Radiolarian faunal characteristics in Oligocene sediments of the Kerguelen Plateau, Leg 183, Site 1138 - Kießling, Wolfgang; et al. (Proceedings of the Ocean Drilling Program: Scientific Results, 2002)
UnivIS-Import:2015-03-09:Pub.2002.nat.dgeo.IGM.LP.radiol_7

Ramp morphology controlling the facies differentiation of a Late Ordovician reef complex at Bachu, Tarim Block, NW China - Zhang, Yuandong; Munnecke, Axel; Wang, Jianpo; Lin, Yue (Lethaia, 2015)
A carbonate ramp in the shallow-marine northwestern part of the Central Tarim Uplift, Bachu, NW China, exhibits an extraordinary Late Ordovician reef complex along the Lianglitag Mountains, exposed for a distance of about 25 km. Seven localities within the 'Middle Red Limestone' of the Upper Member of the Lianglitag Formation (Katian, Late Ordovician) illustrated the changes in biofacies and lithofacies: northern, seaward-directed patch reefs are replaced towards the south by coeval grain banks. The patch reef units are dominated by microbial and calcareous algal components. The reefs at the northernmost locality are knoll-shaped, kalyptra-shaped or irregularly shaped with sizes of individual reefs increasing from about 2 m in height and diameter. Stratigraphically upward, reefs notably expand to larger structures by several mounds coalescing; they are generally about 10 m thick and tens of metres in lateral extent. The maximum thickness of the main patch reef is more than 30 m, and its diameter is around 100 m. The reefal units turn into biostromes with gentler relief southward and still further south grade into banks composed of peloids and coated grains. The southernmost locality is still a shallow-water bank, and the coastline is not documented in the study area. The present evidence indicates that the Late Ordovician palaeo-oceanography provided a number of environments for the optimal growth of carbonate build-ups; microbial-calcareous algal communities could thrive in areas where the innovative metazoan reef frameworks consisting of corals and stromatoporoids did not play a significant role. The ramp morphology, especially changes in water depth, controlled the configuration of the reef complex.
Keywords: Bachu; Late Ordovician; Lianglitag Formation; NW China; Reef complex; Tarim Block

Rapid groundwater recharge dynamics determined from hydrogeochemical and isotope data in a small permafrost watershed near Umiujaq (Nunavik, Canada) - Cochand, M.; Molson, J.; Barth, Johannes; van Geldern, Robert; Lemieux, J-M; Fortier, R.; Therrien, R. (Hydrogeology Journal, 2020)
Hydrogeochemical data are used to better understand recharge dynamics and to support a hydrogeological conceptual model in a 2-km2 watershed in a discontinuous permafrost zone in Nunavik, Canada. The watershed contains an upper (surficial) and lower aquifer within Quaternary deposits, above and below a marine silt layer containing ice-rich permafrost mounds. The analysis is based on water samples from precipitation, groundwater monitoring wells, ground ice in permafrost mounds, thermokarst lakes and a perennial stream. Groundwater geochemistry in both aquifers reflects young, poorly evolved waters, with mainly Ca-HCO3 water types and low mineralisation ranging from 11 to 158 mg/L total dissolved solids (TDS), implying short pathways and rapid travel times of a year or less. While relatively low, TDS signatures in groundwater and surface water show increasing values downgradient. Groundwater isotope values (δ18OH2O and δ2HH2O) are often strongly influenced by snowmelt, while those of thermokarst lakes show evidence of evaporation. Recharge along the cuesta contributes to a transverse component of groundwater flow within the valley with higher TDS and δ13CDIC values influenced by open-system weathering. Even where permafrost-free, the marine silt unit has a strong confining effect and plays a more important role on recharge dynamics than the discontinuous permafrost. Nevertheless, the vulnerability of these types of hydrogeological aquifer systems is expected to increase due to rapid recharge dynamics associated with the gradual loss of the confining effect of permafrost. This hydrogeochemical data set will be useful as a baseline to document impacts of permafrost degradation on the hydrogeological system.
CRIS-Team Scopus Importer:2020-02-04
Keywords: Canada; Cold regions hydrogeology; Hydrochemistry; Natural isotope tracers; Permafrost

Rare peak and ubiquitous post-peak zircon in eclogite: Constraints for the timing of UHP and HP metamorphism in Erzgebirge, Germany - Schmädicke, Esther; Will, Thomas M.; Ling, Xiaoxiao; Li, Xian-Hua; Li, Qiu-Li (Lithos, 2018)
Keywords: Erzgebirge; Exhumation; Eclogite; UHP metamorphism; Symplectite; U-Pb dating

Rate of E–W extension in the Volcanic Tableland, California (USA): A comparison of strain rates on two different timescales - Salomon, Eric (Geosphere, 2023)
The Eastern California shear zone (USA) is a broad zone of transtensional deformation related to the relative motion between the Pacific and North American plates. Due to its active deformation and seismicity, the zone receives great attention, with specific focus on slip rates of major active faults. To contribute to a better understanding of the long-term strain accumulation in this zone, this study quantifies the long-term E–W-directed extensional strain rate based on the analysis of N–S-trending normal fault scarps in the 765-k.y.-old Bishop tuff (Volcanic Tableland). The average extensional strain rate determined over the past 765 k.y. is 0.29 ± 0.10 mm/yr per 10 km (29 ± 10 nanostrain/yr) and similar to the current rate of elastic strain accumulation rate in the Volcanic Tableland (0.30 ± 0.13 mm/yr per 10 km; 30 ± 13 nanostrain/yr) determined by Global Positioning System (GPS) data. The present-day E–W strain rate across the entire Eastern California shear zone at the latitude of the Volcanic Tableland is 0.36 ± 0.05 mm/yr per 10 km (36 ± 5 nanostrain/yr). This suggests that the local rate of E–W extension has not changed significantly since the mid-Pleistocene. Furthermore, if the Volcanic Tableland is representative of the greater region, as the GPS data suggest, this would also indicate a constant extension rate across the Eastern California shear zone at the latitude of 37.5°N over the 765 k.y. time period. These results suggest that late Pleistocene and Holocene extension rates of major faults in this zone can be interpreted in light of a presumably unchanged far-field stress system since at least the mid-Pleistocene. <br

Raw material origin and preference of the Lärbro Group, Tjängvide Group and D-type picture stones at Statens Historiska Museet in Stockholm, Sweden - Hänsel, Patrick; Wendt, Antje; Oehrl, Sigmund; Munnecke, Axel (GFF, 2025)
The Lärbro Group and Tjängvide Group are two special groups of picture stones from Gotland, Sweden. They are characterised by their motifs and decorations. The picture stones of the Lärbro Group seem to belong to the same tradition of one group of crafters, whereas the picture stones of the Tjängvide Group were probably produced by the same crafter. In this study, we present the carbon (δ13C) and oxygen (δ18O) isotope values, and visual facies analyses of the raw material, which were carried out on five sampled picture stones of the Lärbro Group and three sampled picture stones of the Tjängvide Group at Statens Historiska Museet in Stockholm, Sweden. The crafters mainly used local materials from single geological units, Slite Group and Hemse Group, to produce picture stones. In addition, we determine possible transport distance minima up to 10 km between the raw material source area and the find place of the analysed picture stones. Finally, we present that coarse and fine reef debris limestones were preferred by the crafters for producing those picture stones.
CRIS-Team Scopus Importer:2025-05-16
Keywords: Carbon isotopes; facies analysis; Gotland; Iron Age; oxygen isotopes; raw material preference; transport distances

Reaction kinetics during early hydration of calcined phyllosilicates in clinker-free model systems - Scherb, Sebastian; Maier, Matthias; Beuntner, Nancy; Thienel, Karl Christian; Neubauer, Jürgen (Cement and Concrete Research, 2021)
Keywords: Supplementary cementitious material; Thermogravimetry; In situ X-ray diffraction; Reaction kinetics; Calorimetry; Calcined clay

Reaction kinetics of dual setting α-tricalcium phosphate cements - Hurle, Katrin; Christel, Theresa; Gbureck, Uwe; Moseke, Claus; Neubauer, Jürgen; Götz-Neunhoeffer, Friedlinde (Journal of Materials Science: Materials in Medicine, 2016)
Addition of ductile polymers to calcium-deficient hydroxyapatite (CDHA)—forming bone cements based on α-tricalcium phosphate (α-TCP) is a promising approach to improve the mechanical performance of α-TCP cements and extend their application to load-bearing defects, which is else impeded by the brittleness of the hardened cement. One suitable polymer is poly-(2-hydroxyethylmethacrylate) (p-HEMA), which forms during cement setting by radical polymerisation of the monomer. In this study the hydration kinetics and the mechanical performance of α-TCP cements modified with addition of different HEMA concentrations (0–50 wt% in the cement liquid) was investigated by quantitative in situ XRD and four-point bending tests. Morphology of CDHA crystals was monitored by scanning electron microscopy. The hydration of α-TCP to CDHA was increasingly impeded and the visible crystal size of CDHA increasingly reduced with increasing HEMA concentration. Modification of the cements by adding 50 wt% HEMA to the cement liquid changed the brittle performance of the hardened cement to a pseudoplastic behaviour, reduced the flexural modulus and increased the work of fracture, while lower HEMA concentrations had no significant effect on these parameters. In such a composite, the extent of CDHA formation was considerably reduced (34.0 ± 1.8 wt% CDHA with 50 % HEMA compared to 54.1 ± 2.4 wt% CDHA in the reference formed after 48 h), while the general reaction kinetics were not changed. In conclusion, while the extent of CDHA formation was decreased, the mechanical properties were noticeably improved by addition of HEMA. Hence, α-TCP/HEMA composites might be suitable for application in some load-bearing defects and have adequate properties for mechanical treatment after implantation, like insertion of screws.
Keywords: Association reactions; Bearings (machine parts); Bending tests; Bone cement; Brittle fracture; Defects; Fracture; Fracture mechanics; Free radical reactions; Hardening; Hydration; Kinetics; Polymers; Scanning electron microscopy; Setting; Shear thinning 2-hydroxyethylmethacrylate; Calcium deficient hydroxyapatite; Four-point bending test; Hydration kinetics; Mechanical performance; Mechanical treatments; Tri-calcium phosphates; Tricalcium phosphate cement

Reactivity of metakaolin in alkaline environment: Correlation of results from dissolution experiments with XRD quantifications - Scherb, Sebastian; Köberl, Mathias; Beuntner, Nancy; Thienel, Karl Christian; Neubauer, Jürgen (Materials, 2020)
Systematic investigation of filtrates and filter residues resulting from a 24 h treatment of metakaolin in different alkaline solutions were performed. On filtered metakaolin particles, inductively coupled plasma-optical emission spectrometry (ICP-OES) measurements reveal an enrichment of iron and titanium, which suggests an inhomogeneous distribution of these cations. Since the SiO2/Al2O3 ratio remains constant in all filter residues examined, the dissolution of the Si and Al monomers is congruent. Structural differences, identified by attenuated total reflection-Fourier transform infrared spectroscopy (ATR-FTIR) as a consequence of alkali uptake, influence the X-ray scattering contribution of metakaolin, and thus quantifications with the partial or no known crystal structure (PONKCS) method. This leads to deviations between the degree of reaction calculated from Si and Al solubility from filtrate and that quantified by quantitative powder X-ray diffraction (QPXRD) using the filter residue. Nevertheless, the described changes do not cause a shift in the X-ray amorphous hump in case of congruent dissolution, and thus allow the quantification of the metakaolin before and after dissolution with the same hkl-phase model.
CRIS-Team Scopus Importer:2020-06-05
Keywords: Alkaline solution; Calcined clay; Degree of reaction; Metakaolin; PONKCS; Supplementary cementitious material

Reading traces of the past - the Burghöhle Wolfsegg as meeting place for humans, cave lions and co. Spurenlesen in der Vergangenheit - die Burghohle Wolfsegg als Treffpunkt fur Mensch, Hohlenlowe und Co. - Hilpert, Brigitte (Mitteilungen - Verbandes der Deutschen Hohlen- und Karstforscher, 2023)
On the occasion of a tour into the "Burghohle Wolfsegg" in the Franconian Alb (Bavaria), the castle complex was also visited. The faunal remains found there originate from various sites in the cave and are described for the first time. A faunal complex was excavated from the Barenkeller in 1985. The fauna determined here with brown bear (Ursus arctos), cave bear (Ursus spelaeus), cave lion (Panthera leo spelaea) as well as some herbivores can be placed in a rather cool to cold climatic phase of the late Pleistocene around 60,000 - 20,000 years BP. Of particular note is an upper arm bone of a cave lion on which cut marks were found. This is the first such evidence for a cave in the Franconian Alb. Some cut and impact marks on other bones also prove the presence of humans and their impact on animal carcasses or hunted prey. All the material shows traces of various transport phases that led via a former cave room and a shaft step to its current site. At the Rittersaal site, finds were recovered in the 1980s and 1990s. The fauna consists of various domestic animals such as cattle, pigs, sheep/goats, horses and dogs. Wild animals such as red deer (Cervus elaphus) and some predators also occur. Accompanying finds such as pottery shards, a barrel stopper and other human remains prove that the finds can be considered as kitchen waste of the Middle Ages and more recent periods. In 2018, further finds were recovered during the removal of a pile of earth on the wall of the castle building, which are likely to date from the 15th - 17th centuries. In addition to pottery sherds, the find complex consists of fragmented bones of cattle, pig, sheep/goat and horse, with evidence of red deer alongside. Traces of the cutting of the carcasses suggest an interpretation as kitchen waste.
CRIS-Team Scopus Importer:2023-09-22

Rebuilding biodiversity of Patagonian marine molluscs after the end-Cretaceous mass extinction - Aberhan, Martin; Kießling, Wolfgang (PLoS ONE, 2014)
We analysed field-collected quantitative data of benthic marine molluscs across the Cretaceous-Palaeogene boundary in Patagonia to identify patterns and processes of biodiversity reconstruction after the end-Cretaceous mass extinction. We contrast diversity dynamics from nearshore environments with those from offshore environments. In both settings, Early Palaeogene (Danian) assemblages are strongly dominated by surviving lineages, many of which changed their relative abundance from being rare before the extinction event to becoming the new dominant forms. Only a few of the species in the Danian assemblages were newly evolved. In offshore environments, however, two newly evolved Danian bivalve species attained ecological dominance by replacing two ecologically equivalent species that disappeared at the end of the Cretaceous. In both settings, the total number of Danian genera at a locality remained below the total number of late Cretaceous (Maastrichtian) genera at that locality. We suggest that biotic interactions, in particular incumbency effects, suppressed post-extinction diversity and prevented the compensation of diversity loss by originating and invading taxa. Contrary to the total number of genera at localities, diversity at the level of individual fossiliferous horizons before and after the boundary is indistinguishable in offshore environments. This indicates an evolutionary rapid rebound to pre-extinction values within less than ca 0.5 million years. In nearshore environments, by contrast, diversity of fossiliferous horizons was reduced in the Danian, and this lowered diversity lasted for the entire studied post-extinction interval. In this heterogeneous environment, low connectivity among populations may have retarded the recolonisation of nearshore habitats by survivors. © 2014 Aberhan, Kiessling.
UnivIS-Import:2015-03-09:Pub.2014.nat.dgeo.IGM.LP.rebuil

Recent advances in heteromorph ammonoid palaeobiology - Hoffmann, René; Slattery, Joshua S.; Kruta, Isabelle; Linzmeier, Benjamin J.; Lemanis, Robert E.; Mironenko, Aleksandr; Goolaerts, Stijn; de Baets, Kenneth; Peterman, David J.; Klug, Christian (Biological Reviews, 2021)
Heteromorphs are ammonoids forming a conch with detached whorls (open coiling) or non-planispiral coiling. Such aberrant forms appeared convergently four times within this extinct group of cephalopods. Since Wiedmann's seminal paper in this journal, the palaeobiology of heteromorphs has advanced substantially. Combining direct evidence from their fossil record, indirect insights from phylogenetic bracketing, and physical as well as virtual models, we reach an improved understanding of heteromorph ammonoid palaeobiology. Their anatomy, buoyancy, locomotion, predators, diet, palaeoecology, and extinction are discussed. Based on phylogenetic bracketing with nautiloids and coleoids, heteromorphs like other ammonoids had 10 arms, a well-developed brain, lens eyes, a buccal mass with a radula and a smaller upper as well as a larger lower jaw, and ammonia in their soft tissue. Heteromorphs likely lacked arm suckers, hooks, tentacles, a hood, and an ink sac. All Cretaceous heteromorphs share an aptychus-type lower jaw with a lamellar calcitic covering. Differences in radular tooth morphology and size in heteromorphs suggest a microphagous diet. Stomach contents of heteromorphs comprise planktic crustaceans, gastropods, and crinoids, suggesting a zooplanktic diet. Forms with a U-shaped body chamber (ancylocone) are regarded as suspension feeders, whereas orthoconic forms additionally might have consumed benthic prey. Heteromorphs could achieve near-neutral buoyancy regardless of conch shape or ontogeny. Orthoconic heteromorphs likely had a vertical orientation, whereas ancylocone heteromorphs had a near-horizontal aperture pointing upwards. Heteromorphs with a U-shaped body chamber are more stable hydrodynamically than modern Nautilus and were unable substantially to modify their orientation by active locomotion, i.e. they had no or limited access to benthic prey at adulthood. Pathologies reported for heteromorphs were likely inflicted by crustaceans, fish, marine reptiles, and other cephalopods. Pathologies on Ptychoceras corroborates an external shell and rejects the endocochleate hypothesis. Devonian, Triassic, and Jurassic heteromorphs had a preference for deep-subtidal to offshore facies but are rare in shallow-subtidal, slope, and bathyal facies. Early Cretaceous heteromorphs preferred deep-subtidal to bathyal facies. Late Cretaceous heteromorphs are common in shallow-subtidal to offshore facies. Oxygen isotope data suggest rapid growth and a demersal habitat for adult Discoscaphites and Baculites. A benthic embryonic stage, planktic hatchlings, and a habitat change after one whorl is proposed for Hoploscaphites. Carbon isotope data indicate that some Baculites lived throughout their lives at cold seeps. Adaptation to a planktic life habit potentially drove selection towards smaller hatchlings, implying high fecundity and an ecological role of the hatchlings as micro- and mesoplankton. The Chicxulub impact at the Cretaceous/Paleogene (K/Pg) boundary 66 million years ago is the likely trigger for the extinction of ammonoids. Ammonoids likely persisted after this event for 40–500 thousand years and are exclusively represented by heteromorphs. The ammonoid extinction is linked to their small hatchling sizes, planktotrophic diets, and higher metabolic rates than in nautilids, which survived the K/Pg mass extinction event.
CRIS-Team Scopus Importer:2021-01-22
Keywords: anatomy; cephalopods; facies distribution; geochemistry; heteromorph ammonoids; palaeobiology

Recharge velocity and geochemical evolution for the Permo-Triassic Sherwood Sandstone, Northern Ireland - Barth, Johannes; et al. (Journal of Hydrology, 2005)

Recharging Mechanisms and Seawater Intrusion in Karst Aquifers in Northwest Sri Lanka, Based on Hydrogeochemistry and Water Isotopes - Bandara, U. G. Chaminda; Diyabalanage, Saranga; Barth, Johannes; Chandrajith, Rohana (ACS ES&T Water, 2023)
Geochemical and isotope data of karstic aquifer systems in the Mulankavil area in northwest Sri Lanka were investigated to constrain recharging and discharging mechanisms, and possible seawater intrusions. The electrical conductivity (EC) of groundwater was measured in the dry (n = 139) and rainy (n = 78) seasons to assess possible saltwater intrusions, from which 25 wells were selected for detailed geochemical analyses. Water isotope analyses (expressed as delta 2HH2O, delta 18OH2O) were measured in 32 wells for five months. The mean EC of groundwater during both seasons was 2,435 mu S/cm, and higher values from the coastal stretch indicated seawater intrusion. Increasing EC values in the dry period indicated a temporary inland saltwater wedge. High hydraulic gradients with rapidly discharging groundwater partially removed seawater intrusions during the monsoon season. Water isotopes in the region defined an individual evaporation line with delta 2HH2O= 6.69*delta 18OH2O -0.77 (r2 = 0.989), indicating a long enough residence time to allow evaporation before infiltration. Groundwater near sinkhole systems was found to be predominantly of the Ca-Mg-HCO3 type and changes to the Na-Cl type toward the coast. The results of this study revealed conduit systems in the karst subsurface as essential pathways for controlling seawater intrusion.
CRIS-Team WoS Importer:2023-03-10

Recognition of drilling-induced remanent magnetization by Q-factor analysis: A case study from the KTB-Drillholes - de Wall, Helga; et al. (Journal of Applied Geophysics, 2001)
Keywords: Drill cores; German Continental Deep Drilling Program; Koenigsberger ratio; Secondary magnetization

Recognition of the Boda event in the Pin Formation of northern India based on new d13C and conodont data. - Buggisch, Werner; Lehnert, Oliver; Joachimski, Michael; et al. (Acta Palaeontologica Sinica, 2007)
UnivIS-Import:2015-03-09:Pub.2007.nat.dgeo.IGM.LG.recogn

Reconstructing Depositional Rates and Their Effect on Paleoenvironmental Proxies: The Case of the Lau Carbon Isotope Excursion in Gotland, Sweden - Jarochowska, Emilia; Nohl, Theresa; Grohganz, Madleen; Hohmann, Niklas; Vandenbroucke, Thijs; Munnecke, Axel (Paleoceanography and Paleoclimatology, 2020)
Variations in depositional rates affect the temporal depositional resolutions of proxies used for paleoenvironmental reconstructions; for example, condensation can make reconstructed environmental changes appear very abrupt. This is commonly addressed by transforming proxy data using age models, but this approach is limited to situations where numerical ages are available or can be reliably inferred by correlation. Here we propose a new solution, in which relative age models are constructed based on proxies for depositional rates. As a case study, we use the onset of the late Silurian Lau Carbon Isotope Excursion (LCIE) in Gotland, Sweden. The studied succession is a gradual record of shallowing upward in a tropical, neritic carbonate platform. As proxies for depositional rates we tested thorium concentration, carbonate content, and the concentration of pelagic palynomorphs. These three proxies were used to create relative age models using the previously published DAIME model. We applied these models to transform the δ13Ccarb values as well as concentrations of selected redox‐sensitive elements. The three relative age models yielded qualitatively similar results. In our case study, variations in depositional rates resulted in peaks of redox proxies appearing up to 76% higher when taken at face value, compared to when accounting for these rates. In the most extreme cases, our corrections resulted in a reversal in the stratigraphic trend of elemental concentrations. This approach can be applied and developed across depositional setting and types of paleoenvironmental proxies. It provides a flexible tool for developing quantitative models to improve our understanding of the stratigraphic record.<br

Reconstructing environmental signals across the Permian-Triassic boundary in the SE Germanic Basin: A Quantitative Provenance Analysis (QPA) approach - Caracciolo, Luca; Ravidà, Domenico; Chew, David; Janßen, Meike; Luensdorf, Keno Nils; Heins, William A.; Stephan, Tobias; Stollhofen, Harald (Global and Planetary Change, 2021)
Global tectonic and climatic models for the Permian-Triassic boundary (PTB) are highly debated. One of the most disputed topics is the temperature increase associated with CO2 emissions generated by the Siberian Trap volcanism and its potential influence on chemical weathering and associated variations in sediment fluxes. By integrating crustal architecture, plate modelling, structural kinematics, and two climatic models, we reconstruct the drainage evolution of Variscan tectonostratigraphic units from the SE portion of the Germanic Basin, from which we also extract the parameters necessary to calculate sediment flux across a time-scale of 28 Ma (Guadalupian-Lower Triassic). We reconstruct the sedimentary response to climatic and tectonic perturbations using Quantitative Provenance Analysis (QPA) and integrate compositional data into a sedimentological framework, paleodrainage and paleoclimatic models. Raman heavy mineral analysis, as well as geochronology and geochemistry of detrital apatite, zircon, and rutile, document variation in drainage lithologies and sediment flux which are controlled by regional extensional tectonics and increasingly humid conditions at the PTB. The sedimentary successions of the SE Germanic Basin record climatic perturbations on a 104 years timescale, while the effects of tectonics are visible on a 106 years timescale. The interplay of climate, tectonics and lithology, and their effects on sediment production and drainage evolution resulted in changes in sediment flux from 2.3 Mt./yr during the Guadalupian (Capitanian), to 3.80 Mt./yr in the Lopingian (Changhsingian) to 7.44 Mt./yr at the end of the Lower Triassic (Olenekian). The multifaceted workflow provided in this study represents the first step towards more precise reconstructions of sediment routing systems in deep-time and provides the first ground-truthed quantification of sediment flux across the Permian-Triassic Boundary.
CRIS-Team Scopus Importer:2021-09-24
Keywords: Tectonic and climatic perturbations; Environmental signals; External forcing controls; Quantitative Provenance Analysis; Permian-Triassic Boundary

Reconstructing environmental signals across the Permian-Triassic boundary in the SE Germanic basin: Paleodrainage modelling and quantification of sediment flux - Ravidà, Domenico; Caracciolo, Luca; Heins, William A.; Stollhofen, Harald (Global and Planetary Change, 2021)
Reconstructing sediment load in deep-time is one of the greatest challenges in the reconstruction of ancient sediment routing systems, particularly because solid statistical models are absent and paleo-climatic, paleo-tectonic, and sedimentary constraints are lacking. This study proposes a reliable workflow for the estimation of paleo-sediment fluxes (Qs) applying the BQART model to a case study from the SE Germanic Basin across the Middle Permian – Early Triassic interval. The input parameters of the simulations derive from: integrated plate modelling and structural kinematics; paleodrainage and paleogeographic reconstructions; global circulation models; and sandstone compositional signatures. We apply Monte Carlo simulation to overcome the input uncertainties for eight different scenarios obtained from the combination of two area estimates, two climate models, and two time resolutions. All the models are in general agreement and show changes in sediment flux (i) being steady or declining slightly through the Middle Permian, (ii) an increase of 31% at the beginning of the Late Permian (3.6–4.6 Mt yr−1), (iii) and a nearly 100% rise at the onset of the Early Triassic (7.4 Mt yr−1). The variation of sediment load across the PTB is coeval to the transition from meandering/sabkha to perennial braided depositional settings recorded from the well data of Obernsees-1 and Lindau-1; it results from both increased tectonism and seasonal precipitation. The Qs estimates agree with those of modern drainages under analogous environmental conditions, highlighting the reliability of the workflow included in this study for the quantification of sediment flux in deep time. Furthermore, the results of this study provide new insights on the highly debated evolution of the continental sequences across the PTB with strong implications for both past and future paleo-environmental reconstructions.
CRIS-Team Scopus Importer:2021-09-17
Keywords: Central European Basin Systems; External forcing controls; Paleodrainage reconstruction; Permo-Triassic boundary; Sediment flux; Sediment routing system

Reconstructing post-Jurassic overburden in central Europe: new insights from mudstone compaction and thermal history analyses of the Franconian Alb, SE Germany - Freitag, Simon; Drews, Michael; Bauer, Wolfgang; Duschl, Florian; Misch, David; Stollhofen, Harald (Solid Earth, 2022)
The Franconian Alb of SE Germany is characterized by large-scale exposures of Jurassic shallow marine limestones and dolostones, which are frequently considered to be outcrop analogues for deep geothermal reservoir rocks in the North Alpine Foreland Basin farther south. However, the burial history of the Franconian Alb Jurassic strata is not well known as they were affected by emersion, leading to extensive erosion and karstification with only remnants of the original Cretaceous and Cenozoic cover rocks preserved. To estimate the original thicknesses of the post-Jurassic overburden we investigated the petrophysical properties and the thermal history of Lower and Middle Jurassic mudstones to constrain their burial history in the Franconian Alb area. We measured mudstone porosities, densities, and maturities of organic material and collected interval velocities from seismic refraction and logging data in shallow mudstone-rich strata. Mudstone porosities and P-wave velocities vertical to bedding were then related to a normal compaction trend that was calibrated on stratigraphic equivalent units in the North Alpine Foreland Basin. Our results suggest maximum burial depths of 900-1700 m, 300-1100 m of which is attributed to Cretaceous and younger sedimentary rocks overlying the Franconian Alb Jurassic units. Compared to previous considerations this implies a more widespread distribution and increased thicknesses of up to similar to 900 m for Cretaceous and up to similar to 200 m for Cenozoic units in SE Germany. Maximum overburden is critical to understand mechanical and diagenetical compaction of the dolostones and limestones of the Upper Jurassic of the Franconian Alb. The results of this study therefore help to better correlate the deep geothermal reservoir properties of the Upper Jurassic from outcrop to reservoir conditions below the North Alpine Foreland Basin. Here, the Upper Jurassic geothermal reservoir can be found at depths of up to 5000 m.
CRIS-Team WoS Importer:2022-07-22

Reconstructing the environmental conditions around the Silurian Ireviken Event using the carbon isotope composition of bulk and palynomorph organic matter - Vandenbroucke, Thijs R.A.; Munnecke, Axel; Leng, Melanie J.; Bickert, Torsten; Hints, Olle; Gelsthorpe, David; Maier, Georg; Servais, Thomas (Geochemistry Geophysics Geosystems, 2013)
The carbon isotope composition (δ13C) of bulk organic matter and two palynomorph groups (scolecodonts and chitinozoans) from the Llandovery-Wenlock strata of Gotland (E Sweden) are compared to gain knowledge about carbon cycling in the Silurian (sub)tropical shelf environment. The δ13C values of the palynomorphs are mostly lower than the δ13C values of the bulk organic matter, and the δ13C values of the benthic scolecodonts are lower than those of the planktonic chitinozoans. While the difference between bulk and palynomorph δ13C may be in part a function of trophic state, the lower values of the scolecodonts relative to those of chitinozoans, which are assumed to live in the well-mixed water column, might imply an infaunal mode of life for the polychaetes that carried the scolecodonts. Lower δ13C for the scolecodonts in the middle of the section may represent variations in primary marine productivity (supported by acritarch abundance data), oxidation of organic matter in the bottom waters, or genera effects. In general, however, trends between the three data sets are parallel, indicating similarities in the low frequency, environmentally forced controls. The δ13C data show a decreasing trend from the base of the section, up to a horizon well below the base of the Upper Visby Formation. At this level, and therefore probably several 10 kyr before the δ13C increase in the carbonates, the δ13C organic values increase by ∼1‰. This perhaps is an expression of a changed composition of the bulk organic matter associated with the extinction events prior to the Llandovery-Wenlock boundary. ©2013. American Geophysical Union. All Rights Reserve
Keywords: bulk organic matter; carbon isotopes; chitinozoans; Gotland; Llandovery-Wenlock; scolecodonts; trophic chain

