Über das Alter und Altern von Gesteinen - Koch, Roman; Stollhofen, Harald (Geologische Blätter für Nordost-Bayern und angrenzende Gebiete, 2009)
UnivIS-Import:2015-04-14:Pub.2009.nat.dgeo.IGM.LG.berdas

Über die jurassische Gastropodenfauna der Tongrube Mistelgau bei Bayreuth - Schulbert, Christian; Nützel, Alexander (Berichte der Naturwissenschaftlichen Gesellschaft Bayreuth, 2009)
UnivIS-Import:2015-03-09:Pub.2009.nat.dgeo.IGM.LP.berdie
Keywords: Gastropoden; Jura; Tongrube; Mistelgau

Ultrafast and Reproducible Synthesis of Tailor-Made Octacalcium Phosphate - Choudhary, Rajan; Indurkar, Abhishek; Rubenis, Kristaps; Grava, Andra; Dubnika, Arita; Hurle, Katrin; Locs, Janis (ACS Omega, 2024)
Octacalcium phosphate (OCP) has excellent bone formation ability and a good resorption rate as compared to the commercial bone substitutes [e.g., Bio-Oss (Geistlich Pharma AG) and MBCP+ (Biomatlante)], as well as synthesized biomaterials (hydroxyapatite and tricalcium phosphate). The synthesis approach to obtain phase-pure OCP possesses a great challenge due to its complex reaction mechanism and narrow synthesis window. Thus, the current study aimed to overcome the synthesis challenges and to define the precise reaction conditions required for controllable and reproducible synthesis of OCP. Using the principles of the coprecipitation method, novel synthesis protocols were developed ensuring ultrafast synthesis of OCP within minutes. XRD analysis confirmed that phase-pure OCP was obtained. These processing schemes enabled the synthesis of tailor-made OCP with specific surface areas ranging from 16 to 91 m2/g. The synthesized OCPs exhibited plate-like morphology. The interaction of the synthesized OCPs with MC3T3-E1 cells was found to be nontoxic, confirming their cytocompatibility. The synthesis approach developed in this study indicates that challenges such as the reaction volume, stirring rate, and flow rate need to be addressed in the future to upscale the technology.
CRIS-Team Scopus Importer:2024-08-23

Ultra-shallow-marine anoxia in an Early Triassic shallow-marine clastic ramp (Spitsbergen) and the suppression of benthic radiation - Wignall, Paul B.; Bond, David; Grasby, Stephen; Beauchamp, Benoit; Joachimski, Michael; Blomeier, Dirk; Sun, Yadong; Sun, Yadong (Geological Magazine, 2016)
Lower Triassic marine strata in Spitsbergen accumulated on a mid-to-high latitude ramp in which high-energy foreshore and shoreface facies passed offshore into sheet sandstones of probable hyperpycnite origin. More distal facies include siltstones, shales and dolomitic limestones. Carbon isotope chemostratigraphy comparison allows improved age dating of the Boreal sections and shows a significant hiatus in the upper Spathian. Two major deepening events, in earliest Griesbachian and late Smithian time, are separated by shallowing-upwards trends that culminated in the Dienerian and Spathian substages. The redox record, revealed by changes in bioturbation, palaeoecology, pyrite framboid content and trace metal concentrations, shows anoxic phases alternating with intervals of better ventilation. Only Dienerian-early Smithian time witnessed persistent oxygenation that was sufficient to support a diverse benthic community. The most intensely anoxic, usually euxinic, conditions are best developed in offshore settings, but at times euxinia also developed in upper offshore settings where it is even recorded in hyperpycnite and storm-origin sandstone beds: an extraordinary facet of Spitsbergen's record. The euxinic phases do not track relative water depth changes. For example, the continuous shallowing upwards from the Griesbachian to lower Dienerian was witness to several euxinic phases separated by intervals of more oxic, bioturbated sediments. It is likely that the euxinia was controlled by climatic oscillations rather than intra-basinal factors. It remains to be seen if all the anoxic phases found in Spitsbergen are seen elsewhere, although the wide spread of anoxic facies in the Smithian/Spathian boundary interval is clearly a global event.
Keywords: anoxia; extinction; shallow marine; Spitsbergen; Triassic

Ultraslow Spreading and Volcanism at the Eastern End of Gakkel Ridge, Arctic Ocean - Jokat, Wilfried; O'Connor, John; Hauff, Folkmar; Koppers, Anthony A. P.; Miggins, Dan P. (Geochemistry Geophysics Geosystems, 2019)
Ultraslow spreading ridges are poorly understood plate boundaries consisting of magmatic and amagmatic segments that expose mostly mantle peridotite and only traces of basalt and gabbro. The slowest part of the global spreading system is represented by the eastern Gakkel Ridge in the Central Arctic Ocean, where crustal accretion is characterized by extreme focusing of melt to discrete magmatic centers. Close to its eastern tip lies the unusual 5,310-m-deep Gakkel Ridge Deep (GRD) with limited sediment infill, which is in strong contrast to the broader sediment-filled rift valleys to the east and west. Here, we report an 40Ar/39Ar age of 3.65 ± 0.01 Ma for a pillow basalt from a seamount located on the rim the GRD, confirming ultraslow spreading rates of 7 mm/year close to the Laptev Sea as suggested from aeromagnetic data. Its geochemistry points to an alkaline lava, attributed to partial melting of a source that underwent prior geochemical enrichment. We note that the GRD extracts compositionally similar melts as the sparsely magmatic zone further west but at much slower spreading velocities of only 6−7 mm/year, indicating the widespread occurrence of similarly fertile mantle in the High Arctic. This enriched source differs from subcontinental lithospheric mantle that influences magmatism along the Western Volcanic Zone (Goldstein et al., 2008, https://doi.org/10.1038/nature06919) and is similar to metasomatized mantle, shown to influence melt genesis along the Eastern Volcanic Zone.
CRIS-Team Scopus Importer:2019-12-24
Keywords: Arctic Ocean; Eastern Gakkel Ridge; ultra slow spreading

Ultrasonic logging across unconformities outcrop and core logger sonic patterns of the Early Triassic Middle Buntsandstein Hardegsen unconformity, southern Germany. - Filomena, Claudio; Stollhofen, Harald (Sedimentary Geology, 2011)
The recognition of unconformities in thick and monotonous sandstone successions of consistent grain size is often difficult in locally exposed surface outcrop sections and also poorly constrained by changes of petrophysical properties across the boundary surfaces. Here, a mobile ultrasonic device is tested as a time-efficient handheld logging tool to investigate relative changes in sandstone cementation and porosity across the Early Triassic Middle Buntsandstein Hardegsen unconformity in southern and central Germany.A persistent offset of 18-20% sonic transit time occurs in all tested sections across the unconformity. This offset is not restricted to single peaks but clearly separates the different sonic patterns of the Hardegsen and Solling Formations below and above the unconformity. Integrated thin section analysis, porosity-permeability measurements and gamma-density logging suggest that these changes in sonic transit time are due to major variations in sandstone cementation and the formation of secondary porosity associated with the unconformity.Field-based ultrasonic measurements thus provide a useful addition to established outcrop logging methods and may help in the non-destructive in-situ identification of porosity/cementation heterogeneities in sandstones, in the localization of unconformities and in the correlation of borehole measured sequence boundaries to outcrop analogs. © 2011 Elsevier B.V.
UnivIS-Import:2015-03-09:Pub.2011.nat.dgeo.IGM.LG.ultras
Keywords: Buntsandstein; Diagenesis; Porosity; Sandstone; Sonic log; Unconformity

Ultrastructure of the epidermal gland system of Tetranchyroderma suecicum Boaden, 1960 (Gastrotricha: Macrodasyida) indicates a defensive function of its exudate - Schnier, Jannik; Ahlrichs, Wilko; Gruhl, Alexander; Schulbert, Christian; Teichert, Sebastian; Kieneke, Alexander (Zoomorphology, 2019)
Although the phylum Gastrotricha is known and studied for more than 150 years, some cell types, tissues and organ systems are still not well understood in terms of their morphology, ultrastructure, function and role. One of these features is the epidermal gland system (EGS). As yet, there is just a single detailed electron microscopic investigation of the epidermal glands of the species Turbanella cornuta Remane, 1925, plus scattered ultrastructural data of few additional species. We comprehensively investigated the epidermal glands of Tetranchyroderma suecicum Boaden, 1960 by means of serial sectioning and transmission electron microscopy (TEM) and with scanning electron microscopy. Furthermore, light microscopical, confocal laser scanning microscopical and micro-computed tomographical (μCT) techniques were additionally used for this investigation. Computer programs for 3D-reconstructions were used to analyse the data obtained by TEM and μCT. Tetranchyroderma suecicum possesses up to 100, mostly pairwise arranged, glandulocytes. Each single-celled gland con-tains a large anastomosing secretory cistern with granular content, has a very electron-dense cytoplasm, a basally positioned nucleus, peripherally arranged mitochondria and a cuticulated, ‘chimney-like’ apical neck, which carries the cellular pore. Each merocrine glandulocyte is associated with an adjacent ciliated sensory cell. There is currently no coherent hypothesis of the glandulocytes’ functional role, but different ideas are discussed. We refer to evidence that the secretory product of the EGS of Tetranchyroderma suecicum most likely acts as a repellent against potential predator
Keywords: marine meiofauna; benthos; defence mechanism; reconstruction; 3D modelling

Ultrastructures of porostromate microproblematica from a Mulde Event (Homerian, Silurian) Bioherm in Podolia, Western Ukraine - Castagner, Ariane; Jarochowska, Emilia; Munnecke, Axel; Desrochers, André (Estonian Journal of Earth Sciences, 2015)
The Mulde Event (Homerian, Wenlock) of the Silurian is characterized by a positive δ13C isotope excursion, a stepwise extinction of the hemipelagic fauna and an increase in non-skeletal deposits thought to be microbial, proliferating in shallow marine environments. There is little known about whether the proliferation of microbialites is due to reduced grazing, increased seawater saturation state or an increase in nutrient supply. We have studied a Mulde Event-associated buildup from the Muksha Formation in Bagovytsya, Podolia, Western Ukraine. This buildup differs from a typical Silurian skeletal reef in its low abundance of rugose and favositid corals. The framework of this reef is dominated by stromatoporoids, heliolitid corals and calcimicrobes, the last ones encrusting the stromatoporoids and shells and also forming oncoids. Several microproblematica are present, including Girvanella, Rothpletzella and Hedstroemia, along with Ortonella-like porostromate problematica. This study attempts to further identify the Ortonella-like porostromate problematica and Hedstroemia through SEM analyses which have revealed a recrystallized structure with microdolomite, indicating an originally high-Mg calcite composition. This suggests a red algal affinity or possibly a microbial origin. Our observations may help to constrain the environmental controls on the development of microbial- and microproblematica-dominated deposits during the Mulde Event.
UnivIS-Import:2015-04-14:Pub.2015.nat.dgeo.IGM.LP.ultras
Keywords: Calcimicrobes; Carbon isotope excursion; Hedstroemia; Microbialite; Reefs; Silurian

Uncovering and quantifying the subduction zone sulfur cycle from the slab perspective - Li, Ji Lei; Schwarzenbach, Esther M.; John, Timm; Ague, Jay J.; Huang, Fang; Gao, Jun; Klemd, Reiner; Whitehouse, Martin J.; Wang, Xin Shui (Nature Communications, 2020)
Sulfur belongs among H2O, CO2, and Cl as one of the key volatiles in Earth’s chemical cycles. High oxygen fugacity, sulfur concentration, and δ34S values in volcanic arc rocks have been attributed to significant sulfate addition by slab fluids. However, sulfur speciation, flux, and isotope composition in slab-dehydrated fluids remain unclear. Here, we use high-pressure rocks and enclosed veins to provide direct constraints on subduction zone sulfur recycling for a typical oceanic lithosphere. Textural and thermodynamic evidence indicates the predominance of reduced sulfur species in slab fluids; those derived from metasediments, altered oceanic crust, and serpentinite have δ34S values of approximately −8‰, −1‰, and +8‰, respectively. Mass-balance calculations demonstrate that 6.4% (up to 20% maximum) of total subducted sulfur is released between 30–230 km depth, and the predominant sulfur loss takes place at 70–100 km with a net δ34S composition of −2.5 ± 3‰. We conclude that modest slab-to-wedge sulfur transport occurs, but that slab-derived fluids provide negligible sulfate to oxidize the sub-arc mantle and cannot deliver 34S-enriched sulfur to produce the positive δ34S signature in arc settings. Most sulfur has negative δ34S and is subducted into the deep mantle, which could cause a long-term increase in the δ34S of Earth surface reservoirs.
CRIS-Team Scopus Importer:2020-02-04

Understanding Palaeozoic stromatoporoid growth - Kershaw, Stephen; Munnecke, Axel; Jarochowska, Emilia (Earth-Science Reviews, 2018)
Stromatoporoids were abundant components of reefs, reef complexes and associated facies for ca. 100 million years between Middle Ordovician and end-Devonian time. A lot of environmental information stored in their skeletons may be used to develop: a) understanding of stromatoporoid growth controls; and b) interpretations of sedimentary environments in which they lived. General patterns of stromatoporoid distribution are well known, but knowledge of detailed interactions between stromatoporoids and their environments is poorly developed and under-used, potentially of great value in analysis of facies and palaeoecology. From a pool of several thousand specimens examined over four decades, this study identifies four key attributes of stromatoporoids that may be applied to enhance broad-scale knowledge of these fossils and their environments: 1) Substrates: Most stromatoporoids grew directly on wackestone to packstone substrates comprising micrite, clay and bioclasts. Evidence from the relationship between stromatoporoids and sediments demonstrates they were able to grow on soft substrates, but also leads to interpretation of partial lithification of the sea floor (and/or stabilisation by microbial filaments that may not be preserved) in mid-Palaeozoic carbonate facies, with potential implications for models of oceanic carbonate cycling. 2) Growth interruption: Almost all stromatoporoids examined show growth interruption, mostly caused by sedimentation and movement. Stromatoporoids normally recovered quickly and completely from interruption, thus were resilient to interruption events; 3) Associated organisms: Stromatoporoids have abundant associated organisms in two groups: (i) epibiotic encrusters and borers; and (ii) endobiotic organisms embedded in their structure, alive as the stromatoporoids grew. Epibionts used stromatoporoid surfaces that are presumed dead in almost all cases; some are associated with interruption events, but in most cases those were overgrown by successive stromatoporoid growth. Endobionts (mostly corals, plus spirorbids and others) are common to abundant in many stromatoporoid taxa. Stromatoporoid growth was little affected by presence of endobionts but in many cases (commonly restricted to certain stromatoporoid taxa) there was a complex biological interaction valuable in understanding controls on stromatoporoid development. 4) Growth form and taxonomy: Stromatoporoid assemblages are low diversity in almost all cases, regardless of age and facies, with two or three taxa much more abundant than the others. Some stromatoporoid taxa are limited to certain growth forms, thus taxonomic information is very important for facies analysis and palaeobiological interpretations. Stromatoporoids occur commonly with rugose and tabulate corals, both of which could also live on unconsolidated fine-grained substrates, therefore sediment-tolerance cannot be the only reason for stromatoporoid ability to outgrow corals in reefs. Arguments in the literature for photosymbiosis in both stromatoporoids and Palaeozoic corals are currently inconclusive for both fossil groups. Nevertheless, the sum of evidence indicates stromatoporoids were fast-growing, resilient and flexible benthic organisms, in a range of water depths, capable of dealing with soft substrates and largely unaffected by presence of endobionts. These characteristics are interpreted to have made stromatoporoids successful during mid-Palaeozoic time and valuable as tools in facies analysis. Recognition of the four key attributes which encompass all aspects of stromatoporoid growth controls makes palaeobiological study of stromatoporoids, in palaeoenvironmental reconstructions where they occur, readily accessible to researchers.
Keywords: Stromatoporoids Corals Symbionts Sedimentation Substrates Palaeozoic

Understanding sedimentary processes in the uphill catchment of Source-to Sink-Systems: An example from the Sierra Nevada de Santa Marta (NE Colombia) - Caracciolo, Luca; Hatzenbühler, Diana; Chew, D.; Weltje, G. J.; Liedel, Stefan; Vermeesch, P.; Piraquive, A.; Regelous, Marcel; Lünsdorf, K.; Villamizar-Escalante, N. (Earth-Science Reviews, 2025)
The character of sediments generated in the uphill catchments is markedly variable and exert a primary control on the sediment cascade and the evolution of source-to-sink systems. Understanding these processes is therefore critical to better understand how these systems function in both modern and deep-time settigns. This study aims to understand and quantify the processes regulating sediment generation and transfert in the uphill catchments of the Sierra Nevada de Santa Marta (SNSM) - the world's highest coastal range within subtropical regions. We tackle the complex task of quantify the role of external forcings on sediment production in 17 drainages basins within the SNSM by challenging conventional assumptions and introducing new compositional models. Our research significantly expands the existing knowledge base on compositional modelling by presenting a systematic framework for characterizing sediment generation, particularly focusing on the influence of tectonics, climate, lithological factors, and analytical reliability. We produced a robust compositional database encompassing optical petrography (11,463 grains), Raman heavy mineral analysis (44,782 grains), detrital geochronology (apatite, titanite, and zircon – 6378 grains), apatite (1159 grains) and titanite (1571 grains) geochemistry, and bulk-rock and silt-clay geochemistry.We present a novel linear log-ratio (end-member) sediment generation model calibrated on geomorphological parameters as connectivity and erodibility, facilitating the evaluation of sediment generation capacities from metamorphic, plutonic, and volcanic lithologies. Sediment texture and composition vary remarkably from drainage to drainage, providing the elements to model both the relative (by comparing lithologies) and absolute capacity of drainage lithologies to produce sediments, in the settings of the SNSM. Our results reveal significant variations in sediment texture and composition among drainages, providing insights into both the relative and absolute capacity of different lithologies to produce sediments in the SNSM setting. We found that metamorphic rocks produce higher amounts of sand compared to plutonic and volcanic lithologies, while the sediment generation capacity of plutonic rocks is up to 9 times higher than that of volcanic lithologies. In mixed drainages with equal proportions of metamorphic and other rocks, metamorphic detritus can constitute up to 60 % of sand compositions. Surprisingly, geomorphological parameters like structural connectivity and erodibility played a minor role in sediment generation in this tectonic setting, contrary to findings in other regions. This study underscores the importance of understanding processes operating in uphill catchments to better constrain those acting in other sectors of Source-to-Sink systems. Our findings contribute to advancing quantitative methods in provenance analysis and improve our understanding of sediment generation and routing in complex tectonic and climatic settings.
CRIS-Team Scopus Importer:2025-05-16
Keywords: Compositional data analysis; Quantitative provenance analysis; Sediment budget; Sediment generation models; Source to sink systems

Understanding the Great Ordovician Biodiversification Event (GOBE): Influences of paleogeography, paleoclimate, or paleoecology? - Servais, Thomas; Harper, David A.T.; Li, Jun; Munnecke, Axel; Owen, Alan W.; Sheehan, Peter M. (GSA Today, 2009)
"The Great Ordovician Biodiversification Event" (GOBE) was arguably the most important and sustained increase of marine biodiversity in Earth's history. During a short time span of 25 Ma, an "explosion" of diversity at the order, family, genus, and species level occurred. The combined effects of several geological and biological processes helped generate the GOBE. The peak of the GOBE correlates with unique paleogeography, featuring the greatest continental dispersal of the Paleozoic. Rapid sea-floor spreading during this time coincided with warm climates, high sea levels, and the largest tropical shelf area of the Phanerozoic. In addition, important ecological evolutionary changes took place, with the "explosion" of both zooplankton and suspension feeding organisms, possibly based on increased phytoplankton availability and high nutrient input to the oceans driven by intense volcanic activity. Extraterrestrial causes, in the form of asteroid impacts, have also been invoked to explain this remarkable even
Keywords: Great Ordovician Biodiversification Event; GOBE; biodiversity; Paleozoic; sea-floor spreading; zooplankton

