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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

Spatial and temporal variations of pCO2, dissolved inorganic carbon, and stable isotopes along a temperate karstic watercourse - van Geldern, Robert; Schulte, Peter; Mader, Michael; Baier, Alfons; Barth, Johannes (Hydrological Processes, 2015)

Spatial distribution analysis of mass movements triggered by the 2005 Kashmir earthquake in the Northeast Himalayas of Pakistan - Basharat, Muhammad; Baig, Mirza Shahid; Khan, Muhammad Rustam; Rohn, Joachim (Geomorphology, 2014)
Keywords: 2005 Kashmir earthquake; Epicentre; Mass movement concentration; Reactivated Muzaffarabad Fault

Spatial distribution of rockslide deposits and their morphological features suggest timing and palaeo-environmental conditions for rock slope failures in innerdalen and innfjorddalen, møre og romsdal county, Western Norway - Schleier, Markus; Hermannsdörfer, Ralf; Rohn, Joachim (Italian Journal of Engineering Geology and Environment, 2013)
Keywords: Morphological analyses; Multiple landslide deposits; Palaeo-environmental conditions; Rock avalanche; Western norway

Spatially referenced 3D-Characterisation of Fracture Networks - Drews, Michael; Deckert, Hagen; Gessner, Klaus; et al. (Conference Proceedings, 2007)

Spatially resolved quantitative in-situ phase analysis of a self-leveling compound - Seifert, Severin; Neubauer, Jürgen; Götz-Neunhoeffer, Friedlinde (Cement and Concrete Research, 2012)
The development of the crystalline microstructure of a hydrating self-leveling compound (SLC) was analyzed using a two-dimensional XRD (GADDS). The application of non-destructive micro-diffraction with the GADDS, combined with a custom-made sample holder, made it possible to carry out position-sensitive in-situ measurements of a Calcium-Aluminate-Cement-(CAC)- dominated SLC. Different substrates were used in the measurement procedures so as to acquire data regarding the influence of the properties of the ground surface on the process of hydration. The results show that the crystalline microstructure is strongly affected by the availability of free water. The strongly vertically-fluctuating water-content of the hydrating mortar, which is mainly influenced by outside conditions, has a very significant effect upon the resulting ettringite content. This fact is also reflected in the resulting microstructure of the cured SLC. © 2012 Elsevier Ltd. All rights reserved.
UnivIS-Import:2015-04-14:Pub.2012.nat.dgeo.IGM.LM.spatia
Keywords: Calcium Aluminate Cement (D); Hydration (A); Microstructure (B); Mortar (E); X-ray diffraction (B)

Spatial-temporal analysis of precipitation characteristics in Artvin, Turkey - Aydin, Olgu; Raja, Nussaïbah Begum (Theoretical and Applied Climatology, 2020)
The region of Artvin, located in the northeast of Turkey, usually experiences high-intensity precipitation events that occur within a short-time period. Along with other environmental impacts, these events also lead to flash floods in this region. The purpose of this study was to evaluate the changing spatial and temporal characteristics of precipitation on August 24, 2015 and November 11 to 12, 2015 that triggered flash floods and landslides in Artvin. We apply spatiotemporal (ST) kriging as a tool to investigate these ST patterns. The average hourly precipitation data were used, taking episodes of heavy rainfall into account. Our results show that precipitation reached the highest values of 30–50 mm between 8:00 and 9:00 pm in the Hopa district on August 24, 2015. On November 11, 2015, rainfall values reached ≥ 15 mm at 4:00 PM in the Borçka district. During both events occurred on November 12, 2015, it rained for 7 h continuously with precipitation values ranging between 5 and 10 mm. The duration of the precipitation lasted for 8 h. In addition, flood events also occurred in the districts of Arhavi and Murgul. This highlights that these districts are vulnerable in the Artvin region and paves the way for decision-makers to implement measures against flash floods in these at-risk districts. In conclusion, the analysis of spatiotemporal characteristics of heavy rainfall events represents an indispensable basis to ensure that necessary precautions regarding flash flood events in the city are take
Keywords: precipitation characteristics; flood events; space and time; kriging; artvin

Spatial variability of source composition and petrogenesis in rift and rift flank alkaline lavas from the Eger Rift, Central Europe - Haase, Karsten; Beier, Christoph; Regelous, Marcel; Rapprich, Vladislav; Renno, Axel (Chemical Geology, 2016)
Geochemical data on Oligocene melilititic and nephelinitic rocks from the northern Eger Rift flank in Central Europe reveal significant differences to nephelinites and basanites of volcanic complexes in the rift axis. The mafic rift flank lavas are more enriched in TiO, PO and CaO but have lower SiO compared to the alkaline volcanic rocks in the Eger Rift. The differences in major element compositions imply (1) lower degrees of partial melting beneath the rift flank than beneath the rift axis evident from lower SiO and higher (Ce/Yb) ratios in the off-axis basalts and (2) different assemblages of fractional crystallization. The mafic rift flank magmas experienced crystal fractionation of olivine followed by clinopyroxene fractionation in contrast to early simultaneous olivine and clinopyroxene fractionation in the magmas below the rift basin. In addition, assimilation of continental crustal rocks is associated with crystal fractionation and changes the composition of the lavas. The rift axis lavas are enriched in Nb and Ba relative to La and have higher Sr and lower Nd isotope ratios than the rift flank magmas indicating different mantle sources. The melting zones beneath the rift axis and the rift flank region are separated although they are only some 20km apart and no melt exchange between the magma systems is observed. All magmas probably experienced mixing between a deep carbonatitic and a shallower low-degree silicate melt.
Keywords: Continental rifting; Crustal assimilation; Fractional crystallization; Intraplate volcanism; Magma formation

Spatial Variations in Magmatic Volatile Influx and Fluid Boiling in the Submarine Hydrothermal Systems of Niuatahi Caldera, Tonga Rear-Arc - Falkenberg, Jan; Keith, Manuel; Haase, Karsten; Sporer, Christian; Bach, Wolfgang; Klemd, Reiner; Strauss, Harald; Storch, Bettina; Peters, Christian; Rubin, Kenneth H.; Anderson, Melissa O. (Geochemistry Geophysics Geosystems, 2022)
Submarine caldera volcanoes may host several hydrothermal systems along the caldera wall and related to volcanic cones. Fluid boiling and magmatic volatile influx are common processes in shallow (<2,000 mbsl) subduction zone-related environments causing variations in the mineralogical and chemical composition of seafloor hydrothermal mineralizations that remain poorly constrained. The submarine caldera of Niuatahi volcano, Tonga rear-arc, hosts four active vent sites discharging high temperature fluids (<334 degrees C) with variable salinities (369-583 mM Cl) that are indicative of fluid boiling, recorded by distinct Te/As and Te/Au in pyrite, sphalerite, and chalcopyrite. High sulfidation mineral assemblages (e.g., enargite), stable S isotope data and similar trace element signatures in sulfides and native S condensates suggest a minor and/or infrequent contribution of magmatic SO2 to the hydrothermal systems located proximal to the caldera center causing a volatile element (e.g., Se, Bi, Te) enrichment. The hydrothermal system at the northern caldera wall is decoupled from the magmatic SO2 source, as revealed by radiogenic Pb isotopes. Instead, S isotope and trace element constraints propose a host rock-dominated hydrothermal system, lacking a magmatic volatile influx. The observed hydrothermal fractionation processes (fluid boiling) and the distinct metal (loid) sources (magmatic volatiles vs. host rock) represent a continuum from magmatic volatile- to host rock-dominated hydrothermal systems within the Niuatahi caldera. This leads to seafloor mineralizations with spatially selective trace element enrichments, like Te, Se, and Bi (+/- Au, Ag) in the caldera center compared to Au, Ag, Zn, Cd, and Pb at the northern caldera wall.
CRIS-Team WoS Importer:2022-04-29

Species–area relationships in continuous vegetation: Evidence from Palaearctic grasslands - Dengler, Jürgen; Matthews, Thomas J.; Steinbauer, Manuel; Wolfrum, Sebastian; Boch, Steffen; Chiarucci, Alessandro; Conradi, Timo; Dembicz, Iwona; Marcenò, Corrado; García-Mijangos, Itziar; Nowak, Arkadiusz; Storch, David; et al. (Journal of Biogeography, 2019)
Aim: Species–area relationships (SARs) are fundamental scaling laws in ecology although their shape is still disputed. At larger areas, power laws best represent SARs. Yet, it remains unclear whether SARs follow other shapes at finer spatial grains in continuous vegetation. We asked which function describes SARs best at small grains and explored how sampling methodology or the environment influence SAR shape. Location: Palaearctic grasslands and other non-forested habitats. Taxa: Vascular plants, bryophytes and lichens. Methods: We used the GrassPlot database, containing standardized vegetation-plot data from vascular plants, bryophytes and lichens spanning a wide range of grassland types throughout the Palaearctic and including 2,057 nested-plot series with at least seven grain sizes ranging from 1 cm2 to 1,024 m2. Using nonlinear regression, we assessed the appropriateness of different SAR functions (power, power quadratic, power breakpoint, logarithmic, Michaelis–Menten). Based on AICc, we tested whether the ranking of functions differed among taxonomic groups, methodological settings, biomes or vegetation types. Results: The power function was the most suitable function across the studied taxonomic groups. The superiority of this function increased from lichens to bryophytes to vascular plants to all three taxonomic groups together. The sampling method was highly influential as rooted presence sampling decreased the performance of the power function. By contrast, biome and vegetation type had practically no influence on the superiority of the power law. Main conclusions: We conclude that SARs of sessile organisms at smaller spatial grains are best approximated by a power function. This coincides with several other comprehensive studies of SARs at different grain sizes and for different taxa, thus supporting the general appropriateness of the power function for modelling species diversity over a wide range of grain sizes. The poor performance of the Michaelis–Menten function demonstrates that richness within plant communities generally does not approach any saturation, thus calling into question the concept of minimal area.
CRIS-Team Scopus Importer:2019-11-01
Keywords: logarithmic function; Michaelis–Menten function; minimal area; nested-plot sampling; nonlinear regression; Palaearctic grassland; plant biodiversity; power law; scaling law; species–area relationship (SAR)

Speicherminerale mit Ellestadit, Nasonit, Ganomalit und Silicocarnotit Struktur - Pöllmann, Herbert; Stemmermann, Peter; Neubauer, Jürgen (European Journal of Mineralogy, 1991)
UnivIS-Import:2015-03-05:Pub.1991.nat.dgeo.IGM.LM.speich

Sponge-microbial build-ups from the lowermost Triassic Chanakhchi section in southern Armenia: Microfacies and stable carbon isotopes - Friesenbichler, Evelyn; Richoz, Sylvain; Baud, Aymon; Krystyn, Leopold; Sahakyan, Lilit; Vardanyan, Sargis; Peckmann, Joern; Reitner, Joachim; Heindel, Katrin (Palaeogeography, Palaeoclimatology, Palaeoecology, 2018)

Sponge Takeover from End-Permian Mass Extinction to Early Induan Time: Records in Central Iran Microbial Buildups - Baud, Aymon; Richoz, Sylvain; Brandner, Rainer; Krystyn, Leopold; Heindel, Katrin; Mohtat, Tayebeh; Mohtat-Aghai, Parvin; Horacek, Micha (Frontiers in Earth Science, 2021)
The end-Permian mass extinction was the most severe biotic crisis in Earth’s history. In its direct aftermath, microbial communities were abundant on shallow-marine shelves around the Tethys. They colonized the space left vacant after the dramatic decline of skeletal metazoans. The presence of sponges and sponge microbial bioherms has largely gone unnoticed due to the sponges’ size and the cryptic method of preservation. In addition to sponge dominated facies recently described in South Armenia and Northwestern Iran, we describe here sponge-microbial bioherms cropping out in two well-known Permian-Triassic boundary localities: the Kuh-e Hambast section, south-east of Abadeh city and the more distal Shahreza section, near Isfahan. In both sections, the extinction horizon is located at the top of an upper Changhsingian ammonoid-rich nodular limestone, called Paratirolites limestone. At Kuh-e Hambast, the overlying decimetric thick shale deposit called “boundary clay,” the latest Permian in age, is conformably overlain by well-dated transgressive basal Triassic platy limestone containing four successive levels of decimeter to meter scale, elongated to form cup-shaped mounds made of branching columnar stromatolites. Sponge fibers from possibly keratose demosponge, are widely present in the lime mudstone matrix. At the Shahreza section, above the extinction level, the boundary clay is much thicker (3 m), with thin platy limestone intervals, and contains two main levels of decimeter to meter scale mounds of digitate microbialite crossing the Permian-Triassic boundary with similar sponge fibers. Three levels rich in thrombolite domes can be seen in the overlying 20 m platy limestone of earliest Triassic age. Sponge fibers and rare spicules are present in their micritic matrix. These sponge fibers and spicules which are abundant in the latest Permian post-extinction boundary clay, followed microbial buildups during the Griesbachian time.
CRIS-Team Scopus Importer:2021-06-18
Keywords: carbonate mounds; end-permian mass extinction; Induan; keratose demosponge; metazoan bioherms

Spumispongia merklei nov. sp. (Porifera) from the Upper Jurassic (South Germany, Swabian Alb, Blautal) - Senowbari-Daryan, Baba; Koch, Roman (Geologische Blätter für Nordost-Bayern und angrenzende Gebiete, 2012)
UnivIS-Import:2017-11-07:Pub.2012.nat.dgeo.IGM.LP.spumis

Spurenlesen in der Vergangenheit - die Burghöhle Wolfsegg als Treffpunkt für Mensch, Höhlenlöwe und Co. - Hilpert, Brigitte (Mitteilungen - Verbandes der Deutschen Hohlen- und Karstforscher, 2023)

Sr/Ca and Ba/Ca ratios support trophic partitioning within a Silurian conodont community from Gotland, Sweden - Terrill, David F.; Jarochowska, Emilia; Henderson, Charles M.; Shirley, Bryan; Bremer, Oskar (Paleobiology, 2022)
Conodonts were a highly diverse and abundant vertebrate group whose fossils are found in marine Paleozoic and Triassic strata around the world. They inhabited environments ranging from lagoons to open oceans and are represented by a wide variety of dental morphologies. Conodonts may have filled many different ecological niches and represent a significant proportion of nekton before the Devonian. Despite this, very little is known about trophic ecology of conodonts. While morphological diversity suggests a complex trophic structure within conodont communities, there is little evidence to support dietary niche partitioning among conodonts. We tested the hypothesis that individual conodont taxa occupied different trophic niches, using Sr/Ca and Ba/Ca ratios preserved in the dental elements of assemblages from Silurian strata of Gotland, Sweden. Sr/Ca and Ba/Ca have been shown to vary in vertebrate skeletal tissues depending on trophic positioning, although biological and environmental conditions can affect these ratios. Environmental influences were minimized by examining entire conodont communities from a tropical epeiric sea and by measuring strontium isotope ratios using thermal ionization mass spectrometry in the most metropolitan taxon (Ozarkodina confluens). Composition of white matter, a tissue unique to conodonts, was also analyzed using microprobe analysis, revealing significantly lower Sr concentrations than in surrounding lamellar tissue, suggesting taxon-specific histology should be considered when analyzing conodonts for geochemical data. Excluding taxa with highly variable quantities of white matter, the results show that each taxon preserves different Sr/Ca and Ba/Ca ratios with limited overlap, indicating variation in trophic positioning.
CRIS-Team Scopus Importer:2022-04-29

Sr/Ca ratios and oxygen isotopes from sclerosponges: Temperature history of the Caribbean mixed layer and thermocline during the Little Ice Age - Haase, Alexandra; Böhm, Florian; Eisenhauer, Anton; Dullo, Wolf-Christian; Joachimski, Michael; Hansen, Bent; Reitner, Joachim; Schramm, Alexandra (Paleoceanography, 2003)
We investigate aragonitic skeletons of the Caribbean sclerosponge Ceratoporella nicholsoni from Jamaica, 20 m below sea level (mbsl), and Pedro Bank, 125 mbsl. We use SO and Sr/Ca ratios as temperature proxies to reconstruct the Caribbean mixed layer and thermocline temperature history since 1400 A.D. with a decadal time resolution. Our age models are based on U/Th dating and locating of the radiocarbon bomb spike. The modern temperature difference between the two sites is used to tentatively calibrate the C. nicholsoni Sr/Ca thermometer. The resulting calibration points to a temperature sensitivity of Sr/Ca in C. nicholsoni aragonite of about -0.1 mmol/mol/K. Our Sr/Ca records reveal a pronounced warning from the early 19th to the late 20th century, both at 20 and 125 mbsl. Two temperature minima in the shallow water records during the late 17th and early 19th century correspond to the Maunder and Dalton sunspot minima, respectively. Another major cooling occurred in the late 16th century and is not correlatable with a sunspot minimum. The temperature contrast between the two sites decreased from the 14th century to a minimum in the late 17th century and subsequently increased to modern values in the early 19th century. This is interpreted as a long-term deepening and subsequent shoaling of the Caribbean thermocline. The major trends of the Sr/Ca records are reproduced in both specimens but hardly reflected in the SO records.
Keywords: Caribbean Sea; Little Ice Age; Oxygen isotopes; Sclerosponges; Sr/Ca; Temperature; Thermocline

Stability conditions and compositional variations of deerite in high-pressure meta-ironstone during subduction–exhumation processes (SW Tianshan, China) - Li, Ji Lei; Klemd, Reiner; Höfer, Heidi E.; Gao, Jun (Lithos, 2021)
Index minerals in metamorphic rocks, such as coesite, glaucophane, or lawsonite, are of great importance to understand high-pressure (HP) to ultrahigh-pressure (UHP) metamorphism, the thermal gradient, and the geodynamics of subduction zones. Deerite is thought to be diagnostic for blueschist-facies metamorphism in cold subduction environments and a sensitive indicator of the oxygen fugacity (fO2) in Fe-rich rocks. However, little is known concerning its stability and compositional variation during subduction and exhumation cycles. In this study, we provide the first detailed investigation of deerite in eclogite-facies meta‑ironstones (deerite–garnet riebeckitite) from the Southwestern Tianshan (U)HP metamorphic belt. Petrological observation and textural evidence suggest that the meta‑ironstones –enclosing eclogite blocks– form part of an initially coherent volcano-sedimentary sequence that underwent a common tectono-metamorphic evolution, including HP metamorphism and subsequent exhumation. Two types of deerite, which display a different texture (inclusion vs. matrix) and composition (TiO2 content), occur in the deerite–garnet riebeckitite. Dee_1 and aegirine–augite appear exclusively as fine-grained inclusions in garnet, and together with garnet, riebeckite, quartz and magnetite form the peak metamorphic mineral assemblages at P–T conditions of 510 °C and 2.6 GPa. Matrix deerite (Dee_2), on the other hand, mainly occurs as coarse-grained rods and acicular needle-like grains in quartz, and rarely as inclusions in riebeckite and garnet intimately in the riebeckitite, representing the blueschist-facies retrogression of the meta‑ironstones during exhumation. The garnet–clinopyroxene oxybarometer and thermodynamic calculations show that the fO2 of the deerite–garnet riebeckitite increases from ΔFMQ–0.64 at the peak eclogite-facies stage to ΔFMQ+1.5 at the blueschist-facies retrogression. This fO2 variation corresponds to the chemical variation of deerite, whereby the TiO2 content increases gradually from <0.1 wt% in the Dee_1 in garnet to about 5 wt% in the matrix Dee_2. Our study reveals the detailed metamorphic P–T–fO2 evolution of the prograde eclogite- and retrograde blueschist-facies deerite-bearing meta‑ironstones during subduction–exhumation processes. This study further emphasizes the potential of deerite to reveal the P–T–fO2 evolution of subduction-related high-pressure rocks.
CRIS-Team Scopus Importer:2021-06-11
Keywords: Deerite; Eclogite; Oxygen fugacity; P–T evolution; Subduction zone; Tianshan