Reconstructing the Upper Permian sedimentary facies distribution of a tight gas field in Central Europe on the basis of an analog field study in the Panamint Valley, western U.S. - Vackiner, Anna Alexandra; Antrett, Philipp; Strozyk, Frank; Stollhofen, Harald; Back, Stefan; Kukla, Peter (Geosphere, 2012)
Comparison of modern deposits in the Panamint Valley, western United States, to core and geophysical data from a Permian (Rotliegend, Germany) tight gas field allows for improved understanding of the interaction of tectonics and sedimentary processes during Rotliegend deposition. The Panamint Valley was selected for a modern analog of the subsurface Rotliegend Basin because both study sites are characterized by (1) elongated grabens with large-scale bounding fault zones resulting from synsedimentary transtensional tectonics; (2) fault-controlled paleotopography as key controlling parameter for the sediment facies distribution, including alluvial fans, dunes, wet and damp interdune sandflats, and ephemeral dry lake deposits; and (3) local sediment provenance from sedimentary and volcanic rocks. The analysis of satellite images and field data from the Panamint Valley enabled the development of a conceptual model involving topography, synsedimentary faulting, and wind activity as controlling factors for the sediment facies distribution. The application of the model to the reconstructed Rotliegend paleotopography of the German subsurface study site allows for prediction of the facies distribution prior to the Triassic-Cretaceous tectonic overprinting. As a consequence, we expect a sediment facies succession from (1) alluvial fan deposits along the hanging walls of the basin-bounding fault zones to (2) distributary fluvial channel deposits toward the basin center and (3) ephemeral lake deposits in the deepest basin area. (4) Eolian dune accumulation and preservation is mainly concentrated on hanging-wall locations. However, additional dune deposits are proposed above overlapping step faults and on footwalls of synsedimentary active faults. (5) Sandflats occur on the upwind and downwind margins of the dune field. These predictions are calibrated to core and geophysical well log data. © 2012 Geological Society of America.
UnivIS-Import:2015-03-09:Pub.2012.nat.dgeo.IGM.LG.recons

Reconstructing time and diagenesis of limestone-marl alternations from the selective compaction of colonies of the tabulate coral Halysites - Nohl, Theresa; Munnecke, Axel (Bulletin of Geosciences, 2019)

Reconstruction of cyclic Mesozoic-Cenozoic stress development in SE Germany using fault-slip and stylolite inversion - Köhler, Saskia; Duschl, Florian; Fazlikhani, Hamed; Köhn, Daniel; Stephan, Tobias; Stollhofen, Harald (Geological Magazine, 2022)
The Franconian Platform of SE Germany and the underlying Permian and Triassic rocks that developed from latest Permian to Triassic time were affected by multiple compressional and extensional events that created a complex fracture, fault and stylolite network. We reconstructed the spatio-temporal variations of post-Triassic palaeostress fields in the Franconian Platform and Triassic strata using fault-slip and tectonic stylolite inversion. Our highly resolved stress inversion enables us to demonstrate a cyclic stress evolution from the stress regime of normal faulting to thrusting, strike-slip and back to normal faulting. Five main stress fields correlating with two stress cycles are determined for Late Jurassic to Cenozoic time. The first cycle consists of: (SF1) an initially NE-SW-directed horizontal extension during Late Jurassic to Early Cretaceous time; (SF2) NNE-SSW-directed horizontal compression with an early set of tectonic stylolites prior to the development of reverse and thrust faults; and (SF3) a strike-slip-dominated setting with (N)NE-(S)SW horizontal compression representing a first relaxation. The second cycle comprises (SF4) NW-SE-directed horizontal extension during Oligocene-Miocene time; and (SF5) a second strike-slip-dominated regime with WNW-ESE to NW-SE horizontal compression during the Alpine shortening, creating the youngest set of tectonic stylolites. In addition, we consider the transitional stages between thrusting and a strike-slip regime as a snapshot in the process of intraplate tectonics.
CRIS-Team WoS Importer:2022-08-26

Reconstruction of Late Bajocian - Bathonian marine palaeoenvironments using carbon and oxygen isotope ratios of calcareous fossils from the Polish Jura Chain (central Poland). - Joachimski, Michael; Wierzbowski, Hubert (Palaeogeography, Palaeoclimatology, Palaeoecology, 2007)
Oxygen and carbon isotope analyses were carried out on Upper Bajocian - Bathonian calcitic belemnite rostra and oyster shells as well as aragonitic ammonite, nautiloid and trigoniid shells from the "Ore-bearing Czeogonekstochowa Clay Formation" in south-central Poland. All samples were studied by means of cathodoluminscence microscopy, trace element, X-ray, and scanning electron microscope (SEM) analysis in order to select best-preserved material. SEM studies allowed classifying some aragonitic ammonite and nautiloid shells (> 99% aragonite) as diagenetically altered. Average δ18O values of oysters, belemnites and trigoniids translate into relatively low palaeotemperatures of 10.1, 9.2 and 7.4 °C, respectively. The comparable δ18O values of bivalves and belemnites indicate that belemnites had a nectobenthic lifestyle and did not record surface water temperatures. The ammonite fauna is interpreted to have been nektonic, however, palaeotemperatures derived from ammonite δ18O (around 18.6 °C) may be overestimated due to a lower, than normal marine, salinity of surface waters. The reduced salinity is inferred as well from sedimentological observations and faunal composition. The obtained δ18O values indicate cool climatic conditions during the Late Bajocian-Bathonian in south-central Poland, which may have been linked with the occurrence of a cold climatic episode. Despite the fact that all studied shells were not precipitated in carbon isotope equilibrium with ambient waters, the δ13C shell values enabled us to roughly estimate isotope composition of dissolved inorganic carbon (DIC) in the Late Bajocian-Bathonian sea of south-central Poland. Water δ13CDIC values calculated from ammonite δ13C are lower in comparison to δ13CDIC values calculated from oyster and belemnite carbon isotope ratios, which in conjunction with ammonite δ18O values indicates lower salinity of surface or shallow near-coastal waters. © 2007 Elsevier B.V. All rights reserved.
UnivIS-Import:2015-03-09:Pub.2007.nat.dgeo.IGM.LG.recons
Keywords: Ammonites; Bajocian; Bathonian; Belemnites; Bivalves; Oxygen and carbon isotopes

Reconstruction of the Temperature Conditions of Burial-Related Pressure Solution by Clumped Isotopes Validates the Analysis of Sedimentary Stylolites Roughness as a Reliable Depth Gauge - Beaudoin, Nicolas E.; Köhn, Daniel; Aharonov, Einat; Billi, Andrea; Daeron, Matthieu; Boyce, Adrian (Minerals, 2025)
Rough surfaces known as stylolites are common geological features that are developed by pressure solution, especially in carbonate rocks, where they are used as strain markers and as stress gauges. As applications are developing in various geological settings, questions arise regarding the uncertainties associated with quantitative estimates of paleostress using stylolite roughness. This contribution reports for the first time a measurement of the temperature at which pressure solution was active by applying clumped isotopes thermometry to calcite cement found in jogs linking the tips of the stylolites. This authigenic calcite formed as a redistribution of the surrounding dissolved material by the same dissolution processes that formed the extensive stylolite network. We compare the depth derived from these temperatures to the depth calculated from the vertical stress inversion of a bedding parallel stylolite population documented on a slab of the Calcare Massiccio formation (early Jurassic) formerly collected in the Umbria-Marches Arcuate Ridge (Northern Apennines, Italy). We further validate the coevality between the jog development and the pressure solution by simulating the stress field around the stylolite tip. Calcite clumped isotopes constrain crystallization to temperatures between 35 and 40 °C from a common fluid with a δ18O signature around −1.3‰ SMOW. Additional δ18O isotopes on numerous jogs allows the range of precipitation temperature to be extended to from 25 to 53 °C, corresponding to a depth range of 650 to 1900 m. This may be directly compared to the results of stylolite roughness inversion for stress, which predict a range of vertical stress from 14 to 46 MPa, corresponding to depths from 400 to 2000 m. The overall correlation between these two independent depth estimates suggests that sedimentary stylolites can reliably be used as a depth gauge, independently of the thermal gradient. Beyond the method validation, our study also reveals some mechanisms of pressure solution and the associated p,T conditions favouring their development in carbonates.
CRIS-Team Scopus Importer:2025-02-14
Keywords: clumped isotopes; depth modelling; paleopiezometry; stylolites

Reconstruction of the trophic levels of a fossil fish community from the Late Jurassic Solnhofen Archipelago - Dimitrijevic, Danijela; Ebert, Martin; Kölbl-Ebert, Martina; Munnecke, Axel (EGU 2020, 2020)
Trophic interactions of extinct fishes are central to our understanding of evolution, paleoecology, and their role in the paleo communities, but can be challenging, as these are limited by the incompleteness of the fossil record and by a lack of behavioral data. The extensive fossil record of Actinopterygii comes mostly from Conservation deposits. They provide exceptionally rich information on fossil ecosystems and open outstanding windows into the evolution of life. The best-preserved Late Jurassic actinopterygians are known from the Solnhofen Archipelago, Germany. Despite that the ichthyofauna diversity of the Solnhofen Archipelago has been extensively explored in the last several decades, the dietary preferences of most fish remain unknown or have to be deduced by analogy from dentition and jaw morphology. The aim of this study was to reconstruct the trophic levels of Late Jurassic fish assemblages using Sr / Ca and Ba / Ca measured from phosphatic fish remains, mostly ganoin and cycloid scales recovered from the Ettling locality, which is characterized by exceptionally well-preserved fossil fishes and moderate diagenetic alteration. We classified fish species into four trophic levels (durophagous, lower, middle, and higher trophic level) based on morphology available from the literature. Mean values ​​of Sr, Ca, Ba and their ratios measured by Thermo Scientific iCAP Q inductively coupled plasma mass spectrometer in this study are in accordance with the mean values ​​of previous studies. Differences in values ​​between cleaned and uncleaned samples showed that the cleaning process successfully isolated primary dietary Sr content while dissolving away the diagenetic strontium present in carbonate in the pore spaces. All trophic levels showed low variation of Sr / Ca (0.003 - 0.008 μg / g) and high variation of Ba / Ca values ​​(0.0003 - 0.0014 μg / g). The results showed significant differences between the middle and higher trophic levels (p = 0.03), while durophagous and lower trophic levels fell into the same range of values ​​as the higher trophic level. We demonstrate that the enamel of fossil vertebrates from the Solnhofen Archipelago still contains near-in vivo Sr, Ba, and Ca. The clear distinction between middle and higher trophic levels offers a new functional perspective on the ecological and evolutionary relationships among fishes. However, future studies should not neglect the importance of diagenetic alteration of the samples; proper sample cleaning before measuring isotopic signatures, and careful selection of the analyzed tissue (ie tooth enamel instead of scales or bones due to its resistance to diagenesis).<br

Record of assembly and breakup of Rodinia in the Southwestern Altaids: Evidence from Neoproterozoic magmatism in the Chinese Western Tianshan Orogen - Gao, Jun; Wang, Xin-Shui; Klemd, Reiner; Jiang, Tuo; Qian, Qing; Mu, Li-Xiu; Ma, Yu-Zhou (Journal of Asian Earth Sciences, 2015)
Neoproterozoic gneissic granitoid rocks and a bimodal intrusive complex exposed in the Chinese Western Tianshan Orogen were geochemically and geochronologically studied in order to evaluate the assembly and breakup of Rodinia in the Southwestern Altaids. Zircon U–Pb ages of 903.5 ± 2.2 Ma and 933.6 ± 1.2 Ma were obtained for the Huoshaoqiao and the Wulasutanwutuaiken gneissic granitoid plutons, respectively. Both intrusions have a calcic to calci-alkalic composition and display an enrichment of LREE and LILE and a depletion of HREE and HFSE resembling the geochemical characteristics of Andean arc granites. Their in-situ zircon εHf(t) values of −1.7 to +1.9 and −2.2 to +4.5 further suggest a Late Paleoproterozoic crustal source with limited input of juvenile materials. The Wuwamen bimodal intrusive complex consists of meta-gabbro host rocks and crosscutting granitic dykes. Zircon U–Pb ages of 733 ± 5 Ma and 730 ± 5 Ma were determined for the meta-gabbros and the granitic dykes, respectively. The relative depletion of Nb, Ta and Ti, the Nd isotopic value (εNd(t) = −4.3) of the meta-gabbros, and the Hf isotopic values of gabbroic zircon grains (εHf(t) = +0.4 to +2.8) suggest that the protolithic mafic magma originated from a sub-continental fertilized lithospheric mantle source. Furthermore, the Nd isotopic value (εNd(t) = −11.2) of the granitic dykes and the Hf isotopic values of granitic zircon grains (εHf(t) = −14.3 to −5.6) indicate that the acidic magma originated from lower crustal melting. The dataset presented here in conjunction with previously published data suggest that the ∼900 Ma plutons originated from remelting of older crust in an Andean-type active continental arc setting associated with the assembly of Rodinia, whereas the development of the ∼730 Ma bimodal intrusive magmatism is interpreted as a result of the Rodinia breakup. Thus, the Neoproterozoic magmatism is believed to be a direct consequence of the geodynamic process related to the assembly and breakup of Rodinia in the Southwestern Altaids.<br
Keywords: Altaids; Tianshan; Rodinia; Neoproterozoic magmatism

Record of intermediate-depth subduction seismicity in a dry slab from an exhumed ophiolite - Pennacchioni, G.; Scambelluri, M.; Bestmann, Michel; Notini, L.; Nimis, P.; Plümper, O.; Faccenda, M.; Nestola, F. (Earth and Planetary Science Letters, 2020)
The ophiolitic peridotite and gabbro of Moncuni (Southern Lanzo Massif, Western Alps) retain pre-subduction mantle-to-oceanic, high-temperature (>700C∘) ductile fabrics. These fabrics are overprinted by seismic fracturing and faulting associated with pseudotachylytes. Within the gabbro, the pseudotachylytes preserve dry glass and pristine microlites. The occurrence of rare, minute garnet and the static development of eclogite-facies assemblages in local hydrated domains indicate that pseudotachylytes experienced subduction conditions of 600C∘ and 2.1 GPa. The exceptional survival of glass and the absence of post-oceanic ductile deformation demonstrate prevailing dry conditions during the entire Alpine subduction and exhumation path. Dry conditions inhibited reaction kinetics and viscous flow. In contrast, the majority of the Alpine ophiolites, derived from the upper hydrated portions of the oceanic lithosphere, show pervasive fluid-assisted metamorphism and ductile deformation. The Moncuni body can, therefore, be regarded as representative for the rheological behaviour during subduction of seismic, dry, deeper oceanic lithosphere that is rarely exhumed to the Earth's surface. In Moncuni, the brittle-ductile transition of dry oceanic rocks is constrained to be between 600 and 750C∘. This temperature range corresponds to the observed cut-off of intermediate-depth seismicity within subducting slabs. We infer that the base of the seismic layer corresponds to the brittle-ductile transition of a dry slab rather than the locus of antigorite breakdown triggering earthquakes by dehydration embrittlement.
CRIS-Team Scopus Importer:2020-08-21
Keywords: earthquake; eclogite; fluids; ophiolite; pseudotachylyte; subduction

Recurrence analysis of the mass movement activity at Stambach (Austria) based on radiocarbon dating - Unkel, Ingmar; Ehret, Dominik; Rohn, Joachim (Geomorphology, 2013)
Keywords: Earth flow; Holocene palaeoclimate; Landslide; Northern Calcareous Alps; Radiocarbon dating; Recurrence interval

Red Devonian trilobites with green eyes from Morocco and the silicification of the trilobite exoskeleton - Klug, Christian; Schulz, Hartmut; de Baets, Kenneth (Acta Palaeontologica Polonica, 2009)
Latest Emsian (Early Devonian) sediments at the famous mud-mound- and trilobite-locality Hamar Laghdad (Tafilalt, Morocco) yielded some red-coloured remains of phacopid trilobites. Closer examination revealed that the eyes of these phacopids are often greenish in colour. EDX-analyses showed that the lenses retained their original calcitic composition, possibly greenish due to Fe- and Mn-impurities, while most of the exoskeleton was silicified. The silicified parts contain elevated concentrations of iron which causes the red colour. This phenomenon is explained by the porosity of the exoskeleton in contrast to the homogeneous and massive construction of the lenses and their Mg-content. These incompletely silicified trilobites enabled a reconstruction of the silicification process in trilobites. Their diagenetic alteration probably occurred as a result of events associated with the Cretaceous transgression.
Keywords: Trilobita; taphonomy; diagenesis; silicification; transgression; mud-mounds; Devonian; Morocco

Re-description and neotypification of Archamphiroa jurassica Steinmann 1930, a calcareous red alga from the Jurassic of Argentina - Bucur, Ioan I.; Kießling, Wolfgang; Scasso, Roberto A. (Journal of Paleontology, 2009)
UnivIS-Import:2015-03-09:Pub.2009.nat.dgeo.IGM.LP.redesc

Redox processes in subducting oceanic crust recorded by sulfide-bearing high-pressure rocks and veins (SW Tianshan, China) - Li, Jilei; Gao, Jun; Klemd, Reiner; John, Timm; Wang, Xin-Shui (Contributions To Mineralogy and Petrology, 2016)
The oxidized nature of the sub-arc mantle and hence arc magmas is generally interpreted as a result of the migration of subduction-related oxidizing fluids or melts from the descending slab into the mantle wedge. This is of particular importance seeing that the oxidization state of sub-arc magmas seems to play a key role in the formations of arc-related ore deposits. However, direct constraints on the redox state of subducted oceanic crust are sparse. Here, we provide a detailed petrological investigation on sulfide- and oxide-bearing eclogites, blueschists, micaschists, eclogite-facies and retrograde veins from the Akeyazi high-pressure (HP) terrane (NW China) in order to gain insight into the redox processes recorded in a subducting oceanic slab. Sulfides in these rocks are mainly pyrite and minor pyrrhotite, chalcopyrite, bornite, molybdenite, sphalerite and chalcocite, including exsolution textures of bornite–chalcopyrite intergrowth. Magnetite, ilmenite and pyrite occur as inclusions in garnet, whereas sulfides are dominant in the matrix. Large pyrite grains in the matrix contain inclusions of garnet, omphacite and other HP index minerals. However, magnetite replacing pyrite textures are commonly observed in the retrograded samples. The eclogite-facies and retrograde veins display two fluid events, which are characterized by an early sulfide-bearing and a later magnetite-bearing mineral assemblage, respectively. Textural and petrological evidences show that the sulfides were mainly formed during HP metamorphism. Mineral assemblage transitions reveal that the relative oxygen fugacity of subducted oceanic crust decreases slightly with increasing depths. However, according to oxygen mass balance calculations, based on the oxygen molar quantities (nO2), the redox conditions remain constant during HP metamorphism. At shallow levels (<60 km) in the subduction channel, interaction with oxidized fluid seems to have caused an increase of the oxygen fugacity and the oxidation state of exhuming HP rocks. This study suggests that oxygen components are not released in significant amounts during HP metamorphism of subducted oceanic crust and, thus, cannot be responsible for oxidizing the mantle wedge and increasing the oxidation state of sub-arc mantle melts.<br
Keywords: Subducted oceanic crust; Fluids; Oxygen fugacity; Eclogite; Sulfides; Magnetite

Reducing taxonomic noise in problematic fossils: Revision of the incertae sedis genus allonema based on shape analysis - Jarochowska, Emilia; Hierl, Florian; Vinn, Olev; Munnecke, Axel (Bulletin of Geosciences, 2016)
Organisms of unknown biological affinity are widespread in Paleozoic ecosystems and play key ecological roles. Recognition of these roles relies on consistent identification and sound taxonomy, yet many microproblematica lack complex morphological features that could be the basis for qualitative taxonomic diagnoses. Allonema is an incertae sedis calcareous sclerobiont widespread in Paleozoic carbonates. At least seven species of Allonema have been proposed, but their diagnoses based on size ranges overlap. In this work, dimensions of 590 individuals from the Silurian of Estonia and Sweden have been measured. Regression analysis of the dimensions revealed two groups, overlapping in size ranges, but differing significantly in proportions. These groups could be matched with previously described A. botellus and A. moniliforme, but both showed a wider range of sizes than previously reported. Another previously described species, A. minimum, fell within the range of dimensions of A. moniliforme and is proposed to be its junior synonym. Differences in proportions revealed in the study do not seem to be dependent on sedimentary environment or local growth conditions such as competition for space, and thus may represent consistent interspecific variability. Although the affinity of Allonema remains unknown, this quantitative approach to its taxonomy reduces unnecessary species in the genus. The success of this approach may encourage its application to other microproblematica populating the fossil record.
Keywords: Baltica; Devonian; Encrusters; Microproblematica; Pseudobryozoans; Sclerobionts; Wetheredella

Reef-building red algae from an uppermost Permian reef complex as a fossil analogue of modern coralline algal ridges - Chen, Weihan; Wang, Yongbiao; Huang, Yafei; Wang, Tan; Yi, Zhixing; Kießling, Wolfgang (Facies, 2020)
Calcareous red algae have been important components in reefal facies since the Mesozoic but their volumetric contribution to Palaeozoic reefs was usually low. Here, we report a reef-building community dominated by Parachaetetes, a genus of solenoporacean red algae, overgrowing uppermost Permian sponge reefs in Cili (Hunan Province, South China). The fossil assemblage in the community consists of about 88% Parachaetetes, 7% rugose corals, and 5% reef-dwelling organisms, including gastropods, brachiopods, foraminifera and Tubiphytes. Although the biodiversity of this community is far lower than that in modern reefs, the association of red algae and rugose corals shares several attributes with the coral–coralline algal communities of modern tropical reefs. Analysis of sedimentary facies indicates that the reef-building Parachaetetes grew in a turbulent setting near the margin of a carbonate platform, perhaps in a reef-crest environment known from modern coralgal reefs. Although calcifying red algae have been recorded from the Cambrian onwards, this is the oldest site where crustose red algae played a dominant role in reef construction.
CRIS-Team Scopus Importer:2020-08-14
Keywords: Late Permian; Palaeoecology; Reef; Rugose coral; Solenoporacean; South china

Reef expansion during the Triassic: Spread of photosymbiosis balancing climatic cooling - Kießling, Wolfgang (Palaeogeography, Palaeoclimatology, Palaeoecology, 2010)
The PaleoReefs Database indicates that reef abundance increased profoundly during the Triassic period, from a pronounced low in the Early Triassic to a major peak in the Norian. This expansion is also evident when standardizing for sampling. Corresponding to the reef expansion is a relative increase of scleractinian corals as reef builders, whereas the contribution of hypercalcifying sponges and microbes decreased during the Triassic. The numerical expansion of corals is paralleled by a proportional increase of morphological features that are suggestive of photosymbiosis, such that the Norian reef boom might be explained by the spread of photosymbiosis in corals. The geographical expansion of reefs was far less pronounced especially concerning palaeolatitude. Late Triassic reef growth was limited to more or less the same latitudinal range as modern reefs. As oxygen isotope data and new modeling results indicate declining temperatures and CO2 concentrations during the Late Triassic, the lack of latitudinal expansion might be attributed to global cooling. Reef development during the Triassic can thus be explained by the evolutionary spread of photosymbiosis balancing the effects of climatic cooling. © 2009 Elsevier B.V. All rights reserved.
UnivIS-Import:2015-03-09:Pub.2010.nat.dgeo.IGM.LP.reefex
Keywords: Climate; Corals; Evolution; Photosymbiosis; Reefs; Triassic

Reef Fish Beware! Aggressive Mimicry in a Pycnodontid? - Kölbl-Ebert, Martina; Ebert, Martin; Bellwood, David R.; Schulbert, Christian (Abstracts of the 90th Annual Meeting of the Paläontologische Gesellschaft, 2019)
Pycnodontiformes are an extinct order of Actinopterygian fishes, present from the Late Triassic (Norian) to the Eocene. Their mostly deep, laterally compressed bodies and comparatively large fins indicate that these fishes were mostly highly manoeuvrable reef fish. With their characteristic durophagous dentition, columnar to incisiform anterior teeth (on premaxilla and dentary) and the posterior crushing teeth of the prearticular and vomer, the whole group was highly specialized as predators on hard-shelled organisms. In 2016, however, a new pycnodontid was found in the quarry of Ettling (Markt Pförring, Bavaria; Late Jurassic) by the excavation team of the Jura-Museum Eichstätt. The most striking feature of this new pycnodontid, Piranhamesodon pinnatomus Kölbl-Ebert et al., 2018 (JME-ETT4103), is its unusual dentition: It has long, pointed teeth at the front (on premaxilla and dentary), dagger-shaped teeth with a sharp, posterior cutting edge along the exterior-most tooth row of the vomer, and triangular teeth with serrations on their anterior margin along the exterior-most tooth row of the prearticulars. As revealed by CT-scanning, the inner teeth of prearticular and vomer are limpet-shaped cones on a columnar tooth base. The “fangs” along the exterior-most tooth row of the prearticulars and vomer of Piranhamesodon pinnatomus interact like scissors; a comparison of their functional morphology with other actinopterygians stress the exceptional high bite-force (a legacy of their pycnodont ancestry), which is comparable to modern piranhas, suggesting a completely unusual mode of predation compared to all other known pycnodontids. We propose this species to have exploited aggressive mimicry: Seemingly harmless and inconspicuous through the typical pycnodontid shape and possibly aided by corresponding colouring, it may have approached and then attacked unsuspecting other fish in the reef, biting and tearing a mouthful of flesh or fin from their unwary prey. Alternatively, it may also have acted at least occasionally as scavenger.<br
Keywords: Pycnodontiformes; Piranhamesodon; Late Jurassic; Ettling

Reefmounds im unteren Wenlock auf Gotland: Beispiele früher Korallenriffe - Samtleben, Christian; Munnecke, Axel (Meyniana, 1999)
Die Reefmounds im unteren Wenlock auf Gotland sind im doppelten Sinne Riffe in einem Frühstadium: Einerseits bilden sie die erste Phase in der Entwicklung der silurischen Riffkomplexe auf Gotland, andererseits stellen sie in der erdgeschichtlichen Entwicklung moderner Korallenriffe ein Beispiel früher Riffbildungen mit einer nur wenig ausgebildeten Internstruktur und Synökologie dar.   The reefmounds in the Lower Wenlockian of Gotland represent in a twofold sense early stages of reef development. On the one hand, they form the first stage in the development of the reef succession on Gotland, on the other hand, they are early examples of reef formation in the geological history of coral reefs, lacking important criteria of modern reefs like strict internal structure, framework, and complex synecology.
Keywords: Reefmounds; Silurian; Gotland; Cnidaria

Reef refugia in the aftermath of past episodes of global warming - Dimitrijević, Danijela; Santodomingo, Nadia; Kießling, Wolfgang (Coral Reefs, 2024)
In the face of rising global temperatures, coral reefs experience coral mass bleaching and mortality. Subtropical and mesophotic environments may represent refugia for reef corals under climate change, where they can survive and eventually recolonize degraded areas. Using a comprehensive database of fossil reefs, we empirically assess the efficacy of subtropical, deeper, and turbid mesophotic environments to restore coral reefs after past global warming events. We focus on tropical coral reefs over the last 275 million years and four rapid climate warming events, which coincided with global reef crises in the geological record. In the aftermath of such hyperthermal events, we observed an increase in the proportions of reefs occurring in deeper (blue) mesophotic environments. Additionally, we found a trend of reef distributions and coral shifting towards higher latitudes. The number of coral occurrences in turbid (brown mesophotic) environments also increased after hyperthermal events. Our results suggest that subtropical, blue, and brown mesophotic environments may have served as immediate refugia for shallow-water coral species escaping warming seawater. While the patterns of reef range shifts and the establishment of blue and brown mesophotic refugia following ancient hyperthermal events provide some hope for coral reefs under current climate change, re-establishement of background reef conditions took most times millions of years. Ante el incremento de temperatura global, los arrecifes coralinos están experimentando eventos masivos de blanqueamiento y mortalidad. Los ambientes subtropicales y mesofóticos pueden representar refugios para los corales arrecifales, en los cuales pueden escapar de los efectos del cambio climático, sobrevivir y desde allí recolonizar áreas previamente degradadas. Mediante el uso de una exhaustiva base de datos en arrecifes coralinos, en este estudio se evaluó empíricamente la eficacia de los ambientes subtropicales y mesofóticos, tanto de aguas turbias someras (marrones) como de aguas claras profundas (azules), en la recuperación de arrecifes coralinos después de eventos hipertermales en el pasado. Nuestro enfoque estuvo en los arrecifes coralinos tropicales durante los últimos 275 millones de años y cuatro eventos de calentamiento climático rápido, los cuales coinciden con crisis globales en la ocurrencia de arrecifes en el registro fósil. Como consecuencia de dichos eventos hipertermales, observamos un aumento del número de arrecifes en ambientes mesofóticos de aguas profundas (azules). Además, encontramos una tendencia en la distribución de arrecifes y corales que se desplazan hacia latitudes más altas. También se observó un aumento en el número de corales que estuvieron presentes en ambientes de aguas turbias (marrones) después de dichos eventos hipertermales. Nuestros resultados sugieren que, en el pasado, los ambientes subtropicales, mesofóticos azules y mesofóticos marrones pudieron haber servido como refugios inmediatos para las especies de coral de aguas someras, en los cuales encuentran condiciones atenuantes ante el calentamiento oceánico. Si bien los patrones de desplazamiento de los arrecifes en el rango latitudinal y el establecimiento de refugios mesofóticos de aguas marrones y azules posteriores a eventos hipertermales brindan una luz de esperanza para el futuro de los arrecifes coralinos de cara al cambio climático actual, nuestros resultados evidencian que el restablecimiento de los arrecifes puede tomar millones de años.
CRIS-Team Scopus Importer:2024-09-13
Keywords: Fossil record; Hyperthermal events; Mesophotic reefs (mesophotic coral ecosystems); Reef refugia; Scleractinian corals; Turbid reefs

Reefs as cradles of evolution and sources of biodiversity in the Phanerozoic - Kießling, Wolfgang; Simpson, Carl; Foote, Michael (Science, 2010)
Large-scale biodiversity gradients among environments and habitats are usually attributed to a complex array of ecological and evolutionary factors. We tested the evolutionary component of such gradients by compiling the environments of the geologically oldest occurrences of marine genera and using sampling standardization to assess if originations tended to be clustered in particular environments. Shallow, tropical environments and carbonate substrates all tend to have harbored high origination rates. Diversity within these environments tended to be preferentially generated in reefs, probably because of their habitat complexity. Reefs were also prolific at exporting diversity to other environments, which might be a consequence of low-diversity habitats being more susceptible to invasions.
UnivIS-Import:2015-03-09:Pub.2010.nat.dgeo.IGM.LP.reefsa

Reefs - Kießling, Wolfgang (Encyclopedia of Sediments and Sedimentary Rocks, 2003)
UnivIS-Import:2015-04-20:Pub.2003.nat.dgeo.IGM.LP.reefs