Uneven spatial sampling distorts reconstructions of Phanerozoic seawater temperature - Jones, Lewis A.; Eichenseer, Kilian (Geology, 2022)
Paleotemperature proxy records are widely used to reconstruct the global climate throughout the Phanerozoic and to test macroevolutionary hypotheses. However, the spatial distribution of these records varies through time. This is problematic because heat is unevenly distributed across Earth's surface. Consequently, heterogeneous spatial sampling of proxy data has the potential to bias reconstructed temperature curves. We evaluated the spatiotemporal evolution of sampling using a compilation of Phanerozoic delta O-18 data. We tested the influence of variable spatial coverage on global estimates of paleotemperature by sampling a steep "modern-type" latitudinal temperature gradient and a flattened "Eocene-type" gradient, based on the spatial distribution of delta O-18 samples. We show that global paleotemperature is overestimated in similar to 70% of Phanerozoic stages. Perceived climatic trends for some intervals might be artifactually induced by shifts in paleolatitudinal sampling, with equatorward shifts in sampling concurring with warming trends, and poleward shifts concurring with cooling trends. Yet, the magnitude of some climatic perturbations might also be underestimated. For example, the observed Ordovician cooling trend may be underestimated due to an equatorward shift in sampling. Our findings suggest that while proxy records are vital for reconstructing Earth's paleotemperature in deep time, consideration of the spatial nature of these data is crucial to improving these reconstructions.
CRIS-Team WoS Importer:2022-02-11

Uneven spatial sampling in Phanerozoic palaeoclimate curves - Jones, Lewis A.; Eichenseer, Kilian (Annual Meeting of the Palaeontological Association, 2019)

Unexpected contributions by carbonates and organic matter in a silicate-dominated tropical catchment: An isotope approach - Senarathne, Sachintha Lakshan; van Geldern, Robert; Chandrajith, Rohana; Barth, Johannes (Science of the Total Environment, 2024)
The understanding of global carbon has rarely extended to small-scale tropical river basins. To address these uncertainties, this study aims to investigate the importance of rock weathering and organic matter turnover in the carbon cycle in a terrain dominated by crystalline silicate rocks. The geochemical composition of the dissolved and particulate carbon phases (DIC, DOC and POC) and their stable carbon isotopes were studied in the Deduru Oya River in Sri Lanka. Dissolved inorganic carbon (DIC) was the most dominant carbon phase and its contribution to the total carbon pool varied between 67 and 89 %. Furthermore, the δ13CDIC values in the river varied between −1.1 and −16.5 ‰. The lithological characteristics and molar ratios between Ca2+, Mg2+ and HCO3− indicated rock weathering mainly by CO2 and carbonic acid. The δ13CDIC values for groundwater input were −15.9 ‰, while for carbonate weathering, mainly due to fertiliser input, they reached a value of −12.7 ‰. This input was fed into an isotope mass balance to determine the relative contributions. However, the isotope mass balance was only plausible after correcting for the effects on δ13CDIC caused by degassing and photosynthesis. Our study demonstrated that carbonate weathering and organic matter turnover are essential components of the river carbon cycle even in a silicate dominated catchment. They can represent up to 60 % of the DIC pool. Combined with the higher organic matter turnover and high pCO2 in the river water, it can be suggested that the Deduru Oya River acts as a net source of CO2 in the atmosphere. Our study shows that CO2 degassing and in-stream photosynthesis in tropical river systems need to be considered along with chemical weathering to account for carbon transport and turnover in tropical rivers.
CRIS-Team Scopus Importer:2024-07-26
Keywords: Carbon species; CO; Deduru Oya; Isotope geochemistry; Organic matter; Rock weathering

Unravelling provenance from Eocene-Oligocene sandstones of the Thrace Basin, North-east Greece - Caracciolo, Luca; et al. (Sedimentology, 2011)
New sandstone petrology and petrostratigraphy provide insights on Palaeogene (Middle Eocene to Oligocene) clastics of the Thrace Basin in Greece, which developed synchronously with post-Cretaceous collision and subsequent Tertiary extension. Sandstone petrofacies are used as a tool to unravel complex geodynamic changes that occurred at the southern continental margin of the European plate, identifying detrital signals of the accretionary processes of the Rhodope orogen, as well as subsequent partitioning related to extension of the Rhodope area, followed by Oligocene to present Aegean extension and wide magmatic activity starting during the Early Oligocene. Sandstone detrital modes include three distinctive petrofacies: quartzolithic, quartzofeldspathic and feldspatholithic. Major contributions are from metamorphic basement units, represented mostly by low to medium-grade lithic fragments for the quartzolithic petrofacies and high-grade metamorphic rock fragments for the quartzofeldspathic petrofacies. Volcaniclastic sandstones were derived from different volcanic areas, with a composition varying from dominantly silicic to subordinate intermediate products (mainly rhyolitic glass, spherulites and felsitic lithics). Evolution of detrital modes documents contributions from three key source areas corresponding to the two main crystalline tectonic units: (i) the Variegated Complex (ultramafic complex), in the initial stage of accretion (quartzolithic petrofacies); (ii) the Gneiss-Migmatite Complex (quartzofeldspathic petrofacies); and (iii) the Circum-Rhodope Belt. The volcaniclastic petrofacies is interbedded with quartzofeldspathic petrofacies, reflecting superposition of active volcanic activity on regional erosion. The three key petrofacies reflect complex provenance from different tectonic settings, from collisional orogenic terranes to local basement uplift and volcanic activity. The composition and stratigraphic relations of sandstones derived from erosion of the Rhodope orogenic belt and superposed magmatism after the extensional phase in northern Greece provide constraints for palaeogeographic and palaeotectonic models of the Eocene to Oligocene western portions of the Thrace Basin. Clastic detritus in the following sedimentary assemblages was derived mainly from provenance terranes of the Palaeozoic section within the strongly deformed Rhodope Massif of northern Greece and south-east Bulgaria, from the epimetamorphic units of the Circum-Rhodope Belt and from superposed Late Eocene to Early Oligocene magmatism related to orogenic collapse of the Rhodope orogen. The sedimentary provenance of the Rhodope Palaeogene sandstones documents the changing nature of this orogenic belt through time, and may contribute to a general understanding of similar geodynamic settings.
Keywords: Eocene-Oligocene; magmatism; North-east Greece; Rhodope Massif; sandstone detrital modes; Thrace Basin

Unravelling slab δ34S compositions from in-situ sulphide δ34S studies of high-pressure metamorphic rocks - Li, Ji-Lei; Klemd, Reiner; Huang, Gao-Feng; Ague, Jay J.; Gao, Jun (International Geology Review, 2020)
Sulphur is of particular importance in the subduction zone system, as it is thought to be intimately related to the arc redox state and metallogenesis above the slab. Knowing the sulphur isotope compositions of the subducted slab, and identifying the δ34S variations between the pre-subduction oceanic lithosphere and its high-pressure (HP) equivalents is of great importance for understanding the sulphur behaviour in subduction zones and the long-term sulphur recycling of the Earth. In this study, we undertook secondary ion mass spectroscopy (SIMS) in-situ δ34S analyses of sulphides from metasediments, mafic blueschists/eclogites, and ultramafic slab serpentinites from the Southwestern Tianshan HP–UHP metamorphic belt, which represents one of the deepest fossil subduction zones on Earth. By integrating the in-situ δ34S compositions of sulphides studied here and those reported from worldwide HP–UHP metamorphic terranes, we found that prograde to peak metamorphic sulphides of metasediments, metabasites/metagabbros, and slab HP serpentinites have δ34S values ranging from –33 to –6‰, –4 to +4‰, and +2 to +18‰, respectively. However, retrograde metasomatism of HP rocks during exhumation may alter the δ34S compositions of sulphides. The integrated dataset proposes that sulphides in subducting slab sequences retain their protolith’s δ34S signatures during HP metamorphism. The δ34S inheritance indicates that no large isotope fractionation is expected to occur in subduction zones. It further suggests that evaluations of slab subduction effects on the δ34S signature of arc magmatism and the deep mantle should consider pre-subduction processes such as ridge geodynamic setting and hydrothermal alteration.
CRIS-Team Scopus Importer:2020-10-23
Keywords: eclogite; high-pressure metamorphism; subduction zone; sulphide; sulphur isotope

Unravelling the P-T-t history of three high-grade metamorphic events in the Epupa Complex, NW Namibia: Implications for the paleoproterozoic to mesoproterozoic evolution of the Congo Craton - Brandt, Sönke; Klemd, Reiner; Xie, Hanqiang; Bobek, Patrick (American Journal of Science, 2021)
The Epupa Complex of northern Namibia constitutes the south-western margin of the Archean Congo Craton of central Africa. We present new petrological and geochronological data for metasedimentary migmatites that decode the poorly-known Paleoproterozoic to Mesoproterozoic evolution of this remote part of the craton. Detrital magmatic zircons with concordant 207Pb/206Pb ages between 1898 and 1774 Ma are interpreted to demonstrate the formation of the metasedimentary protoliths through reworking of Paleoproterozoic granitoids of a magmatic arc in a back-arc basin. SHRIMP U-Pb zircon analyses of metamorphic rims around the detrital grains linked with constraints from pseudosection modelling revealed three distinct high-grade metamorphic events in the migmatites. Late Paleoproterozoic regional HT-LP metamorphism between 1740 and 1720 Ma constitutes the oldest event and only affected the rocks of the northernmost part of the Epupa Complex (Eyao Unit). Heating to mid-amphibolite facies peak P-T conditions of 720 °C and 4 kbar caused the partial replacement of early biotite-sillimanite by garnet-cordierite assemblages during melt-producing reactions in metapelites. The near-isobaric heating-cooling P-T paths and the high geothermal gradient (60 °C/km) are consistent with HP-LP metamorphism in a back-arc basin setting with up-rising basic melt as heat source. Early Mesoproterozoic (1530 Ma) HT-LP metamorphism is recorded by rare Mg-rich Opx-Crd rocks that are restricted to the westernmost part of the Eyao Unit. Near-isobaric P-T paths culminate at granulite facies peak-conditions of 830 °C and 2 kbar. This local HP-LP event is interpreted to record contact metamorphism related to the coeval emplacement of early-Mesoproterozoic granitoids or the emplacement of intimately associated gabbros. Metapelitic Grt-Bt-Sil migmatites record the third high-grade metamorphic event that was active at ca. 1330 Ma and is restricted to the southern part of the Epupa Complex (Orue Unit). Sillimanite pseudomorphs after kyanite and late cordierite coronas around garnet indicate a clockwise P-T path during regional upper-amphibolite facies metamorphism that peaks at lower crustal conditions of 770 °C and 7.5 kbar. The clockwise P-T path is interpreted to reflect crustal thickening through magmatic accretion of basic melts that produced the coeval Kunene Intrusive Complex, the largest massif-type anorthosite in the world. The metamorphic events detected in the migmatites record a change of the geotectonic position of the Epupa Complex from a convergent continental margin during the late Paleoproterozoic to an intracratonic position in the Mesoproterozoic. The migmatites of the Eyao Unit were affected by an intense hydrothermal alteration during the Pan-African orogeny (ca. 520 Ma) that also caused the partial re-setting of the U-Pb zircon isotope system.
CRIS-Team Scopus Importer:2021-05-21
Keywords: Amphibolite facies; Congo Craton; Epupa Complex; HT-LP metamorphism; Migmatite; P-T-t path; Paleoproterozoic; Pseudosections

Untersuchungen im System Al2O3 CaO SiO2 CaSO4 Na2O - Schmidt, Rainer; Neubauer, Jürgen; Pöllmann, Herbert (European Journal of Mineralogy, 1996)
UnivIS-Import:2015-03-05:Pub.1996.nat.dgeo.IGM.LM.unters

Unusual exsolution phenomena in omphacite and partial replacement of phengite by phlogopite + kyanite in an eclogite from the Erzgebirge - Schmädicke, Esther; et al. (Contributions To Mineralogy and Petrology, 2000)

Unveiling coastal dynamics: Investigating beach sediment distribution patterns along the Lithuanian Baltic Sea coast through heavy mineral analysis - Karlonienė, Dovilė; Caracciolo, Luca; Pupienis, Donatas (Marine Geology, 2024)
Effective coastal management requires an understanding of sediment dynamics. This study examines the distribution of heavy minerals (HMs) in two distinct coastal regions: the mainland and spit, each with unique sediment deposition patterns. The spit accumulates sediment through alongshore sediment transport (AST), while the mainland experiences erosive processes and significant human impacts. The hydrodynamic behaviour and weathering resistance of HMs enables source identification. This has helped to reveal differences between the two regions, with apatite being characteristic of spit sediments and garnet of mainland beaches. Coastal processes, such as erosion, sediment transport, and accumulation, significantly shape the distribution of the HMs, with garnets dominating erosive shores and amphiboles dominating accumulative shores. Furthermore, the study found that human-made coastal infrastructure also affects the composition of HMs and the sediment distribution through AST. This research has implications beyond the local level, providing global insights into the complexities of coastal dynamics. The study emphasises the importance of using HM analysis in conjunction with grain size analysis to understand the distribution of beach sediment composition. It also highlights the significant role of coastal processes, including anthropogenic impacts such as jetty construction or deepening port entrance canals on AST.
CRIS-Team Scopus Importer:2024-06-07
Keywords: Coastal management; Coastal processes; Heavy minerals; Sediment dynamics

U-Pb dating of calcite veins reveals complex stress evolution and thrust sequence in the Bighorn Basin, Wyoming, USA - Beaudoin, Nicolas; Lacombe, Olivier; Roberts, Nick M.W.; Köhn, Daniel (Geology, 2019)
CRIS-Team Scopus Importer:2019-09-17

U-Pb zircon ages and (isotope) geochemical signatures of the Kamanjab Inlier (NW Namibia): constraints on Palaeoproterozoic crustal evolution along the southern Congo craton. - Kleinhanns, I. C.; Fullgraf, T.; Wilsky, F.; Nolte, N.; Fliegel, D.; Klemd, Reiner; Hansen, B. T. (Continent Formation Through Time, 2015)
The formation of the Kamanjab Inlier (KI) in NW Namibia is poorly known and constrained to Palaeoproterozoic times. With the Epupa complex (EC) and Grootfontein Inlier (GI), the KI marks the southwestern Congo craton margin. Our new geochemical data for granitoids and orthogneisses indicate formation along an active continental margin. Single zircon ages frame granitoid emplacement to 1.86–1.83 Ga, roughly 75 myr older than ages from the northern EC and approximately 100 myr younger than from the GI. The southern EC is the only known Archaean Namibian basement with ɛNd1.85 Ga of −10.2 to −6.3, in contrast to northern EC (−1.8 to 4.4) and KI (−6.2 to 2.6). Thus, earlier speculation that the southern EC is an exotic terrane, among the Namibian basement complexes, is supported by our data. In contrast, the KI is geochemically comparable to the northern EC and GI. The c. 2.0 Ga Lufubu metamorphic complex roughly 1000 km further east shows similar geochemistry, and a common evolution in the Kamanjab–Bangeweulu magmatic arc has already been proposed. Therefore, our new data point to a major Palaeoproterozoic crustal growth event at the southwestern margin of the Congo Craton starting in the present east and gradually moving towards the present NW.

U-Pb zircon ages and (isotope) geochemical signatures of the Kamanjab Inlier (NW-Namibia): constraints on Paleoproterozoic crustal evolution along the southern Congo craton - Kleinhanns, I. C.; Fullgraf, T.; Wilsky, F.; Nolte, N.; Fliegel, D.; Klemd, Reiner; Hansen, Bent (Continent Formation Through Time., 2013)
The formation of the Kamanjab Inlier (KI) in NW Namibia is poorly known and constrained to alaeoproterozoic times. With the Epupa complex (EC) and Grootfontein Inlier (GI), the KI marks the southwestern Congo craton margin. Our new geochemical data for granitoids and orthogneisses indicate formation along an active continental margin. Single zircon ages frame granitoid emplacement to 1.86–1.83 Ga, roughly 75 myr older than ages from the northern EC and approximately 100 myr younger than from the GI. The southern EC is the only known Archaean Namibian basement with 1Nd1.85 Ga of 210.2 to 26.3, in contrast to northern EC (21.8 to 4.4) and KI (26.2 to 2.6). Thus, earlier speculation that the southern EC is an exotic terrane, among the Namibian basement complexes, is supported by our data. In contrast, the KI is geochemically comparable to the northern EC and GI. The c. 2.0 Ga Lufubu metamorphic complex roughly 1000 km further east shows similar geochemistry, and a common evolution in the Kamanjab–Bangeweulu magmatic arc has already been proposed. Therefore, our new data point to a major Palaeoproterozoic crustal growth event at the southwestern margin of the Congo Craton starting in the present east and gradually moving towards the present NW.<br
UnivIS-Import:2015-04-20:Pub.2013.nat.dgeo.IGM.c3geoc.upbzir

Upper Cretaceous (Coniacian-Santonian) low diversity oyster-dominated macrofaunal association in the Eastern Desert of Egypt: Taphonomy versus ecology - Abdelhady, Ahmed Awad; Ayoub-Hannaa, Wagih; Ahmed, Mohamed S.; Hussain, Ali M. (Journal of African Earth Sciences, 2023)
In contrast to the Cenomanian-Turonian, the Coniacian-Santonian macroinvertebrates of the Middle East and North Africa are rarely investigated. Previous investigations indicated the occurrence of low diversity faunal associations, which can be attributed either to ecological (primary/biogenic) or taphonomic (secondary/sedimentologic) factors. The poorly preserved macrofauna of the Hawashia Formation (north Eastern Desert, Egypt) has been quantitively analyzed resulting in the identification of fifteen macrofaunal species including five bivalve, seven gastropod, two ammonite taxa, and one echinoid taxon. The occurrence of the ammonites Metatissotia fourneli Bayle and Texanites (T.) texanus Roemer confirm the Coniacian‒Santonian age for the Hawashia Formation. Based on litho- and biofacies, this fauna likely lived in a normal oxygen tidal-influenced shallow subtidal environment under arid conditions. Taphofacies indicates a low-energy regime with low sedimentation rate. Most shells are highly damaged (encrusted, bioeroded, and fragmented) due to their long residence time in the Taphonomic Active Zone (TAZ). Few of the benthic species have a wide geographic distribution (e.g., Oscillopha dichotoma), which generally imply low sea-level. In contrast, ammonites have been precariously recorded from Africa, Europe, and Asia in addition to South America, outlines a cosmopolitan attitude.
CRIS-Team Scopus Importer:2023-10-27
Keywords: Hawashia formation; Macrofaunal associations; North Africa; Paleoecology; Taphofacies; Upper cretaceous