Stable and radiogenic isotope analyses on shark teeth from the Early to Middle Permian (SakmarianRoadian) of the southwestern USA - Fischer, Jan; Schneider, Joerg W.; Hodnett, John-Paul M.; Elliott, David K.; Johnson, Gary D.; Voigt, Silke; Joachimski, Michael; Tichomirowa, Marion; Goetze, Jens (Historical Biology, 2014)
δ18OPvalues and87Sr/86Sr ratios were determined on disarticulated xenacanthiform, hybodontid and ctenacanthid shark tooth material from several Early Permian (Sakmarian–Kungurian) continental bone beds of northern Texas and southern Oklahoma as well as from the marine Middle Permian (Roadian) of northern Arizona. The δ18OPvalues derived from the teeth of bone beds are in the range of 17.6–23.5‰ VSMOW, and are mostly depleted in18O by 0.5–5‰ relative to proposed coeval marine δ18OPvalues. This indicates an adaptation to freshwater habitats on the Early Permian coastal plain by several sharks. Distinctly higher δ18OPvalues from two bone beds are attributed to significant evaporative enrichment in18O in flood plain ponds.87Sr/86Sr ratios of around 0.71077 are notably more radiogenic than87Sr/86Sr of contemporaneous seawater. In contrast, the isotopic composition of teeth from the marine Kaibab Formation is characterised by low δ18OPvalues in the range of 13.4–15.6‰ VSMOW while87Sr/86Sr ratios of around 0.70821 are closer to the Roadian seawater value. The distinctly depleted δ18OPvalues cannot be readily explained by fluvially affected freshening in a nearshore marine environment, so a diagenetic alteration of the Kaibab material seems to be more likely, excluding it from further interpretation.
UnivIS-Import:2015-03-09:Pub.2014.nat.dgeo.IGM.LG.stable
Keywords: bioapatite; bone beds; Early–Middle Permian; freshwater shark; Kaibab Formation; oxygen isotopes; strontium isotopes

Stable carbon and oxygen equilibrium isotope fractionation of supercritical and subcritical CO2 with DIC and H2O in saline reservoir fluids - Becker, Veith; Myrttinen, Anssi; Nightingale, Michael; Shevalier, Maurice; Rock, Luc; Mayer, Bernhard; Barth, Johannes (International Journal of Greenhouse Gas Control, 2015)

Stable carbon and oxygen isotope geochemistry as provenance indicator for the picture stones on Gotland (Sweden) - Hänsel, Patrick; Oehrl, Sigmund; Ideström, Lena; Widerström, Per; Reddin, Carl James; Munnecke, Axel (GFF, 2023)
The picture stones from Gotland are one of the most famous and exceptional groups of monuments known from Swedish Prehistory. These carved memorial stones and their extraordinarily rich imagery are a unique source for the study of Late Iron and Viking Age culture and in particular Scandinavian pre-Christian religions. The Gotlandic picture stones are mainly made from the thickly layered limestones surrounding the reefs and bioherms of Gotland’s carbonate platform from the middle part of the Silurian (latest Llandovery to Ludlow, Telychian–Ludfordian). However, the exact origins of the picture stones’ raw materials on Gotland have remained undetermined. In this paper, we investigate the geological origin of the raw material by isotope geochemistry. Whereas the oxygen (δ18O) and strontium isotope ratio (87Sr/86Sr) were strongly altered by diagenesis the carbon isotope ratio (δ13C) is quite stable. Because the different geological units on Gotland show specific isotope signatures, the δ13C values from picture stones can be used to assign them to the respective geological unit, and thus to the source area of the raw material. This also allows for an estimation of transport distance minima between the raw material source area and the find place of each sampled picture stone. Most of the picture stones seem to be produced from local material with short transport distances, less than 10 km and only a few were transported at a far distance exceeding 10 km. In summary, the transport distance was dependent mostly on the local availability of picture-stone-suitable rocks.
CRIS-Team Scopus Importer:2023-12-01
Keywords: Carbon isotopes; Gotland; Iron Age; oxygen isotopes; picture stones; strontium isotopes; transport distances

Stable carbon isotope analysis of dissolved inorganic carbon (DIC) and dissolved organic carbon (DOC) in natural waters - Results from a worldwide proficiency test - van Geldern, Robert; Verma, Mahendra P.; Carvalho, Matheus C.; Grassa, Fausto; Delgado-Huertas, Antonio; Monvoisin, Gael; Barth, Johannes (Rapid Communications in Mass Spectrometry, 2013)

Stable carbon isotope development and sea-level changes during the Late Ludlow (Silurian) of the Łysogóry region (Rzepin section, Holy Cross Mountains, Poland) - Kozłowski, Wojciech; Munnecke, Axel (Facies, 2010)
The Ludlow deposits of the Winnica Formation in the Rzepin section (Holy Cross Mountains, Poland) have been studied with respect to their facies evolution and stable carbon isotope ratios from whole-rock samples. The C-isotope curve of the Rzepin section records a distinct positive excursion with maximal values of +8.9‰. A Late Ludlow positive isotope excursion is known from different paleocontinents and thus is regarded as a global isotope event. The presence of the event allows for a chemostratigraphic correlation of the Rzepin profile with the classical, biostratigraphically well-dated Gotland section. The Ludlow deposits of the Holy Cross Mountains are interpreted in terms of sea-level changes during the isotope excursion. Because the Rzepin and Gotland sections are positioned on the opposite sides of the same foreland basin, a comparison of their sequence stratigraphy allows to test the regularities of the sea-level changes on the shelf of Baltica. In the present paper, a modified view of the recently published sequence stratigraphy of the Gotland succession is presented. Our results indicate that the positive Ludlow δC excursion is connected with prolonged low-stand conditions with small, internal transgressive pulses. © 2010 Springer-Verla
Keywords: C-isotope excursion; Gotland; Holy Cross Mountains; Ludlow; Poland; Sea-level changes; Upper Silurian

Stable carbon isotope fractionation data between H2CO 3 * and CO2(g) extended to 120 °c - Myrttinen, Anssi; Becker, Veith; Mayer, B.; Barth, Johannes (Rapid Communications in Mass Spectrometry, 2014)

Stable carbon isotope stratigraphy in the Ordovician of South China - Munnecke, Axel; Zhang, Yuandong; Xiao, Liu; Cheng, Junfeng (Palaeogeography, Palaeoclimatology, Palaeoecology, 2011)
About 500 samples from 11 Ordovician sections in South China have been analysed for their δC composition. Four sections are located in the Yangtze platform region, the remaining seven sections in the Jiangnan slope region. The sections span more or less the entire Ordovician, but the sample resolution in its lower part (Tremadocian to Dapingian) is lower than in its upper part (Darriwilian to Hirnantian). Overall, the data show a good correlation with the published global isotope curve. At the Cambrian-Ordovician boundary positive values are observed. In the succeeding Tremadocian the values decrease and remain negative into the early Floian. In the late Floian, the values increase to slightly positive. The correlation of Dapingian rocks between the Yangtze and the Jiangnan regions is somewhat problematic which might be due to high siliciclastic input in the Yangtze section. In the Darriwilian a small positive excursion is observed in the Yangtze platform area, however, it is missing in the Jiangnan slope area. This excursion probably correlates with the mid-Darriwilian excursion (MDICE) reported from Baltoscandia. Both chemostratigraphy and conodont biostratigraphy indicate a possible gap between the Shihtzupu Formation and the Pagoda Formation, i.e. most of the Sandbian is probably not represented in the Upper Yangtze region. The earliest Katian is characterised by a pronounced positive excursion correlating with the well-known global Guttenberg excursion (GICE). In the late Katian at least one additional positive excursion was determined. The precise biostratigraphy, however, is not clear, and therefore it is not known which of the known four to five remaining Katian δC excursions identified in Baltica correlate(s) with the one(s) observed in the present study, and further biostratigraphic study is required. The lower part of the Hirnantian excursion (HICE) is probably not preserved, with only small remnants of the HICE observed near the base of the Kuanyinchiao Bed. © 2011 Elsevier B.
Keywords: Graptolites; Ordovician; South China; Stable carbon isotopes; Stratigraphy

Stable carbon isotope techniques to quantify CO 2 trapping under pre-equilibrium conditions and elevated pressures and temperatures - Myrttinen, Anssi; Jeandel, E.; Ukelis, O.; Becker, Veith; van Geldern, Robert; Blum, Philipp; Barth, Johannes (Chemical Geology, 2012)

Stable isotope and dissolved inorganic carbon sampling, monitoring and analytical methods in CO2 injection and EGR projects - Myrttinen, Anssi; Becker, Veith; van Geldern, Robert; Barth, Johannes; Nowak, Martin (Underground Storage of CO2 and Energy, 2010)

Stable isotope and ostracode species assemblage evidence for lake level changes of Nam Co, southern Tibet, during the past 600 years - Wrozyna, Claudia; Frenzel, Peter; Steeb, Philip; Zhu, Liping; van Geldern, Robert; Mackensen, Andreas; Schwalb, Antje (Quaternary international, 2010)

Stable isotope and trace element geochemistry of Upper Cretaceous carbonates and belemnite rostra (Middle Campanian, north Germany) - NIebuhr, Sara; Joachimski, Michael (Geobios, 2002)
Trace element contents and stable isotopic composition of Middle Campanian marl-limestone rhythmites and belemnite rostra of Belemnitella mucronata were investigated. High strontium and low iron as well as manganese and magnesium contents of belemnite calcite and bulk rock samples suggest no diagenetic overprint. However, the orange-coloured cathodoluminescence of coccolith-rich sediments indicates diagenetic cementation and/or recrystallization. The non-luminescent belemnite rostra reveal an extraordinary preservation of the microstructures that is interpreted to have been favoured by a silification of the outer rim of the belemnite rostra. Carbon isotope ratios of the coccolith limestones and belemnite rostra are comparable, with higher δC variations observed for belemnite calcite. The 1.5-2‰ depletion in δO of the marl-limestone rhythmites relative to belemnite calcite is explained by diagenetic alteration of the sediments. Palaeotemperatures, calculated from the δO values of the well-preserved belemnite rostra, are around 12.5 ± 2 °C and suggest rather low sea-surface temperatures for the Middle Campanian epicontinental sea of north Germany assuming a water depth of less than 100 m. © 2002 Éditions scientifiques et médicales Elsevier SAS. All rights reserved.
Keywords: Belemnites; Carbon and oxygen isotopes; Carbonate diagenesis; North Germany; Palaeotemperatures; Upper Cretaceous

Stable isotope and trace element geochemistry of Upper Cretaceous coccolith limestones and belemnite rostra (Middle Campanian, North Germany) - Joachimski, Michael; et al. (Geobios, 2002)
UnivIS-Import:2015-03-09:Pub.2002.nat.dgeo.IGM.LG.stable

Stable isotope geochemistry of pore waters and marine sediments from the New Jersey shelf: Methane formation and fluid origin - van Geldern, Robert; Hayashi, Takeshi; Boettcher, Michael E.; Mottl, Michael J.; Barth, Johannes; Stadler, Susanne (Geosphere, 2013)

Stable isotope mass balances versus concentration differences of dissolved inorganic carbon – implications for tracing carbon turnover in reservoirs - Barth, Johannes; Mader, Michael; Nenning, Franziska; van Geldern, Robert; Friese, Kurt (Isotopes in Environmental and Health Studies, 2017)

Stable isotopes, elemental distribution and growth rings of belemnopsid belemnite rostra: proxies for belemnite life habitat. - Wierzbowski, Hubert; Joachimski, Michael (Palaios, 2009)
Stables isotopes and elemental composition of two well-preserved belemnite rostra (Hibolithes beyrichi and H. hastatus) from the Bathonian of central Poland were studied. Average temperatures calculated from the oxygen isotope ratios of Hibolithes beyrichi and H. hastatus are 10°C and 6°C, respectively. The absence of highamplitude variations in high-resolution temperature profiles suggests these belemnites lived in deeper waters. This interpretation is compatible with a nektobenthic habitat of belemnopsid belemnites. Carbon isotope ratios of the rostra are assumed to be affected by vital fractionation with prominent fluctuations in the δ 13C records resulting from changes in the metabolic activity. Observed variations in Mg:Ca ratios of the rostra (from 5 mmol-mol -1 to 28 mmol-mol -1) are predominantly a primary signal. Temperature dependence of the Mg:Ca ratio is inferred for H. beyrichi on the basis of a correlation with δ 180 values; however, no such correlation is observed for H. hastatus. No significant correlation is observed between Sr:Ca ratios and δ I80 values in either taxon. Sulphur contents in the rostra vary from 630 ppm to 4400 ppm and are interpreted to be largely coprecipitated with belemnite calcite. Extreme compositions of sulphur are interpreted to result from the incorporation of diagenetic sulphur during early marine diagenesis, which is also characterized in these rostra by high Mg:Ca and Sr:Ca ratios and low δ 13C values. A total number of growth rings in the rostrum of H. beyrichi is calculated at around 600, thus, an expected life span of H. beyrichi is considered to be ∼1.5 years assuming daily precipitation of growth bands. © 2009, SEPM.
UnivIS-Import:2015-03-09:Pub.2009.nat.dgeo.IGM.LG.stable

Stable isotope signatures of Middle Paleozoic ahermatypic rugose corals - deciphering vital effects, alteration patterns, and palaeoecological implications - Jakubowicz, Michal; Berkowski, Blazej; López Correa, Matthias; Jarochowska, Emilia; Joachimski, Michael; Belka, Zdzislaw (PLoS ONE, 2015)
This study investigates stable isotope signatures of five species of Silurian and Devonian deep-water, ahermatypic rugose corals, providing new insights into isotopic fractionation effects exhibited by Palaeozoic rugosans, and possible role of diagenetic processes in modifying their original isotopic signals. To minimize the influence of intraskeletal cements on the observed signatures, the analysed specimens included unusual species either devoid of large intraskeletal open spaces ('button corals': Microcyclus, Palaeocyclus), or typified by particularly thick corallite walls (Calceola). The corals were collected at four localities in the Holy Cross Mountains (Poland), Mader Basin (Morocco) and on Gotland (Sweden), representing distinct diagenetic histories and different styles of diagenetic alteration. To evaluate the resistance of the corallites to diagenesis, we applied various microscopic and trace element preservation tests. Distinct differences between isotopic compositions of the least-altered and most-altered skeleton portions emphasise a critical role of material selection for geochemical studies of Palaeozoic corals. The least-altered parts of the specimens show marine or near-marine stable isotope signals and lack positive correlation between δ13C and δ18O. In terms of isotopic fractionation mechanisms, Palaeozoic rugosans must have differed considerably from modern deep-water scleractinians, typified by significant depletion in both 18O and 13C, and pronounced δ13C-δ18O co-variance. The fractionation effects exhibited by rugosans seem similar rather to the minor isotopic effects typical of modern non-scleractinian corals (octocorals and hydrocorals). The results of the present study add to growing evidence for significant differences between Scleractinia and Rugosa, and agree with recent studies indicating that calcification mechanisms developed independently in these two groups of cnidarians. Consequently, particular caution is needed in using scleractinians as analogues in isotopic studies of extinct coral lineages. Answering some of the pertinent palaeoecological questions, such as that of the possibility of photosymbiosis in Palaeozoic corals, may not be possible based on stable isotope data.
UnivIS-Import:2015-10-26:Pub.2015.nat.dgeo.IGM.LP.stable

Stable isotopes (δ18O and δ13C), trace and minor element compositions of Recent scleractinians and Last Glacial bivalves at the Santa Maria di Leuca deep-water coral province, Ionian Sea - López Correa, Matthias; Montagna, Paolo; Taviani, Marco; Vendrell-Simón, Begona; McCulloch, Malcolm (Deep-Sea Research Part Ii-Topical Studies in Oceanography, 2010)
The aragonitic skeletons of bathyal cold-water corals have a high potential as geochemical in situ archives for paleoceanography. Oxygen isotopes and stable carbon isotopes (δ18O and δ13C) have been analyzed, as well as trace and minor element compositions (e.g. Mg/Ca, Sr/Ca, U/Ca, B/Ca and P/Ca) in Lophelia pertusa, one of the most important frame-builders at the Santa Maria di Leuca (SML) deep-water coral hotspot in the Central Mediterranean. The Apulian Bank is swept by strong currents of the Adriatic Deep Water Outflow. The temperature of 13.9 °C is the highest temperature recorded for L. pertusa and provides an important end-member of environmental conditions for geochemical analyses on living Atlantic and Mediterranean cold-water corals. Temperature and salinity (38.77 PSU) are stable throughout the year, and thus virtually no changes should be observed in the stable oxygen isotope signal-if the coral precipitates its skeleton in equilibrium with seawater. We measured various marine properties, such as the seawater oxygen isotope composition (δ18Osw), stable carbon isotope composition (δ13CDIC) of dissolved inorganic carbon (DIC), and dissolved inorganic nutrient concentrations (PO4, NO3, NO2, NH3 and SiO2). Bottom water at the coral sites shows a mean oxygen isotope composition of 1.47‰ δ18Osw-VSMOW, and δ13CDIC showed a mean of 1.1‰ VPDB. A section of a living L. pertusa with a thick theca calcification was probed with a Merchantek MicroMill at a high spatial sampling resolution with 10 samples per 1 mm. This reduced the signal-smoothing inherent to conventional sampling. The δ18Oag of coral aragonite ranges between -2.0‰ and +2.8‰ VPDB and the δ13Cag ranges between -7.77‰ and +1.47‰ VPDB. The Gaussian data distribution for both parameters, including heavy equilibrium values, suggests the completeness of the captured isotopic variability. The strict linear correlation of δ13C and δ18O displays a strong 'kinetic' vital effect. The intercept of the δ13C/δ18O correlation line with the δ13CDIC-composition permits recognition of δ18O equilibrium values of aragonite and thus reconstruction of water temperatures despite strong disequilibrium precipitation. Since the environmental parameters (T, S and δ18Osw) are stable, the entire isotopic signal of the coral must be driven by biological fractionation and might reflect growth speed variations, potentially related to pH variations and changes in the saturation state of the calcifying fluid or seasonally varying nutrient availability. Laser ablation tracks show a trace element composition dependent to microstructural zones (fibrous aragonite vs. centres of calcification). The parabolic relation of the classical temperature proxies Mg/Ca and U/Ca point to trace element vital effects, rendering them unreliable in L. pertusa. The P/Ca ratio shows similar values as Desmophyllum dianthus, for which a linear dependence with seawater phosphate (DIP) has been previously demonstrated. Consequently L. pertusa might be an additional nutrient recorder at bathyal depths. From the same site we also analysed the stable isotopic composition of the Last Glacial pectinid bivalve Pseudamussium peslutrae, which has been radiocarbon-dated (AMS-14C) at 26.3 ka 14C yr BP. The isotope values of the shell calcite document a strongly differing glacial temperature-salinity regime preceding the Holocene coral growth above a prominent hiatus. © 2009 Elsevier Ltd. All rights reserved.
UnivIS-Import:2015-03-09:Pub.2010.nat.dgeo.IGM.LP.stable
Keywords: Cold-water corals; Lophelia pertusa; Stable isotopes; Trace elements; Vital effects