REE investigation of the Plattkopf fluorite mineralization an extension of the Vergenoeg fluorite deposit (South Africa) - Günther, Thomas; Klemd, Reiner (BGR-Jahrestagung2014, 2014)
Plattekop hill with its concordant hematite-fluorite ore body represents an extension of the Vergenoeg pipe, one of South Africa's world-class fluorite deposits located in the Bushveld Complex. The pipe-shaped body of Vergenoeg strikes discordantly with a minimum depth of circa 650 meters through the rhyolitic bedrocks of the Palaeoproterozoic Rooiberg Group and accommodates different Fe-mineral dominated rock types, which are enriched in fluorite. Both deposits host an additional commodity in terms of Rare-Earth-Element (REE) minerals in their Fe-oxide (hematite or magnetite) and fluorite rich rocks. These are represented by the fluorocarbonate bastnaesite-(Ce) and the REE-phosphates monazite-(Ce) and xenotime-(Y). Combined whole rock and single grain analyses via XRF and LA-ICP-MS and EMP, respectively show the high REE-potential of the sampled rocks from the uppermost gossan ores of Plattekop and Vergenoeg as well as from their deeper unweathered equivalent rock type with whole rock contents of REEs <4.5 wt. %. Thereby, C1-chondrite normalized REE-patterns show on average (La/Lu)CNratios of <5.3 with a relatively flat trend. The major rock forming minerals contain 100 ppm to 2500 ppm REEs/Fe-oxide and 3000 ppm to 7000 ppm REEs/fluorite on average. The minerals bastnaesite, monazite and xenotime are intercalated between Fe-minerals and fluorites with an abundance of <4 vol. % per sample. The light rare earth elements (LREE) are preferentially incorporated into bastnaesite and monazite with an order of abundance of Ce > La > Nd > Pr in contrast to xenotime, which exhibits enriched concentrations of heavy rare earth elements (HREE) and an order of abundance of Y > Er > Dy > Gd. Average concentrations are between 50 and 60 wt. % REEs/REE-mineral. Petrological and geochemical evidences of sampled rocks suggest a hydrothermal origin for the REE-minerals after the primary mineralization of Vergenoeg and Plattekop precipitated. Secondary fluid inclusions within fluorite record temperatures between 150 °C and 500 °C for late stage hydrothermal events (Borroket al., 1998) from which bastnaesite may have crystallized at intermediate to basic pH conditions. Their alteration to monazite and xenotime marks a change of the hydrothermal conditions to a more acidic and phosphate rich environment. Thereby, balance calculations indicate a renewed REE-enrichment by the P-rich fluids. The remarkable enrichment of fluorite and REE-minerals within the upper 200 meters of Vergenoeg is probably a result of changes in temperature, pressure, and pH of the fluid system due to the channelized upward migration of the hydrothermal solutions towards the top of the pipe and the interaction to the adjacent bedrocks in contact. Regarding the origin of the primary mineralization of Vergenoeg and Plattekop and the mineralizing fluids, negative Eu anomalies (Eu/Eu*) ranging from 0.08 to 0.57 for the Fe-oxides and 0.05 to 0.08 for the fluorites display the influence of reduced conditions in a possible felsic igneous-related source like the Lebowa Granite Suite of the Bushveld Complex. Furthermore, the chemical signature of the Vergenoeg magnetites correlates well with those of igneous Climax-Mo deposits (enriched in Al, Ga, Sn and depleted in Cr, Mg) and therefore, indicates a genetic relationship to the porphyry deposit type.<br

Reentering of an overpressured basin - The south German Molasse - Drews, Michael; Bauer, Wolfgang; Stollhofen, Harald (1st EAGE Workshop on Pore Pressure Prediction: At the Well Scale from Today to Tomorrow, State of the Art, Recent Progress and Technology Gap, 2017)

Re-evaluating the general dynamic theory of oceanic island biogeography - Steinbauer, Manuel; Dolos, Klara; Field, Richard; Reineking, Björn; Beierkuhnlein, Carl (Frontiers of Biogeography, 2013)
The general dynamic model of oceanic island biogeography integrates temporal changes in ecological circumstances with diversification processes, and has stimulated current research in island biogeography. In the original publication, a set of testable hypotheses was analysed using regression models: specifically, whether island data for four diversity indices are consistent with the ‘B ATT2’ model, in which B is a diversity index, A is log(area) and T is time. The four indices were species richness, the number and percentage of single‐island endemic species, and a diversification index. Whether the relationships between these indices and time are unimodal (i.e., ‘hump‐shaped’) was a key focus, based on the characteristic ontogeny of a volcanic oceanic island. However, the significance testing unintentionally used zero, rather than the mean of the diversity index, as the null hypothesis, greatly inflating F‐ values and reducing P‐values compared with the standard regression approach. Here we first re‐analyze the data used to evaluate the general dynamic model in the seminal paper, using the standard null hypothesis, to provide an important qualification of its empirical results. This supports the significance of about half the original tests, the rest becoming non‐significant but mostly suggestive of the hypothesized relationship. Then we expand the original analysis by testing additional, theoretically derived functional relationships between the diversity indices, island area and time, within the framework of the ATT2 model and using a mixed‐effects modelling approach. This shows that species richness peaks earlier in island life‐cycles than endemism. Area has a greater effect on species richness and the number of single‐island endemics than on the proportion of single‐island endemics and the diversification index, and was always better fit as a log–log relationship than as a semi‐log one. Finally, the richness–time relationship is positively skewed, the initial rise happening much more quickly than the later decline.

Refined ettringite (Ca6Al2(SO4)3(OH)12x26H2O) structure for quantitative X-Ray diffraction analysis - Götz-Neunhoeffer, Friedlinde; Neubauer, Jürgen (Powder Diffraction, 2006)
A revised structure model of ettringite is presented, in order to provide quantitative X-ray diffraction (QXRD) of this mineral in cement pastes. The model is derived from two different existing structure models, both of which are suitable for restricted use but are inferior to the refined ettringite structure presented. In the first published ettringite structure proposed by Moore and Taylor [Acta Crystallogr. B 26, 386-393 (1970)], none of the 128 positions for H are given in the unit cell, which results in reduced scattering power for use of this model for quantification purposes. For the precise quantification of ettringite in samples together with anhydrous phases, the scattering factors of all atoms including the H positions are indispensable. The revised structure model is based on the data of Moore and Taylor, supplemented by the H positions determined by Berliner (Material Science of Concrete Special Volume, The Sydney Diamond Symposium, American Ceramic, Society, 1998, pp. 127-141) on the basis of a neutron diffraction structural investigation of deuterated ettringite at 20 K. Berliner's (Material Science of Concrete Special Volume, The Sydney Diamond Symposium, American Ceramic Society, 1998, pp. 127-141) thermal parameter should not, however, be used, since a normal application is at room temperature. In order further to improve the structure model of ettringite, Rietveld refinement with the rigid body approach for OH and H2 O molecules and SO4 tetrahedra was employed. The refined and improved ettringite structure model was tested for quantitative phase analysis by the determination of actual ettringite contents in mixtures with an internal standard. Synthesized and orientation-free prepared ettringite powders were investigated by X-ray powder diffraction analysis and quantified in four different blends with zircon. The quantification results with the new structure model demonstrate the superior quality of the revised ettringite structure. © 2006 International Centre for Diffraction Dat
UnivIS-Import:2015-03-09:Pub.2005.nat.dgeo.IGM.LM.refine
Keywords: Cement hydration; Ettringite; Quantitative X-ray powder diffraction analysis (QXRPD); Rietveld refinement; Structure

Regional geology of the Skåne province, Sweden - Calner, Mikael; Erlström, Mikael; Eriksson, Mats; Lehnert, Oliver; Ahlberg, Per (The Lower Palaeozoic of southern Sweden and the Oslo Region, Norway. Field Guide for the 3rd Annual Meeting of the IGCP project 591., 2013)
UnivIS-Import:2015-03-09:Pub.2013.nat.dgeo.IGM.LG.lowerp

Regional geology of the Västergötland province, Sweden - Ahlberg, Per; Calner, Mikael; Lehnert, Oliver; Wickström, Linda (The Lower Palaeozoic of southern Sweden and the Oslo Region, Norway. Field Guide for the 3rd Annual Meeting of the IGCP project 591., 2013)
UnivIS-Import:2015-03-09:Pub.2013.nat.dgeo.IGM.LG.region

Regional geology of Västergötland Province, Sweden - Ahlberg, Per; Calner, Mikael; Lehnert, Oliver; Wickström, Linda; Lindskog, Anders (The Ordovician of Västergötland and Dalarna, Sweden. Field guide for the ISOS 14 post-conference excursion., 2023)

Regionalization of precipitation in Mauritius: a statistical approach - Raja, Nussaïbah Begum; Aydin, Olgu (Meteorological Applications, 2019)
The aim of this study was to quantify the regional precipitation patterns of Mauritius using the total mean annual precipitation of 52 meteorological stations for the period 1981–2010. Principal component analysis was first used to determine the significant variables influencing precipitation in Mauritius. A cluster analysis was then applied to group the stations according to the significant variables identified. Finally, a spatial interpolation of precipitation in Mauritius using the kriging with external drift technique was carried out to examine the spatial distribution of precipitation on the island. The principal component analysis results showed that elevation and coastal proximity caused the most variance in the dataset with respect to precipitation. Using the cluster analysis and kriging results, six regions of precipitation were determined: three inland and three coastal regions. A decreasing gradient in precipitation between the southeast and northwest is observed due to the southeast trade winds and the altitudinal difference between the coastal areas and the central plateau. The central plateau represents a distinct precipitation zone which receives the highest precipitation on the island. The windward-facing south and eastern highlands experience orographic precipitation as a result of adiabatic air expansion and therefore are more humid. On the other hand, the northeast highlands region, together with the north and western coasts which lie in the leeward rain shadow, are notably drier.
CRIS-Team Scopus Importer:2019-07-02
Keywords: cluster analysis (CA); kriging; Mauritius; precipitation; principal component analysis (PCA); regional precipitation pattern

Regional mudstone compaction trends in the Vienna Basin: top seal assessment and implications for uplift history - Skerbisch, Lukas; Misch, David; Drews, Michael; Stollhofen, Harald; Sachsenhofer, Reinhard F.; Arnberger, Klaus; Schuller, Volker; Zamolyi, Andras (International Journal of Earth Sciences, 2023)
Seal quality assessment is not only essential in petroleum systems studies but also in the context of other geo energy applications such as underground hydrogen storage. Capillary breakthrough pressure controls top seal capacity in the absence of faults or other discontinuities. In basins that lack measured capillary pressure data (e.g., from drill cores), regional compaction-porosity trends can be used as a first prediction tool to estimate the capillary properties of mudstones. Mathematical compaction models exist but need to be calibrated for each basin. This study aims to establish a compaction trend based on theoretical models, then compare it with theoretical maximum hydrocarbon column heights inferred from true measured capillary pressure curves. Middle to upper Miocene mudstone core samples from the Vienna Basin, covering a broad depth interval from 700 to 3400 m, were investigated by X-ray diffractometry, with an Eltra C/S analyzer, and by Rock–Eval pyrolysis for bulk mineralogy, total organic carbon, and free hydrocarbon contents. Broad ion beam—scanning electron microscopy, mercury intrusion capillary porosimetry, and helium pycnometry were applied to obtain pore structural properties to compare the mathematical compaction models with actual porosity data from the Vienna Basin. Clear decreasing porosity depth trends imply that mechanical compaction was rather uniform in the central Vienna Basin. Comparing the Vienna Basin trend to global mudstone compaction trends, regional uplift causing erosion of up to 500 m upper Miocene strata is inferred. A trend of increasing Rock–Eval parameters S1 and production index [PI = S1/(S1 + S2)] with decreasing capillary sealing capacity of the investigated mudstones possibly indicates vertical hydrocarbon migration through the low-permeable mudstone horizons. This observation must be considered in future top-seal studies for secondary storage applications in the Vienna Basin.
CRIS-Team Scopus Importer:2023-08-11
Keywords: BIB-SEM; Helium pycnometry; MICP; Mudstone compaction; Top seal quality; Uplift history; Vienna Basin

Regional-scale paleofluid system across the Tuscan Nappe-Umbria-Marche Apennine Ridge (northern Apennines) as revealed by mesostructural and isotopic analyses of stylolite-vein networks - Beaudoin, Nicolas E.; Labeur, Aurelie; Lacombe, Olivier; Köhn, Daniel; Billi, Andrea; Hoareau, Guilhem; Boyce, Adrian; John, Cedric M.; Marchegiano, Marta; Roberts, Nick M.; Millar, Ian L.; Claverie, Fanny; et al. (Solid Earth, 2020)
We report the results of a multiproxy study that combines structural analysis of a fracture-stylolite network and isotopic characterization of calcite vein cements and/or fault coating. Together with new paleopiezometric and radiometric constraints on burial evolution and deformation timing, these results provide a first-order picture of the regional fluid systems and pathways that were present during the main stages of contraction in the Tuscan Nappe and Umbria-Marche Apennine Ridge (northern Apennines). We reconstruct four steps of deformation at the scale of the belt: burial-related stylolitization, Apenninic-related layer-parallel shortening with a contraction trending NE-SW, local extension related to folding, and late-stage fold tightening under a contraction still striking NE-SW. We combine the paleopiezometric inversion of the roughness of sedimentary stylolites - that constrains the range of burial depth of strata prior to layer-parallel shortening - with burial models and U-Pb absolute dating of fault coatings in order to determine the timing of development of mesostructures. In the western part of the ridge, layer-parallel shortening started in Langhian time (similar to 15 Ma), and then folding started at Tortonian time (similar to 8 Ma); late-stage fold tightening started by the early Pliocene (similar to 5 Ma) and likely lasted until recent/modern extension occurred (similar to 3 Ma onward). The textural and geochemical (delta O-18, delta C-13, Delta 47CO2 and Sr-87/Sr-86) study of calcite vein cements and fault coatings reveals that most of the fluids involved in the belt during deformation either are local or flowed laterally from the same reservoir. However, the western edge of the ridge recorded pulses of eastward migration of hydrothermal fluids (>140 degrees C), driven by the tectonic contraction and by the difference in structural style of the subsurface between the eastern Tuscan Nappe and the Umbria-Marche Apennine Ridge.
CRIS-Team WoS Importer:2020-09-25

Reinvestigation of the Fe-rich part of the pseudo-binary system SrO-Fe_2_O_3_ - Langhof, Nico; Seifert, Daniela; Göbbels, Matthias; Toepfer, Joerg (Journal of Solid State Chemistry, 2009)
The phase relations in the Fe-rich part of the pseudo-binary system SrO–Fe2O3 (>33 mol% Fe2O3) were reinvestigated between 800 and 1500 °C in air. A combination of microscopy, electron probe micro-analysis, powder X-ray diffraction and thermal analysis was used to determine phase relations, crystal structure parameters and phase transition temperatures. M-type hexagonal ferrite SrFe12O19 (85.71 mol% Fe2O3) is stable up to 1410 °C. No indication of a significant phase width was found; Sr4Fe6O13±δ appears as a second phase in compositions with <85.71±0.2 mol% Fe2O3. Sr4Fe6O13±δ itself is stable between 800 and 1250 °C. Two other hexagonal ferrites were found to exist at high temperatures only: W-type SrFe2+2Fe3+16O27 is stable between 1350 and 1440 °C and X-type ferrite Sr2Fe2+2Fe3+28O46 between 1350 and 1420 °C, respectively, which is shown here for the first time. These findings in combination with previously published data were used to derive a corrected phase diagram of the Fe-rich part of the pseudo-binary system SrO–Fe2O3.
UnivIS-Import:2015-03-09:Pub.2009.nat.dgeo.IGM.LM.reinve
Keywords: Hexagonal ferrites; Hard magnets; Phase diagram; Sr–Fe–O

Rekonstruktion orbital gesteuerter Klimaschwankungen eine Fallstudie an pelagischen Karbonaten der norddeutschen Oberkreide - de Wall, Helga; et al. (Zeitschrift der Deutschen Gesellschaft für Geowissenschaften, 2005)
UnivIS-Import:2015-03-09:Pub.2005.nat.dgeo.IGM.c3tekt.rekons

Relating ettringite formation and rheological changes during the initial cement hydration: A comparative study applying XRD analysis, rheological measurements and modeling - Jakob, Cordula; Jansen, Daniel; Ukrainczyk, Neven; Koenders, Eddie; Pott, Ursula; Stephan, Dietmar; Neubauer, Jürgen (Materials, 2019)
In order to gain a deeper understanding of the rheological development of hydrating ordinary Portland cement (OPC) pastes at initial state, and to better understand their underlying processes, quantitative X-ray diffraction (XRD) analysis and rheological measurements were conducted and their results combined. The time-dependent relation between phase development and flow behavior of cement paste was investigated at two different temperatures (20 and 30 °C), over a period of two hours. Regarding the phase development during hydration, ettringite precipitation was identified as the dominant reaction in the first two hours. For both temperatures, the increasing ettringite content turned out to correlate very well with the loss of workability of the reacting cement paste. An exponential relationship between ettringite growth and flow behavior was observed that could be explained by applying the Krieger-Dougherty equation, which describes the influence of solid fraction on the viscosity of a suspension.
CRIS-Team Scopus Importer:2019-10-01
Keywords: Ettringite formation; Hydration kinetics; Modeling; OPC; Rheology; Scanning electron microscopy (SEM); Temperature

Relating phase transitions to pore size distributions and mechanical mortar properties in CSA-OPC-C based systems – The potential impact of delayed straetlingite formation - Wolf, Julian; Jansen, Daniel; Götz-Neunhoeffer, Friedlinde; Neubauer, Jürgen (Cement and Concrete Research, 2021)
The scope of this research is to investigate the performance evolution of five ternary CSA-OPC-Cs systems. Time resolved thermodynamic modeling was employed to gain insight into changes in the volume fractions of the hydrating pastes and link these changes to trends in the pore size distributions of the mortars. Pore solution analyses were performed to investigate which hydrates have the potential to exert high crystallization pressures. In three out of five blends the resulting tensile stress exceeded the tensile strength of the materials, resulting in the occurrence of coarse pores, which could be linked to the measured compressive strengths. Two damaging crystallization processes were identified in the investigated blends. One is the continuous precipitation of ettringite at high supersaturation in a system with high anhydrite addition. The other is the delayed crystallization of straetlingite at high supersaturation and crystallization pressure in the confined environment of mature pastes.
CRIS-Team Scopus Importer:2021-06-18
Keywords: Calcium sulfoaluminate cement; Crystallization pressure; Pore size distribution; Portland cement; Strätlingite

Relationship between stylolite morphology and the sealing potential of stylolite-bearing carbonate cap rocks - Wu, Jun; Fan, Tailiang; Gomez-Rivas, Enrique; Cao, Qian; Travé, Anna; Gao, Zhiqian; Kang, Zhihong; Köhn, Daniel; Bons, Paul D. (Geological Society of America Bulletin, 2023)
We analyzed the sealing effectiveness of cap rocks bearing different types of stylolites using a combination of petrographic, petrophysical, pore structure, and sealing capacity characterization techniques. This study was based on examples of carbonate cap rocks that seal ultradeep hydrocarbon reservoirs of the Tarim Basin (China). Samples from both drill cores and their outcrop analogues were investigated to quantify how morphology influences the sealing capacity of different types of stylolite-bearing rocks. The study cap rocks consisted of mudstone, wackestone to packstone, grainstone, and dolomitic limestone. Four types of stylolites were identified: rectangular layer, seismogram pinning, suture and sharp peak, and simple wave-like types. The difference in the sealing capacity of carbonate cap rocks is attributed to their pore structure connections and the types of stylolites they develop. Samples bearing simple wave-like stylolites showed the best sealing capacity, followed by those with rectangular layer and suture and sharp peak types, whereas carbonates hosting seismogram pinning types had the lowest sealing capacity. The impact of stylolite segments on the rock sealing properties, however, differed from one segment to another. Rectangular layer–type stylolites could be divided into three distinct segments (with good, moderate, and poor sealing, respectively). Both the seismogram pinning and suture and sharp peak stylolite types were divided in two parts, with the former one having moderate and poor sealing and the latter exhibiting good and moderate sealing. The simple wavelike type had a good sealing capacity all along the pressure-solution seam. The most effective sealing barriers for vertical fluid flow form when (1) calcite and siliceous cements are pervasively distributed in the vicinity of stylolites, forming highly cemented zones with lower porosity and permeability than their surrounding host rocks; (2) stylolites are enriched in insoluble residues; and (3) rare microfractures and dissolution vugs are found along the stylolites. This work provides useful examples for the prediction of the sealing potential of stylolite-bearing carbonate rocks according to stylolite morphology in other geologic settings.
CRIS-Team Scopus Importer:2023-03-31

Relationship between thermal conductivity and saturation conditions in soils interested by very shallow geothermal systems: an overview of ITER Project - Di Sipio, Eloisa; Bertermann, David (44th NATAS (North American Thermal Analysis Society) Conference, 2017)

Relationship Between Thermal Conductivity, Mineral Composition and Major Element Composition in Rocks from Central and South Germany - Suft, Oliver; Hagenauer, Hannes; Bertermann, David (Geosciences, 2025)
Thermal conductivity is a decisive parameter in all geothermal applications. In addition to the influencing factors of density, saturation, porosity, temperature and pressure, it is, above all, the geochemical and mineralogical composition that determines the thermal conductivity in rocks and soils. This study focuses on selected rock samples from Southern and Central Germany regarding major element oxides and minerals as well as distributed thermal conductivity. We examined clastic and chemical sedimentary, as well as igneous and metamorphic rocks, ranging from the Paleozoic to Cenozoic age. Measurements were conducted by X-ray fluorescence analysis (XRF), X-ray diffraction (XRD) and optical scanning with a thermal conductivity scanner (TCS). The results show significant correlations between thermal and geochemical parameters. Chemical composition significantly impacts thermal conductivity. Higher quartz and SiO2 contents generally lead to increased thermal conductivity, while aluminum silicates, common in clay minerals, correlate with lower conductivity. For carbonates, increased density or reduced porosity enhances conductivity. Structural differences and differing mineral concentrations influence the measurement variability along the sampling axis. This is especially visible in clastic sedimentary rock samples, where porosity decreases while cementation of the matrix increases thermal conductivit
Keywords: thermal conductivity; rock geochemistry; major element analytic; mineral composition

Relationships between fracture toughness, Y2O3 fraction and phases content in modern dental Yttria-doped zirconias - Belli, Renan; Hurle, Katrin; Schürrlein, Jana; Petschelt, Anselm; Werbach, Katharina; Peterlik, Herwig; Rabe, Torsten; Mieller, Björn; Lohbauer, Ulrich (Journal of the European Ceramic Society, 2021)
The relationship between fracture toughness and Yttria content in modern zirconia ceramics was revised. For that purpose, we evaluated here 10 modern Y2O3-stabilized zirconia (YSZ) materials currently used in biomedical applications, namely prosthetic and implant dentistry. The most relevant range between 2-5 mol% Y2O3 was addressed by selecting from conventional opaque 3 mol% YSZ up to more translucent compositions (4−5 mol% YSZs). A technical 2YSZ was used to extend the range of our evaluation. The bulk mol% Y2O3 concentration was measured by X-Ray Fluorescence Spectroscopy. Phase quantification by Rietveld refinement considered two tetragonal phases or an additional cubic phase. A first-account of the fracture toughness (KIc) of the pre-sintered blocks is given, which amounted to 0.4 – 0.7 MPa√m. In the fully-densified state, an inverse power-law behavior was obtained between KIc and bulk mol% Y2O3 content, whether using only our measurements or including literature data, challenging some established relationships. A linear relationship between KIc and the fraction of the transformable t-phase was established within the range of 30–70 vol%.
CRIS-Team Scopus Importer:2021-10-08
Keywords: Dental; Fracture toughness; Power-law; X-ray-diffraction; Yttria; Zirconia

Relative rates of fluid advection, elemental diffusion and replacement govern reaction front patterns - Köhn, Daniel; Piazolo, Sandra; Beaudoin, Nicolas E.; Kelka, Ulrich; Spruženiece, Liene; Putnis, Christine V.; Toussaint, Renaud (Earth and Planetary Science Letters, 2021)
Replacement reactions during fluid infiltration into porous media, rocks and buildings are known to have important implications for reservoir development, ore formation as well as weathering. Natural observations and experiments have shown that in such systems the shape of reaction fronts can vary significantly ranging from smooth, rough to highly irregular. It remains unclear what process-related knowledge can be derived from these reaction front patterns. In this contribution we show a numerical approach to test the effect of relative rates of advection, diffusion, and reaction on the development of reaction fronts patterns in granular aggregates with permeable grain boundaries. The numerical model takes (i) fluid infiltration along permeable grain boundaries, (ii) reactions and (iii) elemental diffusion into account. We monitor the change in element concentration within the fluid, while reactions occur at a pre-defined rate as a function of the local fluid concentration. In non-dimensional phase space using Péclet and Damköhler numbers, results show that there are no rough fronts without advection (Péclet<70) nor if the reaction is too fast (Damköhler>10−3). As advection becomes more dominant and reaction slower, roughness develops across several grains with a full microstructure mimicking replacement in the most extreme cases. The reaction front patterns show an increase in roughness with increasing Péclet number from Péclet 10 to 100 but then a decrease in roughness towards higher Péclet numbers controlled by the Damköhler number. Our results indicate that reaction rates are crucial for pattern formation and that the shape of reaction fronts is only partly due to the underlying transport mechanism.
CRIS-Team Scopus Importer:2021-05-07
Keywords: advection; diffusion; grain boundary network; reaction front; replacement; roughness

Reliable estimates of beta diversity with incomplete sampling - Roden, Vanessa; Kießling, Wolfgang (GSA Annual Meeting in Seattle, Washington, USA - 2017, 2017)

Reliable estimates of beta diversity with incomplete sampling - Roden, Vanessa; Kocsis, Ádám; Zuschin, Martin; Kießling, Wolfgang (Ecology, 2018)
Beta diversity, the compositional variation among communities or assemblages, is crucial to understanding the principles of diversity assembly. The mean pairwise proportional dissimilarity expresses overall heterogeneity of samples in a data set and is among the most widely used and most robust measures of beta diversity. Obtaining a complete list of taxa and their abundances requires substantial taxonomic expertise and is time consuming. In addition, the information is generally incomplete due to sampling biases. Based on the concept of the ecological significance of dominant taxa, we explore whether determining proportional dissimilarity can be simplified based on dominant species. Using simulations and six case studies, we assess the correlation between complete community compositional data and reduced subsets of a varying number of dominant species. We find that gross beta diversity is usually depicted accurately when only the 80th percentile or five of the most abundant species of each site is considered. In data sets with very high evenness, at least the 10 most abundant species should be included. Focusing on dominant species also maintains the rank-order of beta diversity among sites. Our new approach will allow ecologists and paleobiologists to produce a far greater amount of data on diversity patterns with less time and effort, supporting conservation studies and basic scienc
Keywords: beta diversity; Bray-Curtis dissimilarity; community composition; distance matrices; dominant species; heterogeneity; proportional dissimilarity; sampling

Remagnetisation and magnetic refraction in proterozoic dykes from Central Scandinavia during Caledonian deformation - de Wall, Helga; et al. (PHYS CHEM EARTH PT A, 2000)

Remarks on the Permian dasycladalean alga Sinoporella leei Yabe, 1949 - Bucur, Ioan I.; Munnecke, Axel; Granier, Bruno; Yan, Jiaxin (Geobios, 2009)
Sinoporella leei was first described and illustrated by Yabe in 1949 as a new species and was ascribed to a new subgenus of the genus Triploporella (Steinmann). This alga was not illustrated again until Mu published 25-years later a photomicrograph of a longitudinal-tangential section. The recent finding of new specimens in Permian strata of the Guangxi region (South China) allows us to better illustrate this alga, and to improve our understanding of its morphology to the extent that we find it necessary to emend the current diagnosis. The new observations focus mainly on the morphology of the second-order laterals, on their relationship to the first-order laterals, and the connection of the first-order laterals to the main stem. These data suggest that Sinoporella represents a self-standing, discrete genus that differs from Triploporella. We also consider the lack of cystophores (cyst containers sensu De Castro) and the possible occurrence of individual cysts in the first order laterals as characteristics that do not accord with Barttolo's emended diagnosis of Triploporella. © 2009 Elsevier Masson SAS. All rights reserved.
Keywords: Dasycladalean alga; Permian; Sinoporella; First description

Renewable energy potentials for the post-socialist urban environments of Ub (Serbia) – A shallow geothermal approach - Müller, Johannes; Jocic, Nikola; Pozar, Tea; Bertermann, David (Book of Abstracts / 8th International Urban Geographies of Post-communist States Conference, 2019)

Renewable energy sources in a post-socialist transitional environment: The influence of social geographic factors on potential utilization of very shallow geothermal energy within heating systems in small serbian town of Ub - Jocic, Nikola; Müller, Johannes; Požar, Tea; Bertermann, David (Applied Sciences, 2020)
Energetic stability is a precondition for a regular functioning of society and economy. Actual climate change raised the awareness of population and policy makers about the importance of exploited energy sources. Renewable energy sources are revealed as the solution which should satisfy both needs-a need for energetic stability, as well as a need for producing 'clean' and 'sustainable' energy, and therefore reduce humans' influence on the climate change. Very shallow geothermal energy offers wide range for utilization, among others for heating and cooling living spaces. This article shows potentials of low temperature heating system networks in a small Serbian town of Ub. In addition to technical possibilities, this article combines geographical and social, as well as political and economic circumstances in the town of Ub, which emerge as a result of a complex (post-socialist) transitional vortex.
CRIS-Team Scopus Importer:2020-05-22
Keywords: Low temperature district heating; Post-socialist transitional environment; Renewable energy sources; Very shallow geothermal potential (vSGP)

Repeated Folding during Late Holocene Earthquakes on the La Cal Thrust Fault near Mendoza City (Argentina) - Salomon, Eric; Schmidt, Silke; Hetzel, Ralf; Mingorance, Francisco; Hampel, Andrea (Bulletin of the Seismological Society of America, 2013)
In 1861, one of the most destructive earthquakes in the history of Argentina destroyed the city of Mendoza (currently 1 million inhabitants). The magnitude M-S similar to 7.0 earthquake is inferred to have occurred on the 31-km-long La Cal thrust fault, which extends from Mendoza to the north, where it offsets an alluvial fan and small inset terraces along a well-preserved fault scarp. A trench excavated on a terrace that is vertically offset by similar to 2.5 m exposes two main stratigraphic units separated by an erosional unconformity. The coarse-grained upper unit is deformed by three east-vergent folds (F-1-F-3). Retrodeformation of these folds yields total displacements of similar to 2.0 m, similar to 2.4 m, and similar to 0.5 m on the underlying fault splays, respectively. The displacement of similar to 2.0 m recorded by fold F-1 is interpreted as the result of the fault rupture that caused the 1861 earthquake. F-2 and F-3 were presumably generated during the penultimate event with an inferred magnitude of M-w similar to 7.0, although formation during two distinct ruptures cannot be excluded. Finite-element modeling shows that coseismic folding above the tip of a blind thrust fault is a physically plausible mechanism to generate these folds. A published luminescence age of 770 +/- 76 years, which is interpreted to date the formation of the deformed terrace, indicates that the two (or possibly three) scarp-forming events occurred during the last similar to 800 years. The fine-grained sediments below the erosional unconformity-that contain evidence for at least one older earthquake-are dated at similar to 12 kyr. Our results indicate that elastic strain energy, which is accumulating at the front of the Precordillera today as shown by Global Positioning System (GPS) data, was repeatedly released during earthquakes on the La Cal fault in the past. Hence, the La Cal thrust fault poses a serious threat to the city of Mendoza.