Upper crustal fluids in a large fault system: microstructural, trace element and oxygen isotope study on multi-phase vein quartz at the Bavarian Pfahl, SE Germany - Schaarschmidt, Anna; Haase, Karsten; de Wall, Helga; Bestmann, Michel; Krumm, Stefan; Regelous, Marcel (International Journal of Earth Sciences, 2018)
Fault systems are zones of crustal weakness and are used as pathways for ascending hydrothermal fluids. One impressive example is the more than 150 km long Bavarian Pfahl system at the SW boundary of the Bohemian Massif. Dextral ductile shearing of Moldanubian basement has shaped a several hundred meter wide zone of mylonites and ultramylonites. This setting was reactivated under brittle conditions and infiltrated by fluids resulting in a multi-phase quartz lode. Structural analysis using scanning electron microscopy cathodoluminescence (SEM–CL) images has been carried out in combination with trace element and oxygen isotope analysis on quartz along the system. Three successive quartz phases have been distinguished due to their structural details and trace element contents. Cryptocrystalline quartz fabric in the first quartz phase results from crystallization from a silica gel, whereas in phases II and III, quartz precipitation is characterized by repeated fragmentation and sealing, visible due to strongly varying CL intensities. The δ18O of Bavarian Pfahl quartz decreases from 13.8‰ in the NW to 8.5‰ in the SE, whereas quartz from the close-by-situated Wölsendorf fluorite deposit shows δ18O between 15.9 and 18.5‰ (vs. SMOW). Flat shale-normalized rare earth element patterns point towards an upper crustal origin of the hydrothermal fluids. The southeastern part of the Bavarian Pfahl is interpreted to represent a deeper crustal level with higher mineralization temperatures (about 350 °C) compared to the rest of the Pfahl (< 250 °C
Keywords: Quartz microfabric; Cathodoluminescence; Hydrothermal fluid; Trace elements; Oxygen isotopes

Upper Ordovician carbon isotope chemostratigraphy and a high-resolution assessment of the Hirnantian Stage in the Baltic Sea subsurface - Gunnarsson, Niklas; Calner, Mikael; Rasmussen, Christian M.Ø.; Wu, Rongchang; Lehnert, Oliver; Dahlqvist, Peter (GFF, 2024)
Based on a new deep drilling on southern Gotland (Sweden), this study is the first to document the carbon isotope chemostratigraphy of the Upper Ordovician through lowermost Silurian sedimentary record from the central parts of the Baltic Sea subsurface. The lithological record of the Stora Sutarve core has similarities with adjacent successions in both the Viki core in the East Baltic area and the Borenshult core in the Swedish mainland. The core includes the Kahula (including 13 bentonites in the “Kinnekulle K-bentonite complex”), Hirmuse(?), Rägavere, Paekna, Jonstorp, Loka, Motala and Kallholn formations. Several of the internationally recognized upper Ordovician δ13C excursions have been identified in the core, including the Guttenberg Isotope Carbon Excursion (GICE), Moe excursion, Hirnantian Isotope Carbon Excursion (HICE), and an undefined early Silurian carbon isotope excursion, presumably the Early Aeronian Carbon Isotope Excursion (EACIE). We particularly address the microstratigraphy of the Hirnantian Stage and the finer details of the HICE, which is not fully complete and entirely confined to the 2.09-m-thick Loka Formation. This formation yields abundant, but low-richness brachiopod faunas characteristic of the Hirnantian Stage and is, based on erosional-depositional surfaces and facies, interpreted as reflecting interglacial warming and eustatic transgression related to ice-sheet contraction in Gondwana. Based on very dense carbon isotope sampling we identify four clusters of δ13C values that aid to define significant changes in the preserved record of the HICE and which may facilitate global correlation of the succession and the herein interpreted sea-level record.
CRIS-Team Scopus Importer:2024-05-17
Keywords: Brevilamnulella; Carbon isotope stratigraphy; eustasy; Hirnantia fauna; Loka Formation; Palaeoclimate; sea-level; Skultorp Member; Sweden

Upper Rotliegend to Early Cretaceous basin development. - Stollhofen, Harald; Bachmann, Gerhard; Barnasch, Jens; Bayer, Ulf; Beutler, Gerhard; Franz, Matthias; Kästner, Marleen; Legler, Berit; Mutterlose, Jörg; Radies, Dirk (Dynamics of complex intracontinental basins. The Central European Basin System., 2008)
UnivIS-Import:2015-04-20:Pub.2008.nat.dgeo.IGM.LG.upperr

Upper Triassic reefs of southwestern Turkey: evidence of reef boulders (‘Cipits’) - Flügel, Erik; Link, Michael (Göttinger Arbeiten zur Geologie und Paläontologie, 1996)
Most Carnian and Norian reefs occurring in Southwestern Turkey (Antalya and Isparta region) are represented by redeposited reef talus (“Cipits”). The “Cipits” occur in “Cipit fields” within siliciclastic basinal sediments and represent redeposited parts of sponge and coral patch reefs. Lower Carnian Cipit blocks differ distinctly in faunal composition and association patterns from the Upper Norian/Rhaetina reefs.
Keywords: Cipit; reef; reef talus; sponge; coral; Carnain; Norian; Antalya; Isparta; Turkey

Uranium-series dating of travertine from Süttö: Implications for reconstruction of environmental change in Hungary - Sierralta, Melanie; Sandor Kele,; Melcher, Frank; Hambach, Ulrich; Reinders, Jan; van Geldern, Robert; Frechen, Manfred (Quaternary international, 2010)

Ursachenforschung zur geothermischen Anomalie in Nordbayern - Drews, Michael; Bauer, Wolfgang; Fazlikhani, Hamed; Stollhofen, Harald; Kämmlein, Marion; Potten, Martin; Thuro, Kurosch; de Wall, Helga (Geothermische Energie, 2019)

Use of Electrical Resistivity Tomography measurements for investigation of different grouting materials for very shallow geothermal applications within varying seasonal conditions; applied on a geothermal Earth-Air Heat Exchanger system. - Schwarz, Hans; Lin, Jian; Bertermann, David (Renewable Energy, 2024)
To achieve the current climate targets, heat pump systems like very shallow geothermal applications are gaining ground. However, the dimensioning of these ground coupled systems is soil-dependent and thus subject to significant differences in efficiency. Furthermore, the thermal properties of the grouting materials are essential for heat transfer in the direct vicinity of the geothermal application. To provide a non-invasive assessment of relevant soil and grouting characteristics, electrical resistivity tomography (ERT) measurements were performed. In this case, the surrounding of an Earth Air-Heat Exchanger – system (EAHE) with different grouting materials (fine sand and fine sand with bentonite) was investigated. For investigation the electrical resistivity (ER) of initial and modified soil conditions were measured regarding soil texture and moisture content. Thereby, the different grouting materials are clearly identified. Thus, based on the ERT measurements, a characterisation of key soil and grouting material properties for applications focusing on heat transfer in soil has been carried out. Furthermore, the depth of soil disturbance due to the EAHE installation could have been traced. Due to a monitoring over different season (February and May) changes in raw ER data could have been ascribed to temperature change
Keywords: Electrical resistivity tomography; Soil properties; Earth air-heat exchanger; Very shallow geothermal; Grouting material; Seasonal impact

Use of single-grain geochemistry of cryptic tuffs and volcaniclastic sandstones improves the tephrostratigraphic framework of Olduvai Gorge, Tanzania. - Mchenry, Lindsay J.; Stollhofen, Harald; Stanistreet, Ian G. (Quaternary Research, 2013)
Single-grain geochemical composition of volcaniclastic sandstones can be a potential tool to improve correlations of mixed pyroclastic/epiclastic deposits. To test this, trachytic tuffs of the paleoanthropologically important FLK, FLK N, and FLK NN sites of Pleistocene Olduvai Gorge Bed I (Tanzania) are used as an established tephrostratigraphic framework against which to test volcaniclastic sandstone correlations. Fluvio-lacustrine sandstones and tuff samples were collected from eight archeological trenches between Tuffs IB and ID across a 500-m transect, including Leakey's famous Zinjanthropus (FLK) and OH 7/OH 8 (FLK NN) sites. A previously unknown, thin, fine, mineralogically unique, black trachyandesitic fallout ash was discovered below Tuff IC. Compositions of individual augite, feldspar and titanomagnetite grains from sandstones between Tuffs IB and IC reveal some IB-equivalent material, and a new compositional assemblage distinct from the sandwiching marker tuffs. Mineral compositions of the "tripartite" volcaniclastic sandstone between Tuffs IC and ID are similar to ID. Volcaniclastic sandstone grain fingerprints further refine correlations between fluvio-lacustrine sections within the area, providing support for proposed high-resolution stratigraphic reconstruction of the Zinjanthropus and OH 7/OH 8 land surfaces. This method might be applied to other sections where pyroclastic particles are admixed but distinct tuffs are not preserved. © 2013 University of Washington.
UnivIS-Import:2015-03-09:Pub.2013.nat.dgeo.IGM.LG.useofs
Keywords: Olduvai Gorge; Pleistocene; Sedimentology; Tephrostratigraphy

Using abundance data to assess the relative role of sampling biases and evolutionary radiations in Upper Muschelkalk ammonoids - Mcgowan, Alistair J.; Kießling, Wolfgang (Acta Palaeontologica Polonica, 2013)
The Middle Triassic ammonoid genus Ceratites diversified spectacularly within the Germanic Muschelkalk Basin during the Anisian/Ladian (244-232 Mya). Previous studies have interpreted this diversification as a sequence of rapid, endemic radiations from a few immigrant taxa. Here we investigate the possibility that geological and sampling biases, rather than ecological and evolutionary processes, are responsible for this pattern. A new specimen-based dataset of Ceratites species-richness and abundance was assembled. This dataset was combined with 1:200 000 geological maps in a geodatabase to facilitate geospatial analyses. One set of analyses compared species richness per geological map with the number of occurrences and localities per map. Per-map change in the amount of rock available to sample for fossils was also included as a variable. Of these three variables, number of occurrences is the most strongly correlated with richness. Variation in the amount of rock is not a strong determinant of species-richness. However, rarefaction of basin-wide species/abundance data demonstrates that differences in species-richness through time are not attributable to sample size differences. The average percent similarity among sites remained close to 50% throughout the Upper Muschelkalk. The rank abundance distribution (RAD) of species from the first interval of the Upper Muschelkalk is consistent with colonization of a disturbed environment, while the other two intervals have RADs consistent with more stable ecosystems. These results indicate that genuine ecological and evolutionary events are partly responsible for the observed differences in richness and abundance. Although changes in the RADs through time support changes in the ammonoid assemblage structure, the processes underlying increasing richness and change in RADs cannot be explained by increasing geographic distinctiveness or isolation among the ammonoid assemblages present at different localities. © 2013 A.J. McGowan and W. Kiessling. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
UnivIS-Import:2015-03-09:Pub.2013.nat.dgeo.IGM.LP.usinga
Keywords: Ammonoidea; Biodiversity; Ceratites; Muschelkalk; Palaeoecology; Rank abundance; Triassic

Using fractured outcrops to calculate permeability tensors: implications for geothermal fluid flow and the influence of seismic-scale faults - Smith, Ruaridh; Lesueur, Martin; Kelka, Ulrich; Poulet, Thomas; Köhn, Daniel (Geological Magazine, 2022)
Faulted and fractured systems form a critical component of fluid flow, especially within low-permeable reservoirs. Therefore, developing suitable methodologies for acquiring structural data and simulating flow through fractured media is vital to improve efficiency and reduce uncertainties in modelling the subsurface. Outcrop analogues provide excellent areas for the analysis and characterization of fractures within the reservoir rocks where subsurface data are limited. Variation in fracture arrangement, distribution and connectivity can be obtained from 2D fractured cliff sections and pavements. These sections can then be used for efficient discretization and homogenization techniques to obtain reliable predictions on permeability distributions in the geothermal reservoirs. Fracture network anisotropy in the Malm reservoir unit is assessed using detailed structural analysis and numerical homogenization of outcrop analogues from an open pit quarry within the Franconian Basin, Germany. Several events are recorded in the fracture networks from the Late Jurassic the Alpine Orogeny and are observed to be influenced by the Kulmbach Fault nearby with a reverse throw of 800 m. The fractured outcrops are digitized for fluid flow simulations and homogenization to determine the permeability tensors of the networks. The tensors show differences in fluid transport direction where fracture permeability is controlled by orientation compared to a constant value. As a result, it is observed that the orientation of the tensor is influenced by the Kulmbach Fault, and therefore faults within the reservoirs at depth should be considered as important controls on the fracture flow of the geothermal system.
CRIS-Team WoS Importer:2022-06-10
Keywords: natural fractures; geothermal; numerical modelling; fluid flow; outcrop; permeability tensors

Using LIDAR and ground truth for landslide recognition and characterization of geotechnical and morphological parameters in sedimentary rocks, a case study in Northern Bavaria (Germany) - Wiedenmann, Johannes; Rohn, Joachim; Moser, Michael (Journal of Mountain Science, 2017)
The use of LIDAR-derived shaded relief maps led to the identification of all potential landslide areas in a hilly region in Northern Bavaria (1590 km2), Germany. Every possible structure was investigated by field investigation which resulted in a detailed database of 1002 landslides within the study area. The analysis of geological, lithological, topographical and morphological properties (spatial ratio, lithological and geological setting, length/width distribution, material properties and slope angle) revealed characteristic appearances of the landslides and possible relationships between different aspects. Strong relations between the lithological setting, spatial ratio of the mapped landslides and distribution of slope angle could be observed. This study shows the value of high-resolution shaded relief maps for detecting and mapping landslides in a large area with comparatively little work and time in comparison to the traditional approach to mapping. It reveals that many landslides were not known before. Landslides are much more common in Northern Bavaria and have a higher influence on the denudation rate of the Franconian Alb than expected before. © 2017, Science Press, Institute of Mountain Hazards and Environment, CAS and Springer-Verlag GmbH Germany.

Using PCA in evaluating event-controlling attributes of landsliding in the 2005 Kashmir earthquake region, NW Himalayas, Pakistan - Basharat, Muhammad; Ali, Abid; Jadoon, Ishtiaq A. K.; Rohn, Joachim (Natural Hazards, 2016)
Keywords: 2005 Kashmir earthquake; Co-seismic landslides; Epicentre; Key influential factors; Muzaffarabad Fault

Using Thermal Springs to Quantify Deep Groundwater Flow and Its Thermal Footprint in the Alps and a Comparison With North American Orogens - Luijendijk, Elco; Winter, Theis; Köhler, Saskia; Ferguson, Grant; von Hagke, Christoph; Scibek, Jacek (Geophysical Research Letters, 2020)
The extent of deep groundwater flow in mountain belts and its thermal effects are uncertain. Here, we use a new database of discharge, temperature, and composition of thermal springs in the Alps to estimate the extent of deep groundwater flow and its contribution to the groundwater and heat budget. The results indicate that thermal springs are fed exclusively by meteoric water and make up 0.1% of the total groundwater budget. Spring water circulates on average to a depth of at least 2 km. The net heat extracted from the subsurface equals 1% of the background heat flow, which equals an average thermal footprint of 7 km2. Cooling by downward flow and heating by upward flow are three and two times higher than the net heat flow, respectively. Comparison with North American orogens shows that hydrothermal activity is higher in areas with high relief or areas under extension.
CRIS-Team Scopus Importer:2020-12-04
Keywords: Alps; groundwater; heat flow; thermal springs

U-Th-Ra disequilibria and the extent of off-axis volcanism across the East Pacific Rise at 9°30′N, 10°30′N, and 11°20′N - Turner, Simon; Beier, Christoph; Niu, Yaoling; Cook, Craig (Geochemistry Geophysics Geosystems, 2011)
There is widespread interest in the distance that mid-ocean ridge magmatism extends beyond the neovolcanic zone. Off-axis magmas also provide a means to map out variations across the melting zone. We present U- Th-Ra data for 35 well-characterized samples that extend up to 50 km away from the ridge axis across the East Pacific Rise at 9°30′N, 10°30′N, and 11°20′N. The ( Th/U) ratios range from 1.00 to 1.19, and the ( Ra/Th) ratios range from 1 to 2.78. The samples have a bimodal (Th/U) distribution with approximately half overlying published axial data on the U-Th diagram and the remainder lying close to the equiline. The U series disequilibria in the majority of the samples can be explained by aging subsequent to eruption in a zone ∼8 km wide about the neovolcanic zone, consistent with visual evidence for sample age. Nevertheless, seven of the samples lie above calculated (Th/ U) axial decay curves and/or have Ra excesses implying eruption tens of kilometers off axis. These are consistent with evidence from seamounts and seismic interpretations that magmatism can extend up to 20 km off axis. The implication is that magma is not as efficiently focused beneath the ridge axis as has generally been believed. There is a decrease in initial (Th/U) in both these and published samples inferred to have formed off axis, but there is no compelling evidence that this reflects source heterogeneity. Simple modeling suggests that this could be explained by a decrease in fertility and melt column length as the overlying lithosphere thickens with age and the solidus shallows. Copyright 2011 by the American Geophysical Union.
Keywords: East Pacific Rise; mid-ocean ridge basalt; off-axis magmatism; U-Th-Ra disequilibria

Variation of magma generation and mantle sources during continental rifting observed in Cenozoic lavas from the Eger Rift, Central Europe - Haase, Karsten; Renno, Axel (Chemical Geology, 2008)
The 400 km long Eger Rift is one of the major extensional structures in Central Europe and is associated with abundant Tertiary to Quaternary volcanic rocks occurring both within the rift and mainly on its NW uplifted flank. Primitive lavas predominate with compositions ranging from alkali basalts to nephelinites and melilitites. Lavas in the rift centre show similar Si-undersaturation, incompatible element enrichment, and Sr, Nd, and Pb isotope compositions as rocks on the flanks of the Eger Rift suggesting similar degrees of partial melting and mantle sources. Crustal assimilation is abundant and increases with evolution of the magmas. The Eger Rift crosses several different lithospheric units but no systematic changes of magma sources appear to exist across lithospheric boundaries. Three different mantle sources can be defined in the Eger Rift magmas. Two of these sources must be enriched in incompatible elements as they yield the most enriched magmas and probably reside in the lithosphere because they show evidence for residual amphibole. The most common of these end-members resembles the so-called FOZO mantle source and occurs in the asthenosphere. The (Ce/Yb)N in the central part of the Eger Rift are lower than at the western end of the rift suggesting higher degrees of partial melting in the central part which apparently correspond to the narrowing of the rift, i.e. less extension in its western part. © 2008 Elsevier B.V. All rights reserved.
UnivIS-Import:2015-03-09:Pub.2008.nat.dgeo.IGM.legeo.ariati
Keywords: Alkaline magmas; Intraplate volcanism; Isotopes; Trace elements

Variation of melting processes and magma sources of the early Deccan flood basalts, Malwa Plateau, India - Haase, Karsten; Regelous, Marcel; Schöbel, Stefan; Günther, Thomas; de Wall, Helga (Earth and Planetary Science Letters, 2019)
The Deccan flood basalts cover large parts of India and represent one of the largest volcanic provinces on Earth. We present geochemical and isotopic data on a magnetically defined stratigraphic section of lavas from the northern portion of the Deccan, the Malwa Plateau, which are dated at similar to 67.5 Ma. These are therefore some of the oldest Deccan lavas, erupted before the Main Deccan units further to the south. Although the younger Malwa Plateau lavas have undergone significant crustal contamination by at least two distinct crustal components, the older, more alkalic lavas are less contaminated and have similar isotope and trace element compositions to Reunion oceanic intraplate basalts. Our data therefore provide geochemical evidence for a contribution of the Reunion hotspot to the generation of the early Deccan flood basalts. Most lavas reflect fractional crystallization and assimilation of less than 10% of a crustal melt but samples with the highest SiO2 and Sr isotope compositions underwent more extreme crustal contamination. The composition of the least contaminated basalts from the Malwa Plateau suggests that the degree of partial melting increased significantly from the base to the top of the section. Most Malwa Plateau basaltic magmas formed by <5% partial melting of garnet peridotite in the Reunion mantle plume whereas the degree of melting in the Main Deccan Volcanic Province increased threefold and included MORB sources. Together, these geochemical variations indicate increasing degrees of melting between 68.5 and 65.4 Ma and a variation of the mantle sources from Reunion plume mantle to an increasing contribution from depleted upper mantle. These changes probably reflect lithospheric erosion by the mantle plume within 2 million years that allows melting of entrained upper mantle material. The geochemical data thus agree with geophysical models of significant thinning of cratonic lithosphere during the passage across mantle plumes. The magma evolution from alkaline to tholeiitic basalts observed in the Deccan flood basalts resembles that observed in early oceanic plume-related volcanism like Hawaii. (C) 2019 Elsevier B.V. All rights reserved.
CRIS-Team WoS Importer:2019-09-24