Stable oxygen isotopes - A new approach for tracing the origin of oxide inclusions in steels - Göbbels, Matthias; Pack, Andreas; Hoernes, Stephan; Bross, Rainer; Buhr, Andreas (European Journal of Mineralogy, 2005)
We introduce a new approach for tracing the origin submerged entry nozzle precipitates (clogging) in continuous casting processes using stable oxygen isotopes. The isotopic signatures of possible oxygen sources are compared with the isotope ratios in the precipitates. We use infra-red laser fluorination in combination with continuous flow gas mass spectroscopy to determine the oxygen ratios in the highly refractory, alumina-rich precipitates and possible oxygen sources. Our isotope data indicate that atmospheric oxygen is not the major source of oxide precipitates in the submerged entry nozzles. Also process oxygen from the converter can be excluded to be source of oxygen in clogging. A possible origin of oxygen in alumina-rich precipitates from olivine from refractory material is discussed. © 2005 E. Schweizerbart'sche Verlagsbuchhandlun
UnivIS-Import:2015-03-09:Pub.2005.nat.dgeo.IGM.LM.stable
Keywords: Continuous casting; Non-metallic inclusions; Oxygen isotopes

Stable Sr-isotope, Sr/Ca, Mg/Ca, Li/Ca and Mg/Li ratios in the scleractinian cold-water coral Lophelia pertusa - Raddatz, Jacek; Liebetrau, Volker; Rüggeberg, Andres; Hathorne, Ed; Krabbenhöft, André; Eisenhauer, Anton; Böhm, Florian; Vollstaedt, Hauke; Fietzke, Jan; López Correa, Matthias; Freiwald, André; Dullo, Wolf-Christian (Chemical Geology, 2013)
The aragonitic skeletons of scleractinian cold-water corals can serve as valuable archives in paleoceanographic studies. The potential of δ88/86Sr, Sr/Ca, Mg/Ca, Li/Ca and Mg/Li ratios of the cold-water coral Lophelia pertusa to record intermediate water mass properties has been investigated. Here we used samples from several locations along the European continental margin spanning a large temperature range from 6 to 14°C. Stable strontium isotope measurements were carried out with the recently developed double spike TIMS technique and our results differ from those obtained with less precise methods. In contrast to the strong positive relationship with temperature of previous studies, our results suggest that δ88/86Sr measured in scleractinian cold-water corals is not controlled by seawater temperature, but reflects the Sr isotopic composition of seawater with an offset of δ88/86Sr=-0.196‰.As found in previous studies, the elemental ratios Sr/Ca, Li/Ca and Mg/Li measured in corals are significantly related to water temperature and do not correlate with salinity. Moreover, Sr/Ca ratios in L. pertusa display the expected inverse correlation with temperature. However, the variance in the Sr/Ca data severely limits the accuracy of paleotemperature estimates. The Li/Ca and Mg/Ca ratios reveal other influences besides temperature such as pH and/or growth or calcification rate. However, corresponding Mg/Li ratios in L. pertusa are more tightly related to temperature as they remove these secondary effects. In particular, the Mg/Li ratio in L. pertusa may serve as a new promising paleotemperature proxy for intermediate water masses. Our dataset represents the most extensive geochemical examination of L. pertusa to date, revealing a temperature sensitivity of 0.015. mol/mmol/°C for Mg/Li. However, using this temperature dependence and the precision of 5.3% (2SD) only temperature variations larger than . 1.5°C can be resolved with 95% confidence. © 2013 Elsevier B.V.
UnivIS-Import:2015-03-09:Pub.2013.nat.dgeo.IGM.LP.temper
Keywords: Cold-water corals; Lophelia pertusa; Mg/Li; Paleotemperature proxy; Sr/Ca; Stable strontium isotopes

Stable water isotope patterns in a climate change hotspot: The isotope hydrology framework of Corsica (western Mediterranean) - van Geldern, Robert; Kuhlemann, Joachim; Schiebel, Ralf; Taubald, Heinrich; Barth, Johannes (Isotopes in Environmental and Health Studies, 2014)

Stacking faults of the hydrous carbonate-containing brucite (HCB) phase in hydrated magnesium carbonate cements - Jansen, Daniel; German, Alexander; Ectors, Dominique; Winnefeld, Frank (Cement and Concrete Research, 2024)
Recently, a hydrous carbonate-containing brucite (HCB) with an approximate composition of MgCO3·35 Mg(OH)2·H2O was postulated as hydration product of binders based on mixtures of reactive magnesia and hydromagnesite (Mg5(CO3)4(OH)2·4H2O). X-ray diffraction showed that the 001 reflection of this phase was split into two reflections at 20 °C, whereas at 60 °C only one reflection occurred. Rietveld refinement revealed that the X-ray pattern of the HCB-phase could be fitted well when a random displacement (stacking faults) and a movement of the layers in x, y and z direction were allowed. The presence of water and/or carbonate leads to different distances between the layers, thus causing the splitting of the 001 reflection. At 60 °C, only carbonate is included in the brucite structure, leading to a similar distance between all brucite layers. The assignment of the additional reflection appearing at 20 °C to a separate, unknown hydrated magnesium carbonate, as suggested in earlier studies, can be excluded.
CRIS-Team Scopus Importer:2024-01-05
Keywords: Brucite; Hydromagnesite; Low-CO; Magnesium carbonate cements; Mineral carbonation

Stapelungsstrukturen von Verbindungen der beta-Tonerde- und Magnetoplumbit-Familien - Ansatz einer strukturellen Systematik - Göbbels, Matthias (Zeitschrift für Kristallographie, Supplement, 1997)
UnivIS-Import:2015-03-05:Pub.1997.nat.dgeo.IGM.LM.stapel

Statistical Approaches Link Sources of Sediment Contamination in Subtropical Reservoirs to Land Use: an Example from the Itupararanga Reservoir (Brazil) - Frascareli, Daniele; Gontijo, Erik Sartori Jeunon; Silva, Sheila Cardoso; Melo, Darllene Silveira; De Castro Bueno, Carolina; Simonetti, Vanessa C.; Barth, Johannes; Carlos, Viviane Moschini; Rosa, Andre Henrique; Friese, Kurt (Water Air and Soil Pollution, 2022)
The identification and characterisation of diffuse pollutant sources in reservoirs remain a challenge due to the complexity of catchments with their variety of land use types. A sediment fingerprinting approach was used in this investigation for determining the sources of contaminants in sediments. By using this approach, we demonstrated how the effects of land use on pollution load of the subtropical Itupararanga Reservoir in Brazil can be de-convoluted. Sediments were collected at seven sampling sites (S1–S7) over the length of the reservoir. This was matched by eight sampling sites (P1–P8) of soils from different land use types (agriculture, urban and forest). Investigated parameters included grain size, total nitrogen (TN), total phosphorus (TP), total carbon (TC), organic matter by loss on ignition (OM), total sulphur (TS), and major ions and metals (Ca2+, Mg2+, Na+, K+, NH4+, SO42−, Cl−, NO3−, As, Al, Ba, Cr, Cu, Fe, Mn, Ni and Zn). Our fingerprinting approach helped to outline horizontal spatial heterogeneities (categorised as riverine, transitional and lacustrine areas) that were attributed mainly to sand (> 26.7%), Si (569 g kg−1) and Cr (336 mg kg−1) at S1 (riverine area). Moreover, fine particles of silt and clay leached from agricultural activities were enriched with OM, TP, TN, TC, As and Cr. These types of sediments were deposited into transitional and lacustrine areas. Furthermore, urban soils were a source of sand and phosphorus to sediments. The fingerprinting method reduced the number of relevant parameters for source identification and helped to identify non-point sources of sediments.
CRIS-Team Scopus Importer:2022-04-29
Keywords: Land use; Non-point pollution sources; Sediment fingerprinting approach; Spatial heterogeneity; Subtropical reservoirs

Statistical independence of escalatory ecological trends in Phanerozoic marine invertebrates - Kießling, Wolfgang; et al. (Science, 2006)
Ecological interactions, such as predation and bioturbation, are thought to be fundamental determinants of macroevolutionary trends. A data set containing global occurrences of Phanerozoic fossils of benthic marine invertebrates shows escalatory trends in the relative frequency of ecological groups, such as carnivores and noncarnivorous infaunal or mobile organisms. Associations between these trends are either statistically insignificant or interpretable as preservational effects. Thus, there is no evidence that escalation drives macroecological trends at global and million-year time scales. We also find that taxonomic richness and occurrence data are cross-correlated, which justifies the traditional use of one as a proxy of the other.
UnivIS-Import:2015-04-14:Pub.2006.nat.dgeo.IGM.LP.statis

Stenolaemate bryozoans from the Graham Formation, Pennsylvanian (Virgilian) at Lost Creek Lake, Texas, USA - Ernst, Andrej; Claußen, Anna Lene; Seuß, Barbara; Wyse Jackson, Patrick (Palaeontologia Electronica, 2022)

Stocks, Flows and Prospects of Water - Barth, Johannes; et al. (Massachusetts Institute of Technology and Frankfurt Institute for Advanced Studies, 2010)

Strain migration during multiphase extension, Stord Basin, northern North Sea rift - Fazlikhani, Hamed; Aagotnes, Synne S.; Refvem, Marte A.; Hamilton-Wright, James; Bell, Rebecca E.; Fossen, Haakon; Gawthorpe, Robert L.; Jackson, Christopher A. -L.; Rotevatn, Atle (Basin Research, 2020)
In regions experiencing multiple phases of extension, rift-related strain can vary along and across the basin during and between each phase, and the location of maximum extension can differ between the rift phase. Despite having a general understanding of multiphase rift kinematics, it remains unclear why the rift axis migrates between extension episodes. The role pre-existing structures play in influencing fault and basin geometries during later rifting events is also poorly understood. We study the Stord Basin, northern North Sea, a location characterised by strain migration between two rift episodes. To reveal and quantify the rift kinematics, we interpreted a dense grid of 2D seismic reflection profiles, produced time-structure and isochore (thickness) maps, collected quantitative fault kinematic data and calculated the amount of extension (beta-factor). Our results show that the locations of basin-bounding fault systems were controlled by pre-existing crustal-scale shear zones. Within the basin, Permo-Triassic Rift Phase 1 (RP1) faults mainly developed orthogonal to the E-W extension direction. Rift faults control the locus of syn-RP1 deposition, whilst during the inter-rift stage, areas of clastic wedge progradation are more important in controlling sediment thickness trends. The calculated amount of RP1 extension (beta-factor) for the Stord Basin is up to beta = 1.55 (+/- 10%, 55% extension). During the subsequent Middle Jurassic-Early Cretaceous Rift Phase 2 (RP2), however, strain localised to the west along the present axis of the South Viking Graben, with the Stord Basin being almost completely abandoned. Rift axis migration during RP2 is interpreted to be related to changes in lithospheric strength profile, possibly related to the ultraslow extension (<1 mm/year during RP1), the long period of tectonic quiescence (ca. 50 myr) between RP1 and RP2 and possible underplating. Our results highlight the very heterogeneous nature of temporal and lateral strain migration during and between extension phases within a single rift basin.
CRIS-Team WoS Importer:2020-11-27

Stratigraphical and δ13C records of Permo-Carboniferous platform carbonates, South China: Responses to late Paleozoic icehouse climate and icehouse-greenhouse transition - Liu, Chao; Jarochowska, Emilia; Du, Yuansheng; Vachard, Daniel; Munnecke, Axel (Palaeogeography, Palaeoclimatology, Palaeoecology, 2017)
Little attention has been focused on the stratigraphical imprints of the Late Paleozoic Ice Age on the equatorial eastern Paleo-Tethys. An integrated study of biostratigraphy, microfacies, and stable carbon isotope stratigraphy was carried out on Pennsylvanian-middle Guadalupian carbonates of the Gongchuan section in the Bama Platform, South China. It records seven cooling and two warming pulses in the pre-Kungurian interval, comparing with ice-proximal stratigraphical records and far-field indirect proxies in lower latitudes. A Kungurian negative δC excursion (from +4.4‰ at the base of the Kungurian to +1.6‰) recorded only in the subequatorial belt is documented here. It is followed by a global positive δC trend reaching +5.3‰ near the Cisuralian-Guadalupian boundary. Seven third-order shallowing-upward cycles are reported for the first time from the Kungurian succession. The duration of each cycle is estimated to ca. 1myr. These cycles are interpreted as being of glacioeustatic origin and mainly driven by long-period modulations of obliquity ( 1.2myr) under major pCO decreasing condition. This interpretation is supported by recent climate-ice sheet modeling and Cenozoic glaciation studies, which argue that astronomical forcing will be amplified by large-magnitude perturbations in the carbon cycle, when only localized ice-centers persist. Our results emphasize the need for integration of sedimentological and paleoclimatological proxies in elucidating the dynamics of the deglacial phases of the Late Paleozoic Ice Ag
Keywords: Carbon isotope; Kungurian; LPIA; Orbital forcing; Shallowing-upward cycles

Stratigraphic and oxygen isotope evidence for My-scale glaciation driving eustasy in the Early-Middle Devonian greenhouse world. - Elrick, Maya; Berkyova, Stana; Klapper, Gilbert; Sharp, Zachary; Joachimski, Michael; Fryda, Jiri (Palaeogeography, Palaeoclimatology, Palaeoecology, 2009)
Million year-scale (3rd-order) depositional sequences (few 10s to 100 m-thick) are common in the Devonian marine record and are correlated between sedimentary basins and across widely separated continents implying a eustatic origin. Tectonically driven changes in mid-ocean ridge spreading rates/lengths are too slow to account for the calculated 3rd-order rise/fall rates and typical orbital frequencies ( 20-400 ky) are too fast. We analyzed oxygen isotopes from conodont apatite to evaluate if Early-Middle Devonian 3rd-order sea-level changes were controlled by paleoclimatically driven ice volume (glacio-eustasy) and seawater temperature change (thermo-eustasy). Two successive depositional sequences in the western U.S. (Nevada) and Czech Republic (Prague Basin) were sampled. The δ18O values range from 17.8‰ to 20.2‰ (SMOW) and show similar trends across the Emsian-Eifelian boundary with increasing and peak values in the lower costatus, decreasing values in the mid costatus, and increasing values in the upper costatus to australis zones. The similarities between these widely separated localities indicate that the isotopic trends are global rather than controlled by local variations in seawater temperature, evaporation/freshwater influx, or diagenesis. In the Nevada section, where the sea-level history is the most complete and best understood, the isotopic values increase and peak in late highstand and lowstand system tracts and decrease to the lowest values in the transgressive and maximum flooding intervals suggesting the My-scale sea-level changes were paleoclimatically controlled. The magnitude of isotopic shift from lowstand to maximum flooding intervals ranges from 0.8‰ to 1.5‰ and occurred over time spans of < 1.7 My. The only known mechanism to explain such large and rapid isotopic shifts is glacio-eustasy. If a reasonable range of My-scale subtropical sea surface temperature changes are assumed ( 1-3 °C), then this requires glacio-eustatic sea-level changes of > 35 m to explain the remaining isotopic shifts. These amplitudes imply that significant continental ice sheets grew and melted on the < 1.7 My time scales during the Early-Middle Devonian and, like recent reports for the mid-Cretaceous and early Eocene, challenge previous assumptions of ice-free greenhouse climates. A plausible climate driver for these My-scale paleoclimate changes is long-period eccentricity ( 2.4 My) and obliquity ( 1.2 My) variations. © 2009 Elsevier B.V. All rights reserved.
UnivIS-Import:2015-03-09:Pub.2009.nat.dgeo.IGM.LG.strati
Keywords: Conodont apatite; Devonian; Glaciation; Glacio-eustasy; Greenhouse; Oxygen isotopes

Stratigraphic ranking of selected invertebrate fossils: A quantitative approach at different temporal and geographic scales - Abdelhady, Ahmed; Seuß, Barbara; Hassan, Hatem (Palaeontologia Electronica, 2019)
Fossil groups are used for biochronological dating of rocks for decades. This manuscript presents a quantitative approach to appraise and compare the quality of selected taxa as biostratigraphic markers. Based on species occurrence of ammonites, bivalves, and planktic and benthic foraminifers we evaluate the potential of these to rank them quantitatively. The spatiotemporal analyses of occurrence data (species duration, geographic range) were integrated in results of the Unitary Association method, which measures superpositional contradictions in addition to the generation of a number of UAs. The results indicate that Jurassic ammonites have the lowest species duration, and that the majority of species is confined to a single UA-zone. Additionally, ammonites have the lowest numbers of contradicted bio-events. However, planktic foraminifers are more valuable at least in the Cenozoic as they have a high geographic reproducibility and diversity, and higher ISP values. The bivalves and benthic foraminifers both show longer average species durations and more superpositional contradictions per species. Therefore, their biostratigraphic potential is more limited at an interregional scale. The shorter species durations of ammonites and planktic foraminifers in the studied sections can be attributed to their higher extinction rates. As an advantage to simple spatio-temporal analyses, the UA-method can accurately assess the stratigraphic potential of a given taxonomic group. The results obtained herein indicate that the life-habit has direct impact on the species duration and thus, the stratigraphic potential of the fossil groups. Based on the results achieved from this study, an index for ranking fossil groups (Index of Stratigraphic Potential ‘ISP’) is introduced.<br

Stratigraphy, metamorphism and nappe‑tectonics in the Shackleton Range (Antarctica). - Buggisch, Werner; Kleinschmidt, Georg; Kreuzer, Hans; Krumm, Stefan (Geodätische und geophysikalische Veröffentlichungen. Reihe I, 1990)
UnivIS-Import:2015-03-05:Pub.1990.nat.dgeo.IGM.LG.strati

Stratigraphy modeling and thermal conductivity computation in areas characterized by Quaternary sediments - Teza, Giordano; Galgaro, Antonio; Destro, Elisa; Di Sipio, Eloisa (Geothermics, 2015)
Keywords: Geoexchange; Borehole heat exchanger; Thermal ground characterization; Stratigraphy; Thermal conductivity; Spatial statistics

Strengthening confidence in climate change impact science - O'Connor, Mary; Holding, Johnna; Kappel, Carrie; Duarte, C. M.; Brander, K.; Brown, C. J.; Bruno, J. F.; Buckley, L.; Burrows, M. T.; Halpern, B. S.; Kießling, Wolfgang; Moore, P.; et al. (Global Ecology and Biogeography, 2015)
Keywords: Abundance; Attribution; Climate change; Distribution; Hypothesis; Impacts; Marine; Phenology; Scientific method; Time series