Reply on Comment by Longinelli (2013) on a revised phosphate-water fractionation equation - Puceat, E.; Joachimski, Michael; Bouilloux, A.; Monna, Fabrice; Bonin, A.; Motreuil, S.; Moriniere, P.; Henard, S.; Mourin, J.; Dera, G.; Quesne, D. (Earth and Planetary Science Letters, 2013)

Reply to Comments by Kale and Pande on: “Machine-learning based re-classification of the stratigraphy of the Rajahmundry Traps, India” - Hoyer, Patrick; Regelous, Marcel; Adatte, Thierry; Haase, Karsten (Journal of Volcanology and Geothermal Research, 2023)
CRIS-Team Scopus Importer:2023-05-26

Reply to discussion by RN Scoon and AA Mitchell on 'Oxygen isotope and trace element compositions of platiniferous dunite pipes of the Bushveld Complex, South Africa - Signals from a recycled mantle component?' - Günther, Thomas; Haase, Karsten; Junge, Malte; Oberthuer, Thomas; Wölki, Dominic; Krumm, Stefan (Lithos, 2019)
CRIS-Team WoS Importer:2019-02-22

Reply to the Discussion by Maravelis and Zelilidis on "Unravelling provenance from Eocene-Oligocene sandstones of the Thrace Basin, North-east Greece" by Caracciolo etal. (2011), Sedimentology, 58, 1988-2011. - Caracciolo, Luca; et al. (Sedimentology, 2013)
Keywords: Compositional signatures; Limnos Island; NAegean evolution; provenance; Thrace basin

Research on mechanical parameters of coarse-grained sliding soil based on CT scanning and numerical tests - Jiang, Jiwei; Xiang, Wei; Schleier, Markus; Pan, Jiajun; Zhang, Wei; Rohn, Joachim (Landslides, 2016)
Keywords: CT scanning; Mechanical parameters; Nondestructive testing; Numerical test; Rock and soil aggregates (RSA); Sliding soil

Research on water–rock (soil) interaction by dynamic tracing method for Huangtupo landslide, Three Gorges Reservoir, PR China - Jiang, Ji-Wei; Xiang, Wei; Zeng, Wen; Schleier, Markus; Rohn, Joachim (Environmental Earth Sciences, 2015)
Keywords: Bad geological elements; Clay mineral; Huangtupo landslide; Multi-sample dynamic tracing method; Three Gorges Reservoir; Water and rock (soil) interaction

Reservoir and Cap Rock Monitoring - Kühn, Michael; Barth, Johannes; Baumann, G.; Becker, Veith; Bock, M.; Buske, S.; Fritschen, R.; Giese, R.; Groß, C.; Henninges, J.; Houpt, L.; Kock, D.; et al. (CLEAN, 2013)

Resilience of cold-water scleractinian corals to ocean acidification: Boron isotopic systematics of pH and saturation state up-regulation - McCulloch, Malcolm; Trotter, Julie; Montagna, Paolo; Falter, Jim; Dunbar, Robert; Freiwald, André; Försterra, Günter; López Correa, Matthias; Maier, Cornelia; Rüggeberg, Andres; Taviani, Marco (Geochimica Et Cosmochimica Acta, 2012)
The boron isotope systematics has been determined for azooxanthellate scleractinian corals from a wide range of both deep-sea and shallow-water environments. The aragonitic coral species, Caryophyllia smithii, Desmophyllum dianthus, Enallopsammia rostrata, Lophelia pertusa, and Madrepora oculata, are all found to have relatively high δ 11B compositions ranging from 23.2‰ to 28.7‰. These values lie substantially above the pH-dependent inorganic seawater borate equilibrium curve, indicative of strong up-regulation of pH of the internal calcifying fluid (pH cf), being elevated by 0.6-0.8units (ΔpH) relative to ambient seawater. In contrast, the deep-sea calcitic coral Corallium sp. has a significantly lower δ 11B composition of 15.5‰, with a corresponding lower ΔpH value of 0.3units, reflecting the importance of mineralogical control on biological pH up-regulation.The solitary coral D. dianthus was sampled over a wide range of seawater pH T and shows an approximate linear correlation with ΔpH Desmo=6.43-0.71pH T (r 2=0.79). An improved correlation is however found with the closely related parameter of seawater aragonite saturation state, where ΔpH Desmo=1.09-0.14Ω arag (r 2=0.95), indicating the important control that carbonate saturation state has on calcification. The ability to up-regulate internal pH cf, and consequently Ω cf, of the calcifying fluid is therefore a process present in both azooxanthellate and zooxanthellate aragonitic corals, and is attributed to the action of Ca 2+-ATPase in modulating the proton gradient between seawater and the site of calcification. These findings also show that the boron isotopic compositions (δ 11B carb) of aragonitic corals are highly systematic and consistent with direct uptake of the borate species within the biologically controlled extracellular calcifying medium.We also show that the relatively strong up-regulation of pH and consequent elevation of the internal carbonate saturation state (Ω cf 8.5 to 13) at the site of calcification by cold-water corals, facilitates calcification at or in some cases below the aragonite saturation horizon, providing a greater ability to adapt to the already low and now decreasing carbonate ion concentrations. Although providing greater resilience to the effects of ocean acidification and enhancing rates of calcification with increasing temperature, the process of internal pH cf up-regulation has an associated energetic cost, and therefore growth-rate cost, of 10% per 0.1 pH unit decrease in seawater pH T. Furthermore, as the aragonite saturation horizon shoals with rapidly increasing pCO 2 and Ω arag<1, increased dissolution of the exposed skeleton will ultimately limit their survival in the deep oceans. © 2012 Elsevier Ltd.
UnivIS-Import:2015-03-09:Pub.2012.nat.dgeo.IGM.LP.resili
Keywords: ocean acidification; coral calcification; biomineralization

Resistivity relaxation, a new approach to study ionic mobility in perovskite mixed conductors like CaTi0.7Fe0.3O3-ð - Mashkina, Elena; Baier, Markus; Magerl, Andreas; Göbbels, Matthias; Seifert, Friedrich (Ionics, 2005)
Oxygen transport of mixed ionic-electronic conductors can be measured by a 'relaxation' technique that permits to investigate the material dynamic properties with oxygen partial pressure change. However, for materials exhibiting higher electronic conductivity than ionic, the time for conductivity change is controlled by bulk ionic transport and any surface reaction can be neglected. By fitting the experimental relaxation data of CaTi 0.7Fe0.3O3-δ composition, the oxidation and reduction kinetics was found to be independent on oxygen partial pressure (PO2) and the rate constants were derived therefrom. From a relaxation experiment at a single PO2 we therefore obtain both the electronic and ionic contributions to the total conductivity as well as the chemical diffusion coefficient.
UnivIS-Import:2015-03-09:Pub.2005.nat.dgeo.IGM.LM.resist

Response - Kießling, Wolfgang (Science, 2010)

Response of an Arctic calcifying macro alga to increasing CO2 and temperature Levels: A habitat at risk? - Büdenbender, Jan; Hellemann, D.; Teichert, Sebastian; Stange, P.; Form, Armin; Riebesell, U. (EPOCA Final meeting, 2012)

Response of Siliceous Marine Organisms to the Permian-Triassic Climate Crisis Based on New Findings From Central Spitsbergen, Svalbard - Foster, W. J.; Asatryan, G.; Rauzi, S.; Botting, J. P.; Buchwald, S. Z.; Lazarus, D. B.; Isson, T.; Renaudie, J.; Kießling, Wolfgang (Paleoceanography and Paleoclimatology, 2023)
Siliceous marine ecosystems play a critical role in shaping the Earth's climate system by influencing rates of organic carbon burial and marine authigenic clay formation (i.e., reverse weathering). The ecological demise of silicifying organisms associated with the Permian-Triassic mass extinction is postulated to have elevated marine authigenic clay formation rates, resulting in a prolonged greenhouse climate during the Early Triassic. Yet, our understanding of the response of siliceous marine organisms during this critical interval is poor. Whilst radiolarians experienced the strongest diversity loss in their evolutionary history and perhaps also the greatest population decline of silica-secreting organisms during this event, only a small number of Griesbachian (post-extinction) localities that record siliceous organisms are known. Here, we report newly discovered latest Changhsingian to early Griesbachian (Clarkina meishanensis - Hindeodus parvus Zone) radiolarians and siliceous sponge spicules from Svalbard. This fauna documents the survival of a low-diversity radiolarian assemblage alongside stem-group hexactinellid sponges making this the first described account of post-extinction silica-secreting organisms from the Permian/Triassic boundary in a shallow marine shelf environment and a mid-northern paleolatitudinal setting. Our findings indicate that latitudinal diversity gradients for silica-secreting organisms following the mass extinction were significantly altered, and that silica productivity was restricted to high latitude and deep water thermal refugia. This result has potential to further shape our understanding of changes in marine dissolved silica levels and in turn rates of reverse weathering, with implications for our understanding of carbon cycle dynamics during this interval.
CRIS-Team Scopus Importer:2023-12-15
Keywords: climate response; hexactinellids; Permian-Triassic; radiolarians; thermal stress

Response to comment on "Lethally hot temperatures during the Early Triassic. - Sun, Yadong; Joachimski, Michael; Wignall, Paul B.; Yan, Chunbo; Chen, Yanlong; Jiang, Haishui; Wang, Lina; Lai, Xulong; Sun, Yadong (Science, 2013)
UnivIS-Import:2015-03-09:Pub.2013.nat.dgeo.IGM.LG.respon

Response to comments on "Statistical independence of escalatory ecological trends in Phanerozoic marine invertebrates - Kießling, Wolfgang; et al. (Science, 2006)
UnivIS-Import:2015-04-14:Pub.2006.nat.dgeo.IGM.LP.respon

REVEALING THE GENESIS OF LIMESTONE-MARL ALTERNATIONS: A TAPHONOMIC APPROACH - Nohl, Theresa; Jarochowska, Emilia; Munnecke, Axel (Palaios, 2019)

Revised correlation of Silurian Provincial Series of North America with global and regional chronostratigraphic units and δ13Ccarb chemostratigraphy - Cramer, Bradley D.; Brett, Carlton E.; Melchin, Michael J.; Männik, Peep; Kleffner, Mark A.; Mclaughlin, Patrick I.; Loydell, David K.; Munnecke, Axel; Jeppsson, Lennart; Corradini, Carlo; Brunton, Frank R.; Saltzman, Matthew Ross (Lethaia, 2011)
Recent revisions to the biostratigraphic and chronostratigraphic assignment of strata from the type area of the Niagaran Provincial Series (a regional chronostratigraphic unit) have demonstrated the need to revise the chronostratigraphic correlation of the Silurian System of North America. Recently, the working group to restudy the base of the Wenlock Series has developed an extremely high-resolution global chronostratigraphy for the Telychian and Sheinwoodian stages by integrating graptolite and conodont biostratigraphy with carbonate carbon isotope (δC) chemostratigraphy. This improved global chronostratigraphy has required such significant chronostratigraphic revisions to the North American succession that much of the Silurian System in North America is currently in a state of flux and needs further refinement. This report serves as an update of the progress on recalibrating the global chronostratigraphic correlation of North American Provincial Series and Stage boundaries in their type area. The revised North American classification is correlated with global series and stages as well as regional classifications used in the United Kingdom, the East Baltic, Australia, China, the Barrandian, and Altaj. Twenty-four potential stage slices, based primarily on graptolite and conodont zones and correlated to the global series and stages, are illustrated alongside a new composite δC curve for the Silurian. Conodont, graptolite, isotope, New York, Ontario, series, Silurian, stage. © 2010 The Authors, Journal compilation © 2010 The Lethaia Foundatio
Keywords: Chronostratigraphy; Silurian; Provincial Series; δ13C; Chemostratigraphy

Revised phosphate-water fractionation equation reassessing paleotemperaturesderived from biogenic apatite. - Puceat, E.; Joachimski, Michael; Bouilloux, A.; Monna, Fabrice; Bonin, A.; Motreuil, S.; Moriniere, P.; Henard, S.; Mourin, J.; Dera, Guillaume; Quesne, D. (Earth and Planetary Science Letters, 2010)
UnivIS-Import:2015-03-09:Pub.2010.nat.dgeo.IGM.LG.revise

Revision of thelodonts, acanthodians, conodonts, and the depositional environments in the Burgen outlier (Ludlow, Silurian) of Gotland, Sweden - Jarochowska, Emilia; Bremer, Oskar; Yiu, Alexandra; Märss, Tiiu; Blom, Henning; Mörs, Thomas; Vajda, Vivi (GFF, 2021)
Ludfordian strata exposed in the Burgen outlier in eastern Gotland record a time of initial faunal recovery after a global environmental perturbation manifested in the Ludfordian Carbon Isotope Excursion (LCIE). Vertebrate microfossils in the collection of the late Lennart Jeppsson, hosted at the Swedish Museum of Natural History, hold the key to reconstruct the dynamics of faunal immigration and diversification during the decline of the LCIE, but the stratigraphic relationships of the strata have been debated. Historically, they had been placed in the Burgsvik Formation, which included the Burgsvik Sandstone and the Burgsvik Oolite members. We revise the fauna in the Jeppsson collection and characterize key outcrops of Burgen and Kapellet. The former Burgsvik Oolite Member is here revised as the Burgen Oolite Formation. In the Burgen outlier, back-shoal facies of this formation are represented and their position in the Ozarkodina snajdri Biozone is supported. The shallow-marine position compared to the coeval strata in southern Gotland is reflected in the higher δ13Ccarb values, reaching +9.2‰. The back-shoal succession includes high-diversity metazoan reefs, which indicate a complete recovery of the carbonate producers as the LCIE declined. The impoverishment of conodonts associated with the LCIE in southern Gotland might be a product of facies preferences, as the diverse environments in the outlier yielded all 21 species known from the formation. Fish diversity also returned to normal levels as the LCIE declined, with a minimum of nine species. In line with previous reports, thelodont scales appear to dominate samples from the Burgen outlier.<br
Keywords: acanthodians; biostratigraphy; Burgsvik Formation; Ludlow; thelodonts; Lau event; carbon isotope excursion; extinction; recovery; palynology

Revisiting reef models in the Oligocene of northern Italy (Venetian Southern Alps) - Bosellini, Francesca R.; Vescogni, Alessandro; Kießling, Wolfgang; Zoboli, Alessandro; Di Giuseppe, Dario; Papazzoni, Cesare Andrea (Bollettino Della Societa Paleontologica Italiana, 2020)
The lower Oligocene coral communities and reefs exposed in the Lessini Shelf of northern Italy may record one of the oldest well-developed barrier reef/lagoon systems of the Cenozoic. However, the rimmed-shelf interpretation has been repeatedly challenged in favour of a ramp model with scattered corals. Based upon a re-analysis of selected localities in the Lessini Shelf, we here provide support for the barrier reef model based on four key observations: 1) systematic changes of coral growth-forms from branching in the proximal areas to massive at the platform margin; 2) a progressive increase of the hydrodynamic energy from the proximal belt towards the more distal environments in the Berici Hills; 3) the occurrence of shallow-water, euphotic conditions throughout the whole depositional system; and 4) the presence of restricted circulation in the proximal environments during sea-level lowstands, with lack of coral colonies. These features, together with the evidence of coral frameworks located on the southeastern edge of the Lessini Shelf, substantiate the occurrence of a reef-rimmed margin. The reefal rim acted as an efficient barrier, with the formation of a landward, wide lagoon protected from the action of waves and currents.
CRIS-Team WoS Importer:2021-01-29

Revisiting the identification of Syllipsimopodi bideni and timing of the decabrachian-octobrachian divergence - Klug, Christian; Stevens, Kevin; Hoffmann, René; Zatoń, Michał; Clements, Thomas; Košťák, Martin; Weis, Robert; De Baets, Kenneth; Lehmann, Jens; Vinther, Jakob; Fuchs, Dirk (Nature Communications, 2023)
CRIS-Team Scopus Importer:2023-12-15

Revisiting the long-term biodiversity dynamics of reef builders in a novel Bayesian framework - Raja Schoob, Nussaibah Begum; Kießling, Wolfgang (13th International Symposium on Fossil Cnidaria, 2019)

Revisiting the Phanerozoic rock-diversity relationship - Na, Lin; Li, Qijian; Krause, Mihaela-Cristina; Zhu, Minghang; Kießling, Wolfgang (Geological Magazine, 2023)
The congruence between rock quantity and biodiversity through the Phanerozoic has long been acknowledged. Rock record bias and common cause are the most discussed hypotheses: the former emphasizes that the changes in diversity through time fully reflect rock availability; the latter posits that the correlation between rock and fossil records is driven by a common cause, such as sea-level changes. Here, we use the Geobiodiversity Database (GBDB), a large compilation of the rock and fossil records, to test the rock bias hypothesis. In contrast to other databases on fossil occurrences, the section-based GBDB also records unfossiliferous units. Our multiple regression analysis shows that 85% of the variation in sampled diversity can be attributed to the rock record, meaning that major peaks and drops in observed diversity are mainly due to the rock record. Our results support a strong covariation between the number of unfossiliferous units and sampled diversity, indicating a genuine rock bias that arose from sampling effort that is independent of fossil content. This provides a compelling argument that the rock record bias is more prominent than common cause in explaining large-scale variations in sampled diversity. Our study suggests that (1) no single proxy can fully represent rock record bias in predicting biodiversity, (2) rock bias strongly governs sampled diversity in both marine and terrestrial communities, and (3) unfossiliferous strata contain critical information in predicting diversity of marine and terrestrial animals.
CRIS-Team Scopus Importer:2024-12-16
Keywords: diversity; fossil record; Geobiodiversity Database; rock record bias

REY and Trace Element Chemistry of Fluorite from Post-Variscan Hydrothermal Veins in Paleozoic Units of the North German Basin - Nadoll, Patrick; Rehm, Meike; Duschl, Florian; Klemd, Reiner; Kraemer, Dennis; Sosnicka, Marta (Geosciences, 2018)
Hydrothermal fluorites from Paleozoic sedimentary rocks and volcanic units in the North German Basin (NGB) have been investigated to create a petrographic and geochemical inventory—with particular focus on strategic elements such as rare earth elements (REE)—and to uncover possible links between the post-Variscan hydrothermal mineralization in the NGB and bordering areas such as the Harz Mountains and Flechtingen Calvörde Block (FCB). Fluorites from ten localities underwent a detailed petrographic examination, including SEM-BSE/CL imagery, and were compositionally analysed using LA-ICP-MS. Overall, REY concentrations are comparatively low in fluorite from all investigated areas—the median sum of REY ranges from 0.3 to 176 ppm. EuropiumCN anomalies are slightly negative or absent, indicating that either the formation fluid experienced temperatures above 250 °C or that fluid-rock interactions and REE enrichment was likely controlled by the source rock (i.e., volcanic) composition and complexation processes. Fluorites from the Altmark-Brandenburg Basin (ABB) and the Lower Saxony Basin (LSB) display distinctly different REYCN signatures, suggesting that fluid compositions and genetic processes such as fluid-rock interaction differed significantly between the two areas. Complex growth zones and REYCN signatures in fluorite from the ABB and the FCB reflect geochemical variability due to adsorption processes and intrinsic crystallographic controls and imply that they are genetically related. Two petrographically and geochemically distinct generations are observed: Fluorite I—light SEM shades, relatively enriched in LREE; Fluorite II—darker SEM shades, comparatively depleted LREE, slightly higher HREE concentrations. These fluorite generations represent zoned (or cyclical) growth within a single progressive hydrothermal event and do not reflect a secondary remobilization process. We demonstrate that increasing Tb/La ratios and decreasing La/Ho ratios can be the result of continuous zoned growth during a single mineralizing event, with significant compositional variations on a micron-scale. This has implications for the interpretation of such trends and hence the inferred genetic evolution of fluorite that displays such geochemical patterns. The complex micro-scale intergrowth of these generations stresses the need for detailed petrographic investigations when geochemical data are collected and interpreted for mineral exploration.<br
Keywords: Remobilization; Trace elements; North German Basin; Rare earth elements; Zoned growth; Hydrothermal veins; Fluorite

Rhodolith beds (Corallinales, Rhodophyta) and their physical and biological environment at 80°31'N in Nordkappbukta (Nordaustlandet, Svalbard Archipelago, Norway) - Teichert, Sebastian; Woelkerling, William; Rüggeberg, Andres; Wisshak, Max; Piepenburg, Dieter; Meyerhöfer, Michael; Form, Armin; Büdenbender, Jan; Freiwald, André (Phycologia, 2012)
UnivIS-Import:2015-03-09:Pub.2012.nat.dgeo.IGM.LP.rhodol
Keywords: Lithothamnion glaciale; Nordkappbukta; Phymatolithon tenue; polar carbonate factory; rhodolith community; Svalbard

Rietveld structure and in vitro analysis on the influence of Magnesium in Biphasic (Hydroxyapatite and beta-Tricalcium phosphate) mixtures - Kannan, Sanjeevi; Götz-Neunhoeffer, Friedlinde; Neubauer, Jürgen; Rebelo, Avito; Valério, Patrícia; da Fonte Ferreira, José Maria (Journal of Biomedical Materials Research Part B-Applied Biomaterials, 2009)
The structure of two different Mg-substituted biphasic (HAP and β-TCP) mixtures along with the biphasic mixtures without substituted Mg2+ was investigated using Rietveld refinement technique. The substituted Mg 2+ was found in the β-TCP phase and its influence on the composition has led to an increase in HAP content of Mg-containing biphasic mixtures when compared with the HAP content detected in pure biphasic mixtures. The refined structural parameters of Ca10(PO4) 6(OH)2 and β-Ca3(PO4) 2 confirmed that all the investigated compositions have crystallized in the corresponding hexagonal (space group P63/m) and rhombohedral (space group R3c) structures. The substitution of lower sized magnesium was found preferentially incorporated at the sixfold-coordinated Ca (5) site of β-TCP, which is due to the strong Ca (5)·O interaction among all the five different Ca sites of β-Ca3(PO4)2. The in vitro tests using primary culture of osteoblasts showed that all the tested samples are biocompatible and promising materials for in vivo studies. © 2008 Wiley Periodicals, Inc.
UnivIS-Import:2015-03-09:Pub.2009.nat.dgeo.IGM.LM.rietve
Keywords: β-tricalcium phosphate; Biphasic mixtures; Hydroxyapatite; In vitro tests; Magnesium; Rietveld

Riffdiversität in der Erdgeschichte - Fossilbericht und Interpretationen. - Kießling, Wolfgang (Biodiversitätsforschung - Die Entschlüsselung der Artenvielfalt in Raum und Zeit., 2003)
Keywords: Riffe; Biodiversität; Riffevolution; Geobiologie

Rifting of the oceanic Azores Plateau with episodic volcanic activity - Storch, Bettina; Haase, Karsten; Romer, René; Beier, Christoph; Koppers, A. A.P. (Scientific Reports, 2020)
Extension of the Azores Plateau along the Terceira Rift exposes a lava sequence on the steep northern flank of the Hirondelle Basin. Unlike typical tholeiitic basalts of oceanic plateaus, the 1.2 km vertical submarine stratigraphic profile reveals two successive compositionally distinct basanitic to alkali basaltic eruptive units. The lower unit is volumetrically more extensive with 1060 m of the crustal profile forming between 2.02 and 1.66 Ma, followed by a second unit erupting the uppermost 30 m of lavas in 100 kyrs. The age of 1.56 Ma of the youngest in-situ sample at the top of the profile implies that the 35 km-wide Hirondelle Basin opened after this time along normal faults. This rifting phase was followed by alkaline volcanism at D. João de Castro seamount in the basin center indicating episodic volcanic activity along the Terceira Rift. The mantle source compositions of the two lava units change towards less radiogenic Nd, Hf, and Pb isotope ratios. A change to less SiO2-undersaturated magmas may indicate increasing degrees of partial melting beneath D. João de Castro seamount, possibly caused by lithospheric thinning within the past 1.5 million years. Our results suggest that rifting of oceanic lithosphere alternates between magmatically and tectonically dominated phases.
CRIS-Team Scopus Importer:2020-11-20

Rift–plume interaction reveals multiple generations of recycled oceanic crust in Azores lavas - Béguelin, Paul; Bizimis, Michael; Beier, Christoph; Turner, Simon (Geochimica Et Cosmochimica Acta, 2017)
Keywords: Azores; Hf isotopes; HIMU; Recycled oceanic crust; Triple ridge junction

Rise and diversification of chondrichthyans in the Paleozoic - Schnetz, Lisa; Dunne, Emma; Feichtinger, Iris; Butler, Richard J.; Coates, Michael I.; Sansom, Ivan J. (Paleobiology, 2024)
The Paleozoic represents a key time interval in the origins and early diversification of chondrichthyans (cartilaginous fishes), but their diversity and macroevolution are largely obscured by heterogenous spatial and temporal sampling. The predominantly cartilaginous skeletons of chondrichthyans pose an additional limitation on their preservation potential and hence on the quality of their fossil record. Here, we use a newly compiled genus-level dataset and the application of sampling standardization methods to analyze global total-chondrichthyan diversity dynamics through time from their first appearance in the Ordovician through to the end of the Permian. Subsampled estimates of chondrichthyan genus richness were initially low in the Ordovician and Silurian but increased substantially in the Early Devonian. Richness reached its maximum in the middle Carboniferous before dropping across the Carboniferous/Permian boundary and gradually decreasing throughout the Permian. Sampling is higher in both the Devonian and Carboniferous compared with the Silurian and most of the Permian stages. Shark-like scales from the Ordovician are too limited to allow for some of the subsampling techniques. Our results detect two Paleozoic radiations in chondrichthyan diversity: the first in the earliest Devonian, led by acanthodians (stem-group chondrichthyans), which then decline rapidly by the Late Devonian, and the second in the earliest Carboniferous, led by holocephalans, which increase greatly in richness across the Devonian/Carboniferous boundary. Dispersal of chondrichthyans, specifically holocephalans, into deeper-water environments may reflect a niche expansion following the faunal displacement in the aftermath of the Hangenberg extinction event at the end of the Devonian.
CRIS-Team Scopus Importer:2024-04-19

River-fed wetland palaeovegetation and palaeoecology at the HWK W site, Bed I, Olduvai Gorge - Albert, R. M.; Bamford, M. K.; Stanistreet, I. G.; Stollhofen, Harald; Rivera-Rondón, Carlos A.; Njau, J. K.; Blumenschine, R. J. (Review of Palaeobotany and Palynology, 2018)
Palaeolandscape studies are an essential tool for understanding adaptation and use of plant- and water-related affordances by hominins. A number of high-resolution palaeolandscape analyses have been carried out at Olduvai Gorge (northern Tanzania) over the last two decades but none have focused on the Tuff ID-IE stratigraphic interval (1.83–1.84 Ma). At locality HWK W, this interval presents earthy facies, including siliceous earth, earthy claystone, sandy earth, and earthy sandstone facies varieties, which are rare for Bed I. These facies have been interpreted at other stratigraphic levels to represent densely vegetated wetlands. Additionally, the HWK W site has yielded quantities of fossil bone and tools eroding to the surface. Within the Tuff ID-IE interval, and during regression periods of Palaeolake Olduvai, fluvial and wetland facies were deposited. During this period, the phytoliths and plant macrofossils show that the vegetation was dominated by palms, associated with a mix of C3 and C4 grasses as well as sedges. The variation in phytolith types within these facies implies a locally diverse palaeoenvironmentalmicro-mosaic, with stacked transgressive sequences, varying from vegetated fluvial channels to vegetated levées and then backswamp subenvironments. Diatoms are particularly rich at Trench T155 and are associated with sponge spicules, indicating the presence of freshwater palaeowetlands with clear water. The extensive diatom valve fragmentation and the differences among trenches suggest that the diatom depositional environment was a heterogeneous river-fed palaeowetland or a vegetated fluvial channel affected by periodic droughts. A diverse fauna was recovered, comprising autochthonous hippopotamus and crocodile elements as well as herbivores drawn to the freshwater resource. Oldowan lithic artifacts were also recovered and some bone was processed through percussion and cutting by early hominins, likely Homo habilis. Overall, the first landscape reconstruction undertaken at HWK W locality during the Tuff ID-IE interval shows a dynamic and richly vegetated area that would have provided hominins with fresh water, scavengeable carcasses, aswell aswith edible plant affordances (palmfruits, starch-rich rhizomes fromsedges and Typha). The presence of palms suggests the area supported a diversity of trees, affording hominins refuge from predators.<br
Keywords: Hominins; Macroplant fossils; Diatoms; Tuff ID-IE interval palaeofacies; Paleovegetation; Phytoliths

Riverine Carbon Cycle - Barth, Johannes; et al. (Journal of the Czech Geological Society, 1997)

Riverine carbon dioxide evasion along a high-relief watercourse derived from seasonal dynamics of the water-atmosphere gas exchange - Juhlke, Tobias; van Geldern, Robert; Huneau, F.; Garel, E.; Santoni, S.; Hemmerle, H.; Barth, Johannes (Science of the Total Environment, 2019)
Keywords: Western Mediterranean; Stable isotopes; Carbon dioxide degassing; Dissolved inorganic carbon; Carbon cycle

River recharge versus O2 supply from the unsaturated zone in shallow riparian groundwater: A case study from the Selke River (Germany) - Mader, Michael; Roberts, André Michael; Porst, David; Schmidt, Christian; Trauth, Nico; van Geldern, Robert; Barth, Johannes (Science of the Total Environment, 2018)
Besides gas-water-exchange in surface waters, respiratory consumption of dissolved oxygen (DO) in adjacent riparian groundwater may trigger the addition of so far hardly explored sources from the unsaturated zone. These processes also systematically influence stable isotope ratios of DO and were investigated together with Cl− as a conservative tracer for water mixing in a near-river riparian groundwater system. The study focused on a losing stream section of the Selke River at the foot of the Harz Mountains (Germany). The study area exposed steep DO gradients between the stream water and riparian groundwater between April 2016 and May 2017. Our results indicated dominant influences of microbial community respiration with observed DO concentration gradients. These observations can be explained by DO from the river that is subject to fractionation by microbial respiration with a typical fractionation factor (αr) of 0.982. However, with such respiration dominance, we expected a simultaneous enrichment of δ18ODO towards values that are more positive than the well-known atmospheric O2 signal of +23.9‰ versus the Vienna Standard Mean Ocean Water standard (VSMOW). Surprisingly, our measurements revealed much lower δ18ODO values between +22‰ and +18‰ in the near-river groundwater. Mass balance calculations revealed that the DO pool in the shallow and unconfined aquifer receives contributions of up to about 80% by diffusion of oxygen from the vadose zone with a distinctly lower isotope value than the one of the atmosphere. This finding about additional oxygen sources from the unsaturated zone has numerous ramifications for oxygen related processes in near-river environments including the oxidation of pollutants, nutrients and ecosystem health.
Keywords: Riparian zone; Dissolved oxygen; Stable isotopes; Diffusion; Vadose zone