Variations in preservation of exceptional fossils within concretions - Saleh, Farid; Clements, Thomas; Perrier, Vincent; Daley, Allison C.; Antcliffe, Jonathan B. (Swiss Journal of Palaeontology, 2023)
Concretions are an interesting mode of preservation that can occasionally yield fossils with soft tissues. To properly interpret these fossils, an understanding of their fossilization is required. Probabilistic models are useful tools to identify variations between different Konservat-Lagerstätten that are separated spatially and temporally. However, the application of probabilistic modeling has been limited to Early Paleozoic Konservat-Lagerstätten preserved in shales. In this paper, the patterns of preservation of three concretionary Konservat-Lagerstätten—the Carboniferous Mazon Creek (USA) and Montceau-les-Mines (France), and the Silurian Herefordshire Lagerstätte (UK)—are analyzed using a statistical approach. It is demonstrated that the degree of biotic involvement, i.e., the degree to which a carcass dictates its own preservation, is connected to internal organ conditional probabilities—the probabilities of finding an internal organ associated with another structure such as biomineralized, sclerotized, cuticularized, or cellular body walls. In concretions that are externally forced with little biological mediation (e.g., Herefordshire), all internal organ conditional probabilities are uniform. As biological mediation in concretion formation becomes more pronounced, heterogeneities in conditional probabilities are introduced (e.g., Montceau-les-Mines and Mazon Creek). The three concretionary sites were also compared with previously investigated Konservat-Lagerstätten preserving fossils in shales to demonstrate how the developed probability framework aids in understanding the broad-scale functioning of preservation in Konservat-Lagerstätten.
CRIS-Team Scopus Importer:2023-09-22
Keywords: Carboniferous; Concretions; Exceptional fossils; Konservat-Lagerstätte; Silurian

Variations in primary aragonite, calcite, and clay in fine-grained calcareous rhythmites of Cambrian to Jurassic age - an environmental archive? - Munnecke, Axel; Westphal, Hildegard (Facies, 2005)
Limestone-marl alternations represent a common type of fine-grained calcareous rhythmites during the entire Phanerozoic. Their diagenetic overprint, however, obliterates their value for palaeoenvironmental interpretations. The original mineralogical composition of the carbonate fraction (aragonite, high-Mg calcite, low-Mg calcite) would potentially yield important information on palaeoenvironmental conditions: for example shallow-water carbonate factories are usually characterised by extensive aragonite production, whereas pelagic carbonate production is dominated by calcitic organisms. Therefore, a reconstruction of the pre-diagenetic mineralogical composition of limestone-marl precursors would be desirable. A particularly conspicuous attribute of fine-grained calcareous rhythmites is the intercalation of two rock types that have undergone two entirely different diagenetic pathways (“differential diagenesis”). As indicated by earlier petrography work, in the interlayers selective aragonite dissolution has taken place, and the dissolved aragonite provided the cement for the limestones. Primary aragonite usually is not preserved in diagenetically mature fine-grained limestones. However, in a recently published paper a method is proposed to quantify the primary mineralogical composition of the precursor sediments of a fine-grained calcareous rhythmite. Here we apply this method to several published data sets from sections of Cambrian to Jurassic age. We try to answer the following questions: Where does the aragonite come from, especially during times of “calcite seas”? What is the impact of the enhanced pelagic carbonate production since the Late Jurassic on the formation of limestone-marl alternations? How much dissolved aragonite is lost to sea water during early marine burial diagenesis, i.e. how closed is the diagenetic system? As demonstrated for the five examples shown here, the new method for reconstructing primary mineralogy potentially provides insight into ancient depositional environments, surface productivity, and ocean chemistr
Keywords: Limestone-marl alternations; Differential diagenesis; Aragonite; Precursor sediment; Calcareous plankton; Phanerozoic

Variscan structures and their control on latest to post-Variscan basin architecture: Insights from the westernmost Bohemian Massif and southeastern Germany - Fazlikhani, Hamed; Bauer, Wolfgang; Stollhofen, Harald (Solid Earth, 2022)
The Bohemian Massif exposes structures and metamorphic rocks remnant from the Variscan orogeny in central Europe and is bordered by the Franconian Fault System (FFS) to the west. Across the FFS, Variscan units and structures are buried by Permo-Mesozoic sedimentary rocks. We integrate existing DEKORP 2D seismic reflection, well, and surface geological data with the newly acquired FRANKEN 2D seismic survey to investigate the possible westward continuation of Variscan tectonostratigraphic units and structures and their influence on latest to post-Variscan basin development. Subsurface Permo-Mesozoic stratigraphy is obtained from available wells and tied to seismic reflection profiles using a synthetic seismogram calculated from density and velocity logs. Below the sedimentary cover, three main basement units are identified using seismic facies descriptions that are compared with seismic reflection characteristics of exposed Variscan units east of the FFS. Our results show upper Paleozoic low-grade metasedimentary rocks and possible Variscan nappes bounded and transported by Variscan shear zones ca. 65km west of the FFS. Basement seismic facies in the footwall of the Variscan shear zones are interpreted as Cadomian basement and overlaying Paleozoic sequences. We show that the location of normal fault-bounded latest to post-Variscan late Carboniferous-Permian basins are controlled by the geometry of underlying Variscan shear zones. Some of these late Carboniferous-Permian normal faults reactivated as steep reverse faults during the regional Upper Cretaceous inversion. Our results also highlight that reverse reactivation of normal faults gradually decreases west of the FFS. Copyright:
CRIS-Team Scopus Importer:2022-03-11

Variscan terrane boundaries in the Odenwald-Spessart basement, Mid-German Crystalline Zone: New evidence from ocean ridge, intraplate and arc-derived metabasaltic rocks - Will, T. M.; Lee, S. -H.; Schmädicke, Esther; Frimmel, H. E.; Okrusch, M. (Lithos, 2015)
Keywords: Metabasite; Eclogite; Odenwald; Mid-German Crystalline Zone; Terrane boundary; Spessart

Vegetation landscape at DK locality, Olduvai Gorge, Tanzania - Albert, Rosa Maria; Bamford, Marion; Stanistreet, Ian G.; Stollhofen, Harald; Rivera-Rondón, Carlos; Rodríguez-Cintas, Agatha (Palaeogeography, Palaeoclimatology, Palaeoecology, 2015)
The Olduvai Gorge palaeoanthropological site, in northern Tanzania, encompasses about two million years of earth history. The sedimentary facies of Palaeolake Olduvai have been used to reconstruct lake transgressions and regressions, up to total drying out, interpreted to reflect wet/dry climate cycles. Although multidisciplinary research has been conducted during the past decades to reconstruct the palaeoenvironments and palaeolandscapes of the Gorge, very few focused on the DK site located about 2 km farther east in the Gorge. We present here a vegetation study at DK for Bed I, the oldest stratum, based upon the phytolith and diatom recovery of the basalt lava to Tuff IB stratigraphic interval. These results have been analysed in relation to the different facies in which they occur: sandy diamictite, sandstone, sandy waxy claystone, waxy claystone, and sandy diatomite. The phytolith results from diamictite samples indicate a similar vegetation composition during these more arid periods. Conversely, waxy claystone and sandy waxy claystone samples show a higher diversity in the vegetation composition. The diatoms were indicative of a fresh water pool environment. Thus the DK site would have provided plant foods for hominins, such as fruits fromtrees and shrubs and starch-rich rhizomes and tubers fromsedges and reeds. Overall, the results at DK site present a different vegetation landscape in comparison to previously published phytolith results from other Olduvai stratigraphic levels and regions.
Keywords: Diatoms; Eastern Africa; Olduvai Gorge; Palaeoenvironment; Phytoliths; Pleistocene

Vertebrate diversity reveals perturbations in faunal communities prior to the Hangenberg event in the Montagne Noire (France) - Assemat, Alexandre; Girard, Catherine; Joachimski, Michael; Adnet, Sylvain (Bulletin of Geosciences, 2022)
The Hangenberg crisis represents a mass extinction marked by a biodiversity turnover at the Devonian-Carboniferous boundary. However, the last million years before this dramatic event have been poorly investigated. Here we report new data on the size and abundances of vertebrate remains as well as carbon isotope data from the latest Famennian in the Montagne Noire (France). A significant decrease in fish abundance and a general reduction in the size of vertebrate remains are observed during a period of stable environment before the onset of the Hangenberg crisis. No perturbations are recorded by the carbon isotopes, supporting the stability of the environment. This significant change in the structuration of vertebrate communities prior to the Hangenberg crisis is not linked to any turnover in other faunal groups. That could be interpreted as changes in faunal repartition that predate mass extinctions.
Keywords: Famennian; Hangenberg; vertebrate teeth; Montagne Noire; vertebrate diversity; carbon isotopes

Vertebrate remains and conodonts in the upper Silurian Hamra and Sundre formations of Gotland, Sweden - Bremer, Oskar; Jarochowska, Emilia; Märss, Tiiu (GFF, 2019)
A long history of geological research on the island of Gotland, Sweden, has resulted in a detailed biostratigraphy based on conodonts for the Gotland sedimentary succession, but the relation between the Hamra and Sundre formations, the youngest strata on southern Gotland, has remained poorly resolved. These formations have also remained relatively poorly described in terms of vertebrates compared to other parts of the succession. A survey of museum collections and newly sampled material reveal that the taxonomical compositions and richness of vertebrate faunas remain similar compared to the underlying Burgsvik Sandstone and Oolite members. However, the relative abundance of the respective groups changes: Paralogania ludlowiensis and rare osteostracan remains of Tahulaspis sp. only occur in samples from the lower Hamra Formation, while Thelodus sculptilis becomes more common in samples from Sundre Formation. Conodont and isotope data give support to previous suggestions that the Hamra and Sundre formations may be largely isochronous, and it is possible that the observed differences in vertebrate faunas reflect changes in depositional setting. This interval on Gotland has been suggested to represent a hiatus in the East Baltic sections, where younger strata show an increased importance of acanthodians in the vertebrate faunas. Gotland could therefore give insights into the early stages of this diversification of gnathostomes during late Silurian times. However, this has to be done in combination with data from other areas, as well as with a review and revision of the scale-based taxonomy of Silurian acanthodians from the Baltic Basin.<br
Keywords: Vertebrate microremains; conodonts; isotope stratigraphy; upper Silurian; Gotland; Sweden

Vertical stress history and paleoburial in foreland basins unravelled by stylolite roughness paleopiezometry: Insights from bedding-parallel stylolites in the Bighorn Basin, Wyoming, USA. - Beaudoin, Nicolas; Lacombe, Olivier; Köhn, Daniel; David, Marie Eléonore; Farrell, Natalie; Healy, David (Journal of Structural Geology, 2020)
We apply the stylolite roughness inversion technique on sedimentary, bedding-parallel stylolites hosted in the Paleozoic carbonates of the Bighorn and Madison formations cropping out in the Bighorn Basin, Wyoming, USA. The inversion technique applied to bedding-parallel stylolites allows determination of the absolute magnitude of the vertical stress experienced at the time dissolution stops along the pressure-solution planes. At the basin scale, reconstructed vertical stress magnitudes range from 19 ± 2 MPa to 35 ± 4 MPa in the Bighorn Fm, and from 12 ± 2 MPa to 37 ± 4 MPa in the Madison Fm. Once converted into depth and compared with up-to-date basin models of burial and contractional history, the dataset highlights that bedding-parallel stylolites accommodated compaction from ca. 220 Ma until ca. 90 Ma, i.e. until stress build-up related to the Sevier contraction made the maximum horizontal principal stress high enough to overcome the vertical principal stress. This study is key to illustrate how stylolites can be used to consistently access paleoburial and to unravel both stress evolution and timing in foreland settings, and indicates that pressure-solution remains active throughout the carbonate deposition history.
CRIS-Team Scopus Importer:2020-04-24

Victims of ancient hyperthermal events herald the fates of marine clades and traits under global warming - Reddin, Carl James; Kocsis, Ádám; Aberhan, Martin; Kießling, Wolfgang (Global Change Biology, 2020)
Organismic groups vary non-randomly in their vulnerability to extinction. However, it is unclear whether the same groups are consistently vulnerable, regardless of the dominant extinction drivers, or whether certain drivers have their own distinctive and predictable victims. Given the challenges presented by anthropogenic global warming, we focus on changes in extinction selectivity trends during ancient hyperthermal events: geologically rapid episodes of global warming. Focusing on the fossil record of the last 300 million years, we identify clades and traits of marine ectotherms that were more prone to extinction under the onset of six hyperthermal events than during other times. Hyperthermals enhanced the vulnerability of marine fauna that host photosymbionts, particularly zooxanthellate corals, the reef environments they provide, and genera with actively burrowing or swimming adult life-stages. The extinction risk of larger sized fauna also increased relative to non-hyperthermal times, while genera with a poorly buffered internal physiology did not become more vulnerable on average during hyperthermals. Hyperthermal-vulnerable clades include rhynchonelliform brachiopods and bony fish, whereas resistant clades include cartilaginous fish, and ostreid and venerid bivalves. These extinction responses in the geological past mirror modern responses of these groups to warming, including range-shift magnitudes, population losses, and experimental performance under climate-related stressors. Accordingly, extinction mechanisms distinctive to rapid global warming may be indicated, including sensitivity to warming-induced seawater deoxygenation. In anticipation of modern warming-driven marine extinctions, the trends illustrated in the fossil record offer an expedient preview.
CRIS-Team Scopus Importer:2020-12-04
Keywords: climate change; extinction; fossil; metabolic activity; photosymbiont; selectivity

Vision and the diversification of Phanerozoic marine invertebrates - Aberhan, Martin; Nuernberg, Sabine; Kießling, Wolfgang (Paleobiology, 2012)
Identifying biological traits that promote evolutionary success is fundamental for understanding biodiversity dynamics and for assessing the evolutionary response of organisms to global change. We tested the hypothesis that image-forming eyes have contributed to the diversification of taxa in the geological past. Using fossil occurrences in the Paleobiology Database, we analyzed the diversity and evolutionary rates of more than 17,000 Phanerozoic genera of marine invertebrates living on or above the shallow-water seafloor according to their visual capabilities. Analysis of the complete data set shows a peak in the proportional diversity of sighted genera early in the Phanerozoic, and their continuance at a relatively low and stable level after the Ordovician. As an explanation of this pattern we suggest that selection pressure to develop eyes rose in the Cambrian, and that behavioral constraints had a balancing effect thereafter. In contrast to the pooled data, a clade-level study of those subgroups that contain both sighted and blind genera revealed thatin trilobites, all epifaunal bivalves, pectinoid bivalves, gastropods, and echinodermssighted genera diversified more strongly than blind genera. This difference is controlled by significantly raised extinction rates of blind genera. These more finely resolved patterns support the hypothesis that good vision is a key trait that promoted preferential diversification. © 2012 The Paleontological Society. All rights reserved.
UnivIS-Import:2015-03-09:Pub.2012.nat.dgeo.IGM.LP.vision

Vitinellopsis nov. gen., a new calcareous alga (Chlorophyta, Bryopsidales) from the Silurian of Gotland (Sweden), and the tribe Vitinelleae nov. nom - Vachard, Daniel; Bucur, Ioan I.; Munnecke, Axel (Geobios, 2021)
The algal genus Vitinellopsis nov. gen. is well represented in the Silurian limestones of Gotland (Sweden). This new taxon is interpreted as a calcified codiacean alga (Chlorophyta, Bryopsidales). In the studied material, the calcareous wall of sparry calcite, probably originally aragonitic, appears well preserved. The subcylindrical thallus, with rounded ends, rarely bifurcated, measures up to 27 mm long and 2.5 mm wide. The medullar zone exhibits 4–6 longitudinal, subtly undulating siphons; the subcortical zone shows inflated, vesiculiform radial siphons, and the cortical zone displays small, relatively short acrophorous siphons. The status of the tribe Vitinelleae nomen novum, formerly Bothryelleae, is discussed. Given its abundance, ease of identification, and short stratigraphic range, Vitinellopsis gotlandica nov. gen., nov. sp. may prove useful for regional correlations, facies and paleobiogeographic studies.
CRIS-Team Scopus Importer:2021-12-24
Keywords: Bryopsidales; Calcareous algae; Codiaceae; Gotland; New taxa; Silurian

Volcanic and sedimentary rocks reveal the Paleozoic tectonic evolution of the Lhasa Terrane, Tibet - He, Qing; Lang, Xinghai; Wang, Xuhui; Deng, Yulin; Xie, Fuwei; Scott, James M.; Lou, Yuming (International Geology Review, 2022)
The central Lhasa Terrane preserves the geological record of the opening, subduction, and closure of the Paleo-Tethys Ocean. However, the early tectonic history of the Paleo-Tethys Ocean remains unclear. Here, we present the results of a systematic study of Paleozoic volcanic-sedimentary rocks of the central Lhasa Terrane. The composition of Paleozoic sandstone includes quartz, potassium feldspar, plagioclase, lithic fragments, and a small amount of sericite. Qt-Ft-Lt Dickinson ternary diagrams reveal that the Paleozoic succession includes feldspatho-litho-quartzose sandstone (Gangsangmu and Yongzhu formations), litho-feldspatho-quartzose sandstone (Lower Laigu and Lower Laga formations), litho-quartzo-feldspathic sandstone (Upper Laigu and Upper Laga formations), and quartzo-litho-feldspathic sandstone (Luobadui formation). The Late Ordovician Gangsangmu formation shows passive margin characteristics controlled by sediment recycling. The Early Carboniferous-Late Carboniferous Yongzhu formation is derived from an evolved arc. The Late Carboniferous Lower Laigu and Lower Laga formations were associated with a passive margin controlled by sediment recycling. The Early Permian (Upper Laga, Upper Laigu, and Luobadui formations) represent active continental margin sedimentary rocks. The Early Permian volcanic rocks (287 similar to 274 Ma) belong to the calc-alkaline-potassic /shoshonitic series with high positive epsilon(Hf)(t) values. The Early Permian volcanic rocks have high LREE and LILE (e.g. Rb, Sr), and are depleted in HREE and HFSE (e.g. Nb and Ta, Ti), which indicate a subduction-related arc setting. Our findings, combined with previous studies, show that the northern margin of Gondwana was passive in the Late Ordovician. In the Early Carboniferous, a back-arc basin formed on this northern margin due to the subduction of the Paleo-Tethys Ocean. In the Late Carboniferous, the Sumdo Paleo-Tethys Ocean opened, and the southern edge of the central Lhasa Terrane was a passive margin. In the Early Permian, the Sumdo Paleo-Tethys Ocean began its initial northward subducted and formed the arc volcanic rocks on the central Lhasa Terrane.
CRIS-Team WoS Importer:2022-10-21