Stress sensitivity of porosity and permeability under varying hydrostatic stress conditions for different carbonate rock types of the geothermal Malm reservoir in Southern Germany - Bohnsack, Daniel; Potten, Martin; Freitag, Simon; Einsiedl, Florian; Zosseder, Kai (Geothermal Energy, 2021)
In geothermal reservoir systems, changes in pore pressure due to production (depletion), injection or temperature changes result in a displacement of the effective stresses acting on the rock matrix of the aquifer. To compensate for these intrinsic stress changes, the rock matrix is subjected to poroelastic deformation through changes in rock and pore volume. This in turn may induce changes in the effective pore network and thus in the hydraulic properties of the aquifer. Therefore, for the conception of precise reservoir models and for long-term simulations, stress sensitivity of porosity and permeability is required for parametrization. Stress sensitivity was measured in hydrostatic compression tests on 14 samples of rock cores stemming from two boreholes of the Upper Jurassic Malm aquifer of the Bavarian Molasse Basin. To account for the heterogeneity of this carbonate sequence, typical rock and facies types representing the productive zones within the thermal reservoir were used. Prior to hydrostatic investigations, the hydraulic (effective porosity, permeability) and geomechanical (rock strength, dynamic, and static moduli) parameters as well as the microstructure (pore and pore throat size) of each rock sample were studied for thorough sample characterization. Subsequently, the samples were tested in a triaxial test setup with effective stresses of up to 28 MPa (hydrostatic) to simulate in-situ stress conditions for depths up to 2000 m. It was shown that stress sensitivity of the porosity was comparably low, resulting in a relative reduction of 0.7–2.1% at maximum effective stress. In contrast, relative permeability losses were observed in the range of 17.3–56.7% compared to the initial permeability at low effective stresses. Stress sensitivity coefficients for porosity and permeability were derived for characterization of each sample and the different rock types. For the stress sensitivity of porosity, a negative correlation with rock strength and a positive correlation with initial porosity was observed. The stress sensitivity of permeability is probably controlled by more complex processes than that of porosity, where the latter is mainly controlled by the compressibility of the pore space. It may depend more on the compaction of precedented flow paths and the geometry of pores and pore throats controlling the connectivity within the rock matrix. In general, limestone samples showed a higher stress sensitivity than dolomitic limestone or dolostones, because dolomitization of the rock matrix may lead to an increasing stiffness of the rock. Furthermore, the stress sensitivity is related to the history of burial diagenesis, during which changes in the pore network (dissolution, precipitation, and replacement of minerals and cements) as well as compaction and microcrack formation may occur. This study, in addition to improving the quality of input parameters for hydraulic–mechanical modeling, shows that hydraulic properties in flow zones largely characterized by less stiff, porous limestones can deteriorate significantly with increasing effective stress.
CRIS-Team Scopus Importer:2021-06-11
Keywords: Carbonate; Effective stress; Geothermal energy; Hydrostatic; Malm; Molasse Basin; Permeability; Poroelastic; Porosity; Stress sensitivity

Stromatoporoid-coral reefs and platform deposits from the Silurian of Gotland - Munnecke, Axel (Mémoires du Muséum national d'Histoire naturelle, 2007)
Keywords: Stromatoporoids; corals; reefs; platform deposits; Silurian; Gotland

Structural and elemental analysis of the freshwater, low-Mg calcite coralline alga Pneophyllum cetinaensis - Ragazzola, Federica; Kolzenburg, Regina; Zekonyte, Jurgita; Teichert, Sebastian; Jiang, Chulin; Žulevíc, Ante; Caragnano, Annalisa; Falace, Annalisa (Plants, 2020)

Structural and geochemical assessment of the coralline alga Tethysphytum antarcticum from Terra Nova Bay, Ross Sea, Antarctica - López Correa, Matthias; Teichert, Sebastian; Ragazzola, Federica; Cazorla Vázquez, Salvador; Engel, Felix; Hurle, Katrin; Mazzoli, Claudio; Kuklinski, Piotr; Raiteri, Giancarlo; Lombardi, Chiara (Minerals, 2023)
Crustose coralline algae (CCA) occur from the tropics to the poles in photic benthic environments. Here, we report on some of the world’s southernmost and coldest CCA sites in Terra Nova, Ross Sea, Antarctica at 74°41′ S. The recently described red alga Tethysphytum antarticum is investigated for its skeletal architecture, its mineralogical and geochemical composition, as well as for its taxonomic classification. A phylogenetic analysis based on molecular genetics and the sequencing of the photosystem II protein D1 (psbA) gave a perfect match with T. antarcticum. Histological sections and micro-CT-scans provide new diagnostic details for the conceptacles (the reproductive organs of the alga). X-ray diffractometry and electron-microprobe measurements yielded a clear high-Mg calcite ( 8 mol%) composition of the skeletal parts. Detailed back-scattered electron imaging of polished petrographic thin sections revealed a two-layered thallus (vegetative plant tissue), comprising an organic-rich irregularly calcified basal layer with rectangular cells, overlain by the main thallus. Elemental maps show relatively increased sulphur in the basal layer, clearly tied to organic cell walls. MgCO3 and SrCO3 were targeted with semiquantitative elemental mappings and in an ontogenetic quantitative spot transect. Compared with temperature (−1.95 °C to +1.08 °C), the MgCO3 (mol%) reflects this world’s coldest CCA site temperature with the lowest MgCO3 content of 7.9 ± 1.6 mol%. The along transect variability, however, shows with 6 mol% a larger MgCO3 variability than expected for the 3 °C intra-annual temperature amplitude in Terra Nova Bay. This implies that in low amplitude settings the biomineralisation control on Mg/Ca ratios can outcompete its temperature sensitivity. Mark-recapture studies, next to the environmental logger station La Zecca are suggested, to perform a detailed growth rate and biomineralisation quantificatio
Keywords: crustose coralline algae; Antarctica; taxonomy; phylogeny; thallus structure; biomineralization; geochemistry; climate change

Structural evidence for sinistral displacement on the Wegener Fault in southern Nares Strait, Arctic Canada - von Gosen, Werner; Piepjohn, K.; Gilotti, J. A.; Mcclelland, W. C.; Reinhardt, L. (Circum-Arctic Structural Events: Tectonic Evolution of the Arctic Margins and Trans-Arctic Links with Adjacent Orogens, 2019)
The sinistral Wegener Fault in the Nares Strait between northwest Greenland and eastern Ellesmere Island (Canadian Arctic) represents a tectonic element in the Arctic whose existence and significance have been controversial for more than 50 years. Some workers interpret the Wegener Fault as an important early Tertiary transform related to movement of the Greenland plate relative to the North American plate. Others view it as insignificant or reject its existence. While onshore studies in the Canadian portion of the northern Nares Strait region have proven the existence of important sinistral strike-slip faults related to the offshore Wegener Fault, the southern continuation of the Wegener Fault in the southern Kane Basin and Smith Sound is unclear. In particular, Smith Sound has been interpreted as a location of an undisturbed continuation of the Proterozoic basement from Greenland to Ellesmere Island, with only one possible location of the Wegener Fault near the east coast of Ellesmere Island.
CRIS-Team WoS Importer:2019-11-15

Structural investigations of selected phases in the system Ca2SiO4 * Ca3(PO4)2 using XRPD and Rietveld method - Müller, Ralf; Neubauer, Jürgen; Götz-Neunhoeffer, Friedlinde (2001)
UnivIS-Import:2015-03-09:Pub.2001.nat.dgeo.IGM.LM.struct

Structurally and climatically-controlled progressive destabilisation of a multi-unit carbonate rockslide with marly interlayers over two decades (Hornbergl, Tyrol/Austria) - Ettenhuber, Regina; Moser, Michael; Krautblatter, Michael; Paysen-Petersen, Lukas (Zeitschrift der Deutschen Gesellschaft für Geowissenschaften, 2022)
Rockslides in intercalated carbonate rocks are among the most common and hazardous rock slide types in the European Alps and other mountains worldwide. Progressive shear plane development in marly or clayey interlayered lime-stones is an issue of debate, especially since the disastrous 200 million m3 carbonate rockslide in Vajont in 1963. Since in-terlayers are often not persistently developed, the processes controlling the progressive shear plane evolution in carbonate rockslides affecting acceleration and deceleration phases are poorly understood. This paper discusses 20 years of progressive shear plane development in a 10 million m3 multi-unit rockslide with marly interlayers (Hornbergl, Austria). We present a two-decade kinematic record, complemented with field mapping, surface geodetical observations, subsurface geophysical investigations, rock and soil mechanical laboratory testing, a snow-referenced infiltration model, as well as a resulting dis-continuum mechanical model. Monthly tape extensometer measurements (3,300 individual measurements) from 1996 to 2016, mapping and geodetic investigations reveal mean absolute displacement rates of 0.2-14.5 mm/month between multi-ple units of the translational rockslide, often separated by > 20 m deep and meter-wide open fractures. Electrical resistivity tomography (ERT) uncovers the geological and structural setting of the upper 40 m of the rockslide's inner structure. Labo-ratory analysis shows that full (100%) saturation of marly interlayers decreases the cohesion from 65 to 21 kPa in compari-son to 50% saturation, presumably explaining seasonal velocity variations. Correspondingly, infiltration models including snow accumulation and melt appear to control movement patterns in some years after snow melt and after heavy convective rainfalls. Discontinuum mechanical models based on mapping, geophysical reconnaissance and mechanical laboratory test -ing show that the multi-unit rockslide is at the fringe of stability with 50% water saturation in marly interlayers and that strain rates rapidly accelerate with the cohesion loss upon their full water-saturation matching with the described kinematic record. Over multiple years, compression and decompression waves between rockslide units become a first order control for progressive rockslide development. Here we show in a 20-year multi-unit rockslide record, that infiltration after snowmelt and extreme precipitation may control monthly and seasonal patterns of carbonate rockslide defor mation, but compression and decompression waves may become key control on a multiannual time scale for progressive destabilisation.
CRIS-Team WoS Importer:2022-10-07

Structure and interactions in benzamide molecular crystals - Ectors, Philipp; Ectors, Dominique; Zahn, Dirk (Molecular Simulation, 2013)
In this study, we resolved discrepancies concerning the experimentally determined structure of benzamide molecular crystals from dispersion-corrected density functional calculations. A clear energy ranking was obtained for the two candidates of the stable (P1) modification of benzamide. This was rationalised by subtle differences of the molecular interactions in the molecular crystal. The potential energy of the different structures was dominated by the interplay of intermolecular attraction and molecular torsion/deformation to accommodate favourable hydrogen-bonded networks. Using suitable proxies arranged in pseudo-crystalline set-ups, we discriminated the contribution of electrostatics, π-π interactions and intra-molecular interactions to the lattice energies. © 2013 Taylor and Francis.
UnivIS-Import:2015-03-09:Pub.2013.nat.dgeo.IGM.LM.struct
Keywords: crystal structure; density-functional theory calculations; molecular interactions; polymorphism

Structure and principles of oxidic hexaphases: A review - Klemenz, Lisa; Richter, Andreas; Langhof, Nico; Göbbels, Matthias (Open Ceramics, 2021)
This paper is about the general structure and the formation of oxidic hexaphase types according to their crystal chemistry. Oxidic hexaphases exhibit hexagonal symmetry and consist of mixed layer structures stacked along the crystallographic c-axis. There are two main types of hexaphases: the magnetoplumbite and β-alumina type. Every hexaphase has a spinel structure that integrates blocks with either a rock salt or β-alumina structure. Both block types contain a characteristic cation. The formation of oxidic hexaphases depends on various factors: In addition to the size and charge of the characteristic cation the size of the spinel block in the crystallographic a-b direction is a decisive factor. Furthermore, the spinel block can be modified by replacing the present trivalent scaffolding cations with bivalent cations, resulting in more complex hexaphases such as the X, W, Z and Y types or β‴ types.
CRIS-Team Scopus Importer:2021-07-02
Keywords: Beta-alumina; Hexaaluminates; Magnetoplumbite; Mixed layer; Stacking

Studies of the stability, nucleophilic substitution reactions, DNA/BSA interactions, cytotoxic activity, DFT and molecular docking of some tetra- and penta-coordinated gold(iii) complexes - Radisavljevic, Snezana; Kesic, Ana Dekovic; Cocic, Dusan; Puchta, Ralph; Senft, Laura; Milutinovic, Milena; Milivojevic, Nevena; Petrovic, Biljana (New Journal of Chemistry, 2020)
Two gold(iii) complexes, square-planar [Au(DPP)Cl-2](+)(1) and distorted square-pyramidal [Au(DMP)Cl-3] (2) (where DMP = 2,9-dimethyl-1,10-phenanthroline and DPP = 4,7-diphenyl-1,10-phenanthroline), were studied by different experimental methods. Their stability in water and in buffer solution (25 mM Hepes, 30 mM NaCl, pH = 7.2) was investigated by UV-Vis spectroscopy while their redox stability is confirmed by CV. Substitution reactions between complexes1and2, and biologically relevant ligands, such as thiourea (Tu), guanosine-5 '-monophosphate (5 '-GMP), glutathione (GSH) andl-methionine (l-Met), were studied by a stopped-flow technique, under the pseudo-first order conditions as a function of ligand concentration and temperature. According to the values of the activation parameters, all studied reactions followed an associative substitution mechanism. DNA binding studies of complexes1and2were performed by UV-Vis and fluorescence spectroscopy and viscosity measurements, as well as interactions with bovine serum albumin (BSA). Density functional theory (DFT) was implemented in order to analyse the wave function of the optimized structures to get better insight into the binding interactions between the inert ligands and gold(iii) center. The experimental results of binding studies with DNA and BSA were simulated and compared by performing a molecular docking study. All results demonstrate the strong connection between the reactivity of the complexes toward biologically important targets and their structural and electronic characteristics. The cytotoxic activity of complexes1and2against different cell lines (MDA-MB-231, HCT-116, and HaCaT) was evaluated 24 and 72 h after treatments. The results indicate reduced viability of cell lines in a time- and dose-dependent manner.
CRIS-Team WoS Importer:2020-07-24

Studies on the early hydration of two modifications of ye'elimite with gypsum - Jansen, Daniel; Spies, Alexandra; Neubauer, Jürgen; Ectors, Dominique; Götz-Neunhoeffer, Friedlinde (Cement and Concrete Research, 2017)
Two modifications of ye'elimite (namely orthorhombic ye'elimite (stoichiometric CA) and iron-containing cubic ye'elimite (CAF)) were synthesized and the reactions without additional sulfate and with gypsum were tracked by means of heat flow calorimetry. Without gypsum the reaction differs significantly for both modifications while the addition of gypsum leads to almost comparable reactions. With addition of gypsum two distinct heat flow maxima could be detected while the reaction without gypsum showed only one distinct maximum for both modifications. For the systems with gypsum additional experiments were performed namely in-situ XRD, NMR, thermodynamic modeling, TGA and pore solution composition. It could be shown that the reaction with gypsum shows two steps of ettringite precipitation for both modifications. The two steps show significant differences. During the first step of ettringite precipitation gypsum and ye'elimite and free water are consumed forming ettringite and a highly hydrated AH. The second ettringite precipitation is powered by ye'elimite consumption but no further gypsum dissolution. In addition, water is removed from the AH used up for the second ettringite precipitation. The two modifications of ye'elimite react comparable with gypsum but show slightly different heats of hydration when reacting with the same calcium sulfate (gypsum) during early hydration; this is due to slightly lower reaction turnover of the cubic, iron-containing modification leading to slightly reduced ettringite formatio

Study of hydration potential and kinetics of the ferrite phase in iron-rich CAC - Hertel, Tobias; Neubauer, Jürgen; Götz-Neunhoeffer, Friedlinde (Cement and Concrete Research, 2016)
With the presence of CA, the hydration kinetics of ferrite phase is influenced and decreased dramatically. Heat flow measurements, QXRD data, and heat flow calculations show concordantly that hydration of ferrite in mix with CA is retarded until the onset of CA hydration and that less ferrite is dissolved. Analysis of the liquid phase of CA paste and CAC-like cement paste displayed significant higher concentrations of Al and Ca compared with pure ferrite paste. Thus, the composition of the liquid phase is set by initial dissolution of CA. We assume that an instant dissolution of the ferrite phase is blocked when solubility equilibrium is dominated by CA. Dissolution of ferrite is only possible after massive precipitation of hydrates and reduction of Ca and Al concentration in the liquid phase.
Keywords: Calcium aluminate cement(D); Calcium aluminoferrite (D); Calorimetry (A); Pore solution (B); X-ray diffraction (B)

Study of thermal migration and induced mechanical effects in double U-tube energy piles - Luo, Jin; Zhao, Haifeng; Gui, Shuqiang; Xiang, Wei; Rohn, Joachim (Computers and Geotechnics, 2017)
This paper investigates two geothermal energy piles using thermal response tests (TRTs). A set of parameters including pile wall temperature, ground temperature and strain are monitored at four different depths. The thermally induced mechanical behavior of the energy piles are then analyzed based on the monitoring data. The results show the following: (1) The temperature at the pile wall clearly varies throughout the heating and cooling cycle, and the ground temperature distribution shows a delay compared to the TRT stages. (2) The thermally induced mechanical effects are influenced by both the temperature and restraint conditions. © 2017 Elsevier Ltd
Keywords: Geothermal energy; Energy piles; Ground temperature; Heating and cooling cycles; Mechanical behavior; Mechanical effects; Restraint conditions; Thermal migration; Thermal response test; Piles; cooling; geothermal energy; heating; mechanical property; pile response; strain; temperature effect

Study on a fossil nautiloid – surprising insights - Seuß, Barbara (Annual Meeting of the Paläontologische Gesellschaft, 2012)
The Buckhorn Asphalt Quarry in Oklahoma, USA, yields a Desmoinesian (Upper Carboniferous) faunal assemblage of outstanding preservation caused by synsedimentary or contemporary impregnation of sediments and fauna with hydrocarbons. These hydrocarbons prevented diagenetic processes to a high degree. The faunal assemblage evolved in a (sub)tropical shallow marine setting and is, with more that 160 reported species, one of the most diverse Paleozoic faunas known to date. The succession is strongly dominated by molluscs, i.e., gastropods, cephalopods, and bivalves, accompanied by e.g., fusulinids, ostracods, echinoderms, and bryozoans. The sediments are mainly mixed siliciclastic-carbonatic and exhibit a single cycle of trans- and regression, with cephalopod-dominated sediments ("cephalopod coquina") representing the deepest marine deposits. Two cephalopod shell remains from the cephalopod coquina were selected for a detailed isotope study (O, C). One shell remain derives from a so far unidentified specimen, the second one from an orthoconic nautiloid which was tentatively assigned to Hebetorthoceras unicamera. Hebetorthoceras is characterized by preservation of two chambers of the phragmocone with nicely preserved cameral and siphuncular deposits. Before samples were prepared the shell remains were intensively studied by using SEM, EDX, XRD-GADDS, and by a series of thin sections. As expected, original shell microstructure and material were still preserved accompanied by parts influenced by diagenetic alteration. Anyhow, both altered and unaltered shell material and both, cameral deposits and shells were sampled with high resolution. Primary isotope signals were used to recalculate local paleotemperatures (unidentified remain: 28-31°C; Hebetorthoceras: 14-15°C) for the sea covering the area of the Buckhorn Asphalt Quarry. Samples exhibiting diagenetic alteration were used to reconstruct diagenetic pathways within the cephalopod remains. So far so good, if there weren't two distinct oval marks on the outside of Hebetorthoceras and the rather abnormal formation and mineralogy of the cameral deposits of this specific specimen. In a subsequent study both, the oval marks and the cameral deposits were examined and it turned out, that a) Hebetorthoceras was victim of a predator, b) this attack was sublethal, c) the specimen was able to precipitate further cameral deposits after the assault, d) it precipitated high magnesium-calcitic cameral deposits during lifetime, and e) the HMC was not a reaction to the heavy injury caused by the attack, but was even formed before. Please download the supplementary material for details on this presented stud