Rivers of North-Rhine Westphalia revisited: Tracing changes in river chemistry - Stoegbauer, Andrea; Strauss, Harald; Arndt, Julia; Marek, Victoria; Einsiedl, Florian; van Geldern, Robert (Applied Geochemistry, 2008)

Roadian-Wordian (Middle Permian) Conodont Biostratigraphy, Sedimentary Facies and Paleotemperature Evolution at the Shuixiakou Section, Xikou Area, Southeastern Qinling Region, China - Wu, Baojin; Li, Hanxiao; Joachimski, Michael; Wignall, Paul B.; Jiang, Haishui; Yan, Jiaxin; Wang, Lina; Wu, Xianlang; Lai, Xulong (Journal of Earth Science, 2021)
Focusing on the Shuixiakou Section (Xikou area, Zhen’an County, Shaanxi Province, southeastern Qinling region, China), the Roadian-Wordian conodonts are investigated. More than 2 000 conodont elements including 6 genera and 14 species have been obtained. Based on these materials, the Guadalupian Jinogondolella nankingensis and J. aserrata zones have been recognized. The Roadian-Wordian boundary is tentatively defined by the first occurrence of J. aserrata in the lower part of Unit III in the Shuixiakou Formation. The sedimentary succession of Xikou area records similar sea-level changes to those observed in Laibin area (South China). The 40 m-thick bioclastic limestone of Unit IV in this section can be correlated with the reefs of Bed 114 in Laibin area. A temperature drop indicated by δ18Oapatite values suggests this Wordian interval coincides with a period of glaciation and global regression.<br
Keywords: biostratigraphic framework; sea-level change; paleotemperature; Roadian-Wordian boundary; Shuixiakou Section

Robust landslide susceptibility analysis by combination of frequency ratio, heuristic GIS-methods and ground truth evaluation for a mountainous study area with poor data availability in the Three Gorges Reservoir area, PR China - Schleier, Markus; Bi, Renneng; Ehret, Dominik; Xiang, Wei; Rohn, Joachim (Environmental Earth Sciences, 2014)
Keywords: Frequency ratio analysis; Geographical Information System (GIS); Ground truth; Landslide susceptibility; Performance evaluation; Three Gorges Reservoir

Rock avalanches in a changing landscape following the melt down of the scandinavian ice sheet, Norway - Schleier, Markus; Hermanns, Reginald L.; Rohn, Joachim (Springer International Publishing, 2017)
Keywords: Innerdalen and innfjorddalen; Rock avalanche; Post-glacial isostatic rebound; Supraglacial rock avalanche; Subaqueous rock avalanche; Western Norway

Rockfall at Proglacial Rockwalls-A Case Study from the Kaunertal, Austria - Vehling, Lucas; Rohn, Joachim; Moser, Michael (Geomorphology of Proglacial Systems: Landform and Sediment Dynamics in Recently Deglaciated Alpine Landscapes, 2019)
Since the Little Ice Age, high alpine regions have faced rapid glacier melting that has contributed to enhanced rockfall activity at recently deglaciated rockwalls. At the Gepatschferner, Kaunertal (Austria), rockfall activity has been quantified for the past several years using rockfall collector nets, `natural' rockfall traps and multi-temporal LiDAR. Toppling and sliding activity of large unstable rock blocks, considered as precursors of rockfalls, were monitored by steel tape measurements and electrical crackmeters. The highest rockfall activity was measured at recently deglaciated rockwalls with low rock mass quality, where rockwall back-weathering rates locally exceeded 10 mm/a. Those rates are among the highest ever published. 108 mid- and high-magnitude rockfalls with volumes between 100 and 30,000 m(3) were released between 2006 and 2012. Their scars are clustered in the proglacial high-altitude parts of the Kaunertal. As well, rockwall activity was concentrated in the autumn and winter months.
CRIS-Team WoS Importer:2021-10-18

Rocks, fabrics and magnetic anisotropy: An introduction to the issue in honour of František Hrouda - Mamtani, Manish A.; Chadima, Martin; de Wall, Helga; Greiling, Reinhard O. (International Journal of Earth Sciences, 2012)

Rock Thermal Conductivity as Key Parameter for Geothermal Numerical Models - Di Sipio, Eloisa; Chiesa, Sergio; Destro, Elisa; Galgaro, Antonio; Giaretta, Aurelio; Gola, Gianluca; Manzella, Adele (Energy Procedia, 2013)
Keywords: thermal conductivity; geothermal energy; low enthalpy resources; thermal conductivity analyzer

Role of seafloor production versus continental basalt weathering in Middle to Late Ordovician seawater 87Sr/86Sr and climate - Avila, Teresa D.; Saltzman, Matthew R.; Adiatma, Y. Datu; Joachimski, Michael; Griffith, Elizabeth M.; Olesik, John W. (Earth and Planetary Science Letters, 2022)
The global climate of the Ordovician Period (486.9 to 443.1 Ma) is characterized by cooling that culminated in the Hirnantian glaciation. Chemical weathering of Ca- and Mg-bearing silicate minerals and the subsequent trapping of carbon in marine carbonates act as a sink for atmospheric CO2 on multi-million-year time scales, with basaltic rocks consuming CO2 at a greater rate than rocks of granitic composition. The oceanic Sr isotope ratio (87Sr/86Sr) can act as a geochemical proxy for the relative proportion of basaltic versus granitic weathering. Oxygen isotopes (O) act as a proxy for paleotemperature and ice volume, providing a useful complement to 87Sr/86Sr in studies of ancient climate. Previous studies have reported stepwise cooling (increasing O) during the Middle to Late Ordovician. Combined with Sr and C cycle models, this has led to the hypothesis that continental silicate weathering of mafic material drove Ordovician cooling (e.g., the Taconic Orogeny). However, Sr and C cycle models have not accounted for an apparent rise in sea level and seafloor production in the Middle Ordovician (Darriwilian), which would increase the hydrothermal Sr flux as well as degassing along continental volcanic arcs. Furthermore, some Ordovician studies contain temporal uncertainty between 87Sr/86Sr and O curves if they are not based on paired analyses, which can obscure the relationship between silicate weathering and cooling. Here, we present new paired 87Sr/86Sr and O data from conodont apatite and integrate this with both a deterministic (forward) and stochastic (reverse) modeling approach to argue that increased hydrothermal weathering played a role in driving marine 87Sr/86Sr, specifically an inflection occurring in the Pygoda serra conodont zone of the mid-Darriwilian Stage (∼ 460.9 Ma ± 1 My). This 87Sr/86Sr inflection is accompanied by an increase in O, consistent with climate cooling. Clarifying the role of seafloor production for marine 87Sr/86Sr and the implications for Ordovician cooling allows for a more nuanced understanding of the factors that drive multi-million-year<br
Keywords: Ordovician; geochemistry; paleoclimatology; silicate weathering; conodont; strontium

Roman coarse ware from Bavaria, Austria and Northern Italy - Joachimski, Michael; et al. (Hyperfine Interactions, 2004)
This interdisciplinary study focuses on a specific type of Roman coarse ware that was widely distributed in Bavaria, Austria and northern Italy during the 1st half of the 1st century AD. Various physical methods were applied to study the provenance of this characteristic marble tempered blackware and to assess its production techniques. The blackware found in large numbers on the Auerberg and at other sites in southern Germany can be identified as imported from East Tyrol, Austria.
UnivIS-Import:2015-03-09:Pub.2004.nat.dgeo.IGM.LG.romanc
Keywords: gas chromatography; Mössbauer spectroscopy; neutron activation analysis; production techniques; provenance studies; Roman coarse ware; stable isotope analysis; thin section microscopy

Römische Keramik mit Marmormagerung: Herkunftsbestimmung mit Hilfe von stabilen Isotopen (Auerbergtöpfe aus Süddeutschland). - Flügel, C.; Joachimski, Michael; Flügel, Erik (Archäologisches Korrespondenzblatt, 1997)
UnivIS-Import:2015-03-05:Pub.1997.nat.dgeo.IGM.LG.rmisch

Röntgenographische Phasenanalyse von eisenreichen Tonerdezementklinkern - Neubauer, Jürgen; Götz-Neunhoeffer, Friedlinde (2000)
UnivIS-Import:2015-03-09:Pub.2000.nat.dgeo.IGM.LM.rntgen

Rostrum size differences between Toarcian belemnite battlefields - Costa Rita, Patrícia; de Baets, Kenneth; Schlott, Martina (FOSSIL RECORD, 2018)
Body size changes have been reported across crisis intervals. Belemnites – now considered extinct stem-decabrachians – have rarely been investigated for this purpose, and the few studies have resulted in ambiguous outcomes. Here we investigate two Toarcian belemnite accumulations in southern Germany from a morphometric point of view with the support of computed tomography data. The aim of this study is to test whether a difference in size can be observed between the rostra of the two studied samples, from individual lineage to community, and which proxy is more reliable. A significant decrease in median size from the Early Toarcian (Dactylioceras tenuicostatum Zone) to the Middle Toarcian (Haugia variabilis Zone) is recognized. This is observed at the community level of organization, considering the whole assemblage, but also within Passaloteuthis–Acrocoelites lineage, at the genus level. It is also demonstrated that diameter-based measurements or maximum preserved length are not reliable proxies for size, and therefore apical length or three-dimensional approximations, such as the geometric mean or the post-phragmocone volume, are more advisable. This is especially important when comparing specimens with markedly different rostrum shapes. Further studies are, however, still necessary to disentangle the mechanisms behind the reduction in rostrum size within the Toarcian and their putative environmental cause

Rotliegend im Saar-Nahe-Becken, am Taunus-Südrand und im nördlichen Rheingraben - Boy, Jürgen A.; Haneke, Jost; Kowalczyk, Gotthard; Lorenz, Volker; Schindler, Thomas; Stollhofen, Harald; Thum, Hubert (Stratigraphie von Deutschland X. Rotliegend. Teil I: Innervariscische Becken., 2012)
UnivIS-Import:2015-04-20:Pub.2012.nat.dgeo.IGM.LG.dasrot

Routine analysis by high precision gas chromatography/mass selective detector/isotope ratio mass spectrometry to 0.1 Parts per mil - Barth, Johannes; Hall, James; Kalin, Robert, M. (Rapid Communications in Mass Spectrometry, 1999)

Routine (an)isotropic crystallite size analysis in the double-Voigt approximation done right? - Ectors, Dominique; Götz-Neunhoeffer, Friedlinde; Neubauer, Jürgen (Powder Diffraction, 2017)
In this study, the application of (an)isotropic size determination using a recently proposed model for the double-Voigt approach is demonstrated and validated against line profile simulations using the Whole Powder Pattern Modelling approach. The fitting of simulated line profiles demonstrates that the attained crystallite sizes and morphologies are in very reasonable agreement with the simulated values and thus demonstrate that even in routine application scenarios credible size and morphology information can be obtained using the double-Voigt approximation. The aim of this contribution is to provide a comprehensive introduction to the problem, address the practical application of the developed model, and discuss the accuracy of the double-Voigt approach and derived size parameters. Mathematical formulations for the visualization of modeled morphologies, supporting the application of the recently developed macros, are additionally provide
Keywords: anisotropic crystallite size; double-Voigt; Rietveld; size–strain; TOPAS

Saalfrank-type Fe2L3 host-guest complexes - Prediction of ion selectivity by quantum chemical calculations VII - Begel, Svetlana; Scheurer, Andreas; Puchta, Ralph (Journal of Coordination Chemistry, 2015)
Keywords: DFT; Metallocryptates; Metallocryptands; Selective ion complexation; Proton affinity

Salinity contrast in the US Midcontinent Sea during Pennsylvanian glacio-eustatic highstands: Evidence from conodont apatite δ 18O - Joachimski, Michael; Lambert, Lance; Joachimski, Michael (Palaeogeography, Palaeoclimatology, Palaeoecology, 2015)
Pennsylvanian phosphatic black shales are widely interpreted to have been deposited in waters deep enough to produce a pycnocline that would have developed as a consequence of increased riverine runoff into the largely landlocked North American Midcontinent Sea during the more humid interglacial intervals of the Late Palaeozoic Ice Age. We tested whether a gradient in surface water salinity existed in the North American Midcontinent Sea during times of maximum flooding by analyzing oxygen isotopes of conodont apatite from correlative Pennsylvanian black shales of the Midland, Midcontinent, Illinois and Appalachian basins. In the Midland and Midcontinent basins, average δ18O values for conodonts from the Oakley (middle Desmoinesian/upper Moscovian), Hushpuckney (lower Missourian, lower Kasimovian) and Heebner black shales (lower Virgilian/lower Gzehlian) are 18.8±0.3‰, 19.1±0.2‰, and 18.9±0.1‰, respectively. Oxygen isotope ratios of conodonts from the Nuyaka Creek black shale (uppermost Desmoinesian/upper Moscovian) of the Midcontinent Basin are 19.8±0.3‰, and thus significantly higher in comparison to the other black shales. These higher values support previous interpretations that the Lost Branch is a minor cyclothem, with south polar regions having been less deglaciated than during the interglacial phases of the more widespread major cyclothems. Conodonts from Oakley shale equivalents from Ohio and Pennsylvania are depleted in 18O on average by 2.5‰ in comparison to conodonts from the Midcontinent Basin. This pattern is also evident for conodonts from the Heebner and Hushpuckney shales, although conodonts from the Appalachian Basin show only a 0.4-0.7‰ depletion in 18O compared to conodonts from the Midcontinent Basin. The differences in δ18O are interpreted as reflecting primarily salinity, assuming that temperature was relatively constant across the palaeotropical Midcontinent Sea.Lower salinities in the Appalachian Basin and a significant salinity gradient in the Midcontinent Sea were reconstructed for the Desmoinesian Oakley shale, supporting the idea that freshwater discharge resulted in a salinity-stratified water column during times of "everwet" tropical palaeoclimate, at least in the eastern part of the epeiric sea. However, the salinity gradient is considerably reduced during the subsequent Missourian and Virgilian periodically dry interglacial periods (Hushpuckney and Heebner shales). This suggests that surface waters in the Midcontinent Sea were not significantly influenced by continental runoff and calls into question whether a halocline was necessary for the formation of phosphatic core shales.
Keywords: Conodont; Oxygen isotopes; Pennsylvanian; Salinity; US Midcontinent

Salinization Processes in the Venetian Coastal Plain (Italy): A General Overview - Di Sipio, Eloisa; Re, Viviana; Cavaleri, Nicoletta; Galgaro, Antonio (Procedia Earth and Planetary Science, 2013)
Keywords: groundwater; salinization; geochemical-isotopic analyses; geoelectrical soundings; Venice coastal plain

Salt kinematics and regional tectonics across a Permian gas field: a case study from East Frisia, NW Germany. - Vackiner, Anna Alexandra; Antrett, Philipp; Strozyk, Frank; Back, Stefan; Kukla, Peter; Stollhofen, Harald (International Journal of Earth Sciences, 2013)
This study presents a reconstruction of the tectonic history of an Upper Rotliegend tight gas field in Northern Germany. Tectonism of the greater study area was influenced by multiple phases of salt movement, which produced a variety of salt-related structural features such as salt walls, salt diapirs as well as salt glaciers (namakiers). A sequential 2D retro-deformation and stratal backstripping methodology was used to differentiate mechanisms inducing salt movement and to discuss their relation to regional tectonics. The quantitative geometric restoration included sedimentary balancing, decompaction, fault-related deformation, salt movement, thermal subsidence, and isostasy to unravel the post-depositional tectonic overprint of the Rotliegend reservoir rock. The results of this study indicate that reactive salt diapirism started during an Early Triassic interval of thin-skinned extensional tectonics, followed by an active diapirism stage with an overburden salt piercement in the Late Triassic, and finally a period of intensive salt surface extrusion and the formation of salt glaciers (namakiers) in Late Triassic and Jurassic times. Since the Early Cretaceous, salt in the study area has been rising by passive diapirism. © 2013 Springer-Verlag Berlin Heidelberg.
UnivIS-Import:2015-03-09:Pub.2013.nat.dgeo.IGM.LG.saltki
Keywords: Backstripping; Salt namakiers/glaciers; Salt tectonics; Sequential restoration; Tectonics and sedimentation

Salt water intrusion in the shallow aquifers of Venice lagoon mainland - Di Sipio, Eloisa; Re, Viviana; Cavaleri, Nicoletta (Rendiconti Online Societa Geologica Italiana, 2013)
Keywords: Geochemical-isotopic analyses; groundwater; salinization; Venice coastal Plain

Sample preparation effects on illite "crystallinity" measurement; gradation and particle orientation. - Krumm, Stefan; Buggisch, Werner (Journal of Metamorphic Geology, 1991)
Specimen thickness is the main experimental factor controlling the results of illite crystallinity (IC) or crystallite size measurements on sedimentation slides. Orientation effects control the measured peak intensity. A plateau with constant peak breadths is observed if thin slides of well ordered, platy illites are used. A similar plateau can be recognized for thick preparations of specimens from less ordered materials, but not from well ordered ones. Therefore, it is suggested that IC is determined on very thin sedimentation slides with a thickness of 0.25 mg/cm2 or less. -from Authors
UnivIS-Import:2015-03-05:Pub.1991.nat.dgeo.IGM.LG.sample

Sampling biases obscure the early diversification of the largest living vertebrate group - Henderson, Struan; Dunne, Emma; Giles, Sam (Proceedings of the Royal Society of London, Series B: Biological Sciences, 2022)
Extant ray-finned fishes (Actinopterygii) dominate marine and freshwater environments, yet spatio-temporal diversity dynamics following their origin in the Palaeozoic are poorly understood. Previous studies investigate face-value patterns of richness, with only qualitative assessment of biases acting on the Palaeozoic actinopterygian fossil record. Here, we investigate palaeogeographic trends, reconstruct local richness and apply richness estimation techniques to a recently assembled occurrence database for Palaeozoic ray-finned fishes. We identify substantial fossil record biases, such as geographical bias in sampling centred around Europe and North America. Similarly, estimates of diversity are skewed by extreme unevenness in the occurrence distributions, reflecting historical biases in sampling and taxonomic practices, to the extent that evenness has an overriding effect on diversity estimates. Other than a genuine rise in diversity in the Tournaisian following the end-Devonian mass extinction, diversity estimates for Palaeozoic actinopterygians appear to lack biological signal, are heavily biased and are highly dependent on sampling. Increased sampling of poorly represented regions and expanding sampling beyond the literature to include museum collection data will be critical in obtaining accurate estimates of Palaeozoic actinopterygian diversity. In conjunction, applying diversity estimation techniques to well-sampled regional subsets of the 'global' dataset may identify accurate local diversity trends.
CRIS-Team Scopus Importer:2022-10-28
Keywords: Actinopterygii; diversity; fossil record bias; Palaeozoic; sampling standardization

Sampling-standardized expansion and collapse of reef building in the Phanerozoic - Kießling, Wolfgang (Fossil Record, 2008)
UnivIS-Import:2015-03-09:Pub.2008.nat.dgeo.IGM.LP.sampli

Sandstone petrology and mudstone geochemistry of the Peruc-Korycany Formation (Bohemian Cretaceous Basin, Czech Republic) - Caracciolo, Luca; et al. (International Geology Review, 2011)
We have studied the petrography and the bulk-rock geochemistry of arenites and mudstones of the Cenomanian Peruc-Korycany Formation to characterize their provenance and sedimentary history, as well as the influence of weathering, hydraulic sorting, and recycling of the source rocks. The Peruc-Korycany Formation contains sedimentary facies reflecting both meandering- and braided-river systems and shallow-marine systems. Differences in the three depositional settings did not cause distinctly different modifications of the framework compositions of the arenites. The sand from the fluvial systems is very mature (Qm98F0Lt2). These fluvial arenites were subsequently modified by shallow-marine processes; reworking produced very slight decreases in the abundance of lithic fragments and polycrystalline quartz grains. The Cenomanian strata of the Bohemian Cretaceous Basin were derived dominantly from metasedimentary and crystalline rocks of the Palaeozoic Tepla-Barrandian and Cadomian Moldanubian units, respectively. Periods of low tectonic activity resulted in the deposition of arenites with quartzose framework compositions, indicating that climatic and/or transport/depositional-environmental controls overwhelmed factors such as source-rock compositions. Ultrastable dense minerals are useful indicators of sedimentary recycling within the Peruc-Korycanytarenites. Mudstone samples are characterized by abundant kaolinite, illite, chlorite, and quartz but by negligible amounts of goethite and gypsum. Concentrations normalized to the post-Archaean Australian shale (PAAS) show that the sediments are strongly depleted of Na, K, Ca, Sr, and Ba, probably because of the mobility of these elements during weathering. Chemical indices of alteration (CIA, CIW, and PIA) show that the degree of weathering of the source area was high. The data fall closer to the compositional fields of highly weathered minerals such as kaolinite, gibbsite, and chlorite on an A-CN-K diagram. The indices of compositional variability of the studied samples are much less than 1, suggesting that the samples are compositionally mature and were likely dominated by recycling. The elemental ratios critical of provenance (La/Sc, Th/Sc, Th/Co, Th/Cr, and Cr/Th) are similar to fine fractions derived from the weathering of mostly granitoids rather than mafic rocks.
Keywords: Bohemian Cretaceous Basin; mudstone; provenance; quartzarenite; sedimentary recycling

Sapropel burn-down and ichnological response to late Quaternary sapropel formation in two ∼ 400 ky records from the eastern Mediterranean Sea - Beier, Christoph; et al. (Palaeogeography, Palaeoclimatology, Palaeoecology, 2006)
Two approximately 400 ky long sedimentary records from the eastern Mediterranean Sea were used to study the factors determining why some sapropels are more or less completely erased while others are preserved. X-ray radiographs, bulk density, organic carbon content, Fe / Al and Mn / Al ratios were used to reconstruct initial thickness and burn-down ratios of sapropels S1 to S11. The results show that, at the low-sedimentation rate, open ocean settings studied, initial carbon content of the sapropel, as well as post-sapropel sedimentation rate and carbon flux have had only limited influence on the preservation of sapropels. In contrast, the regional position relative to the deep-water source controlling bottom water current intensity and bottom water oxygenation played a major role in the preservation of the sapropels. Furthermore, orbitally controlled variations in the intensity of subsequent summer insolation maxima also seem to play an important role in the preservation potential of sapropel layers. Subsequent strong insolation maxima resulting in thick sapropels tend to act as a lid, preventing further burn-down of the older sapropels below. The long and well-dated records also offer an opportunity to study the response of the benthic fauna to the drastic environmental changes related to the formation of sapropels. The sediment in the two cores is generally characterized by mottled burrows, with only scarce occurrences of distinct trace fossils such as Scolicia, Thalassinoides, Chondrites, and Trichichnus. The meager ichnofauna is attributed to the well-oxygenated and warm bottom waters in an oligotrophic environment typical for non-sapropel times. The sparse ichnofauna and the lack of tiered ichnocoenosis render existing models of bioturbational response to changes in bottom water oxygenation unsuitable for this kind of environments. However, observations on individual traces support earlier studies that suggest that the trace fossils Trichichnus and Chondrites are the result of chemosymbiotic activities that benefit from reducing conditions in the pore water, and that the producers of Scolicia have a preference for well-oxygenated conditions and sandy substrates. © 2006 Elsevier B.V. All rights reserved.
Keywords: Anoxia; Bioturbation; Eastern Mediterranean; Pleistocene; Sapropel

Sauropod dinosaur fossils from the Kem Kem and extended ‘Continental Intercalaire’ of North Africa: A review - Holwerda, Femke Marleen (Journal of African Earth Sciences, 2020)
The Cretaceous (likely Aptian-Cenomanian) Kem Kem beds of Morocco are famous for their fossil-richness, including theropods, and several sauropod body fossils, such as Rebbachisaurus garasbae, as well as isolated sauropod teeth. Deposits from this particular age, however, stretch across Algeria and Tunisia, with possibly contemporaneous fossiliferous beds also being known from Egypt and Niger. Although the sediments of North Africa have yielded more complete sauropod specimens in recent years dated to either Cenomanian or Campanian-Maastrichtian, in general, these sites are not well-known. A recent study on isolated sauropod teeth from Morocco and Algeria revealed that a diverse sauropod fauna existed, and, moreover, evidence has been found of sauropod migration from Africa to Europe in the Cretaceous. In order to provide a better overview of the sauropod presence in the Albian-Cenomanian of North Africa, an overview of all sauropod material known from this time is necessary. Therefore, several previous reports on sauropod fossils and teeth from the Kem Kem and the ‘Continental Intercalaire’ of North Africa are here reviewed and summarized.
CRIS-Team Scopus Importer:2020-01-24
Keywords: Africa; Cenomanian; Cretaceous; Gondwana; Neosauropoda; Sauropoda

Scale- and taxon-dependent patterns of plant diversity in steppes of Khakassia, South Siberia (Russia) - Polyakova, Mariya A.; Dembicz, Iwona; Becker, Thomas; Becker, Ute; Demina, Olga N.; Ermakov, Nikolai; Filibeck, Goffredo; Guarino, Riccardo; Janisova, Monika; Jaunatre, Renaud; Kozub, Lukasz; Steinbauer, Manuel; et al. (Biodiversity and Conservation, 2016)
Keywords: Biodiversity; Bryophyte; Environmental factor; Lichen; Species richness; Species–area relationship

Scaling analysis, correlation length and compaction estimates of natural and simulated stylolites - Köhn, Daniel; Köhler, S.; Toussaint, R.; Ghani, I.; Stollhofen, Harald (Journal of Structural Geology, 2022)
Stylolites are rough dissolution surfaces that show three different scaling regimes in space and time. On the small scale surface energy dominates and stylolites roughen very slowly with a growth exponent of about 0.5 and a roughness exponent of about 1.0. On the intermediate scale elastic energy dominates and the surfaces roughening is happening faster with a growth exponent of about 0.8 and a roughness exponent of about 0.5. The transitional length between these two scaling regimes is determined by the stress during stylolite growth and termed as cross-over length scale. On the large scale another transition is reached beyond which the stylolite amplitude remains constant, this length scale is termed the correlation length. The correlation length is determined by time of growth or by the amount of compaction that happened at the interface as well as by the stylolite's system size. This length scale grows as a function of time and the dynamic exponent, which is about 2 in the surface energy dominated regime and 0.625 in the elastic energy dominated regime. We present examples of these scaling regimes for numerical as well as natural stylolites and show how the exponents can be used to determine the stylolite compaction through the different regimes. The numerical stylolites show an increase of correlation length as a function of system size in self-affine time series. Large samples of natural tectonic stylolites from Jurassic limestones of the Franconian Alb (SE Germany) exhibit all three scaling regimes in a self-affine space series. The important length scales in the natural system are the grain size or noise at 30 μm, the cross-over length between the surface and elastic energy dominated regimes at 1.4 mm and the correlation length at 5.7 cm. The overall compaction on the tectonic stylolite is estimated to be in the range of 8 cm.
CRIS-Team Scopus Importer:2022-07-15
Keywords: Compaction; Correlation length; Roughness; Scaling; Stylolites

Scavenging of bacteria or bacterial products by magnetic particles functionalized with a broad-spectrum pathogen recognition receptor motif offers diagnostic and therapeutic applications - Friedrich, Bernhard; Lyer, Stefan; Janko, Christina; Unterweger, Harald; Brox, Regine; Cunningham, Sarah; Dutz, Silvio; Taccardi, Nicola; Bikker, Floris J.; Hurle, Katrin; Sebald, Heidi; Lenz, Malte; et al. (Acta Biomaterialia, 2022)
Sepsis is a dysregulated host response of severe bloodstream infections, and given its frequency of occurrence and high mortality rate, therapeutic improvements are imperative. A reliable biomimetic strategy for the targeting and separation of bacterial pathogens in bloodstream infections involves the use of the broad-spectrum binding motif of human GP-340, a pattern-recognition receptor of the scavenger receptor cysteine rich (SRCR) superfamily that is expressed on epithelial surfaces but not found in blood. Here we show that these peptides, when conjugated to superparamagnetic iron oxide nanoparticles (SPIONs), can separate various bacterial endotoxins and intact microbes (E. coli, S. aureus, P. aeruginosa and S. marcescens) with high efficiency, especially at low and thus clinically relevant concentrations. This is accompanied by a subsequent strong depletion in cytokine release (TNF, IL-6, IL-1β, Il-10 and IFN-γ), which could have a direct therapeutic impact since escalating immune responses complicates severe bloodstream infections and sepsis courses. SPIONs are coated with aminoalkylsilane and capture peptides are orthogonally ligated to this surface. The particles behave fully cyto- and hemocompatible and do not interfere with host structures. Thus, this approach additionally aims to dramatically reduce diagnostic times for patients with suspected bloodstream infections and accelerate targeted antibiotic therapy. Statement of significance: Sepsis is often associated with excessive release of cytokines. This aspect and slow diagnostic procedures are the major therapeutic obstacles. The use of magnetic particles conjugated with small peptides derived from the binding motif of a broad-spectrum mucosal pathogen recognition protein GP-340 provides a highly efficient scavenging platform. These peptides are not found in blood and therefore are not subject to inhibitory mechanisms like in other concepts (mannose binding lectine, aptamers, antibodies). In this work, data are shown on the broad bacterial binding spectrum, highly efficient toxin depletion, which directly reduces the release of cytokines. Host cells are not affected and antibiotics not adsorbed. The particle bound microbes can be recultured without restriction and thus be used directly for diagnostics.
CRIS-Team Scopus Importer:2022-03-11
Keywords: GP-340; Magnetic nanoparticles; Pathogen binding; Sepsis; SRCR domain

Schwankende Umweltbedingungen des süd-westdeutschen Oberjura dokumentiert in Kalk-Mergel-Wechselfolgen - Munnecke, Axel; Westphal, Hildegard (Jahresheft der Gesellschaft für Naturkunde in Württemberg, 2004)
The genesis of limestone-marl alternations such as those present in Upper Jurassic successions of SW Germany has a long history of controversial discussion. The origin of the rhythmic alternation of limestone beds and marl interlayers, the so-called couplets, has been addressed in numerous studies, and similarly the large-scale trends of limestone-dominated and marl-dominated intervals of the Upper Jurassic (Impressamergel, Wohlgebankte Kalke, and Lacunosamergel Formations) have been thoroughly studied. The intermediate scale, in contrast, the so-called bundles, has received markedly less attention. Here we focus on this intermediate scale. A general problem with deciphering of paleoenvironmental information recorded in calcareous successions is the usually pronounced diagenetic overprint that particularly affects mineralogically metastable primary constituents. Primary aragonite, for example, typically is transformed into diagenetically stable calcite. The mineralogical composition of the precursor sediment and the primary aragonite content in particular, however, reflect the environmental conditions under which the sediment was formed. Reconstructing the primary mineralogy therefore would yield valuable information on the palaeo-environment. For this task we employ a new model that allows for assessing the mineralogical composition of the precursor sediment, and apply this model to the example of SW Germany (Neuffen quarry). With this approach, variations of influx of shallow-water carbonate platform sediment into the depositional basin become visible, and are interpreted as fluctuations in biogenic carbonate productivitiy. Thus, new insight is gained into the fluctuating environmental conditions in the Jurassic Sea of SW Germany during the time of deposition of the Impressamergel, Wohlgebankte Kalke, and Lacunosamergel Formation
Keywords: Upper Jurassic; Genesis; Limestone-Marl alternations; SW Germany; Impressamergel; Wohlgebankte Kalke; Lacunosamergel Formations; Kalk-Mergel Wechselfolgen; Oberjura; Karbonate; Malm