Volcanic arcs fed by rapid pulsed fluid flow through subducting slabs - John, Timm; Gussone, Nikolaus; Podladchikov, Yuri Y.; Bebout, Gray E.; Dohmen, Ralf; Halama, Ralf; Klemd, Reiner; Magna, Tomas; Seitz, Hans-Michael (Nature Geoscience, 2012)
At subduction zones, oceanic lithosphere that has interacted with sea water is returned to the mantle, heats up during descent and releases fluids by devolatilization of hydrous minerals. Models for the formation of magmas feeding volcanoes above subduction zones require largescale transport of these fluids into overlying mantle wedges 1-3. Fluid flow also seems to be linked to seismicity in subducting slabs. However, the spatial and temporal scales of this fluid flow remain largely unknown, with suggested timescales ranging from tens to tens of thousands of years 3-5. Here we use the Li-Ca-Sr isotope systems to consider fluid sources and quantitatively constrain the duration of subduction-zone fluid release at ∼ 70 km depth within subducting oceanic lithosphere, now exhumed in the Chinese Tianshan Mountains. Using lithium-diffusion modelling, we find that the wall-rock porosity adjacent to the flowpath of the fluids increased ten times above the background level. We show that fluids released by devolatilization travelled through the slab along major conduits in pulses with durations of about ∼ 200 years. Thus, although the overall slab dehydration process is continuous over millions of years and over a wide range of pressures and temperatures, we conclude that the fluids produced by dehydration in subducting slabs are mobilized in short-lived, channelized fluid-flow events. © 2012 Macmillan Publishers Limited. All rights reserved.
UnivIS-Import:2015-03-09:Pub.2012.nat.dgeo.IGM.c3geoc.volcan

Volcanic Landscapes and Geotourism Development: Analysing How Madeira’s Volcanic Origin Shapes its Tourism Industry, with a Focus on Hiking Tours and Scenic Viewpoints - Sotiriou, Paul; Nunes, Pedro (Geoheritage, 2025)
The volcanic landscapes of Madeira, part of the Madeira Archipelago in the NE Atlantic Ocean, form arguably the defining features of the island. The volcanic landscapes occur in the geoheritage sites of Madeira compiled by Sotiriou and Nunes (2024), and include those in the scenic viewpoints in the Ponta de São Lourenço, Porto da Cruz, São Vicente Valley, Pico Ruivo, and Ponta da Cruz areas. These volcanic landscapes contain geological features of interest, such as lava flows, columnar jointing, dykes, tuffs, and volcanic cones. These volcanic landscapes form the natural scenery for which Madeira is renowned. Geotourism is not as well developed as cultural or biodiversity tourism in Madeira, however, the island’s scenic viewpoints of volcanic landscapes have shaped its tourism industry and provide the potential for the development of hiking tours. Therefore, Madeira’s volcanic origin has greatly shaped the tourism industry on the island and has the potential to continue to do so in the future. Geotourism in Madeira could increase in the future due to the creation of hiking tours of the island’s scenic viewpoints of its volcanic landscapes. The creation of the Madeira Georoute and a UNESCO Global Geopark in Madeira could enhance hiking tours and geotourism, especially if done in a sustainable manner. Hiking tours of the scenic viewpoints of volcanic landscapes in the Ponta de São Lourenço, Porto da Cruz, São Vicente Valley, Pico Ruivo and Ponta da Cruz areas could be set up easily using existing tourism infrastructure, such as roads, parking, accommodation, and restaurants. The existence of hiking trails in Madeira’s geosites provides a good foundation for the development of the proposed Madeira Georoute and UNESCO Global Geopark in Madeira.
CRIS-Team Scopus Importer:2025-04-11
Keywords: Geotourism; Hiking Tours; Madeira; Scenic Viewpoints; Tourism Development; Volcanic Landscapes

Volcanic origin of the mercury anomalies at the Cretaceous-Paleogene transition of Bidart, France - Font, Eric; Chen, Jiubin; Regelous, Marcel; Regelous, Anette; Adatte, Thierry (Geology, 2022)
The timing and mechanisms of the climatic and environmental perturbations induced by the emplacement of the Deccan Traps large igneous province (India) and their contribution to the Cretaceous-Paleogene (K-Pg) mass extinction are still debated. In many marine sediment archives, mercury (Hg) enrichments straddling the K-Pg boundary have been interpreted as the signature of Deccan Traps volcanism, but Hg may also have been derived from the Chicxulub (Mexico) impact. We investigated the Hg isotope composition, as well as the behavior of iridium (Ir) and other trace elements, in K-Pg sediments from the Bidart section in southwest France. Above the K-Pg boundary, Ir content gradually decreases to background values in the Danian carbonates, which is interpreted to indicate the erosion and redistribution of Ir-rich fallouts. No significant enrichment in Ir and W, or Zn and Cu, is observed just below the K-Pg boundary, excluding the hypothesis of downward remobilization of Hg from the boundary clay layer. Positive Delta Hg-199 and slightly negative values in the upper Maastrichtian and lower part of the early Danian are consistent with the signature of sediments supplied by atmospheric Hg2+ deposition and volcanic emissions. Up section, large shifts to strongly negative mass-dependent fractionation values (delta Hg-202) result from the remobilization of Hg formerly sourced by the impactor or by a mixture of different sources including biomass burning, volcanic eruption, and asteroid impact, requiring further investigation. Our results provide additional support for the interpretation that the largest eruptions of the Deccan Traps began just before, and encompassed, the K-Pg boundary and therefore may have contributed to the K-Pg mass extinction.
CRIS-Team WoS Importer:2022-02-11

Volcanic rocks as discriminants in evaluating tectonic versus climatic control on depositional sequences, Permo-Carboniferous continental Saar-Nahe Basin - Stollhofen, Harald; Frommherz, Bernd; Stanistreet, Ian G. (Journal of the Geological Society, 1999)
Keywords: Carboniferous; Permian; Saar-Nahe Basin; Stratigraphy; Strike-slip faults

Volcanic Structures and Magmatic Evolution of the Vesteris Seamount, Greenland Basin - Unger Moreno, Katharina; Thal, Janis; Bach, Wolfgang; Beier, Christoph; Haase, Karsten (Frontiers in Earth Science, 2021)
The formation of isolated seamounts distant from active plate boundaries and mantle plumes remains unsolved. The solitary intraplate volcano Vesteris Seamount is located in the Central Greenland Basin and rises ∼3,000 m above the seafloor with a total eruptive volume of ∼800 km3. Here, we present a new high-resolution bathymetry of Vesteris Seamount and a detailed raster terrain analysis, distinguishing cones, irregular volcanic ridges, volcanic debris fans, U-shaped channels and lava flows. The slope angles, ruggedness index and slope direction were combined with backscatter images to aid geologic interpretation. The new data show that the entire structure is a northeast to southwest elongated stellar-shaped seamount with an elongated, narrow summit surrounded by irregular volcanic ridges, separated by volcanic debris fans. Whole-rock geochemical data of 78 lava samples form tight liquid lines of descent with MgO concentrations ranging from 12.6 to 0.1 wt%, implying that all lavas evolved from a similar parental magma composition. Video footage from Remotely Operated Vehicle (ROV) dives shows abundant pyroclastic and hyaloclastite deposits on the summit and on the upper flanks, whereas lavas are restricted to flank cones. The seamount likely formed above a weak zone of the lithosphere possibly related to initial rifting parallel to the nearby Mohns Ridge, but the local stress field increasingly affected the structure of the volcano as it grew larger. Thus, we conclude that the evolution of Vesteris Seamount reflects the transition from deep, regional lithospheric stresses in the older structures to shallower, local stresses within the younger volcanic structures similar to other oceanic intraplate volcanoes. Our study shows how the combination of bathymetric, visual and geochemical data can be used to decipher the geological evolution of oceanic intraplate volcanoes.
CRIS-Team Scopus Importer:2021-11-19
Keywords: effusive and explosive volcanism; liquid line of descent; oceanic intraplate volcanism; submarine volcano morphology; volcanic flanks

Volcanism of the Central Atlantic magmatic province as the trigger of environmental and biotic changes around the Triassic-Jurassic boundary - Pálfy, József; Kocsis, Ádám (Special Paper of the Geological Society of America, 2014)
In the last decade, major advances have been made in our understanding of the end-Triassic mass extinction, related environmental changes, and volcanism of the Central Atlantic magmatic province. Studies of various fossil groups and synoptic analyses of global diversity document the extinction and subsequent recovery. The concomitant environmental changes are manifested in a series of carbon isotope excursions (CIE), suggesting perturbations in the global carbon cycle. Besides the earlier-recognized initial and main negative anomalies, a more complex picture is emerging with other CIEs, both negative and positive, prior to and following the Triassic-Jurassic boundary. The source of isotopically light carbon remains debated (methane from hydrate dissociation vs. thermogenic methane), but either process is capable of amplifying an initial warming, resulting in runaway greenhouse conditions. Excess CO2 entering the ocean causes acidification, an effective killing mechanism for heavily calcified marine biota that appears implicated in the reef crisis. The spatial and temporal extent of Central Atlantic magmatic province volcanism is established through a growing data set of radiometric ages. Since the Central Atlantic magmatic province is one of the largest Phanerozoic large igneous provinces, volcanic CO2-driven warming is plausible as a key factor in the chain of Triassic-Jurassic boundary events. Greenhouse warming may have been punctuated by short-term cooling episodes due to H2S emission and production of sulfate aerosols, a process more difficult to trace in the stratigraphic record. Taken together, recently generated data significantly increase the support for Central Atlantic magmatic province volcanism as a viable trigger for the environmental and biotic changes around the Triassic-Jurassic boundary.

Volcanism on the flanks of the East Pacific Rise: Quantitative constraints on mantle heterogeneity and melting processes - Brandl, Philipp; Beier, Christoph; Regelous, Marcel; Abouchami, Wafa; Haase, Karsten; Garbe-Schönberg, Dieter; Galer, Steve (Chemical Geology, 2012)
We present major and trace element and Sr, Nd and triple-spike Pb isotope data for 17 fresh volcanic glasses from Seamount 6, a 10-km diameter seamount located 140km east of the East Pacific Rise at 12°45'N. Geological and geochronological evidence show that magma compositions evolved from tholeiitic basalts to alkalic basalts and basaltic trachyandesites during the 1-2Ma active lifetime of the seamount. Major and trace element compositions in Seamount 6 lavas vary systematically with isotope ratios; the youngest lavas with the highest incompatible trace element concentrations have the highest La/Yb, Nb/Zr, K O/TiO , Sr/ Sr, Pb/ Pb and the lowest Nd/ Nd, MgO and CaO. The range in element concentrations, incompatible element ratios, and isotope compositions in Seamount 6 lavas exceeds that observed in lavas erupted at the adjacent ridge axis, and is comparable to the range in lava compositions reported from all near-ridge seamounts studied to date. The observed range in lava compositions is consistent with mixing between enriched and depleted melts at shallow levels in the crust. The inferred difference in composition between these mixing endmembers cannot be explained by variable degrees of melting of a single source composition, and requires that the upper mantle is extremely heterogeneous on the scale of the melting region beneath a single seamount.We can show that the range in composition of EPR seamount lavas cannot be generated by melting of variably heterogeneous mantle in which enriched and depleted materials contribute equally to melting (source mixing). Instead, the trace element and isotope compositions of seamount lavas can be reproduced by melting models in which more enriched, fertile mantle lithologies are preferentially melted during mantle upwelling. At progressively lower degrees of melting, erupted lavas are thus more enriched in incompatible trace elements, have higher La/Yb, K/Ti, Sr/ Sr ratios and lower Nd/ Nd. If this is a common process, then mantle-derived magmas are unlikely to inherit the average incompatible trace element and isotope composition of their mantle source, which is likely to be significantly more depleted, nor will they display the full range of compositions present in the mantle melting region. These results have implications for the way in which oceanic basalts can be used to infer the composition of the upper mantle.
Keywords: EPR; Mantle heterogeneity; Melting dynamics; Modelling; Off-axis; Seamount

Vorwort zum 60-jährigen Bestehen der der Geologischen Blätter für NO-Bayern - Koch, Roman; Baier, Alfons; Schulbert, Christian (Geologische Blätter für Nordost-Bayern und angrenzende Gebiete, 2011)
UnivIS-Import:2015-04-14:Pub.2011.nat.dgeo.IGM.LAG.vorwor

Vulkaniklastika und Siliziklastika des basalen Oberrotliegend im Saar-Nahe-Becken (SW-Deutschland): Terminologie und Ablagerungsprozesse - Stollhofen, Harald (Mainzer Geowissenschaftliche Mitteilungen, 1994)

Was climatic cooling during the earliest Carboniferous driven by expansion of seed plants? - Chen, Bo; Chen, Jitao; Qie, Wenkun; Huang, Pu; He, Tianchen; Joachimski, Michael; Regelous, Marcel; Pogge von Strandmann, Philip A.E.; Liu, Jiangsi; Wang, Xiangdong; Montanez, Isabel; Algeo, Thomas J. (Earth and Planetary Science Letters, 2021)
The expansion of land plants is considered to have played a key role in triggering the Late Paleozoic Ice Age (LPIA), but evidence linking climatic events to terrestrial floral changes is limited. Here, we generated bulk carbonate δ13C, conodont δ18O and 87Sr/86Sr profiles from the lowermost Carboniferous of South China and Vietnam in order to investigate their relationship to contemporaneous land plant evolution. Climatic cooling in the mid-Tournaisian coincided with large perturbations to the global carbon cycle and continental weathering regimes as well as with a major diversification episode among seed plants. These relationships are consistent with terrestrial floral changes triggering intensified weathering of basalts (i.e., lower 87Sr/86Sr), enhanced marine productivity (i.e., higher δ13Ccarb), and reduced atmospheric pCO2 and attendant global cooling (i.e., higher conodont δ18O). The results of our study suggest that expansion of terrestrial floras was a key driver of Early Carboniferous climate change.<br
Keywords: carbon cycle; strontium isotopes; oxygen isotopes; lignophyte; Late Paleozoic Ice Age

Was ist neu bei Grundwasser? - Staffelstab übernommen - Barth, Johannes; Liedl, Rudolf (Grundwasser, 2010)

Wasser ist wertvoll! Interaktives und multimediales E-Book für eine BNE - Baumann, Rebecca; Resch, Gerrit; Regelous, Anette (Grundschulmagazin, 2022)

Water column anoxia, enhanced productivity and concomitant changes in d13C and d34S across the Frasnian - Famennian boundary (Kowala - Holy Cross Mountains/ Poland) - Joachimski, Michael; et al. (Chemical Geology, 2001)
UnivIS-Import:2015-03-09:Pub.2001.nat.dgeo.IGM.LG.waterc

Water contents of nominally anhydrous orthopyroxenes from oceanic peridotites determined by SIMS and FTIR - Wenzel, Kirsten; Wiedenbeck, Michael; Gose, Jürgen; Rocholl, Alexander; Schmädicke, Esther (Mineralogy and Petrology, 2021)
This study presents new secondary ion mass spectrometry (SIMS) reference materials (RMs) for measuring water contents in nominally anhydrous orthopyroxenes from upper mantle peridotites. The enstatitic reference orthopyroxenes from spinel peridotite xenoliths have Mg#s between 0.83 and 0.86, Al2O3 ranges between 4.02 and 5.56 wt%, and Cr2O3 ranges between 0.21 and 0.69 wt%. Based on Fourier-transform infrared spectroscopy (FTIR) characterizations, the water contents of the eleven reference orthopyroxenes vary from dry to 249 +/- 6 mu g/g H2O. Using these reference grains, a set of orthopyroxene samples obtained from variably altered abyssal spinel peridotites from the Atlantic and Arctic Ridges as well as from the Izu-Bonin-Mariana forearc region was analyzed by SIMS and FTIR regarding their incorporation of water. The major element composition of the sample orthopyroxenes is typical of spinel peridotites from the upper mantle, characterized by Mg#s between 0.90 and 0.92, Al2O3 between 1.66 and 5.34 wt%, and Cr2O3 between 0.62 and 0.96 wt%. Water contents as measured by SIMS range from 68 +/- 7 to 261 +/- 11 mu g/g H2O and correlate well with Al2O3 contents (r = 0.80) and Cr#s (r(.) = -0.89). We also describe in detail an optimized strategy, employing both SIMS and FTIR, for quantifying structural water in highly altered samples such as abyssal peridotite. This approach first analyzes individual oriented grains by polarized FTIR, which provides an overview of alteration. Subsequently, the same grain along with others of the same sample is measured using SIMS, thereby gaining information about homogeneity at the hand sample scale, which is key for understanding the geological history of these rocks.
CRIS-Team WoS Importer:2021-09-10

Water fluxes and their control on the terrestrial carbon balance: Results from a stable isotope study on the Clyde Watershed (Scotland) - Barth, Johannes; et al. (Applied Geochemistry, 2007)

Water in Abyssal Peridotite: Why Are Melt-Depleted Rocks so Water Rich? - Schmädicke, Esther; Gose, Jürgen; Stalder, R. (Geochemistry Geophysics Geosystems, 2018)
Keywords: restitic mantle; water content; nominally anhydrous minerals; orthopyroxene; MORB source; abyssal peridotite

Water incorporation in garnet: Coesite versus quartz eclogite from Erzgebirge and Fichtelgebirge - Gose, Jürgen; Schmädicke, Esther (Journal of Petrology, 2018)
Keywords: Water; Eclogite; Amphibole; Fichtelgebirge; Erzgebirge; Nominally anhydrous minerals; Garnet; Ultra-high pressure metamorphism; Subduction

Water in Eclogite and Pyroxenite Xenoliths From the Bottom 100 km of the Slave Craton (Canada) Mantle Root - Schmädicke, Esther; Gose, Jürgen; Stachel, Thomas (Geochemistry Geophysics Geosystems, 2025)
Major and trace elements, including H2O, were determined in garnet and clinopyroxene to constrain the evolution of mantle xenoliths from Diavik, Canada. The 20 samples, derived from 120 to 220 (240) km depth, define a geotherm equivalent to 37 mW/m2 surface heat flow and include three eclogite (A, B, C) and two pyroxenite (B, C) types (A: High Ca/low Mg, B: High Ca/high Mg; C: Low Ca/high Mg). C-type samples invariably come from lower depth (<175 km) than B-types (>200 km); type-A eclogite is present in both intervals. The contents of hydroxyl (referred to as “structural H2O” and given as μg/g H2O) in clinopyroxene of B-type eclogite and pyroxenite (360–1,149 and 225–1,509 μg/g) are higher than in C-type samples (123–165 and 321–393 μg/g). Moreover, clinopyroxene in eclogite has lower H2O contents relative to pyroxenite. Structural H2O of clinopyroxene is positively correlated to Cu, Ni, and K but not to major elements. In garnet, contents of structural H2O are low (0–41 μg/g) and correlate neither with rock type nor with mineral composition. Most garnets additionally contain molecular (non-structural) water, being correlated to compositional parameters of both garnet (positive: Mg; negative: Ca, Sr, Be, Na) and clinopyroxene (positive: MREE, Ca, Th; negative: Al, K, Na, Li). Structural H2O in clinopyroxene and garnet does not correspond to PT conditions but was affected by secondary, metasomatic processes. Most likely, pyroxenite formed from eclogite by metasomatic changes resulting in lower clinopyroxene Na and Zn contents and enhanced Mg#, Cr, Sr, REE, Pb, Th, U, and Cu.
CRIS-Team Scopus Importer:2025-03-28
Keywords: Diavik; eclogite; H; nominally anhydrous minerals; pyroxenite; slave craton