Study on operation management of borehole heat exchangers for a large-scale hybrid ground source heat pump system in China - Luo, Jin; Zhao, Haifeng; Jia, Jia; Wei, Xiang; Rohn, Joachim; Blum, Philipp (Energy, 2017)
For large-scale Ground Source Heat Pump (GSHP) systems, the numerous Borehole Heat Exchangers (BHEs) are generally managed in units. The simultaneous operation of BHEs consume huge amount of energy by operating water-circulating-pumps. However, such an operation condition may waste energy when no peak thermal load is needed. Hence, operation management should be optimized according to timely energy demand to ensure efficient performance with minimum maintenance. In this paper, three operation conditions for a cooling load dominated GSHP system in China are studied. First, specific ground conditions of the BHE field are investigated. The GSHP system operation under intermittent heating and cooling conditions is simulated by Thermal Performance Test (TPT). In order to examine performance of the BHEs and ground temperature migration, a numerical heat transport model is developed. Modeling results indicate similar thermal performance of BHEs and ground temperature disturbance among the three operation alternatives over a 25-year period. Finally, economic performance and operating savings are analyzed. The optimized operation condition in which the operating numbers of BHEs was designed with monthly energy demand of the building could save around 25,000 CNY (∼3000 EUR) annually. © 2017 Elsevier L
Keywords: Energy management; Heat exchangers; Heat pump systems; Pumps; Borehole heat exchangers; Economic performance; Intermittent heating; Minimum maintenances; Operation conditions; Simultaneous operation; Thermal Performance; Water circulating pumps; Geothermal heat pumps; borehole; cooling; fuel consumption; ground conditions; heat transfer; heating; optimization; performance assessment; China

Stylolites and stylolite networks as primary controls on the geometry and distribution of carbonate diagenetic alterations - Gomez-Rivas, Enrique; Martin-Martin, Juan Diego; Bons, Paul D.; Köhn, Daniel; Griera, Albert; Trave, Anna; Llorens, Maria-Gema; Humphrey, Elliot; Neilson, Joyce (Marine and Petroleum Geology, 2022)
There is ongoing debate on whether stylolites act as barriers, conduits, or play no role in fluid transport. This problem can be tackled by examining the spatial and temporal relationships between stylolites and other diagenetic products at multiple scales. Using the well-known Lower Cretaceous Benic`assim case study area (Maestrat Basin, E. Spain), we provide new field and petrographic observations of how bedding-parallel stylolites can influence different diagenetic processes during basin evolution. The results reveal that stylolites can serve as baffles or inhibitors for different carbonate diagenetic reactions, and act as fronts for dolomitization, dolomite recrystallization and dolomite calcitization processes. Anastomosing stylolites that pre-date burial dolomitization probably acted as a collective baffle for dolomitization fluids in the study area, resulting in stratabound replacement geometries at the metre-to-kilometre scale. The dolomitization front coincides with stylolites, and can be traced along consecutive anastomosing ones. Such anastomosing stylolites are typical of mud-dominated facies that characterize limestone-dolostone transition zones. Conversely, dolostone bodies tend to correspond to more grain-dominated facies characterized by parallel (non-anastomosing) stylolites. Stylolites subsequently acted as fluid flow conduits and barriers when the burial and stress conditions changed. Stylolitic porosity enhanced by dissolution within dolostones close to faults appears filled with saddle dolomite riming the stylolite pore, and high-temperature blocky calcite cements filling the remaining porosity. The fluids responsible for these reactions were likely released from below at high pressure, causing hydraulic brecciation, and were channelised through stylolites, which acted as fluid conduits. Stylolites are also found acting as baffles for subsequent dolomite calcitization reactions during meteoric diagenesis and occasionally appear filled with iron oxides likely released by calcitization. This example demonstrates how the same type of stylolites (bedding-parallel) can act as barriers/inhibitors and/or conduits for different types of diagenetic reactions through time, and how important it is to consider their collective role when they form networks.
CRIS-Team WoS Importer:2022-02-11

Subaqueous rock-avalanche deposits exposed by post-glacial isostatic rebound, Innfjorddalen, Western Norway - Schleier, Markus; Hermanns, Reginald L.; Gosse, John C.; Oppikofer, Thierry; Rohn, Joachim; Tonnesen, Jan F. (Geomorphology, 2017)
This paper presents a detailed description of deposits and landforms of multiple rock avalanches in Western Norway, one of which fell onto water-saturated sediments in Innfjorddalen below the former water level. Deposits of the latter are now exposed on the valley floor due to post-glacial isostatic rebound. At least three rock avalanches from the same source at Gråfonnfjellet Mountain have occurred during late glacial and post-glacial time, and their deposits are distributed over an area of 1.44 km2 in the valley. These rock avalanches have volumes of 15.1 × 106 m3, 5.4 × 106 m3 and 0.3 × 106 m3 and yielded cosmogenic radionuclide 10Be ages of 14.3 ± 1.4 ka, 8.79 ± 0.94 ka and 1.028 ± 0.380 ka, respectively. The youngest event dates, within uncertainty limits to a historic rock avalanche in the year 1611–12 CE. The rock avalanches formed a stratified succession of deposits. The rock-avalanche deposits (1.38 m2) have lobate forms, have frontal rims and parallel ridges, extend across the valley floor and up the opposite slope, and form dams on the valley floor. Isolated hills comprised of rock boulders (0.61 km2), interpreted to be ‘toma hills’, are disconnected from the main rock-avalanche deposits by a 520-m-wide zone of deformed, valley-fill sediments. Trenches and a ground penetrating radar survey of these deposits indicate large-scale deformation or liquefaction. Numerical runout modeling of the rock avalanches with the code DAN3D supports the interpretation of their landforms and sources, and highlights their runout behavior. © 2016 Elsevier B.V.
Keywords: cosmogenic radionuclide; dating method; fjord; landform; mountain region; numerical model; Postglacial; rock avalanche; Norway

Subarctic Holocene climatic and oceanographic variability in Stjernsund, Northern Norway: evidence from benthic foraminifera and stable isotopes - Joseph, Nina; López Correa, Matthias; Schönfeld, Joachim; Rüggeberg, Andres; Freiwald, André (Boreas, 2013)
A high-resolution record, covering 9.3-0.2ka BP, from the sub-arctic Stjernsund (70°N) was studied for benthic foraminiferal faunas and stable isotopes, revealing three informally named main phases during the Holocene. The Early- to Mid-Holocene (9.3-5.0ka BP) was characterized by the strong influence of the North Atlantic Current (NAC), which prevented the reflection of the Holocene Climatic Optimum (HCO) in the bottom-water temperature. During the Mid-Holocene Transition (5.0-2.5ka BP), a turnover of benthic foraminiferal faunas occurred, Atlantic Water species decreased while Arctic-Polar species increased, and the oxygen isotope record showed larger fluctuations. Those variations correspond to a period of global climate change, to spatially more heterogeneous benthic foraminiferal faunas in the Nordic Seas region, and to regionally diverging terrestrial temperatures. The Cool Late Holocene (2.5-0.2ka BP) was characterized by increased abundances of Arctic-Polar species and a steady cooling trend reflected in the oxygen isotopes. In this period, our record differs considerably from those on the SW Barents Sea shelf and locations farther south. Therefore, we argue that regional atmospheric cooling triggered the late Holocene cooling trend. Several cold episodes centred at ∼8.3, ∼7.8, ∼6.5, ∼4.9, ∼3.9 and ∼3.3ka BP were identified from the benthic foraminiferal faunas and the δ18O record, which correlated with marine and atmospherically driven proxy records. This suggests that short-term cold events may result from reduced heat advection via the NAC or from colder air temperatures. © 2012 The Authors. Boreas © 2012 The Boreas Collegium.
UnivIS-Import:2015-03-09:Pub.2013.nat.dgeo.IGM.LP.subarc

Subduction and exhumation mechanisms of ultra-high and high-P oceanic and continental crust at Makbal (Tianshan, Kazakhstan and Kyrgyzstan) - Meyer, Melanie; Klemd, Reiner; Hegner, E.; Konopelko, Dmitry (Journal of Metamorphic Geology, 2014)
UnivIS-Import:2015-03-09:Pub.2014.nat.dgeo.IGM.c3geoc.subduc

Subduction channel fluid–rock interaction and mass transfer: Constraints from a retrograde vein in blueschist (SW Tianshan, China) - Li, Jilei; John, Timm; Gao, Jun; Klemd, Reiner; Wang, Xin-Shui (Chemical Geology, 2017)
One widely neglected part of the subduction zone fluid cycle is the retrograde fluid flow along the plate interface. This fluid flow may facilitate the exhumation of slab-derived rocks within the subduction channel. However, our understanding on the nature and behavior of these retrograde fluids is still insufficient. Retrograde veins preserved in HP–UHP rocks can provide valuable information about fluid activities and mass transfer at the plate interface and exhumation processes. In this study, we present a petrological and geochemical investigation of a typical retrograde vein and its blueschist host rock, which occurs throughout the whole Akeyazi (U)HP terrane in the Chinese southwestern Tianshan. The magnetite-bearing albite–calcite vein, representing an external fluid pathway, crosscuts the host blueschist that mainly consists of glaucophane, garnet, epidote and titanite. Along the fluid conduit the immediate wall-rock experienced greenschist-facies overprinting as displayed by an albite-rich selvage that grades into a chlorite–biotite selvage towards the host rock. The replacements of garnet by chlorite and glaucophane by albite are thought to have occurred due to an interface-coupled dissolution-precipitation mechanism. Mass balance calculations show that during fluid–rock interaction large amounts of LILE (K–Rb–Ba–Cs and Pb), Cu and CO2 were added to the selvages (mass gain > 200%), whereas the altered wall-rock released significant amounts of Ca, Li, Sr, REE and transition metal elements (V–Mn–Co–Ni–Zn) (mass loss mainly between 40 and 100%) due to the dissolution of glaucophane, garnet and epidote. The chlorite–biotite selvage experienced additional SiO2 and Na2O mass losses as well as FeO, MgO and H2O mass gains, whereas the albite-rich selvage underwent exactly the opposite mass transfer with respect to these components. The Al, Ti, Nb, Ta and Cr contents were constant during the alteration. Therefore, the retrograde fluid causing greenschist-facies overprinting of the blueschist host in the subduction channel (at ca. 30 km depth) is proposed to be oxidized and enriched in LILE, Cu and CO2components, whereas Ca, Li, Sr, REE, Y and transition metal elements (V–Mn–Co–Ni–Zn) are thought to have been mobilized during fluid-rock interaction. In addition, the main fluid sources (sediments, oceanic crust or serpentinites) diversely contribute to retrograde fluids at different depths in the subduction channel.<br
Keywords: Element mobility; Fluid–rock interaction; Retrograde fluid flow; Albite vein; Blueschist; Tianshan

Subduction initiation of the Neo-Tethys oceanic lithosphere by collision‐induced subduction transference - Wang, Xuhui; Lang, Xinghai; Klemd, Reiner; Deng, Yulin; Tang, Juxing (Gondwana Research, 2022)
Collision-induced subduction transference may have triggered subduction of the Neo-Tethys oceanic lithosphere. To verify this proposition, we present an integrated geochemical and geochronological studies of new and published data of the Permian-Triassic magmatism in the Lhasa Terrane. The newly identified Chongni mafic intrusions (gabbros and diorites) in the North Lhasa Terrane (NLT) were emplaced during the Early Permian (ca. 275 Ma). The mafic rocks have (87Sr/86Sr)t ratios between 0.7037 and 0.7042, and εNd(t) values between + 5.2 and + 5.8. The zircons of the Chongni mafic rock samples have εHf(t) values from + 9.1 to + 12.9. The isotopic data in conjunction with trace element features suggest that the Chongni mafic intrusions have been derived mainly by partial melting of a metasomatized mantle wedge source. The newly identified Quxu granodiorites and hornblende gabbros in the South Lhasa Terrane (SLT) were emplaced in the Late Triassic (ca. 228–203 Ma). The granodiorites are characterized by (87Sr/86Sr)t ratios of 0.7036–0.7037 and εNd(t) values of +6.6 to +6.7, while the hornblende gabbro samples have (87Sr/86Sr)t ratios of 0.7033–0.7035 and εNd(t) values of +7.3 to +7.4. The zircons of the granodiorite and hornblende gabbro samples revealed εHf(t) values of +10.3 to +14.0 and +10.8 to +16.4, respectively. The isotopic data in combination with trace element signatures suggest that the granodiorites were derived from a juvenile basaltic lower crust with a minor input of mantle components, while the hornblende gabbros are interpreted to have formed during partial melting of a formerly metasomatized depleted mantle wedge source. The Early Permian and Late Triassic magmatic rocks consistently show arc-related signatures, which probably record the northward subduction of the Sumdo Paleo-Tethys and the Neo-Tethys oceanic slabs, respectively. This evidence, in combination with that of other studies on the Permian-Triassic magmatism across the Lhasa Terrane, indicates that arc magmatism within the NLT switched to collisional magmatism at ca. 260 Ma due to the collision of oceanic islands/plateaus and, further on, the collision of the SLT with the NLT. Furthermore, the change from ca. 265–255 Ma alkaline magmatism to ca. 240–200 Ma calc‐alkaline magmatism within the SLT may reflect the geodynamic transition from lithospheric extension to Andean-style orogenesis. Therefore, we propose that subduction initiation of the Neo-Tethys oceanic lithosphere in the Tibetan Plateau resulted from the southward transference of the Sumdo Paleo-Tethys subduction zone, involving the collision of oceanic islands/plateaus and, subsequently, the collision of the SLT with the NLT. Additionally, the geological records of the Tethyan orogenic system suggest that the subduction initiation of the Neo-Tethys oceanic lithosphere is a uniform response to the collision between Cimmeria and Eurasia.
CRIS-Team Scopus Importer:2022-05-06
Keywords: Lhasa Terrane; Neo-Tethys; Plate tectonics; Subduction initiation; Subduction transference

Subduction of the oceanic Hikurangi Plateau and its impact on the Kermadec arc - Timm, Christian; Davy, Brian; Haase, Karsten; Hoernle, Kaj; Graham, Ian; De Ronde, Cornel; Woodhead, Jon; Bassett, Dan; Hauff, Folkmar; Mortimer, Nick; Seebeck, H.; Wysoczanski, Richard; et al. (Nature Communications, 2014)

Subglacial bedrock welding associated with glacial earthquakes - Bestmann, Michel; et al. (Journal of the Geological Society, 2006)

Sub log-scale heterogeneity of fine-grained sediments - Implications for effective permeability and top seal risking - Drews, Michael; Aplin, Andrew; Kurtev, Kuncho; Ma, Jingsheng (2nd International Fault and Top Seals Conference: From Pore to Basin Scale, 2009)

Submarine palaeoenvironments during Emeishan flood basalt volcanism, SW China: Implications for plume-lithosphere interaction during the Capitanian, Middle Permian ('end Guadalupian') extinction event - Jerram, Dougal A.; Widdowson, Mike; Wignall, Paul B.; Sun, Yadong; Lai, Xulong; Bond, David P. G.; Torsvik, Trond H. (Palaeogeography, Palaeoclimatology, Palaeoecology, 2016)
Keywords: Extinction; Large igneous province; Plume; Submarine volcanism

Sub-Milankovitch paleoclimatic and paleoenvironmental variability in East Africa recorded by Pleistocene lacustrine sediments from Olduvai Gorge, Tanzania - Colcord, Devon E.; Shilling, Andrea M.; Sauer, Peter E.; Freeman, Katherine H.; Njau, Jackson K.; Stanistreet, Ian G.; Stollhofen, Harald; Schick, Kathy D.; Toth, Nicholas; Brassell, Simon C. (Palaeogeography, Palaeoclimatology, Palaeoecology, 2018)
Over the past century, numerous discoveries throughout East Africa have advanced our understanding of hominin evolution and provided substantive evidence that climatic and environmental variability played a critical role in evolutionary developments. Stratigraphic records with high temporal resolution aid in testing evolutionary hypotheses that invoke changes in climate and environment at various timescales as drivers of hominin evolution. Olduvai Gorge, Tanzania has a rich history of hominin fossil discoveries from its 2.0 Ma sedimentary sequence, which includes multiple deep lake intervals. In 2014, the Olduvai Gorge Coring Project (OGCP) recovered a sequence of sediment cores that provide an extensive record of the Pleistocene sedimentary history, including paleolacustrine systems in this area. With>94% core recovery, these cores are ideally suited for high resolution analyses of organic geochemical proxies and provide an exceptional opportunity to build on previously published outcrop-based paleoenvironmental data from Olduvai. The OGCP core 2A section between 76.6 and 86.9m depth is considered as a time-stratigraphic equivalent of strata that host the hominin fossils OH24 and OH56 at the Olduvai DK archaeological site. This depositional interval age-bracketed between 1.88 Ma (Bed I Basalt) and 1.85 Ma (Tuff IB) was sampled for organic geochemical analyses. The carbon isotopic composition of organic matter (δ13CTOC) from this section varies between values representative of more forested and open grassland ecosystems over 21 kyr. This observation is consistent with the Milankovitch precession cycle driving the availability of water, which was previously observed in lower resolution studies of outcrop samples. Complementary organic geochemical proxies provide further evidence of these shifts in environmental conditions and record sub-Milankovitch scale changes superimposed on the precession cycle. This suggests the occurrence of short-term fluctuations in the environments inhabited by hominins, which opens new lines of investigation on how environmental scenarios may affect particular evolutionary mechanisms that drove various evolutionary responses.
Keywords: Compound-specific isotope analysis; n-Alkane; Sediment core

Subsurface granites in the Franconian Basin as the source of enhanced geothermal gradients: a key study from gravity and thermal modeling of the Bayreuth Granite - de Wall, Helga; Schaarschmidt, Anna; Kämmlein, Marion; Gabriel, Gerald; Bestmann, Michel; Scharfenberg, Lars (International Journal of Earth Sciences, 2019)
The Franconian Basin in NE Bavaria is a region of gravity low between the Bohemian Massif in the east and the Kraichgau Terrane in the west. Borehole measurements have identified the northern part of the Franconian Basin as a regional geothermal anomaly and new heat flow calculations give values of > 100 mW/m2. Distinct negative Bouguer anomalies observed in this basin are modeled as granitic intrusions in the Saxothuringian basement that underlies the Permo-Mesozoic units. The interpretation of gravity gradients, in combination with the filtering of gravity data, gives the possible depth constraints of the intrusive bodies. The resulting depths were cross-checked using microstructural studies of quartz veins in the basement rocks (at > 1341 m depth). The quartz shows structures typical for low-temperature plasticity and we infer a deformation temperature of ca. 300 °C. This indicates a considerable pre-Permian uplift of at least 7 km for parts of the Saxothuringian basement and supports depth estimates from gravity data. The heat supply of granitic intrusions by radiogenic decay is modeled considering several scenarios for the geological conditions recovered by the Obernsees borehole (model for conductive heat transfer). The 1390 m-deep drillhole is in a marginal position to the most-pronounced negative Bouguer anomaly. It could be shown that the Saxothuringian basement, including heat-producing granites (heat production rates: 4–6 μW/m3), covered by the insulating sedimentary rocks (1.35 km of Permian to Lower Jurassic units), can account for the enhanced geothermal gradient (38 °C/km) that were measured in the borehole.
CRIS-Team Scopus Importer:2019-07-09
Keywords: Gravity anomalies; Quartz microfabric; Radiogenic heat; Thermal modeling; Variscan granites

Subsurface thermal conductivity assessment in Calabria (southern Italy): a regional case study - Di Sipio, Eloisa; Galgaro, Antonio; Destro, Elisa; Teza, Giordano; Chiesa, Sergio; Giaretta, Aurelio; Manzella, Adele (Environmental Earth Sciences, 2014)
Keywords: Shallow geothermal energy; Thermal conductivity; GIS; Geological formations; Southern Italy

