Lithostratigraphy and depositional environments in the Waterberg-Erongo area, central Namibia, and correlation with the main Karoo Basin, South Africa. - Holzförster, Frank; Stollhofen, Harald; Stanistreet, Ian G. (Journal of African Earth Sciences, 1999)
The dissected landscape of the Waterberg-Erongo area, central Namibia, exposes Karoo-equivalent strata deposited in basins that occur throughout sub-Saharan Africa. Although many are of economic interest, including coal-bearing strata, their depositional history is not well understood. This study of the Waterberg-Erongo area provides detailed lithostratigraphical data, which suggest sedimentation from the late Early Triassic to the Early Jurassic in a fault-bounded depository. Subsidence and sediment supply were controlled predominantly by the northeast-southwest trending Waterberg-Omaruru Fault Zone, which defines the northwestern margin of the depository. Facies development and thickness distribution of the Karoo strata in the Waterberg-Erongo area, perhaps the most continuous of any of the Karoo basins, indicate a northeastwardly-migrating depocentre alongside that fault, in response to major extensional movements in the early pre-South Atlantic rift zone. Periodic fault movements repeatedly caused basinward progradation of the alluvial facies, which are reflected by stacked fining-upward cycles in the lithological record. On a broader scale, the results of this study suggest that the northward propagation of the rift zone between Southern Africa and South America, was partially accommodated by transfer lineaments. Local depocentres developed along these lineaments, such as those in the Waterberg-Erongo area, with localised enhanced subsidence greater than that revealed in other Namibian onshore exposures, dominated by the rifting itself.
UnivIS-Import:2015-03-05:Pub.1999.nat.dgeo.IGM.LG.lithos_0

Living to the range limit: Consumer isotopic variation increases with environmental stress - Reddin, Carl James; O'Connor, Nessa; Harrod, Chris (PeerJ, 2016)
Keywords: Diet; Intertidal; Isotopic niche; Littorinid; Physiological condition; Range limit; Stable isotopes; Stress gradient; Trophic niche width; Trophic variation

Local-scale assessment of the displacement pattern of a densely populated landslide, utilizing finite element software and terrestrial radar interferometry: a case study on Huangtupo landslide (P.R. China) - Dumperth, Christian; Fleer, Alexander; Xiang, Wei; Rohn, Joachim (Environmental Earth Sciences, 2016)
Keywords: ArcGIS; Finite element analysis; Huangtupo; Radar interferometry; Susceptibility; Three Gorges Dam

Long-term cement hydration studies with isothermal calorimetry - Linderoth, O.; Wadsö, L.; Jansen, Daniel (Cement and Concrete Research, 2021)
The purpose of this study was to investigate for how long the thermal power of hydration can be measured with isothermal calorimetry, which is a general measurement technique with stable properties that, in many cases, can detect low rates of processes. Measurements were conducted for 365 days on cement paste with Portland cement, fly ash blended Portland cement and different water-to-binder ratios. The results showed that all the tested systems still produced a measureable signal after one year. The samples with Portland cement were also analyzed by XRD after 365 days, and phase composition calculations were made with GEMS. Together with the calorimetric results, these results were used to determine the degree of hydration by five methods, the results of which showed good agreement.
CRIS-Team Scopus Importer:2021-01-15
Keywords: Calorimetry; Cement paste; Hydration; Rietveld analysis; X-ray diffraction

Long-term relationships between ecological stability and biodiversity in Phanerozoic reefs - Kießling, Wolfgang (Nature, 2005)
High biodiversity has been shown to enhance ecological stability on small spatial scales and over intervals of weeks to decades. It remains unclear, however, whether this diversity-stability relationship can be scaled up to regional scales, or to longer timescales. Without empirical validation at larger scales, the implications of the diversity-stability relationship for both ecology and long-term conservation strategies cannot readily be resolved. Here I show that in biogenic reefs, ecological stability is related to taxonomic diversity on million-year timescales. The higher the mean reef diversity in a particular time interval, the smaller the change in skeletal density, style of reef building and biotic reef types in the subsequent time interval. Because the relationships apply to a wide spectrum of disturbance regimes and reef types, these results support the hypothesis that species richness itself promotes ecological stability. Carbonate production by reefs, while closely correlated with reef diversity without temporal lag, is not stabilized by reef diversity over these long timescales. This suggests that ecological stability and productivity may be decoupled in natural ecosystems.
UnivIS-Import:2015-03-09:Pub.2005.nat.dgeo.IGM.LP.longte

