual precipitation events in Corte on the island of Corsica in the Mediterranean Sea was performed between April 2017 and April 2018. Tritium concentrations of 46 event samples were compared to their moisture origin and corresponding air mass history. Air mass back-trajectories were generated from the novel high-resolution ERA5 dataset from the ECMWF (European Centre for Medium-Range Weather Forecasts). Geographical source regions with similar tritium concentrations were predefined using generally known tritium distribution patterns, such as the "continental effect", and from data records derived at long-term measurement stations of tritium in precipitation across the working area. Our model-derived source region tritium concentrations agreed well with annual mean station values. Moisture that originated from continental Europe and the Atlantic Ocean was most distinct regarding tritium concentrations with values up to 8.8 TU (tritium units) and near 0 TU, respectively. The seasonality of tritium values ranged from 1.6 TU in January to 10.1 TU in May, and they exhibited well-known elevated concentrations in spring and early summer due to increased stratosphere-troposphere exchange. However, this pattern was interrupted by extreme events. The average altitude of trajectories was correlated with the tritium concentrations in precipitation, especially in spring and early summer and if outlier values of extreme tritium concentrations were excluded. However, in combination with the trajectory information, these outlier values proved to be valuable for improving the comprehension of tritium movement in the atmosphere. Our work shows how event-based tritium research can advance the understanding of its distribution in the atmosphere.
CRIS-Team Scopus Importer:2020-04-07

Trophic relationships between the large scyphomedusa Chrysaora plocamia and the parasitic amphipod Hyperia curticephala - Riascos, J; Docmac, Felipe; Reddin, Carl James; Harrod, Chris (Marine Biology, 2015)

Tube-like schlieren structures in the Fürstenstein Intrusive Complex (Bavarian Forest, Germany): Evidence for melt segregation and magma flow at intraplutonic contacts - Dietl, C.; de Wall, Helga; Finger, Fritz (Lithos, 2010)
Keywords: Intraplutonic contact; Magma flow; Magnetic susceptibility; Microdiapirs; Schlieren structures; Trace element geochemistry

Tubes or cell sheet? A 3-D reconstruction of Halysis Høeg, 1932, from the Upper Ordovician of South China - Frisch, Konstantin; Munnecke, Axel; Schulbert, Christian; Zhang, Yuandong (Facies, 2012)
Halysis is a microfossil found in Ordovician to Devonian shallow-marine carbonates. Up to now, it is only known from thin-sections, and therefore its three-dimensional shape and its systematic position are controversial. Halysis is described as a chain-like microfossil with a shape of the single “chain links” ranging from circular to rounded rectangular. Given that Halysis commonly co-occurs with calcareous algae, it is assumed to also be an alga. Interpretations of the anatomy propose a filiform or tubiform shape. Even a unistratose sheet of cells has been discussed. Since Halysis is comparatively rare, its shape has not been resolved up to now. For the present study, 52 out of several hundred specimens from an Upper Ordovician shallow-water limestone of South China have been investigated in detail, which for the first time offers the opportunity to analyze a great number of sections through Halysis. A three-dimensional computer model of Halysis has been constructed in order to set up planes sectioning the model. These simulated sections have been compared to those from Halysis in thin-sections. The results show that Halysis represents a microfossil with a morphology consisting of parallel juxtaposed, partly branching tubes. A single sheet of cells, which was recently proposed as shape of Halysis, can clearly be excluded.
Keywords: Calcareous algae; Late Ordovician; South China; 3-D reconstruction; Halysis; Blender

Tuff fingerprinting and correlations between OGCP cores and outcrops for Pre-Bed I and Beds I/II at Olduvai Gorge, Tanzania - McHenry, Lindsay J.; Stanistreet, Ian G.; Stollhofen, Harald; Njau, Jackson K.; Toth, Nicholas; Schick, Kathy (Palaeogeography, Palaeoclimatology, Palaeoecology, 2020)
Keywords: Mineral assemblage; Pleistocene; East Africa; Geochemistry; Tephra; Tephrostratigraphy

Tuff layers in the Lower Rotliegend Lebach group of the Saar-Nahe Basin (SW-Germany): Occurence, sedimentation patterns and significance. - Königer, Stephan; Stollhofen, Harald; Lorenz, Volker (Terra Nova, 1995)
UnivIS-Import:2015-03-05:Pub.1995.nat.dgeo.IGM.LG.tuffla