Suitability of Screened Monitoring Wells for Temperature Measurements Regarding Large-Scale Geothermal Collector Systems - Bertermann, David; Rammler, Mario (Geosciences, 2022)
Groundwater temperature (GWT) is usually measured using screened monitoring wells (MWs). The aim of this study was to investigate whether MWs are suitable for monitoring the effects of large-scale geothermal collector systems (LSCs) on GWT, focusing on possible vertical flows within the MWs due to both natural and forced convection. Comparative temperature depth profiles were therefore recorded over a period of nine months in both shallow MWs and in small-diameter, non-screened temperature monitoring stations (TMSs), each of which was installed in a single borehole. Particularly high temperature deviations were measured in MWs in the upper part of the water column where the GWT reached up to 1.8 K warmer than in the surrounding subsurface. These deviations correlate unambiguously with the prevailing positive thermal gradients and are caused by thermal convection. Where forced convection occurred, the GWT was measured to be up to 0.8 K colder. Potential temperature deviations must be considered when monitoring very shallow GWT as thermal gradients can be particularly high in these zones. For monitoring concepts of LSCs, a combination of MW and TMS is proposed for GWT measurements decoupled by the effects of convection and in order to enable further investigations such as pumping tests.
CRIS-Team Scopus Importer:2022-05-06
Keywords: convection; groundwater temperature; hydrogeology; large-scale geothermal collector (LSC); monitoring well; subsurface

Superimposed structures, incremental strain and deformation path from field data to modelling: A case study from the Alpi Apuane metamorphic core complex (NW Tuscany, Italy). - Molli, G.; Köhn, Daniel; Allacorta, L.; Danese, L.; Zampelli, S.; Zazzeri, M. (Journal of Structural Geology, 2022)
In this study, superimposed folds and antitaxial strain fringes are investigated to unravel the deformation path of the core zones of the Alpi Apuane metamorphic complex (northwest Tuscany Italy). Detailed field mapping combined with microstructural analyses is used together with computer-modelling of a complex strain fringe system to disclose the main steps of the Alpi Apuane syn-metamorphic deformation history. A comparison between natural investigated fibres and those produced by paraffine wax experiments provides details of the relative core-object-fringe rotation allowing new insight on the growth kinematics of strain fringes. The results of our analyses show that our composite fringe system is characterized by a first set of fibres to be related with the main composite axial planar foliation of regional scale isoclinal non-cylindric folds. This first set of fibre fringes records a local non-coaxial strain with an absolute core-object rotation (relative to an external reference frame represented by the main foliation) of 140° and a calculated shear strain (γ) of about 4. The second set of fringes, developed after the tilting of the main foliation and the first fringe-set in a sub-vertical orientation, records a lower absolute rotation of the core-object (25°), a lower shear strain (γ) of about 1.4 and a coaxial strain associated with the vertical shortening. This part of the composite fringe system and the related structures may relate to the switch from the crustal scale contractional regime to the extensional one, which characterized the development of the inner northern Apennines orogen.
CRIS-Team Scopus Importer:2022-09-09
Keywords: Alpi Apuane; Modelling incremental strain; Northern Apennines; Strain fringes; Superimposed folds; Tectonics

Superplume mantle tracked isotopically the length of Africa from the Indian Ocean to the Red Sea - O'Connor, John; Jokat, Wilfried; Regelous, Marcel; Kuiper, Klaudia; Miggins, Dan P.; Koppers, Anthony A P (Nature Communications, 2019)
Seismological findings show a complex scenario of plume upwellings from a deep thermo-chemical anomaly (superplume) beneath the East African Rift System (EARS). It is unclear if these geophysical observations represent a true picture of the superplume and its influence on magmatism along the EARS. Thus, it is essential to find a geochemical tracer to establish where upwellings are connected to the deep-seated thermo-chemical anomaly. Here we identify a unique non-volatile superplume isotopic signature ('C') in the youngest (after 10 Ma) phase of widespread EARS rift-related magmatism where it extends into the Indian Ocean and the Red Sea. This is the first sound evidence that the superplume influences the EARS far from the low seismic velocities in the magma-rich northern half. Our finding shows for the first time that superplume mantle exists beneath the rift the length of Africa from the Red Sea to the Indian Ocean offshore southern Mozambique.

Surface water freshening and high-latitude river discharge in the Eocene North Sea. - Zacke, Anne; Voigt, Silke; Joachimski, Michael; Gale, Andrew S.; Ward, David J.; Tuetken, Thomas (Journal of the Geological Society, 2009)
A shark-tooth apatite δ18O record of the early Palaeogene North Sea reflects changes in regional hydrography by showing variable temperatures and salinities. A 2-4 Ma period in the early Eocene was particularly influenced by substantial surface-water freshening, indicated by a 3-4‰ reduction of δ18O values. The magnitude of the δ18O decrease indicates a depletion in 18O of surface waters by 2-3‰ relative to Eocene mean ocean water. This value is lower than that of coeval lakes reconstructed from freshwater gastropod δ18O values from the Paris Basin, suggesting that large rivers with high-latitude catchment areas drained into the North Sea. The period of surface-water freshening began close to the Palaeocene - Eocene thermal maximum, when relative sea-level fall, tectonic uplift and basaltic volcanism caused a temporary isolation of the North Sea. North Atlantic and North Sea surface waters became reconnected during a series of early Eocene transgressions. © 2009 Geological Society of London.
UnivIS-Import:2015-03-09:Pub.2009.nat.dgeo.IGM.LG.surfac

Survivorship dynamics of the flora of Devonian Angarida - Dowding, Elizabeth; Akulov, Nikolay Ivanovich; Mashchuk, Irina Mikhailovna (Proceedings of the Royal Society of London, Series B: Biological Sciences, 2023)
Devonian plants in Siberia present protracted pioneer succession. Research into the survivorship dynamics of early plant communities upon the palaeocontinent Angarida have demonstrated that transgression and volcanogenic nutrient influx were key to the survival of colonizing plants. Taxic proportions show that migrating taxa entered Angarida from the southwest, Kuznetsk and Minusinsk basins, dispersing across the continent in waves through central areas northwards. The patterns of dispersal are consistent throughout the Devonian. Increased nutrient load from the active pulses of the Viluy-Yakutsk Large Igneous Province, biogeomorphic ecosystem engineering and the increased biomass of Angaridan plants are assisted by Late Devonian transgression. These cumulative factors can be linked to the Late Devonian marine extinctions observed in Siberia.
CRIS-Team Scopus Importer:2023-01-20
Keywords: Devonian; Large Igneous Province; phytogeography; Siberia

Susceptibility analysis for slides and rockfall: an example from the Northern Calcareous Alps (Vorarlberg, Austria) - Ruff, Michael; Rohn, Joachim (Environmental Geology, 2008)
In this paper a tool for semi-quantitative susceptibility assessment at a regional scale is presented which is applicable at areas with complex geological setting. At a study area within the Northern Calcareous Alps geotechnical mappings were implemented into a Geographical Information System and analysed as grid data with a cell size of 25 m. The susceptibility to sliding and falling processes was considered according to five classes (very low, low, medium, high, very high). Susceptibility to sliding was analysed using an index method. The layers of lithology, bedding conditions, tectonic faults, slope angle, slope aspect, vegetation and erosion were combined iteratively. Dropout zones of rockfall material were determined with help of a Digital Elevation Model. The movement of rolling rock samples was modelled by a cost analysis of all potential rockfall trajectories. These trajectories were also divided into five susceptibility classes. The susceptibility maps are presented in a general way to be used by communities and spatial planners. Conflict areas of susceptibility and landuse were located and can be presented destinctively. © 2007 Springer-Verlag.
UnivIS-Import:2015-03-09:Pub.2008.nat.dgeo.IGM.profes_3.suscep
Keywords: Austria; GIS; Landslides; Northern Calcareous Alps; Rockfall; Susceptibility; Vorarlberg

Sweet home Lophelia: A multicolour journey into the microcosm of bioeroders from the Propeller Mound, Porcupine Seabight - Beuck, Lydia; Schulbert, Christian; Freiwald, André (Erlanger Geologische Abhandlungen, Sonderband 4, 2003)
Bioerosion (Neumann, 1966) describes the disintegration processes of hard substrates such as calcareous skeletons through the activity of organisms by mechanical removal of carbonates (bioabrasion) or by chemical dissolution (biocorrosion) and is a well-known process in the alteration of shallow-water coral reefs. Endolithic organisms live within the skeleton either for protection or nourishment. The different bioerosional processes result in a destruction of reefal frameworks. The study of these ichnocoenoses (endolithic trace communities) allows to reconstruct (paleo-)environments and applicable depth zonations of neritic environmental settings through the Phanerozoic era. The ichnodiversity in the course of time also forms integrals for the understanding of the longevity and fossilisation potential and will lead to the definition of ecologic "health conditions" of deep-water corals for a rapid large-scale assessment. In this presentation, the prevalent aphotic bioeroder community found within the skeleton of the cosmopolitan coral Lophelia pertusa from the Propeller Mound, Porcupine Seabight, sampled in 629 to 780 m water depth, is demonstrated using the vacuum-cast-embedding method with subsequent SEM analysis: Shown are coloured SEM pictures of resin casts with an accentuation of different boring organism group
Keywords: Lopheloa; Bioerosion; Propeller Mound; Porcupine Seabight

Synchronous Monitoring of Cement Hydration and Polymer Film Formation Using 1H-Time-Domain-NMR with T2Time-Weighted T1Time Evaluation: A Nondestructive Practicable Benchtop Method - Jansen, Daniel; Ectors, Dominique; Kong, Xiangming; Schmidtke, Christian; Deschner, Florian; Pakusch, Joachim; Jahns, Ekkehard; Neubauer, Jürgen (ACS Omega, 2021)
The interactions between latex and cement are still not completely understood. In this work, we would like to address the temporal changes in cement hardening and latex film formation. For this reason, the hydration process and the film formation were simultaneously monitored. This scientific issue is even more challenging as a nondestructive quantitative analysis of the film formation process is not available yet. Here, we report on simultaneous monitoring of the latex film formation and the phase development in cementitious systems via 1H-time-domain-NMR for the first time. The obtained results were validated using classical analytical methods, such as in situ X-ray diffraction, X-ray fluorescence (Rietveld analysis), and confocal laser scanning microscopy.
CRIS-Team Scopus Importer:2021-04-16

Syndepositional Tectonic Controls and Palaeo-Topography of a Permian Tight Gas Reservoir in NW Germany - Vackiner, Anna Alexandra; Stollhofen, Harald; Antrett, Philipp; Back, Stefan; Kukla, Peter; Bärle, Claudia (Journal of Petroleum Geology, 2011)
A combined tectonic-stratigraphic interpretation of three-dimensional seismic reflection, wireline log and core data is presented in this study focussing on a tight gas field in East Frisia, NW Germany. Upper Rotliegend reservoir rocks in the study area are of fluvio-aeolian origin and include dune, minor sandflat and wet to dry interdune deposits. Source rocks are Westphalian coals and a top seal is provided by Zechstein evaporites. Detailed analyses of palaeo-topography, fault activity and accommodation space development for strata of Permian age (Rotliegend and Zechstein groups) indicate that local depocentres developed within small-scale fault-controlled transtensional sub-basins. Synsedimentary half-graben development and fault activity occurred during Upper Rotliegend II (mainly Elbe Subgroup) deposition. Many Upper Rotliegend structures were then reactivated during the Triassic, Jurassic and Cretaceous, often with enhanced offsets and increased lateral extent. As a consequence, Rotliegend structures and stratigraphy were significantly displaced resulting in the relocation of former Rotliegend depocentres and associated tight gas reservoir facies. This tectonic overprint hampers the prediction of potential Rotliegend reservoirs, and shows that palaeo-environmental restoration is required in areas which have undergone multi-phase deformation histories. Exploration strategies in the study area have favoured drilling locations in present-day structural highs. This study suggests that sediment traps were controlled by synsedimentary Upper Rotliegend II to Zechstein palaeo-topography, defining a new concept for future tight gas exploration. © 2011 The Authors. Journal of Petroleum Geology © 2011 Scientific Press Ltd.
UnivIS-Import:2015-03-09:Pub.2011.nat.dgeo.IGM.LG.syndep
Keywords: Isopach map analysis; Palaeo-topography; Rotliegend; Southern Permian Basin; Tectonics and sedimentation; Tight gas

Syn-kinematic inversion in an intracontinental extensional field? A structural analysis of the Waterberg Thrust, northern Namibia - Granath, James; Wanke, Ansgar; Stollhofen, Harald (Journal of Structural Geology, 2022)
A structural analysis of a key area along the Waterberg Thrust in northern Namibia clarifies its geometric and timing relationships to the deposition of rift-related Karoo sediments. The fault brings late Precambrian crystalline rocks up against Permo-Triassic and Lower Jurassic Karoo clastic sediments of the Waterberg Basin between two of the major regional basement-rooted lineaments that cut across northern Namibia, using those subparallel lineaments as transfer faults. Detailed mapping and kinematic analysis have been used to construct and restore several sections across the thrust that put initiation of reverse offset as a thrust in Triassic time. Thinskinned footwall deformation created several unconformities in a footwall cutoff system. The unconformities were subsequently folded during continued motion on the fault. Various dating techniques constrain the initiation of contractional deformation to the Triassic to Jurassic (Karoo time) with episodic progression during the development of the basin, followed by major further reactivation during regional uplift related to the Atlantic margin rifting and subsequent continental breakup. This early phase is linked in time so closely to the basin development that we attribute the driver of inversion to be kinematically linked to the displacement field of Neoproterozoic basement blocks themselves. Hence, we term this relationship as ‘syn-kinematic’ to distinguish it from wholly external, superimposed driving mechanisms (‘allo-kinematic’).<br
Keywords: Waterberg thrust; Karoo tectonics; Namibia geology; Inversion tectonics; Intraplate tectonics

Synsedimentary faults and amalgamated unconformities : Insights from 3D-seismic and core analysis of the Lower Triassic Middle Buntsandstein, Ems Trough, north-western Germany. - Radies, Dirk; Stollhofen, Harald; Hollmann, Gregor; Kukla, Peter (International Journal of Earth Sciences, 2005)
The Late Permian/Early Triassic succession of the Central European Basin (CEB) was repeatedly affected by the tectonic pulses associated with the earliest phases of Tethyan and Arctic-North Atlantic rifting. Effects of the differential tectonic subsidence are particularly well recorded by unconformities, which form widespread sequence boundaries. Such unconformities are most obvious in areas occupied by fault-controlled intra-basinal highs (swells). In that areas, stratigraphic loss may comprise entire Lower and Middle Buntsandstein formations and in places remnant Middle Buntsandstein successions directly rest on Permian strata. Analysis of 3D-seismic data and well logs combined with high-resolution sedimentological logging of drillcores at the western margin of the Ems Trough (NW Germany) reveals details of synsedimentary tectonic control on sequence development. Early Triassic extensional faulting of basement blocks provided stepwise addition of accommodation space for continental sequences by growth faulting along north-south oriented fault zones blocks on the flanks of the East Netherlands High. This process is most evident during the development of the Hardegsen Unconformity, which is characterised by an amalgamation of succeeding unconformity surfaces in areas of structurally controlled intrabasinal highs. © Springer-Verlag 2005.
UnivIS-Import:2015-03-09:Pub.2005.nat.dgeo.IGM.LG.synsed
Keywords: Buntsandstein; Continental sequences; Early Triassic; Synsedimentary tectonics; Unconformities

Syn-tectonic generation of potential reservoir-sandstones in arid low-gradient depositional systems - the Lower Triassic Middle Buntsandstein at the western margin of the Ems Trough, NW Germany. - Radies, Dirk; Stollhofen, Harald; Hollmann, Gregor; Kukla, Peter (Oil Gas-European Magazine, 2005)
Effects of the earliest Tethyan and Arctic-North Atlantic rifting phases on the Early Triassic succession of the Central European Basin are particularly well recorded by unconformities, which form widespread sequence boundaries. Stratigraphic loss related to these unconformities may comprise entire Lower and Middle Buntsandstein formations most obviously developed in areas occupied by fault-controlled intra-basinal highs (swells). Analysis of 3D-seismic data and well logs combined with high-resolution sedimentological logging of drillcores at the western margin of the Ems Trough (NW Germany) reveals details of synsedimentary tectonic control on sequence development. Early Triassic extensional faulting of basement blocks provided stepwise addition of accommodation for continental sequences by growth faulting along north-south trending fault zones blocks on the flanks of the East Netherlands High. This process is most evident during the development of the Hardegsen Unconformity, which is characterized by an amalgamation of succeeding unconformity surfaces in areas of structurally controlled intrabasinal highs. The mainly aeolian toplaya-type sedimentary facies of the Middle Buntsandstein succession suggests very low intrabasinal relief and implies a constant reworking and levelling of the palaeo-surface. Consequently, the development and preservation of stratigraphic units is primarily determined by the potential accommodation provided by synsedimentary tectonics. © 2005 URBAN-VERLAG Hamburg/Wien GmbH.
UnivIS-Import:2015-03-09:Pub.2005.nat.dgeo.IGM.LG.syntec

Syn-tectonic sequence generation in low gradient desert margin systems - the Lower Triassic Middle Buntsandstein at the western margin of the Ems Basin, NW Germany. - Radies, Dirk; Stollhofen, Harald; Hollmann, Gregor; Kukla, Peter (DGMK Tagungsbericht, 2005)
UnivIS-Import:2015-03-09:Pub.2005.nat.dgeo.IGM.LG.syntec_3

Synthese und Rietveldverfeinerung der Gehlenit-Mischkristallreihe - Schmid, Markus; Götz-Neunhoeffer, Friedlinde; Neubauer, Jürgen; Göbbels, Matthias (European Journal of Mineralogy, 2003)
UnivIS-Import:2015-03-09:Pub.2003.nat.dgeo.IGM.LM.synthe

Synthese von Alinit, Hauptbestandteil im Alinitzement - Neubauer, Jürgen; Oberste-Padtberg, Rüdiger; Pöllmann, Herbert (European Journal of Mineralogy, 1991)
UnivIS-Import:2015-03-05:Pub.1991.nat.dgeo.IGM.LM.synthe

Synthese von Fe3+-substitutierten Tricalciumaluminaten und Auswirkungen auf deren Hydratationsverhalten - Kemethmüller, Stefan; Neubauer, Jürgen; Götz-Neunhoeffer, Friedlinde (2001)
UnivIS-Import:2015-03-09:Pub.2001.nat.dgeo.IGM.LM.synthe

Synthesis and characterization of cellular apatite-whitlockite composites for bone substitution - Götz-Neunhoeffer, Friedlinde; Enderle, Ralph; Göbbels, Matthias (Schriftenreihe der Deutschen Gesellschaft für Geowissenschaften, 2005)
UnivIS-Import:2015-03-09:Pub.2005.nat.dgeo.IGM.LM.synthe_2

Synthesis and characterization of chloride bearing silico - sulfate apatite - Neubauer, Jürgen; Pöllmann, Herbert (Neues Jahrbuch für Mineralogie-Abhandlungen, 1992)
UnivIS-Import:2015-03-05:Pub.1992.nat.dgeo.IGM.LM.synthe

Synthesis and mineralogical characterization of calcium ferrate hydrates and their application as reservoir minerals in waste dumps - Götz-Neunhoeffer, Friedlinde; Pöllmann, Herbert (Applied Mineralogy in Research, Economy, Technology, Ecology and Culture, 2000)
UnivIS-Import:2015-03-09:Pub.2000.nat.dgeo.IGM.LM.synthe
Keywords: Angewandte Mineralogie; Applied Mineralogy

Synthesis and Rietveld refinement of Ferri-Gehlenite solid solution series - Schmid, Markus; Götz-Neunhoeffer, Friedlinde; Neubauer, Jürgen; Göbbels, Matthias (Zeitschrift der Deutschen Gesellschaft für Geowissenschaften, 2005)
UnivIS-Import:2015-03-09:Pub.2005.nat.dgeo.IGM.LM.synthe