Lost in transition – the selective compaction of a halysitid coral and its implications for diagenesis and time - Nohl, Theresa; Munnecke, Axel (GeoBonn2018 - Living Earth, 2018)

Louisville Seamount Chain: Petrogenetic processes and geochemical evolution of the mantle source - Vanderkluysen, Loyc; Mahoney, John J.; Koppers, Anthony A. P.; Beier, Christoph; Regelous, Marcel; Gee, Jeffrey S.; Lonsdale, Peter F.; Haase, Karsten (Geochemistry Geophysics Geosystems, 2014)
The Louisville Seamount Chain is a ∼4300 km long chain of submarine volcanoes in the southwestern Pacific that spans an age range comparable to that of the Hawaiian-Emperor chain and is commonly thought to represent a hot spot track. Dredging in 2006 recovered igneous rocks from 33 stations on 22 seamounts covering some 49 Myr of the chain's history. All samples are alkalic, similar to previous dredge and drill samples, providing no evidence for a Hawaiian-type tholeiitic shield-volcano stage. Major and trace element variations appear to be predominantly controlled by small but variable extents of fractional crystallization and by partial melting. Isotopic values define only a narrow range, in agreement with a surprising long-term source homogeneity - relative to the length scale of melting - and overlap with proposed fields for the "C" and "FOZO" mantle end-members. Trace element and isotope geochemistry is uncorrelated with either seamount age or lithospheric thickness at the time of volcanism, except for a small number of lavas from the westernmost Louisville Seamounts built on young (<20 Ma old) oceanic crust. The Louisville hot spot has been postulated to be the source of the ?120 Ma Ontong Java Plateau, but the Louisville isotopic signature cannot have evolved from a source with isotopic ratios like those measured for Ontong Java Plateau basalts. On the other hand, this signature can be correlated with that of samples dredged from the Danger Islands Troughs of the Manihiki Plateau, which has been interpreted as a rifted fragment of the "Greater" Ontong Java Plateau. Key Points LSC mantle source is surprisingly homogeneous A Hawaiian-type tholeiitic shield-volcano stage is absent from LSC seamounts LSC mantle source is isotopically distinct from Ontong Java source © 2014. American Geophysical Union. All Rights Reserved.
Keywords: geochemistry; hot spot; Louisville; mantle plumes; ocean island basalt; seamount

Lower crustal hot zones as zircon incubators: Inherited zircon antecryts in diorites from a mafic mush reservoir - Lim, Hoseong; Nebel, Oliver; Weinberg, Roberto F.; Nebel-Jacobsen, Yona; Barrote, Vitor R.; Park, Jongkyu; Myeong, Bora; Cawood, Peter A. (Geological Society of London, 2024)
Continental arcs are key sites of granitic magmatism, yet details of the origins of these magmas, including the role and contribution of mafic magma, the timing and location of initial zircon formation and how zircon isotopic signatures relate to granite formation, remain as challenges. Here we use U–Pb dating, trace elements and Hf isotopic systematics of zircon in mafic microgranular enclaves (MMEs), from the convergent plate margin Satkatbong diorite (SKD) in Korea to understand lower arc magmatism and zircon pro-duction. The host granitic body and MMEs display similar major element evolutionary trends and similar ranges of Sr, Nd and Hf isotopes, implying a cognatic relationship. Zircons show a large variability in εHf (t)(c. 6 units) and age (>30 Ma). We propose that the SKD and MMEs originated from the same, long-lasting, lower crustal mush reservoir, enabling long and variable residence times for zircons. Prolonged zircon ages, combined with the Hf isotope variability within a single pluton (SKD and its MME), indicate that not all zircons were instantaneously crystallized in a rapidly cooling shallow magma chamber but were continuously formed in a long-lasting hot source. A low-melt-fraction mush type reservoir in a deep crustal hot zone provides a viable model for the source setting. Continuous replenishment of mafic magmas acts as the main re-activator of the reservoir, and provide a critical role in spawning zircons that record a long age span, because (1) the magma adds Zr into the reservoir, enabling it to reach zircon saturation and (2) the generated zircon grains are trans-ported upward as antecrysts by flow inside of the reservoir. This means that antecrysts with different ages may mix with each other in the ascending magma body. The significance of this model is that a conclusive time of intrusion cannot be constrained by such zircon ages, as these antecrysts constitute inherited grains.
CRIS-Team Scopus Importer:2024-01-19