Water in enstatite from Mid-Atlantic Ridge peridotite: Evidence for the water content of suboceanic mantle? - Schmädicke, Esther; et al. (Geology, 2009)

Water in garnet of garnetite (metarodingite) and eclogite from the Erzgebirge and the Lepontine Alps - Schmädicke, Esther; Gose, Jürgen (Journal of Metamorphic Geology, 2020)
Little is known about water in nominally anhydrous minerals of orogenic garnet peridotite and enclosed metabasic rocks. This study is focused on peridotite-hosted eclogite and garnetite (metarodingite) from the Erzgebirge (EG), Germany, and the Lepontine Alps (LA), Switzerland. Newly discovered, peridotite-hosted eclogite in the Erzgebirge occurs in the same ultra-high pressure (UHP) unit as gneiss-hosted coesite eclogite, from which it is petrologically indistinguishable. Garnet is present in all mafic and ultramafic high pressure (HP) rocks providing for an ideal proxy to compare the H2O content of the different rock types. Garnet composition is very similar in EG and LA samples and depends on the rock type. Garnet from garnetite, compared to eclogite, contains more CaO (garnetite: 10.5–16.5 wt%; eclogite: 5–11 wt%) and is also characterized by an anomalous REE distribution. In contrast, the infrared (IR) spectra of garnet from both rock types reveal the same OH absorption bands that are also identical to those of previously studied peridotitic garnet from the same locations. Two groups of IR bands, SW I (3,650 ± 10 cm−1) and SW II (3,570–3,630 cm−1) are ascribed to structural hydroxyl (colloquially ‘water’). A third, broad band is present in about half of the analysed garnet domains and related to molecular water (MW) in submicroscopic fluid inclusions. The primary content of structural H2O, preserved in garnet domains without fluid inclusions (and MW bands), varies systematically—depending on both the location and the rock type. Garnet from EG rocks contains more water compared to LA samples, and garnet from garnetite (EG: 121–241 wt.ppm H2O; LA: 23–46 wt.ppm) hosts more water than eclogitic garnet (EG: 84 wt.ppm; LA: 4–11 wt.ppm). Higher contents of structural water (SW) are observed in domains with molecular water, in which the SW II band (being not restricted to HP conditions) is simultaneously enhanced. This implies that fluid influx during decompression not only led to fluid inclusions but also favoured the uptake of secondary SW. The results signify that garnet from all EG and LA samples was originally H2O-undersaturated. Combining the data from eclogite, garnetite and previously studied peridotite, H2O and CaO are positively correlated, pointing to the same degree of H2O-undersaturation at peak metamorphism in all rock types. This ubiquitous water-deficiency cannot be reconciled with the derivation of any of these rocks from the lowermost part of the mantle wedge that was in contact with the subducting plate. This agrees with the previously inferred abyssal origin for part of the rocks from the LA (Cima di Gagnone). A similar origin has to be invoked for the Erzgebirge UHP unit. We suggest that all mafic and ultramafic rocks of this unit not only shared the same metamorphic evolution but also a common protolith origin, most probably on the ocean floor. This inference is supported by the presence of peridotite-hosted garnetite, representing metamorphosed rodingite.
CRIS-Team Scopus Importer:2020-07-31
Keywords: eclogite; Erzgebirge; garnet; Lepontine Alps; metarodingite; structural water

Water in mantle orthopyroxene-no visible change in defect water during serpentinization - Schmädicke, Esther; et al. (European Journal of Mineralogy, 2011)
Keywords: Infrared spectroscopy; Hydrogen diffusion; Nominally anhydrous minerals; Mid-Atlantic-Ridge; Serpentinization; Orthopyroxene; Water loss; Spinel peridotite

Water in natural olivine - determined by proton-proton scattering analysis. - Gose, Jürgen; Reichart, Patrick; Dollinger, Guenther; Schmädicke, Esther (American Mineralogist, 2008)
Here we present water concentration data for olivine from different host rocks, measured with a nuclear technique using proton-proton scattering. This method, which is used here for the first time on olivine, is very powerful for determining trace amounts of water. The studied olivine specimens differ in their H2O contents, ranging from 4 to 51 wt ppm (=10-117 atom ppm H). The lowest concentrations are found in olivine from spinel peridotite xenoliths, the highest concentrations in olivine from alpine-type peridotite; the contents of an ophiolitic and a hydrothermal olivine are intermediate. Infrared spectroscopy was applied to ensure that the measured water contents stem solely from hydroxyl defects in the mineral structure. The infrared spectra differ from sample to sample. Five of six olivine specimens show absorption bands typical of hydroxyl groups associated with Ti defects. These olivines differ in their Ti contents by two orders of magnitude. However, a correlation of water and Ti content was not observed.
UnivIS-Import:2017-03-24:Pub.2008.nat.dgeo.IGM.legeo.wateri
Keywords: Hydroxyl defects; Nominally anhydrous minerals; Olivine; Peridotite; Proton-proton scattering; Water content

Water in orthopyroxene from abyssal spinel peridotites of the East Pacific Rise (ODP Leg 147: Hess Deep) - Hesse, Kirsten; Gose, Jürgen; Stalder, Roland; Schmädicke, Esther (Lithos, 2015)
Keywords: Geothermometry; East Pacific Rise; Nominally anhydrous minerals; Infrared spectroscopy; Upper mantle; Orthopyroxene water content

Water in the Supra-Subduction-Zone Mantle of the Mariana-Izu-Bonin Forearc: Constraints From Peridotitic Orthopyroxene - Gose, Jürgen; Schmädicke, Esther (Geochemistry Geophysics Geosystems, 2021)
Orthopyroxene was analyzed as a proxy for water supra-subduction-zone peridotite by polarized infrared radiation. Samples from Conical and Torishima seamounts, Mariana-Izu-Bonin forearc (ODP-Leg 125), have very similar average H2O contents of 215 ppm (range: 122–363 ppm; Conical) and 191 ppm (range: 116–292 ppm; Torishima). Conical peridotite equilibrated at lower temperature (760°C) and oxygen fugacity (ΔlogFMQ −0.65) than samples from Torishima (830°C; ΔlogFMQ +0.33). The degree of partial melting is almost identical for the two sites (18% and 20%). The H2O concentrations are considerably higher compared to samples from the Bismarck forearc (31–92 ppm; Tollan and Hermann, 2019). Instead, the average values resemble those of peridotitic orthopyroxene from MOR settings. The measured H2O contents by far exceed values expected for residual peridotite. This implies that secondary uptake of water must have occurred after melt-extraction but prior to exhumation to shallow crustal levels. Most likely, re-equilibration took place at c. 50 km depth. As indicated by elemental correlations and/or enhanced contents, the secondary fluid(s) must have been enriched in B, K, Li, and Sr. The boron contents of orthopyroxene are c. 10 times higher those in MOR samples. These findings suggest that peridotite from Conical and Torishima seamounts was presumably infiltrated by fluid generated by dehydration reactions in a subducting plate. The elemental spectrum points to two source lithologies: (i) serpentinite (liberation of B) and metasediments (liberation of K, Li, and Sr). The varying H2O contents point to heterogeneous fluid supply suggesting that fluid infiltration was not pervasive.
CRIS-Team Scopus Importer:2021-05-07
Keywords: : mantle wedge; Mariana-Izu-Bonin forearc; orthopyroxene; peridotite; water

Water mass exchange and variations in seawater temperature in the NW Tethys during the Early Jurassic: evidence from neodymium and oxygen isotopes of fish teeth and belemnites - Dera, Guillaume; Puceat, Emmanuelle; Pellenard, Pierre; Neige, Pascal; Delsate, Dominique; Joachimski, Michael; Reisberg, Laurie; Martinez, Mathieu (Earth and Planetary Science Letters, 2009)
Oxygen and neodymium isotope analyses performed on biostratigraphically well-dated fish remains recovered from the Hettangian to Toarcian of the Paris Basin were used to reconstruct variations of Early Jurassic seawater temperature and to track oceanographic changes in the NW Tethys. Our results indicate a strong correlation between δ18O trends recorded by fish remains and belemnites, confirming the paleoenvironmental origin of oxygen isotope variations. Interestingly, temperatures recorded by pelagic fishes and nektobenthic belemnites and bottom dwelling fishes are comparable during the Late Pliensbachian sea-level lowstand but gradually differ during the Early Toarcian transgressive episode, recording a difference in water temperatures of 6 °C during the Bifrons Zone. This could suggest that the surface-bottom water temperature difference was not large enough during regressive phases to be recorded by organisms living near the lower and upper part of the water column. The globally unradiogenic Nd budget of Euro-boreal waters through the Early Jurassic suggests that these waters were strongly affected by continental neodymium input from surrounding emerged areas and that exchange with more radiogenic waters from the Tethys and Panthalassa oceans remained limited. This supports the existence of a southward directed current in the Euro-boreal area for most of the Early Jurassic. The only exception is observed at the Early-Late Pliensbachian transition where a positive εNd excursion is recorded, suggesting northward influx of low-latitude Tethyan or Panthalassan waters which may have contributed to the warming of NW Tethyan seawater recorded at this time. The absence of a marked negative excursion in εNd concomitant with a negative δ18O shift recorded during the Falciferum Zone (Exaratum Subzone) argues against the influence of less radiogenic Arctic water influxes with low δ18O values during this interval. Instead, we suggest that enhanced freshwater inputs related to increasing weathering rates could have contributed to the large δ18O shift recorded by marine organisms, especially in Euro-boreal contexts. © 2009 Elsevier B.V. All rights reserved.
UnivIS-Import:2015-03-09:Pub.2009.nat.dgeo.IGM.LG.waterm
Keywords: fish tooth; neodymium isotopes; oxygen isotopes; paleoceanography; paleoclimate; Toarcian

Water mass gradients of the mid-depth Southwest Atlantic during the past 25,000 years - Pöppelmeier, F.; Gutjahr, M.; Blaser, P.; Oppo, D. W.; Jaccard, S. L.; Regelous, Marcel; Huang, K. F.; Süfke, F.; Lippold, J. (Earth and Planetary Science Letters, 2019)
Antarctic Intermediate Water (AAIW) plays a central role in the Atlantic Meridional Overturning Circulation (AMOC) as the return flow of Northern Sourced Water (NSW) and is therefore of significant importance for the global climate. Past variations of the boundary between AAIW and NSW have been extensively investigated, yet available results documenting the prevailing depth of this boundary and the southern extent of NSW during the last ice age remain ambiguous. Here, we present five new timeseries focusing on the authigenic neodymium isotope signal in sediment cores retrieved from the Southwest Atlantic covering the past 25,000 years. The sites are situated along the southern Brazil Margin and form a bathymetric transect ranging between 1000 and 3000 m water depth, encompassing the modern water mass boundaries of AAIW and NSW and therefore allow their reconstruction since the Last Glacial Maximum (LGM). The new Nd isotope records show little change between the LGM and early deglaciation as well as relatively homogeneous values over the full depth range of the cores during these times. These results strongly contrast with epibenthic foraminiferal stable carbon isotope records (δ13C) from the same sites which exhibit highest glacial values at mid-depths, presumably related to NSW mixing into southern sourced water. We propose that the discrepancy between these two independent water mass proxies is partly related to changes in Nd end member properties of glacial AAIW. The combination of elevated glacial dust fluxes and, as a result, sustained export productivity caused high sinking particle flux in the western South Atlantic, where AAIW is forming. Higher particle flux would have increased the removal (scavenging) of Nd from shallow waters thus reducing the Nd concentration and overprinting the isotopic signature of the glacial AAIW end member. Only under consideration of changes in Nd end member properties along with non-conservative processes such as remineralization of organic matter influencing past seawater δ13C can we reconcile the water mass reconstructions from both proxies.
CRIS-Team Scopus Importer:2019-12-03
Keywords: AMOC; Antarctic Intermediate Water; Last Glacial Maximum; neodymium isotopes; Southwest Atlantic

Water mixing in a St. Lawrence river embayment to outline potential sources of pollution - Barth, Johannes; et al. (Applied Geochemistry, 2004)

Water Transpiration and the Carbon Cycle (Communications arising) - Veizer, Jan; Barth, Johannes; Dubois, K.D.; Ferguson, P.; Freitag, H.; Karim, Ajaz; Telmer, Kevin; Wassernaar, Len (Nature, 2014)

Water transport by subduction: Clues from garnet of Erzgebirge UHP eclogite - Schmädicke, Esther; Gose, Jürgen (American Mineralogist, 2017)
Keywords: garnet; Eclogite; nominally anhydrous minerals; infrared spectroscopy; subduction; omphacite; water

Wear, tear and systematic repair: testing models of growth dynamics in conodonts with high-resolution imaging - Shirley, Bryan; Grohganz, Madleen; Bestmann, Michel; Jarochowska, Emilia (Proceedings of the Royal Society of London, Series B: Biological Sciences, 2018)
Conodont elements are the earliest mineralized vertebrate dental tools and the only ones capable of extensive repair. Two models of conodont growth, as well as the presence of a larval stage, have been hypothesized. We analysed normally and pathologically developed elements to test these hypotheses and identified three ontogenetic stages characterized by different anisometric growth and morphology. The distinction of these stages is independently corroborated by differences in tissue strontium (Sr) content. The onset of the last stage is marked by the appearance of wear resulting from mechanical food digestion. At least five episodes of damage and repair could be identified in the normally developed specimen. In the pathological element, function was compromised by the development of abnormal dent ides. This development can be reconstructed as addition of new growth centres out of the main growth axis during an episode of renewed growth. Our findings support the model of periodic retraction of elements and addition of new growth centres. Changes in Sr content coincident with distinct morphology and lack of wear in the early life stage indicate that conodonts might have assumed their mature feeding habit of predators or scavengers after an initial larval stage characterized by a different feeding mode.
Keywords: vertebrate; teeth; conodont; chordate; growth dynamics; apatite

Weathering of crystalline bedrock in Sila Massif and Catena Costiera (Calabria, southern Italy) - Caracciolo, Luca; et al. (Rendiconti Online Societa Geologica Italiana, 2012)
Keywords: Clay minerals; Heavy minerals; Soil development; Weathering; X-ray diffraction

Wechselspiel der Sphären: Fein verzahnte Kreisläufe steuern das System Erde. - Kenkmann, Thomas; Kießling, Wolfgang (Als das Leben laufen lernte, 2007)
Keywords: System Erde; Geobiologie; Evolution; Stoffkreisläufe

Weiterentwicklung eines Wärmeleitungskalorimeters und Hydratationsuntersuchungen an synthetischen Portlandzementphasen - Schmitt, Dirk; Neubauer, Jürgen (European Journal of Mineralogy, 2000)
UnivIS-Import:2015-03-09:Pub.2000.nat.dgeo.IGM.LM.weiter

Well-based, geochemical leakage monitoring of an aquifer immediately above a CO2 storage reservoir by stable carbon isotopes at the Ketzin pilot site, Germany - Nowak, Martin; Myrttinen, Anssi; Zimmer, Martin; Wiese, Bernd; van Geldern, Robert; Barth, Johannes (Energy Procedia, 2013)
Keywords: CO2 storage; Leakage; Overlying aquifer; Stable isotopes; Well-based monitoring

Wet carbonation of C3A and pre-hydrated C3A - Villmow, Sophia; Mielkau, Anika; Götz-Neunhoeffer, Friedlinde; Neubauer, Jürgen (Cement and Concrete Research, 2023)
The carbonation of C3A and pre-hydrated C3A was studied at different initial pH values, temperatures, pre-hydration and carbonation times. Based on these investigations, the reaction kinetics of C3A under humid conditions were considered in more detail. The reaction products were characterized by quantitative X-ray diffraction (QXRD) and thermogravimetric analysis (TGA). C3A shows no significant reaction when carbonated directly in suspension, however, it has been observed that pre-hydrated C3A can be carbonated. A higher reaction degree was obtained with increasing hydration time. Consistent with reaching a stable pH, no further reaction of the hydrate phases was detected after 20 min, indicating fast kinetics of the carbonation reaction. At temperatures ≤21 °C, the CaCO3 polymorph vaterite was found to be the main phase. At a pre-hydration temperature of 40 °C, C3AH6 appeared as a stable hydrate phase, but showed no reaction with CO2 under our experimental conditions.
CRIS-Team Scopus Importer:2023-07-28
Keywords: C; Carbonation (C); Carbonation products (B); CO; pH (A); Reaction kinetics (A); Thermal analysis (B); X-ray diffraction (B)

What caused the Ordovician biodiversification? - Munnecke, Axel; Servais, Thomas (Palaeogeography, Palaeoclimatology, Palaeoecology, 2007)
Keywords: Ordovician; Ordovician Radiation; IGCP; Palaeogeography; Palaeoclimate; Early Palaeozoic

What is boring? - Arctic reef structures as a habitat for boring organisms - Pyko, Ines Anna; Munnecke, Axel; Schulbert, Christian; Wisshak, Max; Teichert, Sebastian (The Arctic Biodiversity Congress, 2018)
The coralline red algal species Lithothamnion glaciale forms rigid frameworks of magnesium calcite. These so called rhodoliths cover large areas of the Svalbard shelf. Thereby, the calcified structures act as ecosystem engineers, comparable to corals in tropical regions, providing habitat for a large variety of organisms. Drilled by boring mussels, many rhodoliths become hollow ecospheres and their interior is intensely colonized by benthic macro- and megafauna. Based on a non-destructive 3-D visualization analysis via micro-computed tomography (µCT), we investigated whether the calcified skeleton itself provides a habitat for certain microorganisms also. Here, we present a first overview of boring microorganisms in Svalbard’s rhodoliths. This study is a contribution to enhance our knowledge about the complicated interrelationships in this large-scale ecosystem. Therefore, it is a step forward in order to estimate the impact of the rhodoliths on Svalbard’s shelf biodiversity and provides a background for their inclusion in future policy recommendations and strategic plans for biodiversit

What is conservation paleobiology? Tracking 20 years of research and development - Dillon, Erin M; Pier, Jaleigh Q; Smith, Jansen A.; Raja Schoob, Nussaibah Begum; Dimitrijevic, Danijela; Austin, Elizabeth L; Cybulski, Jonathan D.; De Entrambasaguas, Julia; Durham, Stephen R; Grether, Carolin; Haldar, Himadri Sekhar; Kocáková, Kristína; et al. (Frontiers in Ecology and Evolution, 2022)
Conservation paleobiology has coalesced over the last two decades since its formal coining, united by the goal of applying geohistorical records to inform the conservation, management, and restoration of biodiversity and ecosystem services. Yet, the field is still attempting to form an identity distinct from its academic roots. Here, we ask a deceptively simple question: What is conservation paleobiology? To track its development as a field, we synthesize complementary perspectives from a survey of the scientific community that is familiar with conservation paleobiology and a systematic literature review of publications that use the term. We present an overview of conservation paleobiology’s research scope and compare survey participants’ perceptions of what it is and what it should be as a field. We find that conservation paleobiologists use a variety of geohistorical data in their work, although research is typified by near-time records of marine molluscs and terrestrial mammals collected over local to regional spatial scales. Our results also confirm the field’s broad disciplinary basis: survey participants indicated that conservation paleobiology can incorporate information from a wide range of disciplines spanning conservation biology, ecology, historical ecology, paleontology, and archaeology. Finally, we show that conservation paleobiologists have yet to reach a consensus on how applied the field should be in practice. The survey revealed that many participants thought the field should be more applied but that most do not currently engage with conservation practice. Reflecting on how conservation paleobiology has developed over the last two decades, we discuss opportunities to promote community cohesion, strengthen collaborations within conservation science, and align training priorities with the field’s identity as it continues to crystallize.<br