Scientific collaborations between Latin America and Europe: An approach from science diplomacy towards international engagement - Echeverría-King, Luisa F.; Fossati, Aura; Raja, Nussaïbah Begum; Bonilla, Kleinsy; Urbani, Bernardo; Whiffen, Radenka Krsmanović; Vizinová, Tereza (Science and Public Policy, 2023)
International collaborations show asymmetries and imbalances that influence how countries take part in international relations. In this context, science diplomacy (SD) could offer possibilities towards building partnerships and meaningful engagement between Europe and Latin America. The purpose of this article is to analyse how scientific collaborations between Latin American and European researchers are carried out, observing trends, behaviours, and perceptions. Qualitative methodologies and the analysis of empirical data collected through a survey allow the extraction of relevant experiences from real cases of international joint projects. Findings indicate that addressing the asymmetries in the collaboration between partnering researchers from Europe and Latin America is essential, and SD approaches may facilitate such endeavour. SD may not represent a panacea; however, it seems to facilitate the internationalisation of research in terms of mobility, international scientific collaborations, and knowledge exchange with under-represented actors in traditional international scientific schemes, such as indigenous communities.
CRIS-Team Scopus Importer:2023-09-08
Keywords: Europe-Latin America; Global South; science diplomacy; scientific collaborations; transnational research

Scientific outcome of the IPBES-IPCC co-sponsored workshop on biodiversity and climate change - Poertner, Hans-Otto; J. Scholes, Robert; Agard, John; Archer, Emma; Arneth, Almut; Bai, Xuemei; Barnes, David Keith Alan; Burrows, Michael T.; Chan, Lena; Cheung, Wai Lung (William); Diamond, Sarah; Donatti, Camila; et al. (2021)
The Scientific Outcome was produced by participants in the first-ever IPCC-IPBES co-sponsored workshop which took place in December 2020. This workshop is placed in the context of recent international agreements including the Paris Agreement, the Strategic Plan for Biodiversity 2011-2020 and ongoing preparation for the post-2020 global biodiversity framework, the Sendai Framework for Disaster Risk Reduction and the 2030 Agenda for Sustainable Development that converge on solving the dual crises of climate change and biodiversity loss as essential to support human well-being. The Scientific Outcome further develops and substantiates the conclusions of the Synopsis, summarizes the emerging state of knowledge involving climate change and biodiversity with the objective to inform decision making and highlight options for action, and to identify knowledge gaps to be filled by scientific research. The Scientific Outcome includes seven sections, the references outlining the evidence reviewed within those sections and the report glossar

Scientometric trends in Burmese amber research - Dunne, Emma; Raja, Nussaïbah Begum (Paleontological Association Annual Meeting, 2020)
Discoveries of fossil inclusions in Burmese (Myanmar) amber have attracted considerable attention due to their exquisite preservation, which offers an unparalleled window into Cretaceous forest ecosystems. However, research on Burmese amber has also attracted controversy due to its alleged role in funding internal conflict, resulting in a devastating humanitarian crisis. The palaeontological community is not yet unified on how to ethically adjust research practices in response to this situation. Using bibliometric methods and networks analyses, we investigated the scientometric trends in research publications on fossils in Burmese amber, and quantitatively examined the collaborative networks of their authors. We find that in the last 30 years, research activity on Burmese amber has generally increased, with a noticeable escalation within the last five years, coincident with the military takeover of the amber mines. The majority of publications are authored by researchers based in countries of the Global North and lack Burmese co-authors, indicating weak or absent collaborations with local researchers and communities. This practice of ‘parachute science’ is harmful generally, but in a conflict region it is acutely problematic because it erodes confidence about whether fossil specimens are – or even can be – ethically collected and trade

Scleractinian cold-water corals in the Gulf of Cádiz - First clues about their spatial and temporal distribution - Wienberg, Claudia; Hebbeln, Dierk; Hiske, Fink; Mienis, Furu; Dorschel, Boris; Vertino, Agostina; López Correa, Matthias; Freiwald, André (Deep-Sea Research Part I-Oceanographic Research Papers, 2009)
This paper presents the first compilation of information on the spatial distribution of scleractinian cold-water corals in the Gulf of Cádiz based on literature research and own observations (video footage, sediment samples). Scleractinian cold-water corals are widely distributed along the Spanish and Moroccan margins in the Gulf of Cádiz, where they are mainly associated with mud volcanoes, diapiric ridges, steep fault escarpments, and coral mounds. Dendrophyllia cornigera, Dendrophyllia alternata, Eguchipsammia cornucopia, Madrepora oculata and Lophelia pertusa are the most abundant reef-forming species. Today, they are almost solely present as isolated patches of fossil coral and coral rubble. The absence of living scleractinian corals is likely related to a reduced food supply caused by low productivity and diminished tidal effects. In contrast, during the past 48 kyr scleractinian corals were abundant in the Gulf of Cádiz, although their occurrence demonstrates no relationship with main climatic or oceanographic changes. Nevertheless, there exists a conspicuous relationship when the main species are considered separately. Dendrophylliids are associated with periods of relatively stable and warm conditions. The occurrence of L. pertusa mainly clusters within the last glacial when bottom current strength in the Gulf of Cádiz was enhanced and long-term stable conditions existed in terms of temperature. Madrepora oculata shows a higher tolerance to abrupt environmental changes. © 2009 Elsevier Ltd. All rights reserved.
UnivIS-Import:2015-03-09:Pub.2009.nat.dgeo.IGM.LP.sclera
Keywords: Coral mounds; Dating; Glacial-interglacial cycle; Gulf of Cádiz; Mud volcanoes; Scleractinian cold-water corals; Spatial distribution

Sclerochronological insights into the environmental response of Corbula gibba from the Adriatic Sea - Strafella, Pierluigi; al-Fudhaili, Najat; de Winter, N.; López Correa, Matthias; Teichert, Sebastian; Scarcella, G; Nohl, Theresa (EGU General Assembly 2022, 2022)
Bivalve shells are accretionary biogenic carbonates that yield a record of the organisms’ life history, also with respect to the physiological response to the ambient environmental conditions. This is reflected by variations in the shells’ growth bands, their chemical composition, and morphological features, making them useful tools in paleobiology and paleoenvironmental reconstructions. Corbula gibba is an abundant bivalve species in the Adriatic Sea that is commonly used to resolve questions in age determinations, paleoenvironmental reconstructions and sequence stratigraphic studies [1,2]. Nevertheless, a detailed analysis of its response in growth bands and chemical signatures to environmental variations is currently missing. This study evaluates growth increments and chemical variations in Corbula gibba shells. The shells have been collected alive from the Western Adriatic Sea between Senigallia and Ancona to shed light on the reliability of the Corbula gibba as an archive for (paleo)environmental information. Mutvei's solution has been used [3] to stain the alternating dark and light bundles in the shell, enhancing the visualization of growth increments. High-resolution elemental profiles have been acquired across the outer shells layer using the non-destructive Micro X-ray fluorescence (µ-XRF) technique [4]. The results are compared to available climatic information for Ancona and indicate that Corbula gibba shells record detailed temporal changes in the environment such as tidal fluctuations caused by lunar cycl

Scleromochlus and the early evolution of Pterosauromorpha - Foffa, Davide; Dunne, Emma; Nesbitt, Sterling J.; Butler, Richard J.; Fraser, Nicholas C.; Brusatte, Stephen L.; Farnsworth, Alexander; Lunt, Daniel J.; Valdes, Paul J.; Walsh, Stig; Barrett, Paul M. (Nature, 2022)
Pterosaurs, the first vertebrates to evolve powered flight, were key components of Mesozoic terrestrial ecosystems from their sudden appearance in the Late Triassic until their demise at the end of the Cretaceous1–6. However, the origin and early evolution of pterosaurs are poorly understood owing to a substantial stratigraphic and morphological gap between these reptiles and their closest relatives6, Lagerpetidae7. Scleromochlus taylori, a tiny reptile from the early Late Triassic of Scotland discovered over a century ago, was hypothesized to be a key taxon closely related to pterosaurs8, but its poor preservation has limited previous studies and resulted in controversy over its phylogenetic position, with some even doubting its identification as an archosaur9. Here we use microcomputed tomographic scans to provide the first accurate whole-skeletal reconstruction and a revised diagnosis of Scleromochlus, revealing new anatomical details that conclusively identify it as a close pterosaur relative1 within Pterosauromorpha (the lagerpetid + pterosaur clade). Scleromochlus is anatomically more similar to lagerpetids than to pterosaurs and retains numerous features that were probably present in very early diverging members of Avemetatarsalia (bird-line archosaurs). These results support the hypothesis that the first flying reptiles evolved from tiny, probably facultatively bipedal, cursorial ancestors1.
CRIS-Team Scopus Importer:2022-10-21

Screening of Micro-organic Compounds in Groundwater from Areas with Chronic Kidney Disease of Unclear Aetiology (CKDu) in the Dry Zone of Sri Lanka - Chandrajith, Rohana; Zwiener, Christian; Daniel, Christoph; Amann, Kerstin Ute; Nanayakkara, Nishantha; Barth, Johannes (Exposure and Health, 2024)
Chronic kidney disease of unknown aetiology (CKDu) occurs in tropical countries, including Latin America, Mexico, Sri Lanka, and India. The disease occurs mainly in men who work in the agricultural sector. Although many studies have been conducted in CKDu areas, hardly any have examined emerging organic contaminants (EOCs) in drinking water. Therefore, this study examined EOCs, including pesticide residues, pharmaceuticals, and personal care products, in 29 shallow groundwater samples collected from wells commonly used by CKDu patients. These patients were identified through renal biopsy examinations from the Girandurukotte and Wilgamuwa regions in the dry zone of Sri Lanka. Of 110 EOCs measured, 40 were found in at least one or more samples. Among the detected EOCs, all groundwater samples examined showed the highest concentrations of caffeine (max: 950 ng/L) and DEET (max: 647 ng/L). In particular, the insect repellents commonly used in the region, such as coils, mats, vaporizers, spray and creams, would be the source of DEET in the environment. Pharmaceuticals and personal care products were the most common EOCs in all groundwater samples, with concentrations ranging from 129 (propylparaben) to 1.26 ng/L (carbamazepine) and 1.25 ng/L (hydrochlorothiazide), respectively, followed by herbicides and fungicides. Sources of such compounds would be insect repellents, antifungal and bactericidal preservatives, and agricultural pesticides. Notably, none of the identified EOCs reached critical values and were often below the values in European drinking water standards. Although primary evidence of EOCs as a cause of the disease does not emerge from the results of this study, regular monitoring of EOCs in groundwater, particularly in the dry zone of Sri Lanka, is essential as the presence of these compounds highlights their vulnerability in shallow groundwater wells.
CRIS-Team Scopus Importer:2024-07-26
Keywords: Emerging contaminants; Personal-care product; Pesticides; Pharmaceuticals; Solid-phase extraction

Seasonal climate variations during Marine Isotope Stages 3 and 2 inferred from high-resolution oxygen isotope ratios in horse tooth enamel from Lower Austria - Reiss, Lilian; Mayr, Christoph; Pasda, Kerstin; Joachimski, Michael; Einwögerer, Thomas; Händel, Marc; Maier, Andreas (Journal of Quaternary Science, 2024)
We present sequential oxygen isotope records (δ18Ophosphate vs. VSMOW) of horse tooth enamel phosphate of six individuals from two adjacent Palaeolithic sites in Lower Austria. Three molars from the site Krems-Wachtberg date to 33–31k cal a bp, and three molars from Kammern-Grubgraben to 24–20k cal a bp. All teeth show seasonal isotope variations, which are used to reconstruct the annual oxygen isotope composition of drinking water (δ18Odw) and palaeotemperatures. Measured δ18Ophosphate values ranged from 8.6 to 13.0‰ and from 10.8 to 13.9‰ at Krems-Wachtberg and Kammern-Grubgraben, respectively. An inverse modelling approach was used to reconstruct summer and winter temperatures after a correction for glacial oceanic source water δ18O. Reconstructed annual δ18Odw was −16.4 ± 1.5‰ at Krems-Wachtberg and −15.3 ± 1.4‰ at Kammern-Grubgraben, resulting in annual temperatures of −5.7 ± 3.1 and −3.5 ± 2.9°C, respectively. Summer and winter temperatures reconstructed from individual teeth exhibit high seasonal variations with moderate summer temperatures and extremely low winter temperatures typical for a polar tundra climate. Isotopic differences between individuals are attributed to interannual climate variability or to different drinking water sources. Our reconstructed temperatures are, overall, consistent with previously reported values from European horse teeth, when taking regional differences into account. <br
Keywords: δ18O; last glacial maximum; palaeotemperatures; phosphate; seasonality; sequential sampling; Upper Palaeolithic

Seasonal climatic fluctuations in the Late Triassic tropics - high-resolution oxygen isotope records from aragonitic bivalve shells (Cassian Formation, Northern Italy) - Nuetzel, A.; Joachimski, Michael; López Correa, Matthias (Palaeogeography, Palaeoclimatology, Palaeoecology, 2010)
Three megalodontoid bivalves from the Upper Triassic Cassian Formation (N Italy, Dolomites) were sampled for δ13C and δ18O sclerochronology (n = 270). With more than 1000 described invertebrate species, the Cassian Formation has one of the best records of an Early Mesozoic tropical fauna. In addition, the Cassian Formation is one of the very few Triassic occurrences with original aragonite preservation, with all studied shells consisting of pristine aragonite. The presence of aragonite and crossed lamellar as well as fibrous prismatic shell microstructures shown for the first time for Triassic megalodontoids suggests absence or minimal impact of diagenetic alteration. The δ13C values range from 3.6 to 5.8‰ and show a distinct cyclicity in two studied shells whereas a third shell shows no obvious cyclicity. In one bivalve specimen, the cycles are somewhat offset from δ18O cycles and in the other specimen δ18O and δ13C curves are inversely correlated. Seasonal variation in freshwater runoff including nutrient input and subsequent changes in plankton productivity during dry and wet seasons may explain δ13C cyclicity. δ18O values show a pronounced cyclicity within each of the studied shells varying from - 3.6 to - 1.4‰. The variations in δ18O suggest a pronounced seasonality in Late Triassic tropical shallow waters of the western Tethys, with inferred seasonal temperature changes ranging from 24 to 32 °C. Influx of fresh water during the rainy seasons (mega-monsoon) or upwelling might also explain part of the variation in δ18O. The presented data suggest that the diverse Cassian fauna lived under conditions characterized by warm sea-surface waters with a pronounced seasonality. Similar conditions are reported for some modern tropical settings. © 2009 Elsevier B.V. All rights reserved.
UnivIS-Import:2015-03-09:Pub.2010.nat.dgeo.IGM.LG.season
Keywords: Bivalves; Climate; Late Triassic; Sclerochronology; Seasonality

Sectioning of radiolarians under continuous observation - Kießling, Wolfgang; et al. (Fossil Record, 2002)
UnivIS-Import:2015-03-09:Pub.2002.nat.dgeo.IGM.LP.sectio

Secular variations in the Phanerozoic reef ecosystem - Kießling, Wolfgang (Phanerozoic Reef Patterns, 2002)
UnivIS-Import:2015-04-20:Pub.2002.nat.dgeo.IGM.LP.secula

Sedimentary and thermal evolution of the Eocene-Oligocene mudrocks from the southwestern Thrace Basin (NE Greece) - Caracciolo, Luca; et al. (Basin Research, 2016)

Sedimentary dykes and genetically related features in the Upper Jurassic Jhuran Formation of the Kachchh Rift Basin, Western India - Fursich, Franz T.; Alberti, Matthias; Pandey, Dhirendra K. (Journal of the Palaeontological Society of India, 2022)
In the Kimmeridgian-Tithonian Jhuran Formation of the Kachchh Rift Basin features such as sedimentary dykes, convolute bedding, and intraformational pillows are documented at several levels and localities. They are interpreted as having been produced by seismic events. Together with features, such as local intraformational unconformities and dying growth faults recorded earlier on in the literature they indicate that the basin was in a syn-rift stage until the end of the Jurassic. Interestingly, signs of seismic activity in the basin are far more conspicuous during the Oxfordian - Tithonian time interval than during the Middle Jurassic.
CRIS-Team WoS Importer:2023-02-10

Sedimentary facies analysis of the Mesozoic clastic rocks in southern Peru (Tacna, 18°S): Towards a paleoenvironmental Re-definition and stratigraphic Re-organization - Alvan, Aldo; Jacay, Javier; Caracciolo, Luca; Sanchez, Elvis; Trinidad, Ines (Journal of South American Earth Sciences, 2018)
The Mesozoic rocks of southern Peru comprise a Middle Jurassic to Early Cretaceous sedimentary sequence deposited during a time interval of approximately 34 Myr. These rocks constitute the Yura Group (Callovian to Tithonian) and the Hualhuani Formation (Berriasian). Basing on robust interpretation of facies and petrographic analysis, we reconstruct the depositional settings of such units and provide a refined stratigraphic framework. Accordingly, nine types of sedimentary facies and six architectural elements are defined. They preserve the record of a progradational fluvial system, in which two types of fluvial systems regulated the dispersion of sediments: (i) a high-to moderate-sinuosity meandering system (Yura Group), and a later (ii) incipient braided system (Hualhuani Formation). The Yura Group (Callovian-Tithonian) represents the onset of floodplain deposits and lateral accretion of point-bar deposits sited on a semi-flat topography. Nonetheless, the progradational sequence was affected by at least two rapid marine ingressions occurred during Middle Callovian and Tithonian times. Such marine ingressions reveal the proximity of a shallow marine setting. In response to increase in topographic gradient, the Hualhuani Formation (Berriasian) deposited as extensive multistory sandy channels. The mineralogy of the Mesozoic sediments suggests sediment supplies and recycling from a craton interior (i.e. Amazon Craton and/or plutonic sources) located eastward of the study are
Keywords: Yura groupMesozoic Arequipa basinCentral AndesFacies analysis

Sediment deformation and production beneath soft-bedded Palaeozoic ice sheets - Le Heron, D. P.; Heninger, M.; Baal, C.; Bestmann, Michel (Sedimentary Geology, 2020)
The expansion of ice sheets over soft, sandy substrates was widespread in the Early Palaeozoic, during the Late Ordovician glaciation of North Africa and Arabia. Similarly, large parts of southern Africa were glaciated by soft bedded ice sheets in the Late Palaeozoic Ice Age. An unanswered question is the extent to which subglacial deformation involved the passive recycling of unconsolidated materials, or the active production of new sediment through erosion and shearing. Here, we compile thin section data dovetailed with scanning electron microscope imagery from sandy subglacial substrates from South Africa, Algeria and Libya. Six samples were collected from soft-sediment striated pavements, i.e., surfaces that were sheared and deformed subglacially in an unconsolidated state. The samples show a considerable variation in deformation style but a unifying trait is the occurrence of striated and facetted quartz sand grains. These textural features testify to grain-grain attrition, and the potential production of sediment in the subglacial environment.
CRIS-Team Scopus Importer:2020-09-25
Keywords: Africa; Glacial; Ice Sheet; Palaeozoic; Subglacial; Tillite

Sediment-derived origin of the putative Munnar carbonatite, South India - Hegner, Ernst; Rajesh, Selvaraj; Willbold, Matthias; Müller, Dirk; Joachimski, Michael; Hofmann, Mandy; Linnemann, Ulf; Zieger, Johannes; Pradeepkumar, Anakkathil Purushothaman (Journal of Asian Earth Sciences, 2020)
Metacarbonate assemblages in high-grade metamorphic terranes often pose challenges when trying to distinguish between mantle-derived carbonatite and sedimentary carbonate protoliths. We present a study of granulite-facies metacarbonate samples of the putative Munnar carbonatite described as decimeter-thick dikes and veins, and layers of a meter-thick metacarbonate and calc-silicate assemblage, respectively. Thin sections of the metacarbonate dike samples show absence of pyrochlore and ubiquitous scapolite, titanite, wollastonite, and detrital zircons are compatible with impure limestone protoliths. Nd and Sr isotope compositions indicate protoliths with Paleoproterozoic crustal residence times which contrast the mantle sources of Indian and global carbonatites. Trace-element patterns display the characteristics of upper crust, and Ce- and Y-anomalies in a number of samples suggest protolith formation under marine conditions. Carbon and oxygen isotope compositions of the metacarbonate samples interlayered with calc-silicate rocks are similar to those in marine limestone. The metacarbonate dikes, however, show mantle-like compositions which are interpreted as reflecting equilibration with mantle-derived CO2 during granulite-facies metamorphism. The dikes yielded a U-Pb zircon crystallization age of 1020 ± 70 Ma and a cross-cutting quartz syenite, thought to be cogenetic, a magmatic age of 620 ± 35 Ma; the hosting gneiss provided a magmatic age of 2452 ± 14 Ma. We conclude that the layered metacarbonate and calc-silicate rocks represent a former marine limestone and marl sequence and the metacarbonate dikes and veins small-volume melts of crust-derived carbonate-rich sediment.
CRIS-Team Scopus Importer:2020-08-07
Keywords: Carbonatite; Geochemistry; Marble; Metacarbonate; Nd-Sr-C-O isotopes; Zircon geochronology

Sediment dynamics from the drainage area into Lake Mladotice (western Czech Republic) in relation to flood events and under the influence of pre- to post-communist landscape changes - Schulte, Achim; Jansky, Bohumir; Daut, Gerhard; Irmler, Ralf; van Geldern, Robert (Reducing the Vulnerability of Societies to Water Related Risks at the Basin Scale, 2007)
In May 1872 a landslide occurred in the western Czech Republic, blocking the Mladoticky stream valley and creating Lake Mladotice. The 1952 and 1975 air photos document that collective farming had a great impact when balks and field terraces were removed and fields were made much larger. Because of this change in land use we expected higher soil erosion and a related increase in the sedimentation rate. Our analysis of the sedimentary record aims to identify the factors controlling sediment input, i.e. soil erosion, which is dependent on rainfall–runoff processes and land use in the drainage basin. The sediment stratigraphy, physics, chemistry, micropalaeontology, isotope content and thin sections yield a detailed temporal resolution of the sedimentation chronology. Surprisingly, the sedimentation rates only indicate a small increase from 2.2 cm/year (1954–1963) to 2.7 cm/year (1963–1978) to 2.5 (1978–1986) and 2.4 cm/year (1986–2003).

Sediment generation and provenance: Processes and pathways - Caracciolo, Luca; et al. (Sedimentary Geology, 2016)

Sediment Generation and Sediment Routing Systems - Caracciolo, Luca; Chew, David; Andò, Sergio (Earth-Science Reviews, 2020)

Sediment generation and sediment routing systems - Caracciolo, Luca; Chew, David; Andò, Sergio (Elsevier, 2021)

Sediment generation and sediment routing systems from a quantitative provenance analysis perspective: Review, application and future development - Caracciolo, Luca (Earth-Science Reviews, 2020)
Sediment Routing Systems (SRS) and Sediment Generation (SG) are two branches of sedimentary geology which are complementary, although their full integration remains incomplete. SRS connect all the steps of the journey of sediments from their formation to final deposition in relation to the denudation of sediment sources, the transfer of erosional products and their final deposition. SG is a branch of provenance analysis focussing on the quantification of the processes governing the production (Qs) and dispersal of sediments from known parent rocks, and the prediction of the amount and compositional-textural properties of sediments produced under given tectonic and climatic settings. The integration of the two disciplines is fundamental to tackle some of the open problems in sedimentary geology, including (i) the dynamics regulating the generation and release of sediments from upstream catchments to the floodplains, (ii) particle trajectories, (iii) residence time and mineralogical modifications in temporary storage environments (iv) sediment selective extraction and (v) the shredding of environmental signal propagation in both (vi) actualistic and deep-time SRS. I introduce all the elements which are necessary to both disciplines, with particular emphasis on quantitative provenance analysis (QPA). The SG approach is required to quantify lithological controls on Qs, and include it into the stream power law. QPA and the ‘Provenance Toolbox’ provide the compositional framework which is necessary for the characterisation of the erosional products. Both the advantages and limitations of each analytical tool are explored, and best practices for successful analytical workflows are discussed in light of a full integration into SRS research.<br

Sediment generation in humid Mediterranean setting: Grain-size and source-rock control on sediment geochemistry and mineralogy (Sila Massif, Calabria) - Caracciolo, Luca; et al. (Sedimentary Geology, 2016)
Grain-size control on sediment composition is investigated in modern proximal sediment from the Sila Massif, where basic to felsic intrusive rocks are exposed in a Mediterranean humid-temperate upland climate. Samples were taken from small creeks and weathering profiles from three areas reflecting different bed rock compositions. Samples were separated into eleven grain size fractions from very coarse sand to clay and analyzed by (i) X-ray fluorescence for chemical composition and (ii) X-ray diffraction and Mineral Liberation Analysis for mineralogical composition. The chemical composition vs. grain size relations were modeled by compositional linear regression. Mineralogical composition of selected samples is used to substantiate the interpretations based on geochemistry. Results: reveal a high degree of chemical weathering with chemical index of alteration (CIA) up to 92. High CIA values are restricted to the fine-grained fractions, while sand-sized sediment average at low to moderate CIA values (similar to 60). Although strongly weathered, the three sample suites reflecting basic to felsic plutonic bed rock can be effectively discriminated across all grain-size classes using trace elements such as V, Rb, and Sr. Linear trend modeling and mineralogical data reflect similar patterns for all sample suites implying similar processes independent of source rock composition. This includes overall decrease of quartz and K-feldspar over the full grain-size range from very coarse sand to clay, which is contrasted by overall increase of sheet silicates from coarse to fine. Among the latter, increase of clay minerals strongly outpaces the increase of micas in silt to clay fractions. A more complex behavior is shown by plagioclase, which is most abundant in intermediate grain-size fractions for all sample suites. This is likely caused by initial hydrolysis along cleavage and twinning planes and subsequent breakage of plagioclase crystals into smaller fragments. Towards finer grain size, intense hydrolysis has destroyed most feldspars. (C) 2015 Elsevier B.V. All rights reserved.
Keywords: Geochemistry; Mineralogy; Chemical weathering; Comminution; Provenance; Compositional linear regression

Sedimentología para la transición energética: proyecto SOSGAS, un ejemplo de flujo de trabajo para la evaluación de calidad de reservorios - Viseras, César; Cabello, Patricia; Yeste, Luis M.; Alcalde, Juan; López-Blanco, Miguel; Cuevas, José L.; Gil-Ortiz, Marc; Caracciolo, Luca; De Mesquita Veloso, Fernanda; Heinemann, Niklas; Falivene, Oriol; Varela, Augusto N.; et al. (Geogaceta, 2024)
The research workflow developed in the SOSGAS project is presented, aimed at the Quality Assessment as a reservoir of CO2 and green H2 of heterogeneous Mesozoic and Cenozoic fluvial and deltaic formations of the Iberian Meseta and the Ebro and Graus-Tremp Basins. Through the integrated study of outcrop and subsurface data (derived from boreholes drilled behind the outcrops), conceptual models are developed for each examined case, describing variations in sedimentary heterogeneities. These models contribute to the static modelling of different geobodies and their petrophysical properties. Finally, dynamic modelling, based on gas injection simulation experiments (CO2 and H2) into static models, enables the analysis of the sustainability of geo-storage projects for these key fluids in the energy transition.
CRIS-Team Scopus Importer:2025-02-04
Keywords: CO; energy transition; geo-storage; green H; sedimentology

Sedimentology, geochemistry and tectonic setting of the Neoproterozoic Malmesbury Group (Tygerberg Terrane) and its relation to neighbouring terranes, Saldania Fold Belt, South Africa - Buggisch, Werner; Kleinschmidt, Georg; Krumm, Stefan (Neues Jahrbuch für Geologie und Paläontologie-Abhandlungen, 2010)
The metamorphic grade and the facies of the Neoproterozoic Malmesbury Group of the Saldania Fold Belt changes abruptly across major fault zones. Therefore three different tectonostratigraphic domains were assumed: The Tygerberg Terrane, the Swartland Terrane and the Boland Terrane. Additionally, a small block with volcanic greenstones and carbonates (Bridgetown Formation) is squeezed between the Swartland and Boland terranes. Based on the investigations of sedimentray and tectonic structures, geochemistry and data from literature, a geodynamic model of the Saldania Belt is proposed including: (1) An ocean between South America with the attached Tygerberg Terrane and the Swartland Terrane, (2) rifting between the Swartland Terrane and South Africa with the attached Boland Terrane, subduction ot the ocean (1) towards west, followed by subduction of the ocean (2) underneath the Swartland Terrane. © 2010 Schweizerbart'sche Verlagsbuchhandlung, Stuttgart, Germany.
Keywords: Malmesbury; Neoproterozoic; Saldania fold belt; Sedimentology structure; South africa

Sedimentology of Middle Ordovician carbonates in the Argentine Precordillera: Evidence of regional relative sea-level changes - Keller, Martin; Eberlein, Stefan; Lehnert, Oliver (Geologische Rundschau, 1993)
Keywords: Early Ordovician; Argentine Precordillera; Sea-level changes

Segmentation and volcano-tectonic characteristics along the SW African continental margin, South Atlantic, as derived from multichannel seismic and potential field data - Koopmann, Hannes; Franke, Dieter; Schreckenberger, Bernd; Schulz, Henning; Hartwig, Alexander; Stollhofen, Harald; Di Primio, Rolando (Marine and Petroleum Geology, 2013)
Regional seismic reflection and potential field data document the South Atlantic’s break-up history, between 39S and 19S, from the Early Cretaceous onwards. Previous maps of distribution of volcanics along the margin showed volcanics along the whole African margin based on extrapolation of data. Based on previously unpublished marine geophysical data, we found the southernmost 460 km long margin segment to be lacking huge volumes of break-up related volcanic effusives. Northwards, break-up was accompanied by the emplacement of huge volumes of volcanic material, prominently featured in seismic sections as huge wedge-shaped seaward dipping reflectors (SDRs). Detailed mapping of offsets (left- and right-stepping) and variations in structural character of the volcanics reveal the segmentation along and the break-up history of the margin. Several superimposed SDR sequences, suggesting episodicity of volcanic emplacement (divided by periods of erosion and sedimentation), are distinct along southerly lines, losing prominence northwards. A main outcome of our study is that this passive margin is not continuously of the volcanic type and that the change from a non-volcanic to a volcanic margin occurs abruptly. We define four distinct First-order Segments along the 2400 km section of the southwestern African margin covered by our seismic data. From south to north these First-order Segments are: Magma-poor Segment I; Segment II with enormous SDRs volumes; decreasing SDRs volumes in Segment III; Segment IV again with enormous volcanic output, likely influenced by Walvis Ridge volcanism. Most important is that there is no systematic increase in the volumes of the effusives towards the Tristan da Cunha hot-spot. Rather there is an alternating pattern in the SDRs’ volumes and widths. The boundary between the volcanic and magma-poor margin segments in the southernmost study area is sharp (10s of km), which we propose is reflected in magnetic anomaly data as well. We suggest that this variability along the margin is mainly due to a change in stretching/rifting character from oblique during the early stages of breakup to conventional seafloor spreading from Chron M4 (c. 130 Ma) onwards.
UnivIS-Import:2015-03-09:Pub.2013.nat.dgeo.IGM.LG.segmen