Lower crustal hydrothermal circulation at slow-spreading ridges: evidence from chlorine in Arctic and South Atlantic basalt glasses and melt inclusions - van der Zwan, Froukje; Devey, Colin; Hansteen, Thor; Almeev, Renat; Augustin, Nico; Frische, Matthias; Haase, Karsten; Basaham, Ali; Snow, Jon (Contributions To Mineralogy and Petrology, 2017)
Keywords: (Ultra)slow-spreading ridges; Chlorine; Crustal assimilation; Crystallization depths; Hydrothermal circulation; MORB

Lower-Middle Ordovician δ 13C chemostratigraphy of western Baltica (Jämtland, Sweden) - Wu, R.; Calner, Michael; Lehnert, Oliver; Petterfy, O.; Joachimski, Michael (Palaeoworld, 2015)
The province of Jämtland, central Sweden, records a well-preserved but very thin suite of the Lower-Middle Ordovician cool-water carbonates. In this study we present the first carbon isotope profile for these strata on the basis of whole-rock samples from the Brunflo 2 core. The studied succession is 41.55m thick and includes, in ascending order, the Bjørkåsholmen Formation, Latorp Limestone, Tøyen Shale, and the Lanna, Holen, and Segerstad limestones. We identify two distinct positive δ13C excursions that can be used for intra- as well as inter-continental correlations. A positive excursion in the Tøyen Shale probably correlates to the mid-late Floian and the Oepikodus evae Zone in Baltica and Precordillera, and the Reutterodus andinus Zone in North America. A continuous increase in δ13C values through the upper Holen Limestone and the preserved part of the overlying Segerstad Limestone is interpreted as the rising limb of the Middle Darriwilian Isotope Carbon Excursion (MDICE), an important tie-point for the global correlation of the Jämtland strata. Negative δ13C values associated with the Latorp Limestone may correlate with similar low values in the late Tremadocian and early Floian of the Argentine Precordillera and the Shingle Pass and Ibex sections in North America.
Keywords: Carbon isotope chemostratigraphy; MDICE; Ordovician; Sweden

Lower Palaeozoic geology of southern Sweden - Calner, Mikael; Erlström, Mikael; Lehnert, Oliver; Ahlberg, Per (The Lower Palaeozoic of southern Sweden and the Oslo Region, Norway. Field Guide for the 3rd Annual Meeting of the IGCP project 591, 2013)
UnivIS-Import:2015-03-09:Pub.2013.nat.dgeo.IGM.LG.lowerp_5

Low-latitude vegetation and climate dynamics at the Paleocene-Eocene transition - A study based on multiple proxies from the Jathang section in northeastern India - Prasad, V.; Utescher, T.; Sharma, A.; Singh, I. B.; Garg, R.; Gogoi, B.; Srivastava, J.; Uddandam, P. R.; Joachimski, Michael (Palaeogeography, Palaeoclimatology, Palaeoecology, 2018)
Keywords: Climate change; Paleotropics; Palynology; PETM; Precipitation; Rainforest