Synthesis and Structure Refinement of Zinc-Doped Beta-Tricalcium Phosphate Powders - Kannan, Surekka; Götz-Neunhoeffer, Friedlinde; Neubauer, Jürgen; da Fonte Ferreira, José Maria (Journal of the American Ceramic Society, 2009)
Zinc substituted β-tricalcium phosphate [β-Ca3(PO 4)2] was formed by substituting a zinc precursor in calcium-deficient apatite through aqueous precipitation technique. Heat treatment at 1000°C led to the formation of well crystalline β-Ca 3(PO4). Refinement technique was used to determine the influence of incorporated zinc in the β-Ca3(PO4) structure. The structural data for all the four different zinc substituted β-Ca3(PO4) ranging from 0-9 mol% of zinc investigated in the present study confirmed the rhombohedral structure of β-Ca 3(PO4) in the hexagonal setting (space group R3c). The incorporation of lower sized Zn2+ (0.745 Å for sixfold coordination with O) at the higher sized Ca2+ (1.00 Å for sixfold coordination with O) site in the β-Ca3(PO4) structure led to the contraction of unit cell parameters. The added zinc prefers to occupy the Ca(5) site of β-Ca3(PO4) structure. © 2009 The American Ceramic Society.
UnivIS-Import:2015-03-09:Pub.2009.nat.dgeo.IGM.LM.synthe

Synthesis an structural characterization of strontium- and magnesium-co-substituted beta-tricalcium phosphate - Kannan, Surekka; Götz-Neunhoeffer, Friedlinde; Neubauer, Jürgen; Pina, Sandra; Torres, Paula M. C.; da Fonte Ferreira, José Maria (Acta Biomaterialia, 2010)
The synthesis of five different Sr2+- and Mg2+-co-substituted β-tricalcium phosphate (β-TCP) has been obtained by heating the calcium-deficient apatites above 800 °C. With the investigated concentrations of Sr2+ and Mg2+ from the present study, no additional phases other than β-TCP have been detected. The synthesized powders have been characterized by X-ray diffraction, Fourier transform infrared spectrometry, elemental analysis and Rietveld refinement studies. The co-substitution of Sr2+ and Mg2+ in the β-TCP has resulted in the formation of crystalline β-TCP at hexagonal setting (space group R3c). The reduction of lattice a- and c-axis parameters with the combined substitution of Sr2+ and Mg2+ in the β-TCP has been found evident from the present results. Sr2+ has been found occupying the Ca(1,2,3,4) sites and Mg2+ was found at the sixfold coordinated Ca(5) site of β-TCP structure. © 2009 Acta Materialia Inc.
UnivIS-Import:2015-03-09:Pub.2010.nat.dgeo.IGM.LM.synthe
Keywords: β-TCP; Co-substitution; Magnesium; Rietveld refinement; Strontium

Synthesis, characterization, antibacterial properties, and in vitro studies of selenium and strontium co-substituted hydroxyapatite - Maqbool, Muhammad; Nawaz, Qaisar; Ur Rehman, Muhammad Atiq; Cresswell, Mark; Jackson, Phil; Hurle, Katrin; Detsch, Rainer; Goldmann, Wolfgang; Shah, Asma Tufail; Boccaccini, Aldo R. (International Journal of Molecular Sciences, 2021)
In this study, as a measure to enhance the antimicrobial activity of biomaterials, the selenium ions have been substituted into hydroxyapatite (HA) at different concentration levels. To balance the potential cytotoxic effects of selenite ions (SeO32−) in HA, strontium (Sr2+) was co-substituted at the same concentration. Selenium and strontium-substituted hydroxyapatites (Se-Sr-HA) at equal molar ratios of x Se/(Se + P) and x Sr/(Sr + Ca) at (x = 0, 0.01, 0.03, 0.05, 0.1, and 0.2) were synthesized via the wet precipitation route and sintered at 900 °C. The effect of the two-ion concentration on morphology, surface charge, composition, antibacterial ability, and cell viability were studied. Xray diffraction verified the phase purity and confirmed the substitution of selenium and strontium ions. Acellular in vitro bioactivity tests revealed that Se-Sr-HA was highly bioactive compared to pure HA. Se-Sr-HA samples showed excellent antibacterial activity against both Gram-negative (Escherichia coli) and Gram-positive (Staphylococcus carnosus) bacterial strains. In vitro cell–material interaction, using human osteosarcoma cells MG-63 studied by WST-8 assay, showed that Se-HA has a cytotoxic effect; however, the co-substitution of strontium in Se-HA offsets the negative impact of selenium and enhanced the biological properties of HA. Hence, the prepared samples are a suitable choice for antibacterial coatings and bone filler applications.
CRIS-Team Scopus Importer:2021-04-30
Keywords: Antibacterial; Co-substituted hydroxyapatite; Cytocompatibility; Selenium; Strontium

Synthesis of Camphor-Derived Bis(pyrazolylpyridine) Rhodium(III) Complexes: Structure-Reactivity Relationships and Biological Activity - Petrovic, Angelina; Milutinovic, Milan M.; Petri, Edward T.; Zivanovic, Marko; Milivojevic, Nevena; Puchta, Ralph; Scheurer, Andreas; Korzekwa, Jana; Klisuric, Olivera R.; Bogojeski, Jovana (Inorganic Chemistry, 2019)
Two novel rhodium(III) complexes, namely, [Rh III (X)Cl 3 ] (X = 2 2,6-bis((4S,7R)-7,8,8-trimethyl-4,5,6,7-tetrahydro-1H-4,7-methanoindazol-3-yl)pyridine or 2,6-bis((4S,7R)-1,7,8,8-tetramethyl-4,5,6,7-tetrahydro-1H-4,7-methanoindazol-3-yl)pyridine), were synthesized from camphor derivatives of a bis(pyrazolylpyridine), tridentate nitrogen-donor chelate system, giving [Rh III (H 2 L∗)Cl 3 ] (1a) and [Rh III (Me 2 L∗)Cl 3 ] (1b). A rhodium(III) terpyridine (terpy) ligand complex, [Rh III (terpy)Cl 3 ] (1c), was also synthesized. By single-crystal X-ray analysis, 1b crystallizes in an orthorhombic P2 1 2 1 2 1 system, with two molecules in the asymmetric unit. Tridentate coordination by the N,N,N-donor localizes the central nitrogen atom close to the rhodium(III) center. Compounds 1a and 1b were reactive toward l-methionine (l-Met), guanosine-5′-monophosphate (5′-GMP), and glutathione (GSH), with an order of reactivity of 5′-GMP > GSH > l-Met. The order of reactivity of the Rh III complexes was: 1b> 1a > 1c. The Rh III complexes showed affinity for calf thymus DNA and bovine serum albumin by UV-vis and emission spectral studies. Furthermore, 1b showed significant in vitro cytotoxicity against human epithelial colorectal carcinoma cells. Since the Rh III complexes have similar coordination modes, stability differences were evaluated by density functional theory (DFT) calculations (B3LYP(CPCM)/LANL2DZp). With (H 2 L∗) and (terpy) as model ligands, DFT calculations suggest that both tridentate ligand systems have similar stability. In addition, molecular docking suggests that all test compounds have affinity for the minor groove of DNA, while 1b and 1c have potential for DNA intercalation.
CRIS-Team Scopus Importer:2019-05-09

Synthesis of Eu-doped SrAl2O4 nanophosphors by CO2 laser vaporization - Zollfrank, Cordt; Gruber, Sabine; Batentschuk, Miroslaw; Osvet, Andres; Götz-Neunhoeffer, Friedlinde; Dittrich, Sebastian; Grabow, Janet; Kurland, Heinz-Dieter; Müller, Frank A. (Acta Materialia, 2013)
A new method of synthesizing spherical nanoparticles with photoluminescent spinel structures using a CO2 laser co-vaporization technique (CoLAVA) is presented. The method applies homogeneous mixtures of oxidic precursors such as Al2O3, SrO and Eu2O 3 and allows the fabrication of quantities exceeding 10 g h -1. During the CoLAVA process, the educt oxides are reacted by a gas phase condensation yielding amorphous spherical particles with diameters ranging from 10 to 100 nm. The as-prepared materials exhibit red emission at 625 nm (1.98 eV) due to the incorporated Eu3+. Temperature treatment up to 1200 C under a reducing atmosphere yielded crystalline particles of the same size, which were slightly sintered. These particles consisted of >90 wt.% SrAl2O4 with minor fractions of Sr3Al 2O6 and SrCO3. The amount of the SrAl 2O4 spinel increased with increasing temperature, whereas the accompanying phases were decreased. A strong green emission centered at 525 nm (2.36 eV) detected at RT was observed at an onset temperature of 900 C, which is due to the presence of Eu2+ in the crystal lattice of SrAl 2O4. The red emission was not observed at higher annealing temperatures. The CoLAVA method represents a fast and facile route for the fabrication of nano- to microstructured phosphor materials for a variety of engineering applications. © 2013 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.
UnivIS-Import:2015-03-09:Pub.2013.nat.dgeo.IGM.LM.synthe
Keywords: Laser vaporization; Nanoparticles; Photoluminescence

Synthesis of monocrystalline Ca3SiO5 using the optical floating zone method - Naber, Christoph; Götz-Neunhoeffer, Friedlinde; Göbbels, Matthias; Rößler, Christiane; Neubauer, Jürgen (Cement and Concrete Research, 2016)
Alite (CaSiO/CS with low concentrations of foreign ions) is the main constituent of Ordinary Portland Cement. Normally it forms during sintering but with quite low crystal sizes (ca. 30 μm). For experiments on alite hydration behavior monocrystalline grains are required. Due to its incongruent melting behavior and its thermodynamic instability below 1250 °C it is very challenging to obtain large alite single crystals. In the present study, the floating zone method was used for annealing polycrystalline rods of monoclinic and triclinic CS just below the melting point of the phase. Large monocrystalline grains (> 500 μm) of the monoclinic (Al, Mg-doped) and triclinic polymorphs could successfully be obtained. Monocrystallinity was demonstrated by electron backscatter diffraction (EBSD). The chemical composition regarding incorporation of foreign ions and thus the resulting crystallographic modification of the CS can easily be adjusted. Chemical homogeneity of the synthesized monocrystalline grains was proven by electron probe microanalysis (EPMA).
Keywords: Ca3SiO5 (D); Crystal size (B); Floating zone method; SEM (B)

Syn-vivo bioerosion of Nautilus by endo- and epilithic foraminiferans (New Caledonia and Vanuatu) - Seuß, Barbara; Wisshak, Max; Mapes, Royal H.; Landman, Neil (PLoS ONE, 2015)
A variety of syn-vivo bioerosion traces produced by foraminiferans is recorded in shells of Nautilus sampled near New Caledonia and Vanuatu. These are two types of attachment scars of epilithic foraminiferans and two forms of previously undescribed microborings, a spiral-shaped and a dendritic one, both most likely being the work of endolithic 'naked' foraminiferans. Scanning electron microscopy of epoxy-resin casts of the latter revealed that these traces occur in clusters of up to many dozen individuals and potentially are substrate-specific. The foraminiferan traces are the sole signs of bioerosion in the studied Nautilus conchs, and neither traces of phototrophic nor other chemotrophic microendoliths were found. While the complete absence of photoautotrophic endoliths would be in good accordance with the life habit of Nautilus, which resides in aphotic deep marine environments and seeks shallower waters in the photic zone for feeding only during night-time, the absence of any microbial bioerosion may also be explained by an effective defence provided by the nautilid periostracum. Following this line of reasoning, the recorded foraminiferan bioerosion traces in turn would identify their trace makers as being specialized in their ability to penetrate the periostracum barrier and to bioerode the shell of modern Nautilus.
UnivIS-Import:2015-07-08:Pub.2015.nat.dgeo.IGM.LP.synviv

Synvulkanische Sedimentation in einem fluviatilen Ablagerungsraum: Das basale "Oberrotliegend" im permokarbonen Saar-Nahe-Becken - Stollhofen, Harald (Zeitschrift der Deutschen Gesellschaft für Geowissenschaften, 1994)
Mächtige basaltisch-andesitische Laven und rhyolithisch-dazitische Tuffe wechsellagern in den Profilen des basalen "Oberrotliegend" mit fluviatilen Ablagerungen. Innerhalb eines durch die Leithorizonte Tuffserie I und II definierten Profilteils werden sowohl die während des beckeninternen Vulkanismus auftretenden Sedimentationsprozesse untersucht, als auch die Fazies und Architektur, die Förderorte und die Eruptionsmechanismen der Vulkanite diskutiert. Verbreitung, Fragmentierungsgrad und die Position der proximalen Faziesbereiche deuten an, daß die Hauptmasse der sauren Pyroklastika durch phreatoplinianische Eruptionen an Tuffringen (Tuffserie I) und durch den Kollaps von intrusiv/extrusiven Domen (Tuffserie II) während der Platznahme der Intrusionen von Donnersberg, Kuhkopf und Holbornerhof-Kuppel gefördert wurden. Andesitische Tuffe weisen meist deutlich höhere Nebengesteinsanteile auf und werden surtseyanischen Eruptionen von Maaren zugeordnet. Aufgrund der Horizontbeständigkeit der beteiligten Gesteinskörper wird angenommen, daß die basischen Laven des Donnersberg- und des Olsbrücken Lagers an Spalten eruptiert wurden, zumal Hinweise auf ausgeprägte Vulkanbauten fehlen. Während aktiver Eruptionsphasen wurde die Sedimentation maßgeblich durch beckeninterne Prozesse gesteuert. Von mehreren, teilweise zeitgleich aktiven Förderorten erfolgte die Eruption von Laven, Aschenfällen, Surges, heißen und kühlen Aschenströmen. Die während oder kurz nach den Eruptionen einsetzende Umlagerung großer Mengen lockeren und leicht erodierbaren pyroklastischen Materials wird durch Ablagerungen von Schichtfluten neben Schutt- und Schlammströmen repräsentiert. Während langer vulkanischer Ruhepausen dominierte im medialen und distalen Faziesbereich hingegen ein mäandrierendes Flußsystems, das siliziklastische Sedimente ablagerte. Hierbei wurde die Sedimentation insbesondere durch beckenexterne Prozesse gesteuert. Eine bevorzugte Erhaltung primärer pyroklastischer Ablagerungen erfolgte auf der ausgedehnten Überflutungsebene dieses nach Norden entwässernden, transversalen Flußsystems, wurde aber auch durch intensive synsedimentäre Tektonik kontrolliert.
Keywords: Intramontane basin; geological sections; Saxonian (Upper Rotliegend); lithofacies; fluvial sedimentation; siliciclastic sediments; eruptions; lavas basaltic-andesitic composition; tuffs; rhyolitic-dacitic composition; key beds; sedimentary cycle; explosive eruptions

Systematic and Temporal Geochemical Changes in the Upper Deccan Lavas: Implications for the Magma Plumbing System of Flood Basalt Provinces - Hoyer, Patrick; Haase, Karsten; Regelous, Marcel; Fluteau, F. (Geochemistry Geophysics Geosystems, 2023)
Large Igneous Provinces (LIPs) are unusual volcanic events in which massive amounts of melt (∼106 km3) erupt in relatively short time periods (<106 years). Most LIP magmas have undergone extensive fractional crystallization and crustal contamination, but the crustal magmatic plumbing systems and the processes triggering eruptions are poorly understood. We present new major and trace element and radiogenic isotope data for 43 individual lava flows from a continuous 1,200 m thick stratigraphic profile through the upper, most voluminous part of the Deccan LIP (Bushe to Mahabaleshwar Formations). Eruption rates for this section are constrained by published paleomagnetic directions and absolute U-Pb ages for zircons from weathered flow tops exposed in the profile. We find four magmatic sequences each lasting ∼104–∼105 years during which major and trace element compositions change systematically, followed by an abrupt change in geochemistry at the start of a new sequence. Within each sequence, the MgO content and proportion of crustal contamination decrease progressively, indicating a continuous replenishment of the associated magma reservoirs with less contaminated but more evolved melts. These geochemical signatures are best explained by repeated episodes of melt recharge, mixing, and eruption of variably evolved magmas originating from relatively small magma reservoir located in different crustal levels.
CRIS-Team Scopus Importer:2023-03-03
Keywords: intraplate processes; magma chamber processes; magma genesis and partial melting; major and trace element geochemistry; radiogenic isotope geochemistry

Systematic occurrences of malformed (teratological) acritarchs in the run-up of Early Palaeozoic δ13C isotope excursions - Munnecke, Axel; Delabroye, Aurélien; Servais, Thomas; Vandenbroucke, Thijs R.A.; Vecoli, Marco (Palaeogeography, Palaeoclimatology, Palaeoecology, 2012)
The Late Ordovician and Silurian are characterised by several strong, global positive δC excursions. Some of them exceed +5‰ and thus belong to the strongest perturbations of the carbon cycle in the Phanerozoic. The onset of the excursions is characterised by extinction and/or turnover events of several groups of marine invertebrates. The causal mechanisms of the carbon cycle perturbations, however, are still unknown and currently a matter of vigorous scientific debate. Our own investigations in the Hirnantian (latest Ordovician) have shown that the onset of the major δC excursion (HICE) is characterised by very high abundances of acritarchs showing abnormal, teratological forms. A critical review of published reports of abnormal acritarchs from the Late Ordovician to Early Devonian, and a correlation of their occurrences with the global stable carbon isotope curve, show that high abundances of teratological forms of acritarchs are often coeval to the run-up of δC excursions. High abundances of teratological forms in modern marine protists are commonly observed in environments with a high degree of environmental stress. In the fossil record, the challenge is to attribute abnormal forms of organisms to specific environmental circumstances. Our study implies that they are somehow related to the global carbon cycle, i.e., to carbon isotopic composition of the ambient sea water, and that they share a common extrinsic cause with the contemporaneous extinction and/or turnover events in other fossil groups. © 2012 Elsevier B.
Keywords: Acritarchs; Anticosti; Gotland; Heavy metals; Ordovician; Silurian; Teratology

Systematic variations in magmatic sulphide chemistry from mid-ocean ridges, back-arc basins and island arcs - Keith, Manuel; Haase, Karsten; Klemd, Reiner; Schwarz-Schampera, Ulrich; Franke, Henrike (Chemical Geology, 2017)
Immiscible sulphide liquids preserved as magmatic sulphide globules are hosted in igneous rocks of highly variable composition formed during magmatic processes at different tectonic settings. Here we report on compositional in situ data of magmatic sulphides from mid-ocean ridge, back-arc and island arc magmatic systems. Iron-Ni-rich monosulphide solid solutions (mss) that mainly consist of pyrrhotite and pentlandite are the dominant phases in magmatic sulphide globules. In subduction-related magmas mss are most abundant in relatively evolved melts and characterised by low Ni and high Fe contents, as well as low Ni/Cu ratios (< 1). In contrast, mss from mid-ocean ridges and back-arcs without subduction input occur in mafic rocks and have high Ni/Cu ratios (> 1). Thus, mss chemistry varies systematically in lavas from the different tectonic settings in terms of their Fe-Ni distribution and Ni/Cu ratio. The observed mineralogical and chemical variations between mss from the different settings reflect early S saturation accompanied by olivine fractionation along mid-ocean ridges compared to later stage S saturation in arc systems associated with Fe-Ti oxide fractionation. These systematics are probably related to the relatively oxidised character of subduction zone magmas opposed to more reduced mid-ocean ridge melts. Large Ni/Cu variations in mss from the same locality and in individual samples suggest that S saturation is a multistage or continuous process leading to inclusions of magmatic sulphides that represent different fractionation stages in the ascending magm
Keywords: Chalcophile elements; Magmatic sulphides; Monosulphide solid solutions; Oxygen fugacity; Sulphur saturation