Seismic Anisotropy in Subduction Zones: Evaluating the Role of Chloritoid - Lee, Jungjin; Mookherjee, Mainak; Kim, Taehwan; Jung, Haemyeong; Klemd, Reiner (Frontiers in Earth Science, 2021)
Subduction zones are often characterized by the presence of strong trench-parallel seismic anisotropy and large delay times. Hydrous minerals, owing to their large elastic anisotropy and strong lattice preferred orientations (LPOs), are often invoked to explain these observations. However, the elasticity and the LPO of chloritoid, which is one of such hydrous phases relevant in subduction zone settings, are poorly understood. In this study, we measured the LPO of polycrystalline chloritoid in natural rock samples, obtained the LPO-induced seismic anisotropy, and evaluated the thermodynamic stability field of chloritoid in subduction zones. The LPO of chloritoid aggregates displayed a strong alignment of the [001] axes subnormal to the rock foliation, with a girdle distribution of the [100] axes and the (010) poles subparallel to the foliation. New elasticity data of single-crystal chloritoid showed a strong elastic anisotropy of chloritoid with 47% for S-waves (VS) and 22% for P-waves (VP), respectively. The combination of the LPO and the elastic anisotropy of the chloritoid aggregates produced a strong S-wave anisotropy with a maximum AVS of 18% and a P-wave anisotropy with an AVP of 10%. The role of chloritoid LPO in seismic anisotropy was evaluated in natural rock samples and a hypothetical blueschist. Our results indicate that the strong LPO of chloritoid along the subduction interface and in subducting slabs can influence the trench-parallel seismic anisotropy in subduction zones with “cold” geotherms.
CRIS-Team Scopus Importer:2021-04-16
Keywords: chloritoid; EBSD; lattice preferred orientation; seismic anisotropy; subduction zone

Seismic imaging of the Olduvai Basin, Tanzania - Lu, Kai; Hanafy, Sherif; Stanistreet, Ian; Njau, Jackson; Schick, Kathy; Toth, Nicholas; Stollhofen, Harald; Schuster, Gerard (Palaeogeography, Palaeoclimatology, Palaeoecology, 2019)
A 5.6-km-long line of refraction and reflection seismic data spanning the Pliocene-Pleistocene fill of the Olduvai Basin, Tanzania is presented. The line is oriented along a northwest-southeast profile through the position of Olduvai Gorge Coring Project (OGCP) Borehole 2A. Our aims are to (1) delineate the geometry of the basin floor by tracing bedrock topography of the metaquartzitic and gneissic basement, (2) map synsedimentary normal faults and trace individual strata at depth, and (3) provide context for the sequence observed in OGCP cores. Results with refraction tomography and poststack migration show that the maximum basin depth is around 405 m (±25 m) in the deepest portion, which quadruples the thickness of the basin-fill previously known from outcrops. Variations in seismic velocities show the positions of lower density lake claystones and higher density well-cemented sedimentary sequences. The Bed I Basalt lava is a prominent marker in the refraction seismic results. Bottom-most sediments are dated to >2.2 Ma near where Borehole 2A bottoms out at the depth of 245 m. However, the seismic line shows that the basin-fill reaches a maximum stratigraphic thickness of around 380 m deep at Borehole 2A, in the western basin where the subsidence was greatest. This further suggests that potential hominin palaeoenvironments were available and preserved within the basin-fill possibly as far back as around 4 Ma, applying a temporal extrapolation using the average sediment accretion rate.
CRIS-Team Scopus Importer:2019-07-09

Selection of backfill grout for shallow geothermal systems: Materials investigation and thermo-physical analysis - Mascarin, Ludovico; Garbin, Enrico; Di Sipio, Eloisa; Dalla Santa, Giorgia; Bertermann, David; Artioli, Gilberto; Bernardi, Adriana; Galgaro, Antonio (Construction and Building Materials, 2022)
A main aspect of the geothermal well design is the selection of grouts backfilling the space between a geothermal probe and the surrounding ground, taking into consideration the mineralogical, thermo–physical, mechanical and flowability properties. The EU GEO4CIVHIC project aimed at developing efficient and cost-effective geothermal systems suitable for the air-conditioning refurbishment of urban buildings. A selection of different grouts was performed to ensure the whole efficiency of shallow geothermal heat exchangers designed within the project. Experimental tests were executed to identify flowable grouts with the best possible combination of different material properties, while also fulfilling a competitive cost target set forth in the preliminary project cost analysis. Grout acceptance criteria were defined: a working time of at least 4 h, a water bleeding target of 2% and a volumetric shrinkage upper bound of 4%, a thermal conductivity in water saturated conditions of at least 1.4 to 1.5 Wm−1K−1, a compressive strength range of 1 to 2.1 MPa, a flow time range of 60 ± 15 s. Two out of six commercial grouts were selected for installations onsite.
Keywords: Shallow geothermal systems; Backfill grouts; Borehole heat exchangers; Thermo physical properties; Grout flowability

Self-Organizing Maps for Evaluation of Biogeochemical Processes and Temporal Variations in Water Quality of Subtropical Reservoirs - Melo, Darllene S.; Gontijo, Erik S. J.; Frascareli, Daniele; Simonetti, Vanessa C.; Machado, Leila S.; Barth, Johannes; Moschini-Carlos, Viviane; Pompeo, Marcelo L.; Rosa, Andre H.; Friese, Kurt (Water Resources Research, 2019)
Water quality in reservoirs is often compromised in many regions worldwide by nutrients and trace metals. This demands continuous monitoring; however, analyses of large data sets collected during regular monitoring remain a difficult task. Multivariate techniques offer a fast and robust approach for interpreting complex results. The objective of this study was to check the efficacy of self-organizing maps (SOMs) as a tool to investigate biogeochemical processes. This tool can also help to illustrate influences of land use patterns on the water quality of reservoirs. Here we use the Itupararanga Reservoir in Brazil as a subtropical example. Vertical profiles were sampled from seven sites in the reservoir in a total of seven campaigns over 24 months. Next to physicochemical parameters in the water column (dissolved oxygen, Eh, pH, and temperature), levels of nutrients (NO3-, NH4+, and PO43-), transition and trace metals (Al, Ba, Ca, Cr, Cu, Fe, K, Mg, Mn, Na, Ni, and Zn), and chlorophyll-a (Chla) were measured. These variables were correlated with land use using SOM. With this technique samples were classified into 17 distinct groups that showed distinct influences of spatial heterogeneity and seasonality. The analyses helped to reveal a seasonal stratification period, where Fe, Mn, and P were released from sediments. Nutrients and some metal inputs (Al and Fe) were related to agricultural, urban, and grass/pasture areas around the reservoir. Our approach also helped to explain physical and biogeochemical seasonality in the reservoir.
CRIS-Team WoS Importer:2019-12-17

Sequence stratigraphy, chemostratigraphy and facies analysis of Cambrian Series 2 – Series 3 boundary strata in northwestern Scotland - Faggetter, Luke E.; Wignall, Paul B.; Pruss, Sara B.; Sun, Yadong; RAINE, ROBERT J.; Newton, Robert J.; Widdowson, Mike; SMITH, PAUL M.; Sun, Yadong; Joachimski, Michael (Geological Magazine, 2018)
Globally, the Series 2 – Series 3 boundary of the Cambrian System coincides with a major carbon isotope excursion, sea-level changes and trilobite extinctions. Here we examine the sedimentology, sequence stratigraphy and carbon isotope record of this interval in the Cambrian strata (Durness Group) of NW Scotland. Carbonate carbon isotope data from the lower part of the Durness Group (Ghrudaidh Formation) show that the shallow-marine, Laurentian margin carbonates record two linked sea-level and carbon isotopic events. Whilst the carbon isotope excursions are not as pronounced as those expressed elsewhere, correlation with global records (Sauk I – Sauk II boundary and Olenellus biostratigraphic constraint) identifies them as representing the local expression of the ROECE and DICE. The upper part of the ROECE is recorded in the basal Ghrudaidh Formation whilst the DICE is seen around 30m above the base of this unit. Both carbon isotope excursions co-occur with surfaces interpreted to record regressive–transgressive events that produced amalgamated sequence boundaries and ravinement/flooding surfaces overlain by conglomerates of reworked intraclasts. The ROECE has been linked with redlichiid and olenellid trilobite extinctions, but in NW Scotland, Olenellus is found after the negative peak of the carbon isotope excursion but before sequence boundary formatio
Keywords: DICE; Durness Group; ROECE; Scotland; trilobite extinction

Sequence stratigraphy in continental settings - examples from the Permo-Carboniferous Saar-Nahe Basin, SW Germany. - Stollhofen, Harald (Zentralblatt für Geologie und Paläontologie, Teil I, Geologie, 2000)
In this study sequence stratigraphic concepts are applied to the purely continental strata of the Permo-Carboniferous Saar-Nahe Basin. The investigated portion of the basin fill comprises syn-rift strata which display a spectrum of cycles, ranging from periodicities of 2 Ma and 200-400 ka all the way down to multiples of sunspot cycles and annual seasonal couplets. On the basis of sequential position, facies associations and systematic changes in stacking patterns and facies architecture it is possible to subdivide the 200-400 ka-cycles into systems tracts. By considering the anatomy of trangressive systems tracts as well as associated synsedimentary tectonic features tectonism turns out to be an important factor in controlling sequence architecture. Nonetheless, the availability of accommodation space and the rates sediments accumulate are dependent on variations of both tectonic subsidence and climate. It is concluded that series of tectonic events, accompanied by the extrusion of volcanic products, temporarily created accommodation space by rapid subsidence of the basin floor or by damming of the hydrological outlet of the basin. This kind of tectonic influence is suggested to work most effective if subsidence events coincide with a climatically induced lake level rise.
UnivIS-Import:2015-03-09:Pub.2000.nat.dgeo.IGM.LG.sequen

Setting mechanism of a CDHA forming α-TCP cement modified with sodium phytate for improved injectability - Weichhold, Jan; Gbureck, Uwe; Götz-Neunhoeffer, Friedlinde; Hurle, Katrin (Materials, 2019)
A calcium deficient hydroxyapatite (CDHA) forming cement with a bimodal grain size distribution, composed of α-TCP and fine grained CDHA at a weight ratio of 9:1, was modified by the addition of sodium phytate (IP6) in variable amounts ranging from 0.25 to 2 wt.%, related to the powder content. The injectability of the cement paste was drastically increased by the IP6 addition, independent of the amount of added IP6. Additionally, the cement paste viscosity during the first minutes decreased. These effects could be clearly related to a slightly more negative zeta potential. Furthermore, IP6 was shown to strongly retard the setting reaction, as can be seen both in the calorimetry and X-ray diffraction measurements. In addition, octacalcium phosphate (OCP) was identified as a further setting product. All measurements were performed at 23 °C and 37 °C to assess the effect of temperature on the setting reaction for both clinical handling by the surgeon and the final hardening in the bone defect.
CRIS-Team Scopus Importer:2019-07-19
Keywords: Calcium phosphate cement; In-situ XRD; Injectability; Phytic acid; Rheology

Seven rules for simulations in paleobiology - Barido-Sottani, Joëlle; Saupe, Erin E.; Smiley, Tara M.; Soul, Laura C.; Wright, April M.; Warnock, Rachel (Paleobiology, 2020)
Simulations are playing an increasingly important role in paleobiology. When designing a simulation study, many decisions have to be made and common challenges will be encountered along the way. Here, we outline seven rules for executing a good simulation study. We cover topics including the choice of study question, the empirical data used as a basis for the study, statistical and methodological concerns, how to validate the study, and how to ensure it can be reproduced and extended by others. We hope that these rules and the accompanying examples will guide paleobiologists when using simulation tools to address fundamental questions about the evolution of life.
CRIS-Team Scopus Importer:2020-11-27

Shallow geothermal energy use: Mapping of geothermal potential and legal status in Italy - Di Sipio, Eloisa; Destro, Elisa; Galgaro, Antonio; Chiesa, Sergio; Manzella, Adele (Rendiconti Online Societa Geologica Italiana, 2012)
Keywords: ground coupled heat pump; low enthalpy energy source; geothermal potential map; geothermal directives; Italy

Shallow recycling of lower continental crust: The Mahoney Seamount at the Southwest Indian Ridge - Woelki, Dominic; Salters, Vincent; Beier, Christoph; Dick, Henry; Koepke, Juergen; Romer, René (Earth and Planetary Science Letters, 2023)
The Mahoney Seamount is a recently discovered volcanic edifice located 4 km north of the ultra-slow spreading Southwest Indian Ridge (SWIR). The SWIR is one of the slowest spreading ridges worldwide with a full spreading rate of ∼14 mm/year and low magmatic productivity. We report that highly vesicular basalts from the Mahoney Seamount have unradiogenic Nd-Hf together with radiogenic Sr isotopic compositions. Their distinct low 206Pb/204Pb isotope signature combined with high 207Pb/204Pb and 208Pb/204Pb is best explained by melting of a mantle that has been strongly influenced by stranded lower continental crust. The geographic distribution of the isotopic variability favors the idea of shallow recycling of lower continental crust isolated for a longer period contributing to melts forming Mahoney Seamount through off-axis fault systems. The isotopic composition of Mahoney Seamount lavas shares many characteristics with EM-1 sources and the DUPAL signature. Previous isotopic studies of the SWIR basalts proposed recycling of ancient subcontinental lithospheric mantle (SCLM) or pelagic sediments with oceanic crust to be responsible for this enriched isotopic signature. Lu/Hf and Sm/Nd ratios of pelagic sediments would result in decoupled 143Nd/144Nd and 176Hf/177Hf ratios. This decoupling is also observed in Ejeda-Bekily dikes from Madagascar, but those are believed to sample the SCLM dispersed in the Indian Ocean. However, Mahoney Seamount shows no decoupling in those isotopic systems and the restricted occurrence of the extreme lower continental crustal signature at Mahoney Seamount implies that the enriched isotopic signature has a different origin.
CRIS-Team Scopus Importer:2023-01-06
Keywords: basalt; lower continental crust; MORB; off-axis; radiogenic isotopes; Southwest Indian Ridge

Shallow-water aragonite recorded in bundles of limestone-marl alternations - The Upper Jurassic of SW Germany - Munnecke, Axel; Westphal, Hildegard; Munnecke, Axel; Munnecke, Axel (Sedimentary Geology, 2004)
Characteristically, limestone-marl alternations are conspicuous in outcrop because of differential weathering, the marls being predisposed to stronger deterioration. Superimposed on the bedding rhythms are in many cases lower-frequency meter-scale rhythms, so-called bundles. These bundles are eye-catching from a distance, and are typified by variations in thickness of limestone beds and marl interbeds. The palaeoenvironmental significance of the bundles received markedly less attention in the literature than the origin of the small-scale couplets. Here we focus on the palaeoenvironmental significance of the bundles by reconstructing the initial mineralogical composition. As an example, we present a classical limestone-marl alternation from the Upper Jurassic (Oxfordian-Kimmeridgian) of SW Germany that is typified by two orders of bundles superimposed on the limestone-marl couplets. Our method of reconstruction of the original mineralogical composition of the precursor sediment of limestone-marl alternations is based on a diagenesis model that assumes dissolution of aragonite and reprecipitation as calcite cement as the major mechanism of early diagenesis. Calculated initial clay, aragonite, and calcite contents show rhythmic variations on a scale of several meters that correspond to the bundles as seen in the outcrop. Limestone-dominated parts of the bundles correspond to intervals of elevated aragonite content in the precursor sediment, but not necessarily to elevated calcite contents. Additionally, an overlain fluctuation in initial mineralogy on the order of tens of meters (mega-bundles), reflecting the former local subdivision of the SW German Upper Jurassic into "Weißjura alpha", "beta", and "gamma", is observed. The limestone- dominated "Weißjura beta" (lower Kimmeridgian) is the interval with highest initial aragonite content. Our new method allows for quantification of initial mineralogical composition. As aragonite and calcite usually have different sources (shallow-water benthic versus planktic), this approach potentially adds significant new possibilities for palaeoceanographic interpretation of calcareous rhythmites. In the Jurassic example, the observed variations in reconstructed aragonite content are interpreted as variations in flooding events and related export of aragonitic material from marginal shallow-water platforms. © 2003 Elsevier B.V. All rights reserve
Keywords: Aragonite; Bundles; Couplets; Jurassic; Limestone; Marl

Shape Matters: Crystal Morphology and Surface Topography Alter Bioactivity of Bioceramics in Simulated Body Fluid - Myszka, Barbara; Schodder, Philipp; Leupold, Simon; Barr, Maissa; Hurle, Katrin; Schüßler, Martina; Demmert, Benedikt; Biggemann, Jonas; Fey, Tobias; Boccaccini, Aldo R.; Wolf, Stephan (Advanced Engineering Materials, 2020)
For bioactive biomaterials such as bioceramics and bioglass, it is generally accepted that, apart from acting as heterogeneous nucleators, it is their solubility and the resulting release of relevant ions such as calcium or basic anions which mainly governs the biomaterial's bioactivity. This contribution reveals that this bioactivity, as assessed by simulated body fluid (SBF), can also be considerably modified by the bioceramic's morphology, i.e., bioactivity is also governed by microstructure and surface morphology. When crystals are forced to adopt out-of-equilibrium crystal habit, this simple change in morphology converts an essentially bioinert material, here calcite, into a bioceramic which shows bioactivity in SBF. On larger length scales, already simple morphological changes, such as scratches, can have inverse effects. Limited mass transport into grooves and pits on a bioceramic surface can lead to local ion depletion which, in turn, causes reduced bioactivity of bioceramics which, otherwise, show distinct bioactivity in SBF. This contribution emblematically illustrates the unforeseen importance of even minor morphology changes on different length scales when assessing and designing a biomaterial's bioactivity through SBF assays.
CRIS-Team Scopus Importer:2020-06-05
Keywords: bioactivity; bioceramics; biomaterials; calcium carbonate; crystallization

Shell architecture, element composition, and stable isotope signature of the giant deep-sea oyster Neopycnodonte zibrowii sp n. from the NE Atlantic - Wisshak, Max; López Correa, Matthias; Gofas, Serge; Salas, Carmen; Taviani, Marco; Jakobsen, Joachim; Freiwald, André (Deep-Sea Research Part I-Oceanographic Research Papers, 2009)
A conspicuous new deep-sea oyster, Neopycnodonte zibrowii sp. n., is described from the Azores Archipelago, where it thrives in 420 to >500 m water depth in high densities concealed underneath overhangs. The new species reaches a relatively large size, which may exceed 20 cm, and is characterised by a very unusual hinge line morphology, straight without a bulge of the resilium. It is compared to the extant Indo-Pacific Empressostrea kostini Huber and Lorenz, 2007 and to the cosmopolitan Neopycnodonte cochlear (Poli, 1791), which has a broadly sympatric distribution at shallower depths in the Azores and Bay of Biscay. Radiocarbon dating reveals that individuals reach an impressive lifespan of one to more than five centuries, placing them among the longest-lived molluscs known to date. They often grow on top of each other, forming stacks that resemble dish piles-an effective measure to optimise shell stability with minimal biomineralisation effort, but with the drawback of increased bioerosion ultimately leading to detachment. Three microstructure types are developed in N. zibrowii: (1) the cross-foliated, calcitic, dorsal to central endostracum and aragonitic ligostracum, (2) the porous vesicular structure of the calcitic ventral endostracum, and (3) the simple prismatic aragonitic myostracum. Foliated and vesicular shell portions show sub-millimetre-scale first-order increments delineated by conchiolin-rich growth breaks (interpreted as reproductive cyclicity), and less distinct second-order increments (interpreted as annual in nature). This pattern is clearly reflected by the elemental composition with the primary growth breaks lacking Ca and Sr but including Mg and S as organic matrix constituents. The second-order increments within the calcite are mirrored by moderately co-varying Mg/Ca and S/Ca fluctuations at stable Sr concentrations, reflecting varying proportions of organic matrix. Dorsal and central endostracum transects reveal a low inter-valve, but considerable inter-specimen variability with high Mg/Ca molar ratios and fluctuations (22.5±17.6 mmol/mol), low Sr/Ca values (0.2±0.1 mmol/mol), and a typical to high S/Ca content (6.9±2.2 mmol/mol), when compared to other calcitic bivalves. Unlike short-lived, shallow-water oysters, N. zibrowii thrives under very stable environmental conditions. Minimal temperature fluctuations and stable open marine salinity provide an optimal basis to recognise biological fractionation processes. Strong Mg/Ca fluctuations indicate a physiological control related to metabolism and biomineralisation, prohibiting the use of this ratio as a temperature or ocean chemistry proxy. Low Sr/Ca ratios indicate rather constant and low long-term accretion rates, while short-scale fluctuations may be attributed to short-term variations in growth rate and Mg incorporation. Oxygen isotopes yield a considerable spread of 1.8‰ with a mean of 2.0±0.3‰ δ18O V-PDB, and low correlation between different contemporaneous parts of the shell and between specimens. These values surprisingly exceed expected equilibrium conditions, calculated from in situ temperature data (annual mean 12.3±0.3 °C) and seawater isotopic composition (0.5±0.1‰ δ18O SMOW), by 0.5‰ on average. Such positively shifting vital effects, previously reported for limpets and barnacles, are often overlooked in high-temperature and high-amplitude settings and may be more common than is currently believed. Carbon isotopes range from 0.2 to 3.5‰ δ13C V-PDB (mean 1.8±0.7‰) and show an ontogenetic decrease, but may incorporate an environmental signal in adult portions, indicated by a strong correspondence of peaks between specimens. This signal is likely driven by a complex interplay of different factors, such as primary production, current-based food supply and metabolism. © 2008 Elsevier Ltd. All rights reserved.
UnivIS-Import:2015-03-09:Pub.2009.nat.dgeo.IGM.LP.shella
Keywords: Azores; Microstructure; Neopycnodonte zibrowii; Oyster; Stable isotopes; Trace elements

Siberian Trap volcanism, global warming and the Permian-Triassic mass extinction: New insights from Armenian Permian-Triassic sections - Joachimski, Michael; Alekseev, A. S.; Grigoryan, A.; Gatovsky, Yu A. (Geological Society of America Bulletin, 2020)
Permian-Triassic boundary sections from Armenia were studied for carbon isotopes of carbonates as well as oxygen isotopes of conodont apatite in order to constrain the global significance of earlier reported variations in the isotope proxies and elaborate the temporal relationship between carbon cycle changes, global warming and Siberian Trap volcanism. Carbon isotope records of the Chanakhchi and Vedi II sections show a 3-5 parts per thousand negative excursion that start in the Clarkina nodosa (C. yini) conodont Zone (latest Permian) with minimum values recorded in Hindeodus parvus to Isarcicella isarcica conodont zones (earliest Triassic). Sea surface temperatures (SST) reconstructed from oxygen isotopes of conodont apatite increase by 8-10 degrees C over an extrapolated time interval of similar to 39 ka with the onset of global warming occurring in the C. iranica (C. meishanensis) Zone of the latest Permian. Climate warming documented in the Armenian sections is comparable to published time-equivalent shifts in SST in Iran and South China suggesting that this temperature change represents a true global signature. By correlating the Armenian and Iranian section with the radiometrically well-dated Meishan GSSP (Global Stratotype Section and Point) section (South China), the negative shift in delta C-13 is estimated to have occurred 12-128 ka prior to the onset of global warming. This temporal offset is unexpected given the synchrony in changes in atmospheric CO2 and global temperature as seen in Pleistocene ice core records. The negative delta C-13 excursion is explained by the addition of emission of isotopically light CO2 and CH4 from thermogenic heating of organic carbon-rich sediments by Siberian Trap sill intrusions. However, the observed time lag in the delta C-13 and delta O-18 shifts questions the generally assumed cause-effect relationship between emission of thermogenically produced greenhouse gases and global warming. The onset of temperature rise coincides with a significant enrichment in Hg/TOC (total organic carbon) ratios arguing for a major volcanic event at the base of the extinction interval. Whether global warming was a major factor for the Late Permian mass extinction depends on the duration of the extinction interval. Warming only starts at the base of the extinction interval, but with the extinction encompassing a time interval of 60 +/- 48 ka, global climate warming in conjunction with temperature-related stressors as hypoxia and reduced nutrient availability may have been one of the major triggers of the most devastating biotic crisis in Earth history.
CRIS-Team WoS Importer:2020-01-21

Siberian Trap volcanism, global warming and the Permian Triassic mass extinction: New insights from Armenian Permian-Triassic sections: Reply - Joachimski, Michael; Alekseev, Alexander S.; Grigoryan, Artyom; Gatovsky, Yu A. (Geological Society of America Bulletin, 2022)
Horacek et al. (2021) commented on our publication arguing that we used an incorrect biochronology to define the Permian-Triassic (PT) boundary and that this inaccurate definition resulted in an erroneous interpretation of the oxygen isotope record in the studied Chanakhchi (former Sovestashen) section. Their comment gives us the opportunity to discuss in depth the identification of the PT boundary and to address some of the flawed arguments of Horacek et al.

Significance of Detrended Correspondence Analysis (DCA) in palaeoecology and biostratigraphy: A case study from the Upper Cretaceous of Egypt - Ayoub-Hannaa, Wagih; Fürsich, Franz; Huntley, John Warren (Journal of African Earth Sciences, 2013)
The Cenomanian-Turonian macrofauna from the Sinai Peninsula, Egypt offers an excellent opportunity to test the applicability of gradient analysis in palaeoecology and biostratigraphy. Detrended Correspondence Analysis (DCA) is a simple multivariate technique for arranging species and samples along environmental gradients. In order to reconstruct palaeoecological patterns and biostratigraphy, 42 samples, 4564 individuals, and 132 species from three sections of eastern Sinai were subjected to DCA. Compared with other multivariate techniques such as cluster analysis, the macrobenthic associations (obtained by DCA) fall fully within or deviate only slightly from associations obtained by cluster analysis. However, DCA makes it possible to arrange these associations from completely random distribution (as tested by cluster analysis) to a temporal gradient. Therefore, it is possible to use this multivariate technique also as a useful tool in biostratigraphy. The first detrended correspondence axis (DC1) reflects a water-depth gradient from onshore to offshore, higher scores being typical of onshore samples from the southernmost section and lower scores being typical of offshore samples from the northern section. Overprinted on the DC1 axis is also a gradient of life and feeding modes, as samples with low scores are dominated by epifaunal species and samples with high scores display a higher proportion of shallow-infaunal taxa. With respect to the second detrended correspondence axis (DC2), substrate composition and water energy are overprinted on this axis as samples with low scores predominantly are coarse-grained carbonates (e.g., reefal rudstone), while samples with high scores primarily are mixed-siliciclastics/carbonates (e.g., marl), which are dominated by low-energy taxa. Because the substrate conditions are closely related to the water energy, the coarse-grained substrates were deposited under high water energy, while the marly facies was deposited under low-energy conditions. Excursions in DC2 scores, reflecting substrate composition and water energy, are used to reconstruct the macrobenthic associations; eight associations and two assemblages were recognized. High stress environments (low DC2 scores) were occupied by less diverse associations such as the Chondrodonta joannae association and the Pchelinsevia coquandiana-Praeradiolites biskraensis association. The latter association is stratigraphically followed by high-diversity associations such as the Ilymatogyra africana-Rhynchostreon suborbiculatum association, which preferred less-stressed environments (high DC2 scores). © 2013 Elsevier Ltd.
UnivIS-Import:2017-12-18:Pub.2013.nat.dgeo.IGM.LP.signif
Keywords: Biostratigraphy; Cenomanian-Turonian; Detrended Correspondence Analysis (DCA); Egypt; Palaeoecology; Sinai Peninsula

Significance of rockfall magnitude and carbonate dissolution for rock slope erosion and geomorphic work on Alpine limestone cliffs (Reintal, German Alps) - Krautblatter, Michael; Moser, Michael; Schrott, Lothar; Wolf, J.; Morche, David (Geomorphology, 2012)
Keywords: Denudation; Cliff retreat; Rock avalanche; Recurrence intervals; Solute transport; Sediment budget

Silicate weathering, land plants, and cooling in the late Silurian and early Devonian - Avila, Teresa D.; Saltzman, Matthew R.; Griffith, Elizabeth M.; Joachimski, Michael (Journal of the Geological Society, 2025)
The development of terrestrial vegetation and its impact on silicate weathering is hypothesized to have driven multiple cooling events throughout the Paleozoic. One such event is the 8 to 10˚C cooling observed from the late Silurian through early Devonian (c.a. 420 to 385 Ma). Chemical weathering of Ca- and Mg-bearing silicate minerals and the subsequent trapping of carbon in marine carbonates are a sink for atmospheric CO2 on multimillion-year time scales. The strontium isotopic ratio (87Sr /86Sr) of seawater acts as a geochemical proxy for this process. In this study, we present new Silurian to Devonian 87Sr/86Sr data paired with oxygen isotopes (⁠ 18O; a proxy for paleotemperature and ice volume) from conodont apatite. The two datasets inflect in the late Silurian to early Devonian, suggesting a connection between enhanced basaltic weathering (leading to lower 87Sr/86Sr) and cooling (increasing 18O). The spread of terrestrial plants likely drove a significant portion of the enhanced basaltic weathering, which would have driven cooling, in addition to coeval tectonic changes in the Pridoli Epoch (422.7 to 419.0 Ma) and Lochkovian Age that further enhanced weathering and drawdown of atmospheric CO2 (419.0 to 412.4 Ma

Silurian - Munnecke, Axel (Mémoires du Muséum national d'Histoire naturelle, 2007)
Keywords: Silurian

Silurian calcispheres (Calcitarcha) of Gotland (Sweden): Comparisons with calcareous dinoflagellates - Servais, Thomas; Munnecke, Axel; Versteegh, Gerard J.M. (Comptes Rendus Palevol, 2009)
Scanning electron microscope examinations of polished and etched surfaces of sediments from the Silurian carbonate platform of Gotland, Sweden, revealed the presence of numerous, morphologically diverse "calcispheres" (Calcitarcha). Some of these spherical calcareous microfossils display wall structures that are surprisingly similar to those of calcareous dinoflagellate cysts. In analogy to the interpretation of the biological affinities of Palaeozoic acritarchs as cysts of organisms that might have been the ancestors of organic-walled dinoflagellates, the Calcitarcha from Gotland can be compared and may possibly be related to organisms that may have been the ancestors of calcareous cyst-producing dinoflagellates that so far have not been observed before the Late Jurassic. © 2009 Académie des sciences.
Keywords: Calcitarcha Calcispheres Calcareous dinoflagellates Silurian Gotland