Tuffs, tectonism and glacially related sea-level changes, Carboniferous-Permian, Southern Namibia. - Stollhofen, Harald; Stanistreet, Ian G.; Bangert, Berthold; Grill, Hermann (Palaeogeography, Palaeoclimatology, Palaeoecology, 2000)
The Carboniferous-Permian glacigene Dwyka Group in southern Africa has been widely regarded as amagmatic. Only in the higher parts of the Permian and subsequent younger strata has evidence of magmatism been recognised, particularly in the form of pyroclastic fallout ash beds. The source of these tufts has been suggested to be Patagonia and West Antarctica, forming part of an extensive volcanic arc which lay some 1500 to 2000 km to the south and west in their pre-break-up Gondwana positions. Rhyolitic/dacitic and basaltic/andesitic tuff beds within the glaciomarine sediments of the Dwyka Group in Namibia reveal new evidence for an early onset of proximal bimodal volcanic activity in southern Africa. Contemporaneous tectonism is recorded by type-1 unconformities and systematic thickness changes across NW-SE trending extensional normal faults. We suggest that this tectonomagmatic period marks initial extensional events in southern Namibia and the Carboniferous-Permian volcanic trend appears to coincide with the position of the eventual Namibian continental margin. Significantly, the stratigraphic positions of the tuff beds show a distinct association with enclosing marine transgressive depositional sequences. Most of them coincide with sharply defined flooding surfaces within relatively thick shaly successions, reflecting their multiple transgressive nature. Widening the study context to the latest Early Permian in southern Africa, the main Karoo Basin of southern Africa exhibits a similar coincidence of marine transgressions and extrusion of volcanics. The relationship between tuff beds and transgressive depositional sequences is not only the result of enhanced preservational potential during transgression, but of a genetic coupling between magmatism, extensional tectonics and basin subsidence, the latter accelerating a rise in relative sea-level. This interaction is significant, not only for understanding potential controls on relative sea-level change, but also for understanding the early geodynamic evolution of the southern South Atlantic continental margin. (C) 2000 Elsevier Science B.V.
UnivIS-Import:2015-03-09:Pub.2000.nat.dgeo.IGM.LG.tuffst
Keywords: Dwyka; Glacial; Glacio-eustatic; Gondwana; Karoo; Namibia; Sea-level; Vo lcanism

Turnover and release of P-, N-, Si-nutrients in the Mexicali Valley (Mexico): Interactions between the lower Colorado River and adjacent ground- and surface water systems - Orozco-Duran, A.; Daessle, L. W.; Camacho-Ibar, V. F.; Ortiz-Campos, E.; Barth, Johannes (Science of the Total Environment, 2015)

Turnover rates of Paleozoic and modern taxa during the Late Paleozoic Ice Age - Seuß, Barbara; Roden, Vanessa; Kocsis, Ádám; Kießling, Wolfgang (GSA Annual Meeting, 2019)

Twentieth century d13C variability in surface water dissolved inorganic carbon recorded by coralline algae in the northern North Pacific Ocean and the Bering Sea. - Joachimski, Michael; et al. (Biogeosciences, 2011)
UnivIS-Import:2015-03-09:Pub.2011.nat.dgeo.IGM.LG.twenti

Two centuries carbon and oxygen isotope record of Porites lutea in the Golf of Aqaba, Red Sea. - Joachimski, Michael; et al. (Senckenbergiana Maritima, 1999)
UnivIS-Import:2015-03-05:Pub.1999.nat.dgeo.IGM.LG.twocen

Two phases of post-onset collision adakitic magmatism in the southern Lhasa subterrane, Tibet, and their tectonic implications - Lu, Tianyu; He, Zhen-Yu; Klemd, Reiner (Geological Society of America Bulletin, 2020)
Abundant Neogene adakitic magmatism occurred in the southern Lhasa subterrane after the onset of the India-Asia collision while convergence continued. However, the tectonic setting and magmatic evolution of the adakitic rocks are still under discussion. This study includes new mineral chemical and whole-rock geochemical data as well as zircon U-Pb and Lu-Hf isotopes of adakitic intrusive rocks from the Gyaca and Nyemo locations in the southern Lhasa subterrane. Laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS) zircon U-Pb dating yielded crystallization ages of ca. 30 Ma for the Gyaca and Nyemo monzogranite and ca. 15 Ma for the Nyemo granodiorite. Both have common chemical signatures such as low MgO and heavy rare earth element contents as well as low compatible element abundances, indicating that these rocks result from partial melting of thickened lower crust with residual eclogite and garnet amphibolite. Furthermore, these rocks are characterized by variable positive zircon εHf(t) values, suggesting a juvenile magma source with variable ancient crustal contributions. Taking previous data into account, the adakitic magmatism concurs with an early late Eocene to Oligocene (ca. 38-25 Ma) and a late Miocene (ca. 20-10 Ma) phase. The adakitic rocks of the two phases are characterized by different fractionation evolutions of light and medium rare earth elements. We propose that the early-phase adakitic rocks were generated by the anatexis of Lhasa terrane lower crust owing to crustal shortening and thickening subsequent to the onset of the India-Asia collision and the upwelling of hot asthenosphere beneath the Lhasa terrane caused by the break-off of the Neo-Tethyan oceanic slab. The latest phase of adakitic rocks, however, relates to upwelling asthenosphere following the delamination and/or break-off of the subducting Indian continental slab.
CRIS-Team Scopus Importer:2020-08-07

Two software tools for facilitating the choice of ground source heat pumps by stakeholders and designers - de Carli, Michele; Castelruiz Aguirre, Amaia; Zarrella, Angelo; Cardoso, Lucia; Noyé, Sarah; Gast, Robert; Graci, Samantha; Emmi, Giuseppe; Bertermann, David; Müller, Johannes; Galgaro, Antonio; Dalla Santa, Giorgia; et al. (E3S Web of Conferences, 2019)