Low water contents in garnet of orogenic peridotite: clues for an abyssal or mantle-wedge origin? - Schmädicke, Esther; Gose, Jürgen (European Journal of Mineralogy, 2019)
Data on water in nominally anhydrous minerals (NAMs) of orogenic garnet-bearing ultramafic rocks (GBU) are extremely rare. In this study, garnet of peridotite and pyroxenite from Erzgebirge (EG), Germany, and two peridotite samples from Alpe Arami (AA), Switzerland, were analyzed by infrared (IR) spectroscopy. Garnet from EG peridotite and pyroxenite yielded IR absorption bands at 3650 +/- 10 cm(-1) (type I) and in the wavenumber range of 3570-3630 cm(-1 )(type II) that are ascribed to structural hydroxyl (colloquially "water"). Additional broad band's centered at <3460 cm(-1), present in about half of the samples, are related to molecular water (MW). The content of structural H2O defined by band types I + II is low (3-68 ppm) in all EG samples. Structural water is negatively correlated to Mg and Ti and positively to Y and HREE in EG garnet. Including molecular water, a pronounced positive correlation between H2O and Li is observed. Because the intensity of the type II band is enhanced in domains with molecular water, the primary, peak metamorphic H2O content in EG garnet was probably as low as 0-11 ppm. Equally low contents of structural water are present in AA garnet (10-13 ppm) in which molecular water is negligible. Such concentrations are distinctly lower than the water storage capacity of garnet at the relevant pressure. Water loss upon decompression cannot serve as an explanation for the low contents because, on the contrary, post-peak-metamorphic influx of H2O led garnet to take up secondary structural water. Hence, the results are interpreted as an indication of severe water deficiency at peak metamorphism. Notably, the obtained data agree with the H2O content of 6 ppm reported in garnet from Cima di Gagnone peridotite, which originated as abyssal peridotite. It remains unknown if these low contents are typical for an abyssal, low-pressure protolith but, if the rocks were part of the lowermost, most hydrated portion of the mantle wedge, they are expected to contain much more water. Given that garnet in basaltic coesite eclogite from the Erzgebirge is equally water-deficient as the GBU samples from the same unit, it is at least a possibility that both rock types share a low-pressure origin in an oceanic setting.
CRIS-Team WoS Importer:2019-11-29

LREE rich perovskite in antiskarn reactions - REE transfer from pyroxenites to carbonatites? - Voropaeva, Daria; Arzamastsev, Andrei A.; Botcharnikov, Roman; Buhre, Stephan; Gilbricht, Sabine; Götze, Jens; Klemd, Reiner; Schulz, Bernhard; Tichomirowa, Marion (Lithos, 2024)
We study three ultrabasic-alkaline carbonatite complexes (UACCs: Afrikanda, Vuorijarvi, Kovdor) from the Kola Alkaline Province to focus on the comparison of REE contents from pyroxenites and carbonatites and the fate of perovskite. Pyroxenites and carbonatites have large REE variations and similar contents in all three complexes. Afrikanda and Vuorijarvi pyroxenites and carbonatites have higher REE contents compared to all Kovdor rocks. Despite their comparable LREE contents, pyroxenites and carbonatites have different REE-carrier minerals. In most studied pyroxenites, perovskite is the main REE-bearing mineral and its abundance controls the LREE enrichment of the whole rock. When perovskite is absent or in low abundance, apatite is the main REE carrier. Instead, in carbonatites and phoscorites, apatite and calcite control REE contents. REE‑carbonates - found in several carbonatite samples - do not play a substantial role in the overall REE budget because of their very low abundance and tiny grain sizes. We found large LREE variations at very low local scales (< 1 mm) in several thin sections. These large variations are related to carbonatite infiltration and associated antiskarn reactions. Perovskite near calcite is replaced by titanite that has much lower LREE contents. Most LREE released from the breakdown of perovskite were probably dissolved in the carbonatite melt because apatite and calcite that crystallized from this melt are highly enriched in LREE. Newly formed apatites and calcites show large LREE variations that probably are controlled by local factors (e.g. variations of Si, Ca, Mg activities). Y/Ho ratios are strongly fractionated in most minerals and often show large variations at local scales (mm) in these antiskarn reactions. The potential of REE remobilization from such perovskite replacement reactions is very high as perovskite contributes about 70% to the REE budget for these three UACCs. Therefore, more attention should be given to perovskite replacement reactions and its role for LREE enrichment of carbonatite melts.
CRIS-Team Scopus Importer:2024-02-02
Keywords: Antiskarn reactions; Apatite; Carbonatite; Kola alkaline province; Perovskite; Rare earth elements