Where are all the fossil pennatulacean octocorals? The need for more research on modern sea pens - Roden, Vanessa; Reich, Mike (Beiträge zur Paläontologie 32, 2011)

Where traditional extinction estimates fall flat: using novel cophylogenetic methods to estimate extinction risk in platyhelminths - Mulvey, Laura; Warnock, Rachel; De Baets, Kenneth (Proceedings of the Royal Society of London, Series B: Biological Sciences, 2022)
Today parasites comprise a huge proportion of living biodiversity and play a major role in shaping community structure. Given their ecological significance, parasite extinctions could result in massive cascading effects across ecosystems. It is therefore crucial that we have a way of estimating their extinction risk. Attempts to do this have often relied on information about host extinction risk, without explicitly incorporating information about the parasites. However, assuming an identical risk may be misleading. Here, we apply a novel metric to estimate the cophylogenetic extinction rate, Ec, of parasites with their hosts. This metric incorporates information about the evolutionary history of parasites and hosts that can be estimated using event-based cophylogenetic methods. To explore this metric, we investigated the use of different cophylogenetic methods to inform the Ec rate, based on the analysis of polystome parasites and their anuran hosts. We show using both parsimony- and model-based approaches that different methods can have a large effect on extinction risk estimation. Further, we demonstrate that model-based approaches offer greater potential to provide insights into cophylogenetic history and extinction risk.
CRIS-Team Scopus Importer:2022-09-09
Keywords: conservation; cophylogenetic extinction risk; cophylogenetics; host–parasite interactions; parasites; platyhelminths

Wide & deep learning for predicting relative mineral compositions of sediment cores solely based on XRF scans, a case study from Pleistocene Paleolake Olduvai, Tanzania - Kodikara, Gayantha R.L.; McHenry, Lindsay J.; Stanistreet, Ian G.; Stollhofen, Harald; Njau, Jackson K.; Toth, Nicholas; Schick, Kathy (Artificial Intelligence in Geosciences, 2024)
This study develops a method to use deep learning models to predict the mineral assemblages and their relative abundances in paleolake cores using high-resolution XRF core scan elemental data and X-ray diffraction (XRD) mineralogical results from the same core taken at coarser resolution. It uses the XRF core scan data along with published mineralogical information from the Olduvai Gorge Coring Project (OGCP) 2014 sediment cores 1A, 2A, and 3A from Paleolake Olduvai, Tanzania. Both regression and classification models were developed using a Keras deep learning framework to assess the predictability of mineral assemblages with their relative abundances (in regression models) or at least the mineral assemblages (in classification models) using XRF core scan data. Models were created using the Sequential class and Functional API with different model architectures. The correlation matrix of element ratios calculated from XRF element intensity records from the cores and XRD-derived mineralogical information was used to select the most useful features to train the models. 1057 training data records were used for the models. Lithological classes were also used for some models using Wide & Deep neural networks since those combine the benefits of memorization and generalization for mineral prediction. The results were validated using 265 validation data records unseen by the model and discuss the accuracy of models using six test records. The optimized Deep Neural Network (DNN) classification model achieved over 86% binary accuracy while the regression models were also able to predict the relative mineral abundances of samples with high accuracies. Overall, the study shows the efficacy of a carefully crafted Deep Learning (DL) model for predicting mineral assemblages and abundances using high-resolution XRF core scan data.
CRIS-Team Scopus Importer:2024-09-06

Will arctic reefs disappear with ongoing global change? - Pyko, Ines Anna; Munnecke, Axel; Teichert, Sebastian (macro 2019 – Bridging local patterns and global challenges, 2019)
Aim: The coralline red algal species Lithothamnion glaciale forms rigid frameworks of magnesium calcite. In the high Arctic, these so-called rhodoliths cover large areas of the Svalbard shelf. Thereby, the calcified structures act as ecosystem engineers, comparable to corals in tropical regions, providing habitat for a large variety of organisms. Furthermore, drilled by boring mussels, many rhodoliths become hollow ecospheres and their interior is intensely colonized by benthic macro- and megafauna. Within this study, we investigate whether the distribution pattern of these arctic reefs will be affected by ongoing global change. Rhodolith beds occur worldwide and have similar ecological impact. Because the effects of global change are projected to be most severe and fast within the Arctic, this ecosystem represents a very appropriate model also for the global impact on rhodolith communities. Location: This study involves rhodolith beds around the Svalbard shelf in the high Arctic. Methods: The distribution of L. glaciale is linked to local ranges of physical parameters like temperature, pH, light regime, and salinity. Following the RCP scenarios provided by the IPCC, we estimate the influence of anticipated large-scale shifts on the rhodoliths. Based on these results, we analyse the future functioning of rhodoliths as niche-providing ecosystem engineers. Results: The first results of this ongoing study indicate that increasing temperatures enhance the respiration of the algae. However, this effect will be outcompeted by reduced water transparency – and therefore reduced photosynthesis – induced by deglaciation. Main conclusions: The geographical distribution of Arctic rhodolith beds is threatened by global change. Due to their key role as ecosystem engineers, this might also result in a decrease of Arctic biodiversity.<br

Windward and leeward margins of an Upper Ordovician carbonate platform in the Central Tarim Uplift, Xinjiang, northwestern China - Zhang, Yuanyuan; Li, Yue; Wang, Guan; Munnecke, Axel (Palaeogeography, Palaeoclimatology, Palaeoecology, 2017)
In the Central Uplift of the Tarim Basin, northwestern China, the Katian (Upper Ordovician) limestones of the Lianglitag Formation extend from outcrops in the Bachu area to the subsurface in the Tazhong Oil Field (TZOF) area. Reefs and inner platform deposits are the dominant facies throughout the formation. The reef composition illustrates a palaeoecologic gradient from microbial-dominated buildups on the northwestern margin to metazoan-dominated reefs on the eastern and southern margins of the platform. Between these areas no outcrops are present. In the present study, data including litho- and biofacies logs and correlations from eight wells are presented, six of them of the region between Bachu and Tazhong, and two wells along the former platform margin from the TZOF. Calcimicrobial carbonates are common in core from the inner platform part. Benthic biota documented here resembles that of the microbial mounds and bioclastic limestones in the Bachu outcrop area, and thus is considered as the eastward extension of this realm. However, metazoan-dominated boundstones formed by corals, stromatoporoids, sponges together with calcareous algae are abundant along the southern platform margin, and are similar in composition to the reefs of TZOF in the easternmost part of the platform. The palaeoecologic differentiation between microbial- and metazoan-dominated reefs suggests a strong environmental gradient from a well-oxygenated windward eastern and southern side of the platform, which favoured the open ocean and which was dominated by metazoan reefs, and the inner platform as well as the northwestern, leeward margin of the platform with warmer, less-oxygenated water, which favoured the growth of microbial carbonates. Assuming the trade winds as cause for the contrasting facies on both sides of the platform a palaeo-position of Tarim south of the ITCZ seems probable because a position north of it would require a post-Ordovician clockwise rotation of Tarim of about 90° which is possible but less probabl
Keywords: Palaeoecologic gradient; Palaeogeographic implication; Metazoan reef; Microbialite; Lianglitag Formation

Wirt-Gast-Komplexe von [bfu.bfu.bfu]: Vorhersage von Ionenselektivitäten mittels quantenchemischer Rechnungen XIII - Palmer, Ursula; Puchta, Ralph (Zeitschrift für Naturforschung Section B-A Journal of Chemical Sciences, 2020)
The CH2-O-C2H4-O-CH2 moieties in Lehn's cryptand [2.2.2] have been substituted by 2,2′-bifurane groups to get the cryptand [bfu.bfu.bfu]. The ion selectivity of this new cryptandwas investigated by DFT calculations (RB3LYP/LANL2DZp, RB3LYP/LACVP∗, RBP86/LANL2DZp and RBP86/LACVP∗) based on model equations and analysis of the [M ⊂ bfu.bfu.bfu]n+ cryptate structures. The cryptand [bfu.bfu.bfu] is best suited for the alkali cations Na+ and K+, and the alkaline earth cation Sr2+ followed by Ca2+. The cavity of [bfu.bfu.bfu] is thus similar to that in [phen.phen.phen] or [bpy.bpy.bpy]. The selectivity of [bfu.bfu.bfu] is due to the flexibility of the OCCO und CN·NC dihedral angles. The results are independent of the selected DFT methods.
CRIS-Team Scopus Importer:2020-12-04
Keywords: Cryptates; DFT calculations; Selectivity of ion complexation; Supramolecular chemistry

XRPD and heat flow calorimetry of iron doped monocalciumaluminate - Neumann, Andreas; Neubauer, Jürgen; Götz-Neunhoeffer, Friedlinde (2001)
UnivIS-Import:2015-03-09:Pub.2001.nat.dgeo.IGM.LM.xrpdan

Xylem formation patterns from Mediterranean to subalpine climate conditions reveal high growth plasticity of pine species on Corsica - Häusser, Martin; Aryal, Sugam; Barth, Johannes; Bendix, Joerg; Garel, Emilie; van Geldern, Robert; Huneau, Frederic; Juhlke, Tobias; Knerr, Isabel; Santoni, Sebastien; Szymczak, Sonja; Trachte, Katja; et al. (Trees-Structure and Function, 2023)
Key messageBlack pine and Maritime pine exhibit considerable differences in growth phenology across elevation belts with a 1-month delay for xylogenesis and increasing growth rates from low, mid to high elevations.Investigating seasonal wood formation is crucial to understand tree growth responses to climate impact. The present study quantifies the variability of xylogenesis along an elevation gradient on the Mediterranean island of Corsica, where two native pine species (Pinus nigra Arnold ssp. laricio Maire and Pinus pinaster Aiton) grow from the upper tree line to sea level, partly in sympatry. We extracted microcores from 35 trees at 5 sites along an East-West transect from the coasts (10 m asl) to the island's central mountain ridge (1600 m asl) during bi-weekly sampling campaigns between 2017 and 2019. We applied generalised additive models to detect radial growth differences in elevation and species along with minimum temperatures for growth initiation. We found that trees in low elevations experienced over 2 months longer growth periods with higher maximum growth rates than in high elevations. The results show a 1-month delay for the beginning of tracheid formation between the low, mid and high-elevation belts but comparable timing for its termination. At the sites where both species co-occur, P. nigra accumulates more radial cells in a shorter time than P. pinaster. Trees at the two contrasting coastal sites have similar growth period lengths, but exhibit a time shift of over a month. Minimum temperatures around growth initiation vary between 3.1 degrees C for P. nigra and 9.9 degrees C for P. pinaster. These findings emphasise the high plasticity in the growth behaviour of one of the most widespread tree genera in Mediterranean and temperate zones.
CRIS-Team WoS Importer:2023-04-07

Young boninitic lavas from the northern Tonga fore-arc unrelated to subduction initiation - Myeong, Bora; Haase, Karsten; Regelous, Marcel; Beier, Christoph; Lim, Hoseong; Park, Jongkyu; Miggins, Daniel P.; Koppers, Anthony A.P. (Chemical Geology, 2025)
The fore-arc crust at subduction zones is generally thought to be considerably older than the overlying arc, and to have formed during subduction initiation. We present new 40Ar/39Ar ages as well as geochemical and petrological data for volcanic rocks from a 500 m-high section along the wall of a rifted basin within the northern Tonga Ridge fore-arc. Compared to lavas from the adjacent Tonga Arc, the samples have relatively high SiO2 and low TiO2 at a given MgO, and the least evolved samples have boninitic bulk-rock compositions. 40Ar/39Ar ages of three samples are about 1.3 Ma, which is younger than the initiation of subduction in northern Tonga (possibly 20 Ma). All lavas are depleted in incompatible trace elements but enriched in fluid-mobile elements as a result of slab dehydration beneath the fore-arc. Although lavas from the adjacent arc front at this latitude have been proposed to contain Pb from the subducting Louisville Seamount Chain (LSC), the unradiogenic Pb isotope compositions (206Pb/204Pb < 18.9) of the older fore-arc lavas indicate that they do not contain a contribution from LSC materials. A dike intruding the lavas is relatively enriched in fluid-immobile Nb and Ta and has higher Nb/Zr ratios than N-MORB. The Nd and Hf isotope compositions resemble those of rejuvenated Samoa lavas, and we propose that Samoa mantle flowed into fore-arc mantle after eruption of the 61ROV lavas at about 1.3 Ma. Our results show that not all boninites (including high-Si boninites) in fore-arc locations are related to subduction initiation.
CRIS-Team Scopus Importer:2025-01-31
Keywords: Boninite; Fore-arc; Louisville Seamount Chain; Samoa mantle; Slab components; Subduction initiation

Zebra dolomites of the Spessart, Germany: implications for hydrothermal systems of the European Zechstein Basin - Kelka, Ulrich; Beaudoin, Nicolas E.; Lorenz, Joachim; Köhn, Daniel; Regenauer-Lieb, Klaus; Boyce, Adrian; Chung, Peter (International Journal of Earth Sciences, 2023)
Zebra dolomites have a distinctive texture and are a peculiar structural variety of dolostones often encountered in the vicinity of base metal deposits commonly in the Mississippi Valley-Type (MVT). We investigate origin and evolution of the zebra dolomites found in the region of the Spessart, northwestern Bavaria, Germany, through diagenetic and petrogenetic analysis using SEM, CL microscopy, O–C isotopes, and fluid inclusion micro-thermometry. Here, we aim to shed light on the nature of the fluids that altered the zebra dolomite of the Zechstein formation. We distinguish the geochemical signatures of two different fluid flow regimes post-dating texture formation, each characterized by specific homogenization temperatures and oxygen–carbon isotope ratios (Event 1: T h = 120 °C; δ 18 O fluids = [0 to 2‰]; Event 2; T h = 300 °C; δ 18 O fluids = 18‰). Comparison of these fluids and the associated mineralization with published regional fluid flow data support that the zebra dolomites in the Spessart most likely coincided with the Permian large-scale fluid flow event that occurred throughout the European Zechstein Basin. Graphical Abstract: [Figure not available: see fulltext.]
CRIS-Team Scopus Importer:2023-11-17
Keywords: Dedolomitization; Dolomitization; Hydrothermal systems; Spessart; Zebra dolomites

Zincian dolomite related to supergene alteration in the Iglesias mining district (SW Sardinia): Characterization and relationships with nonsulfide Zn ores. - Boni, Maria; Mondillo, Nicola; Balassone, Giuseppina; Joachimski, Michael; Colella, A. (International Journal of Earth Sciences, 2013)
UnivIS-Import:2015-03-09:Pub.2013.nat.dgeo.IGM.LG.zincia

Zircon Ages of Metasedimentary Rocks in the Wuwamen Ophiolitic Mélange, Chinese South Tianshan: Implications for the Paleozoic Subduction-Accretion in the Southern Central Asian Orogenic Belt - Wang, Xin Shui; Yang, Fei; Klemd, Reiner; Jiang, Tuo; Gao, Jun (Journal of Earth Science, 2022)
High-temperature and high-pressure (high-grade) metamorphic complexes of variable ages are common in the Central Asian orogenic belt (CAOB), and their precise geochronology and origin are essential to unravel the orogenic architecture and crust-production rate of the CAOB. Hereby it is essential to differentiate between pre-orogenic Precambrian basement and Paleozoic arc-accretionary complexes. This study provides precise in situ zircon U−Pb ages for the metasedimentary rocks in the Wuwamen ophiolitic mélange, which is traditionally thought to represent the pre-orogenic basement of the southwestern CAOB. A meta-sandstone from the meta-flysch sequence revealed a widespread ca. 1.8 Ga high-grade metamorphic overprint similar to that of the underlying orthogneisses and, thus, was interpreted to represent pre-orogenic basement fragments that occur as tectonic blocks in the Paleozoic ophiolitic mélange. In contrast, a schist from the mélange matrix is characterized by a ca. 333 Ma high-grade metamorphic overprint, indicating that the northward subduction of the South Tianshan Ocean was still active at this time. The thrust-imbricated high-grade metamorphic rocks of contrasting origins in an accretionary complex have important implications for the understanding the accretionary history and crustal growth of the CAOB. Furthermore, the strongly deformed ophiolitic mélange was intruded by an undeformed granite dyke with an emplacement age younger than ca. 294 Ma, thus providing a minimum age limit for the final closure of the South Tianshan Ocean.
CRIS-Team Scopus Importer:2022-10-28
Keywords: CAOB; geochemistry; high-temperature/high-pressure metamorphism; ophiolitic mélange; subduction; Tianshan; Zircon U−Pb

Zircon trace element constrains on the link between volcanism and plutonism in SE-China - Yan, Lili Li; He, Zhenyu; Beier, Christoph; Klemd, Reiner (Lithos, 2018)
Trace elements in igneous zircon crystals are variable within single crystals or amongst populations of crystals and are particularly sensitive to changes in melt composition. In this study, we present zircon trace element data from both volcanic and plutonic rocks of the Yandangshan caldera complex from SEChina. The erupted rhyolitic rocks are interpreted to represent the most differentiated magma, whereas the intruded porphyritic quartz syenites are thought to be representative of the residual crystal mush. The zircon crystals of both lithologies are subdivided into two types based on their internal structures: type A with a distinct oscillatory growth zoning and type B crystals are bright in cathodoluminescence (CL-bright). Type B zircon occurs as rims of type A zircon or as individual grains. Compared to type A, type B zircons commonly show lower Hf, U, Th and Y concentrations and higher Ti and Zr/Hf and Eu/Eu* ratios. The zircon trace element compositions of the volcanic samples generally overlap those of the intracaldera porphyritic quartz syenite and mafic microgranular enclaves that contain both type A and type B zircons. Despite a general overlap, zircon grains from the volcanic rocks show relatively higher Hf contents and Y/Dy ratios, lower Ti contents and Th/U ratios and larger negative Eu anomalies than the plutonic samples. We suggest that the inter- and intragrain compositional variability of zircon crystals can be used to track the evolution of magmatic systems. We show that in our case, the volcanic and plutonic rocks crystallized continuously during the magmatic evolution in a common magma system and that the magmas of these rocks may be linked by fractional crystallization. Furthermore, the type B zircon grains are inferred to have crystalized in relatively hot and less evolved magma indicating a magma recharge event. Consequently, the geochemical variability of igneous zircon crystals can be used to infer on the magmatic evolution of single volcanic system which may also be applicable in other geodynamic environments.<br
Keywords: Zircon trace elements; Magma differentiation; Volcanic–plutonic connection; Yandangshan caldera complex; SE China

Zlichovian faunas with early ammonoids from Morocco and their use for the correlation of the eastern Anti-Atlas and the western Dra Valley - de Baets, Kenneth; Klug, Christian; Plusquellec, Yves (Bulletin of Geosciences, 2010)
Two sections were sampled and measured at Mdaour-El-Kbir (Dra Valley, western Anti-Atlas) and at eastern Ouidane Chebbi (Tafilalt, eastern Anti-Atlas). In situ elements of two partially limonitized and one carbonatic fauna were found in both sections. We report this fauna from the upper Merz-Akhsai Formation and the lower Mdaour-el-Kbir Formation at Mdaour-el-Kbir for the first time. Based on these faunas, we recorded a correlation of the early Emsian (Zlichovian) strata in the Tafilalt and the Dra Valley regions, which are about 350 km apart. Additionally, new ammonoid finds (Teicherticeras cf. senior, Lenzites gesinae, Weyeroceras angustus) are figured and described including the stratigraphic context. The diagnoses of Lenzites gesinae and Weyeroceras angustus are emended. Tabulate corals (Michelinia mdaourensis sp. nov., Petridictyum sp.) found in both the Tafilalt and Dra Valley are figured and described for the first time.
Keywords: early Emsian; Ammonoidea; Tabulata; Micheliniidae; biostratigraphy; Anti-Atlas; Morocco