Silurian carbonate high-energy deposits of potential tsunami origin: Distinguishing lateral redeposition and time averaging using carbon isotope chemostratigraphy - Jarochowska, Emilia; Munnecke, Axel (Sedimentary Geology, 2015)
Stable carbon isotope curves are used as a precise stratigraphic tool in the Paleozoic, even though they are commonly based on shallow-water carbonate record, characterized by low stratigraphic completeness. Identification of episodes of large-scale redeposition and erosion may improve δ13Ccarb-based correlations. Here, a series of at least three episodes of high-energy onshore redeposition are described from the Makarivka Member (new unit) of the Ustya Formation from the Homerian (middle Silurian) of Podolia, Ukraine. The Makarivka Member is emplaced within a tidal flat succession. Its most prominent part is divided into a lower polymictic conglomerate of sand- to boulder-sized clasts representing a range of subtidal facies, and an upper heterolithic unit composed of grainstone and mudstone laminae. The aim of the study is to identify the mechanism of deposition of the allochthonous conglomeratic material in this Member. Based on analogies with recent tsunami deposits, the conglomerate is interpreted to reflect the strongest landward-directed current in the tsunami run-up phase, and the heterolith - alternating high-density landward currents, stagnant intervals allowing mud and land-derived debris to settle, and backwash flows. The tsunamite was deposited during an interval of decreasing isotopic values of the Mulde excursion, a global δ13C excursion reaching +5.2‰ in the studied sections. Clast redeposition in an interval characterized by rapidly changing δ13Ccarb offers the opportunity to evaluate the degree of temporal and spatial averaging caused by the tsunami. The clasts in the polymictic conglomerate show scattered δ13Ccarb values (-0.3‰ to +2.1‰) compared to homogenous (1.3‰ to 1.6‰) values in the matrix. The presence of clasts characterized by low δ13Ccarb values is explained by their decrease with bathymetry rather than erosion of pre-excursion strata, whereas high values characterize material entrained from the sea-floor and strata directly underlying the tsunamite. Close (1.3‰ and 1.5‰) average δ13Ccarb values suggest that the matrix of the conglomerate is potentially a product of clast grinding.
UnivIS-Import:2015-04-14:Pub.2015.nat.dgeo.IGM.LP.siluri
Keywords: Homerian; Positive carbon isotope excursion; Sequence stratigraphy; Temporal mixing; Transgressive lag; Wenlock

Simulating Hydraulic Fracturing: Failure in Soft Versus Hard Rocks - Aleksans, Janis; Köhn, Daniel; Toussaint, R.; Daniel, G. (Pure and Applied Geophysics, 2019)
In this contribution we discuss the dynamic development of hydraulic fractures, their evolution and the resulting seismicity during fluid injection in a coupled numerical model. The model describes coupling between a solid that can fracture dynamically and a compressible fluid that can push back at the rock and open fractures. With a series of numerical simulations we show how the fracture pattern and seismicity change depending on changes in depth, injection rate, Young’s Modulus and breaking strength. Our simulations indicate that the Young’s Modulus has the largest influence on the fracture dynamics and the related seismicity. Simulations of rocks with a Young’s modulus smaller than 10 GPa show dominant mode I failure and a growth of fracture aperture with a decrease in Young’s modulus. Simulations of rocks with a Young’s modulus higher than 10 GPa show fractures with a constant aperture and fracture growth that is mainly governed by a growth in crack length and an increasing amount of mode II failure. These results are very important for the prediction of fracture dynamics and seismicity during fluid injection, especially since we see a transition from one failure regime to another at around 10 GPa, a Young’s modulus that lies in the middle of possible values for natural shale rocks.
CRIS-Team Scopus Importer:2019-12-17
Keywords: Hydrofracturing; microseismicity; numerical modelling; Young’s modulus

Skeletal microstructure and stable isotope signature of three bathyal solitary cold-water corals from the Azores - Marali, Soraya; Wisshak, Max; López Correa, Matthias; Freiwald, André (Palaeogeography, Palaeoclimatology, Palaeoecology, 2013)
Skeletons of cold-water corals are potential geochemical archives that record oceanographic parameters, such as bottom water temperature in the deep sea. In this study, the three solitary scleractinian species, Caryophyllia cyathus, Desmophyllum cristagalli and Stenocyathus vermiformis, were sampled from upper bathyal 500m water depths in the southern Faial Channel (Azores archipelago). The stable carbon isotope (δ13C) and oxygen isotope (δ18O) compositions of the corals were analysed and related to their skeletal architecture. Background data, including data from high-resolution temperature logs and on the ambient seawater isotopic composition, were compared with δ18O-based temperature reconstructions to test the suitability of these cold-water corals as geochemical archives and to explore the role of vital effects on skeletal geochemistry. Although all of the corals experienced identical and near-stable salinities and temperatures, the stable isotopic signatures vary within and among species. Both δ13C and δ18O values fluctuate in relation to growth bandings and are therefore most likely dependent on calcification rates and associated kinetic vital effects. The studied specimens are 13C depleted with respect to equilibrium with ambient seawater, indicating significant uptake of respired CO2 by their skeletons. Skeletal δ18O values vary by up to 3.6‰ among the growth bands of one of the coral specimens, translating into an unrealistic reconstructed temperature amplitude of 16°C. This contrasts with the minute intra-annual amplitude of the stable temperature regime (annual mean 12.30±0.25°C). Nevertheless, δ13C vs. δ18O regression lines can be used to deduce ambient temperatures by applying the lines technique (Smith et al., 2000; Palaios 15, 25-32), which yields temperatures that coincide with the measured maximum temperature range in the case of D. cristagalli and for most C. cyathus samples, but deviate by 2.95°C from the measured annual mean in the case of the S. vermiformis specimen. © 2012 Elsevier B.V.
UnivIS-Import:2015-03-09:Pub.2013.nat.dgeo.IGM.LP.skelet
Keywords: Caryophyllia; Desmophyllum; Lines technique; Stenocyathus; Temperature reconstruction

Skeletal reorganisation affects geochemical signals, exemplified in the stylasterid hydrocoral Errina dabneyi (Azores Archipelago) - Wisshak, Max; López Correa, Matthias; Zibrowius, Helmut; Jakobsen, Joachim; Freiwald, André (Marine Ecology-Progress Series, 2009)
The pure white fans of the stylasterid Errina dabneyi are a conspicuous feature on the upper bathyal slopes in Azorean waters and were documented and recovered alive with the aid of a submersible in the southern Faial Channel. Etched vacuum-epoxy-casts of the aragonite skeleton, studied by scanning electron microscopy, reveal the 3-dimensional internal architecture comprising coenosarc canal meshwork, dactylopores, gastropores and ampullae. Near the surface, the canals are narrow and interconnected in a regular 3-dimensional meshwork. Deeper inside the canals are less abundant, more irregular and wider. This pattern implies that the skeletal architecture is modified during growth, with more central canals being enlarged by dissolution, and other canals, gastropores and dactylopores in turn being filled with aragonite reprecipitates. The skeleton is primarily composed of irregular spherulitic aggregates and overprinting during growth is evident from ghost structures in the form of successive semi-spherulitic infill of former canals. Due to differential dissolution and reprecipitation, this internal rebuild process inevitably involves an alteration of initial geochemical signatures such as stable isotope ratios (δ18O and δ13C), trace element signals and the distribution of radiogenic isotopes of carbon and uranium. This has to be taken into account when applying radiometric dating techniques and when using stylasterids as a geochemical archive. © Inter-Research 2009.
UnivIS-Import:2015-03-09:Pub.2009.nat.dgeo.IGM.LP.skelet
Keywords: Biomineralisation; Coenosarc canals; Epoxy-casting technique; Geochemical signals; Hydrozoa; Microstructure; Stable isotopes; Stylasteridae

Slab steepening and rapid mantle wedge replacement during back-arc rifting in the New Hebrides - Haase, Karsten; Regelous, Marcel; Beier, Christoph; Koppers, Anthony A.P. (Nature Communications, 2024)
The effects of the composition and angle of the subducting slab and mantle wedge flow on tectonic and magmatic processes in island arcs and associated back-arcs are poorly understood. Here we analyse the ages and compositions of submarine lavas from the flanks and the floor of the back-arc Futuna Trough some 50 km east of Tanna Island in the New Hebrides arc front. Whereas >2.5 Ma-old back-arc lavas formed from an enriched mantle source strongly metasomatized by a slab component, the younger lavas show less slab input into a depleted mantle wedge. The input of the slab component decreased over the past 2.5 million years while the enriched mantle was replaced by depleted peridotite. The change of Futuna Trough lava compositions indicates rapid (10 s of km/million years) replacement of the mantle wedge by corner flow and slab steepening due to rollback, causing extensional stress and back-arc rifting in the past 2.5 million years.
CRIS-Team Scopus Importer:2024-07-26

Slag infiltration in refractories employing a crystal growth method with thermal gradient - Göbbels, Matthias; Schmid, Markus (Stahl & Eisen Special: Refractories for Metallurgy, 2006)
UnivIS-Import:2015-04-16:Pub.2006.nat.dgeo.IGM.LM.slagin

Smithian and Spathian (Early Triassic) conodonts from Oman and Croatia and their bathymetry revealed - Chen, Yanlong; Joachimski, Michael; Richoz, Sylvain; Krystyn, Leopold; Aljinović, Dunja; Smirčić, Duje; Kolar-Jurkovšek, Tea; Lai, Xulong; Zhang, Zhifei (Global and Planetary Change, 2021)
Conodont ecology of the Early Triassic Smithian–Spathian transition is still poorly understood. Here we use oxygen isotope ratios of monogeneric conodonts from Omani samples to reveal the differences of oxygen isotopic composition between different taxa. Oxygen isotope analyses from Oman reveal that Neogondolella inhabited a deeper part of the water column relative to neospathodids and Icriospathodus. This indicates that species of Neogondolella lived in an environment ca. 1.7 °C cooler than where neospathodids lived. The investigation of conodonts from these Smithian and Spathian sections has also enabled the first recovery of some rarely reported species (e.g., Icriospathodus zaksi, Paullella omanensis sp. nov. Chen and Gladigondolella laii sp. nov. Chen) from Oman. Paullella omanensis sp. nov. was further recovered from Plavno, Croatia, indicating a large geographic distribution, and its value for biostratigraphic correlations. The discovery of these species in both Oman and Croatia expands their geographical distribution.<br

SO2 disproportionation impacting hydrothermal sulfur cycling: Insights from multiple sulfur isotopes for hydrothermal fluids from the Tonga-Kermadec intraoceanic arc and the NE Lau Basin - Peters, Christian; Strauss, Harald; Haase, Karsten; Bach, Wolfgang; De Ronde, Cornel; Kleint, Charlotte; Stucker, Valerie; Diehl, Alexander (Chemical Geology, 2021)
Hydrothermal systems located at intra-oceanic volcanic arcs and in back-arc basins reveal a complex sulfur cycling. Here we present multiple sulfur isotope data for dissolved sulfide and sulfate in hydrothermal fluids from vent sites at the southern Kermadec and the northern Tonga island arcs and the NE Lau Basin. δ34S values for H2S range from −7.4 to +4.6‰ for hydrothermal fluids from arc volcanoes and from +0.2 to +4.5‰ for those located in the NE Lau Basin. Ranges for Δ33S values are −0.010 to +0.033‰ and −0.016 to +0.011‰, respectively. SO42− in fluids from hydrothermal vents at Macauley caldera, the Brothers volcanic cones, and Niua North show ranges in δ34S and Δ33S from +16.7 to +24.7‰ and +0.013 to +0.049‰. The multiple sulfur isotope data suggest a contribution to the hydrothermal sulfur budget from the disproportionation of magmatic SO2 for most hydrothermal vent sites from the Kermadec arc, whereas H2S at the NE Lau Basin vent sites is thought to result mainly from two-component mixing between host rock-derived sulfur and seawater sulfate with an additional local contribution from SO2 disproportionation. Data from Brothers NW Caldera suggest isotope exchange between H2S and SO42−, whereas lowering of fluid acidity by dissolution of mineral phases occurs at the Brothers Lower Cone. δ34S values between −8.5 and +3.1‰ and Δ33S values between +0.009 and +0.036‰ for elemental sulfur indicate changing redox conditions and/or a decrease of magmatic SO2 in the hydrothermal fluids at Macauley, Haungaroa, Brothers Lower Cone, Niua North and Niuatahi. We conclude that acid sulfate venting in particular shows the highest variability in sulfur isotopic composition of hydrothermal sulfur, irrespective of whether located at an intra-oceanic arc or in a back-arc basin. Sulfur isotope heterogeneity is due to variable contributions from SO2 disproportionation and host rock compositions.
CRIS-Team Scopus Importer:2021-11-26
Keywords: Hydrothermal fluids; Intraoceanic arc; Multiple sulfur isotopes; SO

Soil as natural heat resource for very shallow geothermal application: laboratory and test site updates from ITER Project - Di Sipio, Eloisa; Bertermann, David (Geophysical Research Abstracts, Vol. 19, EGU General Assembly 2017, 2017)

Soil thermal behavior in different moisture condition: an overview of ITER Project from laboratory to field test monitoring - Di Sipio, Eloisa; Bertermann, David (5th International Conference Novel Methods for Subsurface Characterization and Monitoring: From Theory to Practice, NovCare 2017, 2016)

Solenoporaceen aus den obertriassischen (Nor) Riffkalken des Taurusgebirges (Antalya-Gebiet, Südtürkei) - Senowbari-Daryan, Baba; Link, Michael (Palaeontologische Zeitschrift, 2005)
From the Upper Triassic (Norian) reef limestones north and west of Antalya (Taurus Mts., Turkey) the red algae (Solenoporaceans) Solenopora undata n. sp., Parachaetetes clatratus n. sp., Parachaetetes riedeli n. sp., Parachaetetes tauricus n. sp., and Tauristorea parallela n. gen., n. sp. are described. Tauristorea is characterized by cells orientated parallel to the substrate (vertically to the growth direction of the alga). In Solenopora undata and Parachaetetes clatratus some cavity structures occur, whose function as reproductive organs are discussed.
UnivIS-Import:2015-03-09:Pub.2005.nat.dgeo.IGM.LP.soleno
Keywords: Algae; Solenopora; Parachaetetes; Tauristorea; Triassic; Norian; Antalya; Turkey

Solid solution series of silico-sulphate-chloride-apatites - Neubauer, Jürgen; Pöllmann, Herbert (Neues Jahrbuch für Mineralogie-Abhandlungen, 1995)
UnivIS-Import:2015-03-05:Pub.1995.nat.dgeo.IGM.LM.solids

Solubility and characterization of synthesized 11 Å Al-tobermorite - Lothenbach, Barbara; Jansen, Daniel; Yan, Y.; Schreiner, Jürgen (Cement and Concrete Research, 2022)
The structure and solubility of hydrothermally prepared 11 Å Al-tobermorite with Al/(Al + Si) = 0.1 has been studied. NMR and FTIR data indicated the formation of a cross-linked, well crystalline 11 Å Al-tobermorite and preferential uptake of Al in the branching sites of the silicate chains. The incorporation of Al in branching sites of 11 Å tobermorite increased the basal spacing of the 11 Å Al-tobermorite by 0.18 Å. Solubility experiments indicated little effect of temperature on the solubility of 11 Å Al-tobermorite and a weak stabilization of 11 Å Al-tobermorite with regard to 11 Å tobermorite. The experimental data confirmed the strong similarity in structure, Al-uptake, and solubility with poorly ordered C-A-S-H gel, although C-A-S-H gels showed a lower degree of ordering, the absence of cross-linking, an increased basal spacing, and a higher solubility.
CRIS-Team Scopus Importer:2022-07-22
Keywords: Al-tobermorite; NMR; FTIR Raman spectroscopy; Solubility; Thermodynamic data; XRD

Sorption of alkylphenols on Ebro River sediments: Comparing isotherms with field observations in river water and sediments - Navarro, Alicia; Endo, Satoshi; Gocht, Tilman; Barth, Johannes; Lacorte, Silvia; Barcelo, Damia; Grathwohl, Peter (Environmental Pollution, 2009)

Source depletion and extent of melting in the Tongan sub-arc mantle. - Caulfield, John T.; Turner, Simon P.; Dosseto, Anthony; Pearson, Norman J.; Beier, Christoph (Earth and Planetary Science Letters, 2008)
The fluid immobile High Field Strength Elements (HFSE) Nb and Ta can be used to distinguish between the effects of variable extents of melting and prior source depletion of the Tongan sub-arc mantle. Melting of spinel lherzolite beneath the Lau Basin back-arc spreading centres has the ability to fractionate Nb from Ta due to the greater compatibility of the latter in clinopyroxene. The identified spatial variation in plate velocities and separation of melt extraction zones, combined with extremely depleted lavas make Tonga an ideal setting in which to test models for arc melt generation and the role of back-arc magmatism. We present new data acquired by laser ablation-ICPMS of fused sample glasses produced without the use of a melt fluxing agent. The results show an arc trend towards strongly sub-chondritic Nb/Ta (< 17) with values as low as 7.2. Melting models show that large degree melts of depleted MORB mantle fail to reproduce the observed Nb/Ta. Alternatively, incorporation of residual back-arc mantle that has undergone less than 1% melting into the sub-arc melting regime reproduces arc values. However, the extent of partial melting required to produce the composition of the Lau Basin back-arc basalts averages 7%. This apparent discrepancy can be explained if only the lowermost 4 km of the residua from the mantle melt column beneath the back-arc is added to the source of arc magmas. We have identified that the degree of arc/back-arc coupling displayed in the rock record provides an index of the depth of hydrous melting beneath the arc. In this case, this would imply a depth of 75 km for generation of arc magmas, indicating that hydrous melting in the mantle wedge is triggered by the breakdown of hydrous phases in the subducting slab.
UnivIS-Import:2015-03-09:Pub.2008.nat.dgeo.IGM.legeo.source
Keywords: back-arc; depletion; HFSE; hydrous; melting; sub-arc

Sources and sinks of nutrients and organic carbon during the 2014 pulse flow of the Colorado River into Mexico - Daesslé, L. W.; Orozco, A.; Struck, U.; Camacho-Ibar, V. F.; van Geldern, Robert; Santamaría-del-Angel, E.; Barth, Johannes (Ecological Engineering, 2015)

Sources and sinks of nutrients and organic carbon during the 2014 pulse flow of the Colorado River into Mexico - Daesslé, L. W.; Orozco, Alexandro; Struck, Ulrich; Camacho-Ibar, V. F.; van Geldern, Robert; Santamaría-del-Angel, E.; Barth, Johannes (Ecological Engineering, 2017)

Sources identification and contamination assessment of heavy metals in soil of Middle Nile Delta, Egypt - Abu Khatita, Atef M.; Koch, Roman; Bamousa, Abdullah O. (Journal of Taibah University for Science, 2020)
Sedimentological and geochemical studies are integrated to determine the potential of heavy metals in the Middle Nile Delta soil. Four sources of trace elements were identified; a geogenic source includes Fe, Co, Cr, Ni and V, along with Ca that partly enhanced by anthropogenic input, and three dissimilar anthropogenic sources grouped the elements as follow; As, Pb, Zn Cu, Ba and P which derived mainly from industrial activities; Ba, Pb, Zn and Cu group is likely dispersed by traffic emissions, and P, As and Cu elements group which influenced by agrochemical application and drain water irrigation. The concentrations of studied elements increasing with decreasing the particle size. Moreover, two groups of mineral assemblages of soil are recognized; the first group deposited with one particle fraction and inherited from parent materials, The second one includes non-silicate minerals clasts, deposited with more than one fraction and most likely of anthropogenic source.
CRIS-Team WoS Importer:2020-06-23

Sources, transport, and deposition of metal(loid)s recorded by sulfide and rock geochemistry: constraints from a vertical profile through the epithermal Profitis Ilias Au prospect, Milos Island, Greece - Grosche, Anna; Klemd, Reiner; Denkel, Katja; Keith, Manuel; Haase, Karsten; Voudouris, Panagiotis C.; Alfieris, Dimitrios; Wiedenbeck, Michael (Mineralium Deposita, 2023)
Drill core samples from the Profitis Ilias Pb-Zn-Cu-Ag-Au vein mineralization on Milos Island, Greece provide new insights into (i) the metal sources, (ii) the primary vertical metal(loid) distribution, and (iii) the supergene enrichment processes in a transitional shallow-marine to subaerial hydrothermal environment. Metal contents of unaltered and altered host rocks combined with Pb isotope analyses of hydrothermal sulfides suggest that most metal(loid)s were derived by leaching of basement rocks, whereas the distinct enrichment of Te is related to the addition of Te by a magmatic fluid. The trace element contents of base metal sulfides record decreasing Au, Te, Se, and Co, but increasing Ag, Sb, and Tl concentrations with increasing elevation that can be related to progressive cooling and fluid boiling during the hypogene stage. The formation of base metal veins with porous pyrite hosting hessite inclusions at 400 m below the surface was triggered by vigorous fluid boiling. By contrast, the enrichment of native Au associated with oxidized Fe and Cu phases in the shallower part of the hydrothermal system resulted from supergene remobilization of trace Au by oxidizing meteoric water after tectonic exhumation to subaerial levels. Disseminated pyrite with higher Tl/Pb ratios and locally elevated Hg concentrations relative to vein pyrite reflects infiltration of the host rocks by boiled liquids and condensed vapor fluids. The vertical and temporal evolution of the Profitis Ilias mineralization, therefore, provides unique insights into the transport and precipitation of Au, Ag, Te, and related metal(loid)s by multiple fluid processes.
CRIS-Team Scopus Importer:2023-04-14
Keywords: Boiling; Epithermal deposits; Gold; Supergene enrichment; Tellurium

Source variations in volatile contents of Bransfield Strait back-arc and Phoenix/West Scotia mid-ocean ridge lavas, northern Antarctic Peninsula - Anderson, D. W.; Saal, A. E.; Mallick, S.; Wang, J.; Riley, T. R.; Keller, R. A.; Haase, Karsten (Chemical Geology, 2024)
We present the first volatile contents (H2O, CO2, Cl, F, S) of young (< 6 Ma) submarine basaltic glasses from the Phoenix and West Scotia mid-ocean ridges and the Bransfield Strait back-arc of the South Shetland subduction zone in the Antarctic Peninsula. The volatile contents of the MORB glasses correspond well with those of published Pacific MORB and reflect covariations in source enrichment and extent of melting. Our results support the hypothesis that decreasing spreading rates at the Phoenix Ridge resulted in preferential melting of less abundant enriched MORB mantle, due to its greater fertility and higher volatile contents, relative to the more abundant depleted MORB mantle. The volatile contents of the Bransfield Strait back-arc glasses correlate with geochemical indicators of subduction processes and reveal an along-axis spatial distribution consistent with a toroidal inflow of sub-slab asthenosphere around the edges of the subducting plate into the mantle wedge. This inflow should be considered when assessing spatial and geochemical variability at subduction zones, particularly those with slab windows and tears. A small group of Bransfield Strait samples have volatile contents that do not correlate with geochemical signals of subduction influence. We speculate that these samples reflect flux melting of residual enriched mantle brought beneath the Bransfield Strait via corner flow following recent alkaline magmatism in the far eastern regions of the Antarctic Peninsula. Our new data on lavas from the W7 segment of the West Scotia Ridge reveal their source was significantly affected by subduction processes. Unexpectedly, these lavas have CO2-H2O pressures of vapor saturation that suggest they were collected in-situ and erupted relatively recently (∼6 Ma), at odds with previous interpretations of their origins. We suggest they originated from a subduction-modified mantle (lithosphere or asthenosphere) left behind by the eastward-migrating South Sandwich subduction zone sometime over the past ∼30 Myr. These lavas demonstrate the long-lasting effects of subduction processes on the upper mantle and their potential to influence melt compositions even in non-subduction environments today. We use the compositions of lavas from the Phoenix Ridge and Bransfield Strait to estimate mantle potential temperatures; our results agree well with global estimates for mid-ocean ridges and subduction zones, respectively.
CRIS-Team Scopus Importer:2024-01-26
Keywords: Back-arc basin; Bransfield Strait; Phoenix Ridge; Subduction; Volatiles

Sourcing the sand: Accessory mineral fertility, analytical and other biases in detrital U-Pb provenance analysis - Chew, David; O'Sullivan, Gary; Caracciolo, Luca; Mark, Chris; Tyrrell, Shane (Earth-Science Reviews, 2020)
Interpreting the wealth of new data derived from the diverse suite of modern single-grain provenance approaches available to a sedimentologist requires a thorough understanding of the potential biases in the information recorded by each mineral-provenance system. This review focuses on the various possible mineral-specific biases in U-Pb accessory mineral provenance studies employing the minerals zircon, rutile, apatite, monazite and titanite, focussing on biases resulting from variations in source-rock mineralogy (fertility). Fertility is intimately linked to the mineral petrogenesis of crystalline basement sources, which is another key aspect of this review. This petrogenetic information, which often resides in the specialist petrology literature, has great relevance to fertility studies (particularly those measuring mineral content in modern river sediment using confluence and along-trunk sampling) as trace-element abundances and/or elemental ratios in many accessory minerals can be linked to specific lithologies. Other mineral-specific biases in single-grain provenance analysis considered include physical and chemical modifications both before and after deposition, while the diverse suite of modern single-grain analytical approaches also requires understanding of potential methodological and laboratory induced-biases. A series of multi-proxy provenance studies are presented where fertility bias apparently plays a significant role. In magma-poor metamorphic belts (e.g. segments of the Himalayas and Caledonides-Appalachians), it is shown that zircon growth is limited, and monazite, apatite or rutile associated with the youngest tectonomagmatic events are significantly more fertile. Such multi-proxy provenance studies will be greatly aided in the future by high-throughput, coupled U-Pb age – trace-element analyses integrated with automated heavy mineral determinations employing highly efficient sample preparation protocol

Sourcing the sand: Accessory mineral fertility, analytical and other biases in detrital U-Pb provenance analysis - Chew, David; O'Sullivan, Gary; Caracciolo, Luca; Mark, Chris; Tyrrell, Shane (Earth-Science Reviews, 2020)
Interpreting the wealth of new data derived from the diverse suite of modern single-grain provenance approaches available to a sedimentologist requires a thorough understanding of the potential biases in the information recorded by each mineral-provenance system. This review focuses on the various possible mineral-specific biases in U-Pb accessory mineral provenance studies employing the minerals zircon, rutile, apatite, monazite and titanite, focussing on biases resulting from variations in source-rock mineralogy (fertility). Fertility is intimately linked to the mineral petrogenesis of crystalline basement sources, which is another key aspect of this review. This petrogenetic information, which often resides in the specialist petrology literature, has great relevance to fertility studies (particularly those measuring mineral content in modern river sediment using confluence and along-trunk sampling) as trace-element abundances and/or elemental ratios in many accessory minerals can be linked to specific lithologies. Other mineral-specific biases in single-grain provenance analysis considered include physical and chemical modifications both before and after deposition, while the diverse suite of modern single-grain analytical approaches also requires understanding of potential methodological and laboratory induced-biases. A series of multi-proxy provenance studies are presented where fertility bias apparently plays a significant role. In magma-poor metamorphic belts (e.g. segments of the Himalayas and Caledonides-Appalachians), it is shown that zircon growth is limited, and monazite, apatite or rutile associated with the youngest tectonomagmatic events are significantly more fertile. Such multi-proxy provenance studies will be greatly aided in the future by high-throughput, coupled U-Pb age – trace-element analyses integrated with automated heavy mineral determinations employing highly efficient sample preparation protocols.
CRIS-Team Scopus Importer:2020-02-04

Southward Migration of Arctic Ocean Species During the Last Glacial Period - Zhang, Penghui; Huang, Huai-Hsuan; Hong, Yuanyuan; Tian, Skye Yunshu; Liu, Jian; Il Lee, Yong; Chen, Jianwen; Liang, Jie; Wang, He; Yasuhara, Moriaki (Geophysical Research Letters, 2022)
The East Asian winter monsoon (EAWM) is associated with northerly surface winds affecting crop and livestock productivity and social and economic activities across East Asia. However, the relationship between EAWM dynamics and marine biota remains poorly understood. In this study, we analyzed fossil ostracods from sediment cores collected in the northwestern Pacific Ocean to detect the appearance/disappearance of circumpolar species during the late Quaternary. We compared our ostracod records, including dating results, with ice-rafted debris records from the Sea of Japan, and identified two southward migration events of Arctic ostracods at 120-100 ka (Marine Isotope Stage [MIS] 5d stadial) and 30-15 ka (MIS 3 and 2, peak Last Glacial), which corresponded to a strengthened EAWM system. Our results indicate that an intensified EAWM influenced the Yellow Sea Bottom Cold Water formation, lowered the winter water temperatures, and allowed Arctic ostracods to migrate southward into the Yellow Sea.
CRIS-Team WoS Importer:2023-03-03

Spatial and temporal variability in Mediterranean climate over the last millennium from vermetid isotope records and CMIP5/PMIP3 models - Amitai, Yael; Yam, Ruth; Montagna, Paolo; Devoti, Saverio; López Correa, Matthias; Shemesh, Aldo (Global and Planetary Change, 2020)
Stable isotope compositions of oxygen (δ18O) and carbon (δ13C) of the aragonite skeleton of the reef-building gastropod Dendropoma petreaum provide high-resolution records of the Mediterranean climate over the last millennium. In particular, the isotopic composition of vermetid cores collected from the west and east Mediterranean reveals that the different regions have had distinct thermal and primary production behaviors throughout the last millennium. The rate of warming in the recent Industrial Period is variable among the different regions of the Mediterranean Sea. The δ18O-derived Sea Surface Temperature (SST) anomalies show that the Eastern Mediterranean surface temperature is increasing much more rapidly than in the Western Mediterranean. Additionally, the signals of the Little Ice Age and of the Medieval Climate Anomaly are more apparent in the western and in the central Mediterranean while they are almost absent in the eastern Mediterranean. We aim to reconcile the SST temporal and spatial pattern with the variability of the North Atlantic Oscillation (NAO) and the South Asian Monsoon (SAM) climate systems by analyzing coupled atmosphere-ocean models from the CMIP5/PMIP3 projects that simulate the global climate of the past 1000 years. We show that even though the NAO is more dominant in the western Mediterranean SST, its latitudinal movement, on a centennial time scale, is evident in the eastern Mediterranean SST signal. We also discuss the Atlantic water inflow role in the observed similarities of the surface productivity signals and the Suess effect that prevail the Industrial Period signal in all regions of the Mediterranean.
CRIS-Team Scopus Importer:2020-03-27
Keywords: CMIP5/PMIP3 models; Dendropoma petreaum; Last Millennium; Mediterranean Sea; Vermetid