Machine learning-based re-classification of the geochemical stratigraphy of the Rajahmundry Traps, India - Hoyer, Patrick; Regelous, Marcel; Adatte, Thierry; Haase, Karsten (Journal of Volcanology and Geothermal Research, 2022)
The lavas exposed at the Rajahmundry Traps have similar ages and geochemical compositions compared to those from the Ambenali and Mahabaleshwar formations of the Deccan Traps, which is why they are believed to represent their eastern extensions. However recent geochronological data for the lavas crop out in the Rajahmundry quarries and paleontological evidence from the expanded sediment-lava sequences preserved in the Krishna-Godavari Basin indicate that the lower Rajahmundry Flow could represent a flow of the Poladpur formation. Here we present new major and trace element data for lavas of the lower (five samples) and middle (three samples) Rajahmundry Flows exposed in the Gowripatnam Quarry. To test whether the lower Rajahmundry Flow show geochemical similarities to the Poladpur formation, we applied a machine learning-based classification model which is able to predict the most probable formation affiliation for an unknown sample. The classification method we used is the Random Forest algorithm and training as well as testing our model with new and published geochemical data from the Poladpur and Ambenali formations (n = 73) by using Repeated K-Fold Cross Validation yields a prediction accuracy of 86%. According to our model results, the lavas of the lower Rajahmundry Flow were assigned to the Poladpur formation, while those from the middle Rajahmundry Flow show geochemical similarities to the Ambenali formation. Flows of each of the voluminous Deccan formations (Poladpur, Ambenali and Mahabaleshwar) are therefore present at Rajahmundry, confirming that these are an eastward extension of the Deccan Traps.
CRIS-Team Scopus Importer:2022-06-17
Keywords: Continental flood basalts; Cretaceous-Paleogene boundary; Deccan Traps; Machine learning classification model; Rajahmundry Traps

Mafic rocks from Erinpura gneiss terrane in the Sirohi region: Possible ocean-floor remnants in the foreland of the Delhi Fold Belt, NW India - Pandit, M. K.; de Wall, Helga; Daxberger, H.; Just, J.; Bestmann, Michel; Sharma, K. K. (Journal of Earth System Science, 2011)
Keywords: Daba mafic rocks; Geochemistry; Magnetic fabric; Neoproterozoic; NW India; Phulad ophiolite

Magma evolution of the Sete Cidades volcano, São Miguel, Azores. - Beier, Christoph; Hansteen, Thor; Haase, Karsten (Journal of Petrology, 2006)
The Sete Cidades volcano (São Miguel, Azores) is situated at the eastern end of the ultraslow spreading Terceira rift axis. The volcano comprises several dominantly basaltic pre-caldera eruptions, a trachytic caldera-forming stage and a post-caldera stage consisting of alternating trachytic and basaltic eruptions. The post-caldera flank lavas are more primitive (>5 wt % MgO) than the pre-caldera lavas, implying extended fractional crystallization and longer crustal residence times for the pre-caldera, shield-building lavas. Thermobarometric estimates show that the ascending alkali basaltic magmas stagnated and crystallized at the crust-mantle boundary (∼15 km depth), whereas the more evolved magmas mainly fractionated in the upper crust (∼3 km depth). The caldera-forming eruption was triggered by a basaltic injection into a shallow trachytic magma chamber. Lavas from all stages follow a single, continuous liquid line of descent from alkali basalt to trachyte, although slight differences in incompatible element (e.g. Ba/Nb, La/Nb) and Sr isotope ratios imply some heterogeneity of the mantle source. Major and trace element data suggest similar partial melting processes throughout the evolution of the volcano. Slight geochemical differences between post- and pre-caldera stage lavas from the Sete Cidades volcanic system indicate a variation in the mantle source composition with time. The oxygen fugacity increased from the pre-caldera to the post-caldera stage lavas, probably as a result of the assimilation of crustal rocks; this is supported by the presence of crustal xenoliths in the lavas of the flank vents. The lavas from the Sete Cidades volcano generally have low Sr isotope ratios; however, rocks from one post-caldera vent on the western flank indicate mixing with magmas resembling the lavas from the neighbouring Agua de Pau volcano, having higher Sr isotope ratios. The different magma sources at Sete Cidades and the adjacent Agua de Pau volcano imply that, despite their close proximity, there is only limited interaction between them. © 2006 Oxford University Press.
UnivIS-Import:2015-03-09:Pub.2006.nat.dgeo.IGM.legeo.magmae
Keywords: Crystallization depth; Fractionation; Stratigraphy; Terceira rift; Volcanic stages