Zur quantitativen Analyse der Ferratphase im Portlandzementklinker - Sieber, Roland; Neubauer, Jürgen; Pöllmann, Herbert (European Journal of Mineralogy, 1996)
UnivIS-Import:2015-03-05:Pub.1996.nat.dgeo.IGM.LM.zurqua

δ13C records across the late Silurian Lau event: New data from middle palaeo-latitudes of northern peri-Gondwana (Prague Basin, Czech Republic) - Lehnert, Oliver; Frýda, Jiři; Buggisch, Werner; Munnecke, Axel; Nützel, Alexander; Křiž, Jiři; Manda, Štěpán; Lehnert, Oliver (Palaeogeography, Palaeoclimatology, Palaeoecology, 2007)
During the late Silurian the Prague Basin was located in middle southern latitudes. In contrast to palaeocontinents positioned in tropical and subtropical latitudes like Baltica, no reefs are developed, which is in accordance with the predicted cooler water. The Prague Basin represents a relatively restricted and shallow rift basin with a complex tectonic history. Sections in different palaeoenvironments have been studied to document the most prominent Silurian stable carbon isotope excursion recorded during the late Silurian (Ludfordian) Lau Event from this part of peri-Gondwana. Deeper water deposits of the Kopanina Formation investigated in the present study were deposited on the slope-to-basin transition near the Kosov volcanic centre in the western part of Prague Basin. The sediments are developed as an alternation of dark, partly laminated limestones and marls with an increase of the limestone-marl ratio in the upper part of the succession. A pronounced positive carbon isotope excursion starts in the Neocullograptus kozlowskii graptolite and in the upper Polygnathoides siluricus conodont zone. The maximum of the shift is observed in the lower part of an interval characterised by the Ananaspis fecunda-Cyrthia postera community. The maximum values scatter around 8‰, which represent the highest values reported hitherto from the Prague Basin. In low latitudes, often a decrease of δC values towards deeper water settings is reported. In contrast, in the present study the δC values of about 8‰ are much higher than those recorded from the contemporaneous shallow-water sections studied in the classical Mušlovka and Požáry quarries. The most reasonable explanation is the presence of stratigraphical gaps in the shallow parts of the basin. As indicated by karstification these gaps were caused by a sea-level drop. Another effect of this sea-level fall was a strongly reduced sedimentation of the cephalopod limestone facies around volcanic and tectonic elevations. © 2006 Elsevier B.V. All rights reserve
UnivIS-Import:2015-03-09:Pub.2007.nat.dgeo.IGM.LG.d13cre
Keywords: Silurian; Ludlow; Lau Event; Stable isotopes; Prague Basin; Peri-Gondwana

地球历史上的极限地区和干旱沙漠 (dìqiú lìshǐ shàng de jíxiàn dìqū hé gānhàn shāmò; Extreme Regions and Arid Deserts in Earth's History). - Lehnert, Oliver (极限地球 (Jíxiàn dìqiú, Extreme Earth), 2021)

A dynamic mid-crustal magma domain revealed by the 2023 to 2024 Sundhnúksgígar eruptions in Iceland - Matthews, Simon W.; Caracciolo, Alberto; Bali, Eniko; Halldórsson, Sæmundur A.; Sigmarsson, Olgeir; Guðfinnsson, Guðmundur H.; Pedersen, Gro B.M.; Robin, Jóhann Gunnarsson; Marshall, Edward W.; Aden, Araksan A.; Gísladóttir, Bryndís Ýr; Bosq, Chantal; et al. (Science, 2024)
Mid-crustal magma domains are the source of many basaltic eruptions. Lavas from individual eruptions are often chemically homogeneous, suggesting that they derive from single, well-mixed magma reservoirs. The 2023 to 2024 eruptions at Sundhnúksgígar in the Svartsengi volcanic system in Iceland provide an opportunity to observe the behavior of a mid-crustal magma domain at high spatial and temporal resolution by detailed sampling and geochemical characterization. We observed substantial mantle-derived geochemical variability in the products erupted in the first hours of the December 2023 and January, February, and March to May 2024 eruptions, indicating that the eruptions derived from multiple magma reservoirs, which mineral-melt equilibration pressures place in the mid crust. The unusual presence of geochemical heterogeneity in the mid-crustal magma domain provides insights into how dynamic and complex mid-crustal magma domains can be.
CRIS-Team Scopus Importer:2024-11-15

Calcimicrobial-archaeocyath-bearing clasts from marine slope deposits of the Cambrian Mount Wegener Formation, Coats Land, Shackleton Range, Antarctica - Rodriguez-Martinez, M.; Perejon, A.; Moreno-Eiris, E.; Menendez, S.; Buggisch, Werner (Estudios Geológicos, 2019)
The carbonate clasts from the Mount Wegener Formation provide sedimentological, diagenetic and palaeontological evidences of the destruction and resedimentation of a hidden/unknown Cambrian carbonate shallow-water record at the Coats Land region of Antarctica. This incomplete mosaic could play a key role in comparisons and biostratigraphic correlations between the Cambrian record of the Transantarctic Mountains, Ellsworth-Whitmore block and Antarctic Peninsula at the Antarctica continent. Moreover, it represents a key record in future palaeobiogeographic reconstructions of South Gondwana based on archaeocyathan assemblages.
CRIS-Team WoS Importer:2020-01-14

Depth transect of an Upper Triassic (Rhaetian) reef from Gosau, Austria: Microfacies and community ecology - Martindale, Rowan C.; Krystyn, Leopold; Bottjer, David J.; Corsetti, Frank A.; Senowbari-Daryan, Baba; Martini, Rossana (Palaeogeography, Palaeoclimatology, Palaeoecology, 2013)
In the Late Triassic (̃ 235-201.3. Ma) scleractinian corals and hypercalcified sponges built large, diverse reef ecosystems, the most famous of which are the Dachstein reefs. This study presents a depth transect along an Upper Triassic (lower Rhaetian) Dachstein reef from the Gosausee margin of the Dachsteingebirge (Gosau, Austria). The Gosausee microbial-sponge-coral reef is a complete barrier reef with an almost continuous fore reef to lagoon transect preserved (a very rare occurrence for the Triassic), and thus provides a window into depth zonation of Dachstein-type reef facies and biotic succession. The Gosausee reef facies exhibit strong depth control and five classic reef facies or zones are identified: the fore reef, reef front, reef crest, back reef, and lagoon facies. Thin, rare microbial fabrics and a high abundance of fine-grained, mud-rich skeletal wackestones (transported reef debris) characterize the deepest fore reef. As the reef shallows, muddy sediments decrease in abundance and are replaced by microbial fabrics, corals, and cements. Abundant sponges, microbial crusts, and thick, marine cements typify the reef crest, whereas microbialite-coated phaceloid corals are dominant in the back reef facies. Heavily cemented oncoids or microbial-sponge bindstones are characteristic of the lagoon. Based on their compositional and biotic similarities, the Gosausee reef was likely part of the same barrier reef systems as the source reef for the Gosaukamm reef breccia (one of the classic Norian-Rhaetian Dachstein reefs). The reef zones of the Gosausee margin can be used to interpret the depth or reef zone of less well preserved reef fragments, can inform models of community ecology and niche utilization in the Late Triassic, and highlight the need for additional research into the environmental factors that controlled biotic distribution in Upper Triassic reefs. © 2012 Elsevier B.V.
UnivIS-Import:2017-11-07:Pub.2013.nat.dgeo.IGM.LP.deptht
Keywords: Dachstein; Dachsteinriffkalk; Gosausee; Late Triassic; Reef; Rhaetian

Fossil Constraints on the Timescale of Parasitic Helminth Evolution - de Baets, Kenneth; Dentzien-Dias, Paula; Harrison, G. William M.; Littlewood, D. Timothy J.; Parry, Luke A. (The Evolution and Fossil Record of Parasitism: Identification and Macroevolution of Parasites, 2021)
The fossil record of parasitic helminths is often stated to be severely limited. Many studies have therefore used host constraints to constrain molecular divergence time estimates of helminths. Here we review direct fossil evidence for several of these parasitic lineages belong to various phyla (Acanthocephala, Annelida, Arthropoda, Nematoda, Nematomorpha, Pentastomida,Platyhelminthes). Our compilation shows that the fossil record of soft-bodied helminths is patchy, but more diverse than commonly assumed. The fossil record provides evidence that ectoparasitic helminths (e.g., worm-like pentastomid arthropods) have been around since the early Paleozoic, while endoparasitic helminths (cestodes) arose at least during, or possibly even before the late Paleozoic. Nematode lineages parasitizing terrestrial plant and animal hosts have been in existence at least since the Devonian and Triassic, respectively. All major phyla (Acanthocephala, Annelida, Platyhelminthes. Nematoda, Nematomorpha) had evolved endoparasitic lineages at least since the Mesozoic. Interestingly, although parasitism is considered derived within Metazoa, the oldest evidence for Nematoda and Platyhelminthes includes body fossils of parasitic representatives. Furthermore, the oldest fossil evidence of these parasitic lineages often falls within molecular divergence time estimates based on host co-evolution suggesting the fossil record of helminths themselves might be just as good or at least complementary (and less circular in justification) to calibration based on host associations. Data also provide evidence for obvious host switches or extinctions, which cautions against models of pure co-divergence where use of host calibrations to constrain divergence time estimates may be considered.
Keywords: parasitic worms; fossil record; molecular divergence estimates; host constraints

Geochemical assessment of potential sources for nitrate in the wasia aquifer, Al Kharj Area, central Saudi Arabia - Khogali, Abid; Birkle, Peter; Al-Shaibani, Abdulaziz; Keller, Martin; Tawabini, Bassam; Makkawi, Mohammad (Water, 2020)
Nitrate (NO3-) represents one of the major groundwater constituents with increasing distribution and concentration in the Kingdom of Saudi Arabia. This study aimed to determine potential sources of nitrate in the Early to Late Cretaceous Wasia aquifer system at the Al Kharj area (Central Saudi Arabia) by an integrative approach using groundwater geochemistry, nitrate isotopes (15N-NO3 and 18O-NO3), and tritium (3H) measurements. The lowest saline groundwater samples (TDS = 1400-2000 mg/L) from the peripheral zone were representative for pristine groundwater from theWasia aquifer with nitrate concentrations below 20 mg/L and low 18O-NO3 ratios (8.7-20.6%) but enriched 15N-NO3 values (up to 10.8‰). In contrast, 11 out of 34 analyzed water samples from irrigation wells and cattle watering wells exceeded the World Health Organization (WHO) drinking water guideline value for nitrate of 50 mg/L with maximum concentrations of up to 395 mg/L. Nitrate fertilizers and atmospheric deposition are the main sources of nitrate in groundwater in the eastern and northern sections of the study area. The combination of elevated salinities (4940-7330 mg/L), NO3 (111-395 mg/L), boron (516-1430 μg/L), and enriched 18O-NO3 (21.7-25.8‰) ratios with depleted 15N-NO3 (5.7-7.6‰) confirm the local influx of evaporated irrigation water with remnants of dissolved fertilizer into the Wasia groundwater system. There was no evidence for the influx of animal or human wastes from adjacent dairy, poultry, and housing infrastructures. Tritium concentrations below the detection limit of 0.8 TU for most borehole samples implied the absence of recent natural recharge. The estimated annual average N influx of 3.34 to 6.67 kg/ha to theWasia aquifer requires a combination of atmospheric deposition and anthropogenic sources (mainly nitrate fertilizers) to increase the nitrogen content of the Wasia aquifer.
CRIS-Team Scopus Importer:2020-06-16
Keywords: Geochemistry; Nitrate sources; Stable isotopes; Wasia aquifer

High resolution Ordovician carbon isotope chemostratigraphy in South China and its significance for global correlation - Gong, Fangyi; Luan, Xiaocong; Calner, Mikael; Lehnert, Oliver; Zhang, Yuchen; Yan, Guanzhou; Wei, Xin; Wu, Rongchang (Global and Planetary Change, 2024)
Based on the Shidi-1 drill core, this paper presents new and highly time resolved carbon isotope data (δ13Ccarb) for the Early Ordovician through Early Silurian of the Yangtze Platform, South China. Five carbon isotopic shifts (C1-C5) through the late Tremadocian to the Katian have been recognized in the Shidi-1 drill core recordings. Together with previously published isotope data, a composite carbon isotope curve for the Yangtze platform, permits the identification of a continuous Ordovician carbon isotope trend with five prominent carbon isotope shifts; including the TSICE, the Late Tremadocian positive Isotopic Carbon Excursion (LTICE, named herein), the Late Floian Rise, the MDICE and the Pagoda Isotopic Carbon Excursion (PICE, named herein). The identification and documentation of these anomalies further strengthen the regional and global correlation of the Ordovician succession on the Yangtze platform. The long-term trend in carbon isotopes indicates that organic carbon burial increased gradually throughout the Great Biodiversification Event (GOBE). A tipping point is also marked by the Dapingian-Darriwilian border, which is followed by a notable shift in the environment and creatures in the middle Darriwilian.
CRIS-Team Scopus Importer:2024-08-02
Keywords: Carbon isotope events; Global correlation; GOBE; Ordovician; South China

Investigating seismicity rates with Coulomb failure stress models caused by pore pressure and thermal stress from operating a well doublet in a generic geothermal reservoir in the Netherlands - Hutka, Gergo András; Cacace, Mauro; Hofmann, Hannes; Mathur, Bakul; Zang, Arno (Netherlands Journal of Geosciences-Geologie En Mijnbouw, 2023)
The utilisation of geothermal energy in the Netherlands is primarily focused on deep sedimentary aquifers, which are often intersected by major faults. Geothermal operations (i.e. fluid production and injection) may alter the effective stress state along these faults and trigger induced seismic events. Pore pressure perturbations have been generally considered the main driver of injection-induced seismicity. However, thermal stresses caused by temperature gradients between the re-injected cold fluid and the reservoir rock may also contribute to the triggering of earthquakes in geothermal reservoirs. While existing geothermal power plants operating in sandstone reservoirs did not produce any major induced seismicity, it is a matter of debate whether a reduction in the temperature of the re-injected fluid could increase the seismic hazard potential. In this study, we applied modified Gutenberg-Richter statistics based on frictional Coulomb stress variations implemented in a coupled thermo-hydro-mechanical model to estimate the seismic hazard caused by the operation of a geothermal doublet. We conducted a systematic parametric study to assess and rank the impact of different intrinsic (geological) and extrinsic (operational) parameters on the induced seismic hazard potential. We identified a competing mechanism between induced variations in pore pressure and thermal stress within the reservoir in controlling induced seismicity. We found that stress changes induced by pore pressure variations are the main cause of seismic hazard, although thermally induced stresses also contribute significantly. The results indicate that by optimising the operational parameters it is possible to increase production efficiency while maintaining a long-term control over the fluid injection-induced seismicity.
CRIS-Team Scopus Importer:2023-07-21
Keywords: deep geothermal energy; Gutenberg-Richter statistics; hazard assessment; induced seismicity; Mohr-Coulomb failure approach; thermal stresses

New bio- and chemostratigraphic data from southwestern China and its relation to Telychian (Llandovery, Silurian) climate change - Yan, Guanzhou; Lehnert, Oliver; Männik, Peep; Calner, Mikael; Li, Lixia; Wei, Xin; Gong, Fangyi; Luan, Xiaocong; Wu, Rongchang (Palaeogeography, Palaeoclimatology, Palaeoecology, 2025)
Integrated conodont and carbon isotope data is presented from the Telychian (upper Llandovery, lower Silurian) from the Baicaoping section, Yunnan Province, southwestern China. Three conodont zonal units, in stratigraphically ascending order, the Pterospathodus eopennatus Superzone, Pterospathodus celloni Superzone, and the Pterospathodus amorphognathoides amorphognathoides Zone, are recognized in the Baizitian Formation. The new high-resolution carbon isotope data, combined with the conodont biostratigraphy, reveal a continuous Valgu carbon isotope excursion (Valgu CIE) in the Pt. eopennatus Superzone and the Manitowoc carbon isotope excursion (Manitowoc CIE) in the Pt. celloni Superzone. Because of this, the studied section in the Baizitian Formation can be precisely correlated with corresponding sections in Baltica (Viki core section in Estonia) and Laurentia (Composite Jupiter-Chicotte section on Anticosti Island, Canada; Sheboygan 541 section, Michigan Basin, USA), based on biostratigraphy and the comparable shape of the carbon isotope curves. The Manitowoc CIE constitutes a relatively minor positive anomaly in the upper Baizitian Formation (middle Telychian), reflecting a widely identifiable perturbation of the carbon cycle during the Manitowoc Icehouse interval. Our high-resolution δ13Ccarb record improves the Telychian bio- and chemostratigraphic framework and refines global correlations and comparisons between Silurian successions in South China, Baltica, and Laurentia.
CRIS-Team Scopus Importer:2025-01-31
Keywords: Conodont biostratigraphy; Manitowoc CIE; Telychian climate change; Valgu CIE

The Petrology and Geochemistry of the 2021 Fagradalsfjall Eruption, Iceland: An Eruption Sourced From Multiple, Compositionally Diverse, Near-Moho Sills - Marshall, E. W.; Caracciolo, A.; Bali, E.; Halldórsson, S. A.; Matthews, S.; Ranta, E.; Rasmussen, M. B.; Robin, J. G.; Guðfinnson, G. H.; Maclennan, J.; Bosq, C.; Auclair, D.; et al. (AGU Advances, 2024)
Magmatic processes at the crust-mantle boundary (i.e., Moho) are commonly studied post facto at fossil ophiolites, oceanic core complexes, or inferred from the compositions of crystals or melt inclusions. The 2021 eruption at Fagradalsfjall on the Reykjanes Peninsula, Iceland, was supplied from magma bodies near the Moho and offers a unique opportunity to study the timescales, structure, and syn-eruptive processes of near-Moho magmatic systems at ∼15 km depth. Here, we present a comprehensive petrological and geochemical investigation of the full 183 day eruption that is based on frequent sampling of the eruption. Lavas erupted in the first 45 days displayed significant and sudden changes in geochemistry, followed by lower amplitude fluctuations until the end of the eruption. This variability can be explained by contribution from multiple magma bodies, as best distinguished using Sr-Nd-Hf-Pb isotope systematics. The lavas display unusual trace element and radiogenic isotope compositions compared to other Icelandic basalts, but are similar to other rare, highly incompatible element enriched lavas on the Reykjanes Peninsula, and thus these lavas may represent a distinct suite of Reykjanes Peninsula basalts. Our geochemical and petrological observations show that numerous, compositionally variable bodies of magma must exist in the lowermost crust or at the crust-mantle boundary. These near-Moho magma bodies transfer magma between one another on timescales as short as days-to-months, but partially crystallize over longer time periods, and periodically inject into the overlying crust.
CRIS-Team Scopus Importer:2024-12-06
Keywords: basalt; Fagradalsfjall; magmatic system; Moho transition zone; volcano monitoring