Systematic variations of trace element and sulfur isotope compositions in pyrite with stratigraphic depth in the Skouriotissa volcanic-hosted massive sulfide deposit, Troodos ophiolite, Cyprus - Keith, Manuel; Haase, Karsten; Klemd, Reiner; Krumm, Stefan; Strauss, Harald (Chemical Geology, 2016)

System controls of coastal and open ocean oxygen depletion - Pitcher, Grant C.; Aguirre-Velarde, Arturo; Breitburg, Denise; Cardich, Jorge; Carstensen, Jacob; Conley, Daniel J.; Dewitte, Boris; Engel, Anja; Espinoza-Morriberón, Dante; Flores, Georgina; Garçon, Véronique; Graco, Michelle; et al. (Progress in Oceanography, 2021)
The epoch of the Anthropocene, a period during which human activity has been the dominant influence on climate and the environment, has witnessed a decline in oxygen concentrations and an expansion of oxygen-depleted environments in both coastal and open ocean systems since the middle of the 20th century. This paper provides a review of system-specific drivers of low oxygen in a range of case studies representing marine systems in the open ocean, on continental shelves, in enclosed seas and in the coastal environment. Identification of similar and contrasting responses within and across system types and corresponding oxygen regimes is shown to be informative both in understanding and isolating key controlling processes and provides a sound basis for predicting change under anticipated future conditions. Case studies were selected to achieve a balance in system diversity and global coverage. Each case study describes system attributes, including the present-day oxygen environment and known trends in oxygen concentrations over time. Central to each case study is the identification of the physical and biogeochemical processes that determine oxygen concentrations through the tradeoff between ventilation and respiration. Spatial distributions of oxygen and time series of oxygen data provide the opportunity to identify trends in oxygen availability and have allowed various drivers of low oxygen to be distinguished through correlative and causative relationships. Deoxygenation results from a complex interplay of hydrographic and biogeochemical processes and the superposition of these processes, some additive and others subtractive, makes attribution to any particular driver challenging. System-specific models are therefore required to achieve a quantitative understanding of these processes and of the feedbacks between processes at varying scales.
CRIS-Team Scopus Importer:2021-09-24
Keywords: Deoxygenation; Eutrophication; Global warming; Respiration; Stratification; Ventilation

Tales from a shale - taxonomy and analysis of life habits of bivalves from the Pennsylvanian Finis Shale (Virgilian) of North Central Texas - Friedel, Julia C.; Amler, Michael R.W.; Seuß, Barbara (Kölner Forum Geol. Paläont. 23, 2019)

Taphonomic and diagenetic implications of reduction spot formation in Cretaceous red beds from the Jiaolai Basin, Eastern China - Fu, Wenzhao; Turner, Peter; Clements, Thomas; Spencer, Alan R.T.; Yu, Jifeng; Yang, Yu; Guo, Bangjie; Ning, Zhenguo; Zhuo, Xizhun; Riley, Michael S.; Hilton, Jason (Journal of Asian Earth Sciences, 2023)
Green-grey coloured reduction spots are common in continental red beds through geological history and occur in a range of different lithologies and depositional environments, but their timing and mode of formation remain controversial. We investigate the Late Cretaceous to earliest Paleogene Jiaozhou Formation using borehole data from the Jiaolai Basin in Shandong province of eastern China, and consider the distribution, morphology, and geochemistry of reduction spots in these continental red beds to evaluate how the reduction spots formed. Here, we report a novel application of three-dimensional X-ray Computed Tomography (XCT) to analyse reduction spot morphology, composition and density. Our data show that individual reduction spots are spheroidal, tubular or irregular shaped, and often contain small, grey, dark brown or black organic cores, referred to as loci. Typically, reduction spots have a similar chemical composition to the host red beds, but with elevated levels of vanadium (V), lower levels of iron (Fe), and lower density. Isolated, small refractory fossils (e.g., charcoal) in the sediment alongside reduction spots but not within them indicates that microbial decay of organic labile (reactive) tissues in early diagenesis is an important control in reduction spot formation. We propose a new taphonomic model of reduction spot formation: post burial, during the primary sedimentary cycle in the groundwater zone, vanadium is released by intrastratal oxidation of titanomagnetite. Decay of organic matter creates localised reducing conditions resulting in the reduction of Fe3+ and the eventual depletion or removal of the resulting Fe2+ (altering the colour of the reduction spot). Simultaneously, the reduction of V4+ and the consequent lowering of the concentration of V as V2+ minerals occur in the reduction spot, explaining their lower density than the host sediment.
CRIS-Team Scopus Importer:2023-01-20
Keywords: 3D X-ray Computed Tomography analysis; Continental red beds; Diagenesis; Redox; Taphonomy; Vanadium

Taphonomic bias in limestones and marls – a quantitative palaeontological approach to the genesis of limestone-marl alternations - Nohl, Theresa; Munnecke, Axel; Jarochowska, Emilia (87th Annual Conference of the Paläontologische Gesellschaft, 2016)

Taphonomic bias in limestones and marls – a quantitative palaeontological approach to the genesis of limestone-marl alternations - Nohl, Theresa; Munnecke, Axel; Jarochowska, Emilia (8th Meeting on Taphonomy and Fossilization, 2019)

Taphonomy of backshore versus deep-marine collected nautilus macromphalus conchs (New Caledonia) - Seuß, Barbara; Hembree, Daniel I.; Wisshak, Max; Mapes, Royal H.; Landman, Neil (Palaios, 2015)

Taxonomical diversity and palaeobiogeographical affinity of belemnites from the Pliensbachian–Toarcian GSSP (Lusitanian Basin, Portugal) - Costa Rita, Patrícia; Duarte, Luís V.; Weis, Robert; de Baets, Kenneth (Papers in Palaeontology, 2021)
High‐resolution analysis of the late Pliensbachian – early Toarcian belemnite assemblages from the Peniche section (Lusitanian Basin) has enabled, for the first time, recognition of eight taxa of the suborder Belemnitina, previously reported from contemporaneous north‐west Tethyan and Arctic sections. The presence of Bairstowius amaliae sp. nov. in the late Pliensbachian (emaciatum Zone) represents a novelty given that hitherto the genus Bairstowius was known only from late Sinemurian and early Pliensbachian deposits. Additionally, the replacement of Bairstowius amaliae by Catateuthis longiforma, during the latest Pliensbachian, suggests an evolutionary relationship between the two taxa. This relationship suggests a new scenario for the subsequent development of endemic Toarcian Boreal–Arctic faunas, characterized by the occurrence of Catateuthis. Comparison of the Peniche belemnite fauna with coeval faunas from the Mediterranean/Submediterranean and Euro‐Boreal domains indicates taxonomic uniformity during the late Pliensbachian and early Toarcian (emaciatum and polymorphum Zones), in the north‐west Tethys. Despite the lack of a marked taxonomic turnover, the Pliensbachian–Toarcian boundary corresponds to a slight decrease in diversity observed not only in the Lusitanian Basin but also in coeval north‐western European basins. Ordination and cluster analyses indicate that the largest changes in belemnite diversity and palaeogeographical distribution occurred rather during the Toarcian Oceanic Anoxic Event (base of the levisoni Zone). This event is marked by the extinction of taxa, affecting more severely the Mediterranean/Submediterranean domain and resulting in a more pronounced provincial differentiation among north‐western European and Arctic belemnite faunas.<br

Taxonomy and diversity of slit-band gastropods (OrderPleurotomariida) and some slit bearing Caenogastropodafrom the Pennsylvanian of the USA - Karapunar, Baran; Nützel, Alexander; Seuß, Barbara; Mapes, Royal H. (Papers in Palaeontology, 2022)

Taxonomy, palaeoecology and palaeobiogeography of upper Cenomanian (Upper Cretaceous) oysters and plicatulids from southern Algeria - Benyoucef, Madani; Ghenim, Asma-Fethia; Ferre, Bruno; Ayoub-Hannaa, Wagih; Koci, Tomas; Adaci, Mohammed; Guendouz, Mohamed-Lassad; Zaoui, Djamila; Bendella, Mohamed; Bensalah, Mustapha (Historical Biology, 2021)
Palaeontological investigation of four lithostratigraphic sections documenting the upper Cenomanian shallow marine carbonates of three palaeogeographic domains of southern Algeria (western Saharan Atlas, Guir Basin and Tinrhert Hamada) has produced a comprehensive collection of large bivalve assemblages for taxonomic purposes. A first inventory list of late Cenomanian oysters and plicatulids from southern Algeria is now available and consists of 15 taxa as follows: Lopha syphax, Ostreidae gen. et sp. indet., Curvostrea rouvillei, Flemingostreidae gen. et sp. indet., Costagyra olisiponensis, Amphidonta obliquata, Ceratostreon flabellatum, Ilymatogyra africana, Rhynchostreon suborbiculatum, Gyrostrea delettrei, Gyrostrea sp. indet., Pycnodonte (Phygraea) vesicularis vesiculosa, Plicatula (Plicatula.) auressensis, Plicatula (Plicatula) batnensis, and Chondrodonta? sp. indet. These taxa build five distinctive oyster-facies patterns, all purportedly recognisable in the field for stratigraphic assignment and regional correlation. Scarce sclerobiontic assemblage (borings: Entobia, Gastrochaenolites and Oichnus; and epibionts: juvenile oysters, serpulid tubes and Berenicean-type bryozoa) observed within these oyster shell assemblages is also identified, briefly described and adressed. This first taxonomic analysis highlights three main palaeogeographic components within these oyster- and plicatuloid-assemblages: endemic Mediterranean, Tethyan-Atlantic and cosmopolitan taxa. Moreover, the present study on these late Cenomanian oyster assemblages provides a first inventory list and stratigraphical baseline data towards further datation and correlation at the regional scale.
CRIS-Team Scopus Importer:2021-11-05
Keywords: ichnology; Ostreoidea; Plicatuloidea; systematics; taphonomy

Tectonic and crustal evolution of the Shackleton Range, East Antarctica: Geochemical and isotope contraints - Will, T. M.; Frimmel, H. E.; Zeh, A.; Le Roux, Petrus; Schmädicke, Esther (Precambrian Research, 2010)
UnivIS-Import:2017-03-24:Pub.2010.nat.dgeo.IGM.profes_1.texton

Tectonic and volcanic controls on Early Jurassic rift-valley lake deposits interleaved with Karoo flood basalts, Southern Namibia. - Stollhofen, Harald; Gerschütz, Stephan; Stanistreet, Ian G.; Lorenz, Volker (Palaeogeography, Palaeoclimatology, Palaeoecology, 1998)
The Karoo Igneous Province of southern Africa is one of the classic Mesozoic flood basalt provinces of the world. In the case of the early Jurassic Kalkrand Formation of Namibia the succession comprises three major flood basalt units that are separated by two stratigraphically important fluvio-lacustrine interlayers. These horizons preserve a record of the complex interplay between sedimentation, effusion of Karoo flood basalts and extensional tectonics that predated and accompanied the break-up of Gondwanaland. Both sediment layers start with the dominantly local derivation of weathered and eroded lava debris, followed by the emplacement of subaqueous mass flows and subsequent deposition of chemical sediments. The latter are characterised by interbedded stromatolitic carbonates, grass-like structured gypsum, and plane-bedded sandstones and mudstones containing euhedral displacive gypsum crystals that grew in the subsurface as well as rosettes which nucleated on the sediment surface. The central parts of the lacustrine units are overlain by thin deltaic sandstones showing bottomset, foreset, and topset layering and, finally, braided fluvial, trough cross-bedded sandstones. Evidence of subsidence synchronous with the formation of lake bodies can be explained by two principal mechanisms. The first acted in localised areas only and is reflected by the development of small, centrally subsiding basins. From the repeated occurrence of onlapping geometries within such a pool, a multiphase history of sagging is deduced, being most likely related to periodic magma withdrawal and reduction in magmatic pressures in subsurface lava feeders beneath the basin floor. Abundant syn-subsident fracture features at lava–sediment contacts, such as sediment-, hydrothermal calcite-, and sometimes basic lava-filled fissure systems indicate the pronounced interaction between the underlying volcanics and these small areas of pronounced subsidence. Fluids passing through the volcanic pile exhaled into the lake, giving it the characteristics of alkaline lake systems described from more recent flood basalt areas associated with the modern African Rift System. On the regional scale, however, northerly trending extensional fault systems controlled half-graben basin geometries and both facies and thickness variations across faults indicate that tectonism operated contemporaneously with volcanism and lacustrine sedimentation. The analysis of faults and associated structures, such as regularly aligned sediment-filled fissures, sets of micro-faults, folds and basaltic dykes constrains the extensional opening direction for the Karoo graben structures in this area that heralded the opening of the South Atlantic and thus provides a basis to discuss the extensional history of the Namibian coastal margin within the regional tectonic framework.
UnivIS-Import:2015-03-05:Pub.1998.nat.dgeo.IGM.LG.tecton
Keywords: Gondwana; Namibia; Karoo; Drakensberg Group; flood basalts; lakes; palaeolimnology

Tectonic blocks and molecular clocks - de Baets, Kenneth; Antonelli, Alexandre; Donoghue, Philip C. J. (Philosophical Transactions of the Royal Society B-Biological Sciences, 2016)
This article is part of the themed issue 'Dating species divergences using rocks and clocks'.
Keywords: molecular clock; calibration; fossil record; biogeography; tectonics

Tectonic control of ocean island basalt sources on São Miguel island, Azores? - Haase, Karsten; Beier, Christoph (Geophysical Research Letters, 2003)
The calderas of the two isotopically distinct volcanoes Sete Cidades and Agua de Pau on São Miguel are only 30 km apart. Sete Cidades lavas generally have 87Sr/86Sr < 0.7038 while Agua de Pau lavas have 87Sr/86Sr > 0.7040. Two overlapping rift zones exist between the two volcanoes and the lava compositions show that each rift zone is connected to the neighbouring volcano. Limited mixing between the volcanic systems implies separate ascent paths and magma sources with diameters of ∼20 km. The two volcanic systems follow contrasting directions; the Sete Cidades volcanic rift strikes NW parallel to the extensional Terceira Rift, while the Agua de Pau volcanic rift zone strikes E-W. The covariation of magma sources and lithospheric tectonics may suggest that the tectonic structure of the lithosphere controls the mantle upwelling beneath São Miguel.
UnivIS-Import:2015-03-09:Pub.2003.nat.dgeo.IGM.legeo.tecton
Keywords: Basalt; Geochemistry; Isotopes; Magma reservoir; Rift zones

Tectonic control on the genesis of magmas in the New Hebrides arc (Vanuatu) - Beier, Christoph; Brandl, Philipp; Martins Lima, Selma Sofia; Haase, Karsten (Lithos, 2018)
Keywords: Vanuatu; Silicic melt; Structural control; Island arc; Geodynamics; New Hebrides; Magma evolution

Tectonic events, continental intraplate volcanism and mantle plume activity in northern Arabia: constraints from geochemistry and Ar-Ar dating of Syrian lavas. - Krienitz, Marc-Sebastian; Haase, Karsten; Mezger, Klaus; van den Bogaard, Paul; Thiemann, Viola; Shaikh-Mashail, M.A. (Geochemistry Geophysics Geosystems, 2009)
[1] New 40Ar/39Ar ages combined with chemical and Sr, Nd, and Pb isotope data for volcanic rocks from Syria along with published data of Syrian and Arabian lavas constrain the spatiotemporal evolution of volcanism, melting regime, and magmatic sources contributing to the volcanic activity in northern Arabia. Several volcanic phases occurred in different parts of Syria in the last 20 Ma that partly correlate with different tectonic events like displacements along the Dead Sea Fault system or slab break-off beneath the Bitlis suture zone, although the large volume of magmas and their composition suggest that hot mantle material caused volcanism. Low Ce/Pb (<20), Nb/Th (<10), and Sr, Nd, and Pb isotope variations of Syrian lavas indicate the role of crustal contamination in magma genesis, and contamination of magmas with up to 30% of continental crustal material can explain their 87Sr/86Sr. Fractionation-corrected major element compositions and REE ratios of uncontaminated lavas suggest a pressure-controlled melting regime in western Arabia that varies from shallow and high-degree melt formation in the south to increasingly deeper regions and lower extents of the beginning melting process northward. Temperature estimates of calculated primary, crustally uncontaminated Arabian lavas indicate their formation at elevated mantle temperatures (Texcess ̃ 100-200°C) being characteristic for their generation in a plume mantle region. The Sr, Nd, and Pb isotope systematic of crustally uncontaminated Syrian lavas reveal a sublithospheric and a mantle plume source involvement in their formation, whereas a (hydrous) lithospheric origin of lavas can be excluded on the basis of negative correlations between Ba/La and K/La. The characteristically high 206Pb/204Pb (̃19.5) of the mantle plume source can be explained by material entrainment associated with the Afar mantle plume. The Syrian volcanic rocks are generally younger than lavas from the southern Afro-Arabian region, indicating a northward progression of the commencing volcanism since the arrival of the Afar mantle plume beneath Ethiopia/Djibouti some 30 Ma ago. The distribution of crustally uncontaminated high 206Pb/204Pb lavas in Arabia indicates a spatial influence of the Afar plume of ̃2600 km in northward direction with an estimated flow velocity of plume material on the order of 22 cm/a. © 2009 by the American Geophysical Union.
UnivIS-Import:2015-03-09:Pub.2009.nat.dgeo.IGM.legeo.tecton
Keywords: Afar; Intraplate volcanism; Mantle plume; Syria

Tectonic evolution of the central steep zone, axum area, Northern Ethiopia: Inferences from magnetic and geochemical data - de Wall, Helga; et al. (2011)

Tectonic focusing of voluminous basaltic eruptions in magma-deficient backarc rifts - Anderson, Melissa; Hannington, Mark; Haase, Karsten; Schwarz-Schampera, Ulrich; Augustin, Nico; McConachy, Tim; Allen, Katie (Earth and Planetary Science Letters, 2016)
The Coriolis Troughs of the New Hebrides subduction zone are among the youngest backarc rifts in the world. They reach depths of >3 km, despite their small size (<100 km in length and only 25-45 km wide) and their proximity to the arc front ( 50 km). The narrow, deep graben morphology is characteristic of magma-deficient arc rifts in the early stages of backarc extension, where the rate of extension and subsidence exceeds the magmatic input. Unexpectedly, the youngest graben, the Vate Trough, contains a centrally-located 1000-tall and 14-km wide shield volcano with a large, 5×8 km breached summit caldera. The Nifonea axial volcano has a volume of 126 km, reflecting unusually high extrusion rates, given its young age (<3 Ma), and the summit caldera hosts the remnants of a large lava lake, the first described from a submarine backarc setting. Extensive diffuse hydrothermal venting and several clusters of black smoker chimneys, with the highest recorded fluid temperatures (368C) in the SW Pacific, occur on the youngest lava flows. Comparison with similar axial volcanoes on the mid-ocean ridges suggests that the 46×10 m of sheet flows in the caldera could have been erupted in <30 hours. The focusing of voluminous basaltic eruptions into an otherwise magma-deficient backarc has been linked to strong left-lateral transtension caused by clockwise rotation and segmentation of the southern portion of the arc after collision with d'Entrecasteaux ridge. This study shows that the upper plate stresses can result in dramatic variability in magma supply and hydrothermal activity at the earliest stages of arc rifting and could explain the wide range of melt compositions, volcanic styles and mineral deposit types found in nascent backarc rifts.
Keywords: Backarc magmatism; Lava lake; Nifonea; Ridge collision; Seafloor sulfides; Vate Trough