Magma genesis and crustal contamination of continental intraplate lavas in NW Syria. - Krienitz, Marc-Sebastian; Haase, Karsten; Mezger, Klaus; Eckhardt, Viola; Shaikh-Mashail, M.A. (Contributions To Mineralogy and Petrology, 2006)
UnivIS-Import:2015-03-09:Pub.2006.nat.dgeo.IGM.legeo.magmag

Magma genesis and mantle dynamics at the Harrat Ash Shamah Volcanic Field (southern Syria). - Krienitz, Marc; Haase, Karsten; Mezger, Klaus; Shaikh-Mashail, M.A. (Journal of Petrology, 2007)
A geochemical and petrological study of Miocene to recent alkali basalts, basanites, hawaiites, mugearites, trachytes, and phonolites erupted within the Harrat Ash Shamah volcanic field was performed to reconstruct the magmatic evolution of southern Syria. The major element composition of the investigated lavas is mainly controlled by fractional crystallization of olivine, clinopyroxene, ± Fe-Ti oxides and ± apatite; feldspar fractionation is restricted to the most evolved lavas. Na2O and SiO2 variations within uncontaminated, primitive lavas as well as variably fractionated heavy rare earth element ratios suggest a formation by variable degrees of partial melting of different garnet peridotite sources triggered, probably, by changes in mantle temperature. The isotopic range as well as the variable trace element enrichment observed in the lavas imply derivation from both a volatile- and incompatible element-enriched asthenosphere and from a plume component. In addition, some lavas have been affected by crustal contamination. This effect is most prominent in evolved lavas older than 3.5 Ma, which assimilated 30-40% of crustal material. In general, the periodicity of volcanism in conjunction with temporal changes in lava composition and melting regime suggest that the Syrian volcanism was triggered by a pulsing mantle plume located underneath northwestern Arabia. © The Author 2007. Published by Oxford University Press. All rights reserved.
UnivIS-Import:2015-03-09:Pub.2007.nat.dgeo.IGM.legeo.magmag
Keywords: Intraplate volcanism; Mantle plume; Partial melting; Syria

Magma genesis by rifting of oceanic lithosphere above anomalous mantle: Terceira Rift, Azores. - Beier, Christoph; Haase, Karsten; Abouchami, Wafa; Krienitz, Marc-Sebastian; Hauff, Folkmar (Geochemistry Geophysics Geosystems, 2008)
The Terceira Rift formed relatively recently (̃1 Ma ago) by rifting of the old oceanic lithosphere of the Azores Plateau and is currently spreading at a rate of 2-4mm/a. Together with the Mid-Atlantic Ridge, the Terceira Rift forms a triple junction that separates the Eurasian, African, and American Plates. Four volcanic systems (São Miguel, João de Castro, Terceira, Graciosa), three of which are islands, are distinguished along the axis and are separated by deep avolcanic basins similar to other ultraslow spreading centers. The major element, trace element and Sr-Nd-Pb isotope geochemistry of submarine and subaerial lavas display large along-axis variations. Major and trace element modeling suggests melting in the garnet stability field at smaller degrees of partial melting at the easternmost volcanic system (São Miguel) compared to the central and western volcanoes, which appear to be characterized by slightly higher melting degrees in the spinel/garnet transition zone. The degrees of partial melting at the Terceira Rift are slightly lower than at other ultraslow mid-ocean ridge spreading axes (Southwest Indian Ridge, Gakkel Ridge) and occur at greater depths as a result of the melting anomaly beneath the Azores. The combined interaction of a high obliquity, very slow spreading rates, and a thick preexisting lithosphere along the axis probably prevents the formation and eruption of larger amounts of melt along the Terceira Rift. However, the presence of ocean islands requires a relatively stable melting anomaly over relatively long periods of time. The trace element and Sr-Nd-Pb isotopes display individual binary mixing arrays for each volcanic system and thus provide additional evidence for focused magmatism with no (or very limited) melt or source interaction between the volcanic systems. The westernmost mantle sources beneath Graciosa and the most radiogenic lavas from the neighboring Mid-Atlantic Ridge suggest a mantle flow from Graciosa toward the Mid-Atlantic Ridge and hence a flux of mantle material from one spreading axis into the other. The Terceira Rift represents a unique oceanic rift system situated within the thickened, relatively old oceanic lithosphere and thus exhibits both oceanic and continental features. © 2008 by the American Geophysical Union.
UnivIS-Import:2015-03-09:Pub.2008.nat.dgeo.IGM.legeo.magmag
Keywords: Azores; Geochemistry; Incompatible elements; Ocean Island Basalts; Radiogenic isotopes; Spreading center

Magmatic evidence for carbonate metasomatism in the lithospheric mantle underneath the Ohře (Eger) Rift - Brandl, Philipp; Genske, Felix; Beier, Christoph; Haase, Karsten; Sprung, Peter; Krumm, Stefan (Journal of Petrology, 2015)
Magmas erupted in intracontinental rifts typically form from melting of variable proportions of asthenospheric or lithospheric mantle sources and ascend through thick continental lithosphere. This ascent of magma is accompanied by differentiation and assimilation processes. Understanding the composition of rift-related intracontinental volcanism is important, particularly in densely populated active rift zones such as the Ohře (Eger) Rift in Central Europe. We have sampled and analysed nephelinites from Železná hůrka (Eisenbühl), the youngest (<300 ka) Quaternary volcano related to the Ohře Rift where frequent earthquake swarms indicate continuing magmatic activity in the crust. This nephelinite volcano is part of a larger eruptive centre (Mỳtina Maar) representing a single locality of recurrent volcanism in the Ohře Rift. We present a detailed petrographic, mineralogical and geochemical study (major and trace elements and Sr-Nd-Hf-O isotopes) of Železná hůrka to further resolve the magmatic history and mantle source of the erupted melt. We find evidence for a highly complex evolution of the nephelinitic melts during their ascent to the surface. Most importantly, mixing of melts derived from different sources and of strong chemical contrast controls the composition of the erupted volcanic products. These diverse parental melts originate from a highly metasomatized subcontinental lithospheric mantle (SCLM) source. We use a combined approach based on mineral, glass and whole-rock compositions to show that the mantle underneath the western Ohře Rift is metasomatized dominantly by carbonatitic melts. The nephelinites of Železná hůrka formed by interaction between a carbonatitic melt and residual mantle peridotite, partial crystallization in the lithospheric mantle and minor assimilation of upper continental crust. Thermobarometric estimates indicate that the stagnation levels of the youngest volcanism in this part of the Ohře Rift were deeper than the focal depths of recent earthquake swarms, indicating that those are not directly linked to magma ascent. Furthermore, close mineralogical and geochemical similarities between the Železná hůrka nephelinite and fresh kimberlites may point towards a genetic link between kimberlites, melilitites and nephelinites.
Keywords: Assimilation; Carbonated peridotite; Continental rift; Mantle metasomatism; Nephelinite

Magmatic evolution and source variations at the Nifonea Ridge (New Hebrides Island Arc) - Lima, Selma; Haase, Karsten; Beier, Christoph; Regelous, Marcel; Brandl, P. A.; Hauff, F.; Krumm, Stefan (Journal of Petrology, 2017)
Keywords: Back-arc melting; Mantle heterogeneity; Nb-enriched basalts; New Hebrides island arc

Magmatic evolution of a dying spreading axis: evidence for the interaction of tectonics and mantle heterogeneity from the fossil Phoenix Ridge, Drake Passage - Haase, Karsten; Beier, Christoph; Fretzdorff, Susanne; Leat, Phil; Livermore, Roy; Barry, Tiffany; Pearce, Julian; Hauff, Folkmar (Chemical Geology, 2011)
New <sup style="border-top-width: 0px; border-right-width: 0px; border-bottom-width: 0px; border-left-width: 0px; border-style: initial; border-color: initial; font-size: 0.75em; font-weight: 100; margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; padding-top: 0px; padding-right: 0px; padding-bottom: 0px; padding-left: 0px; vertical-align: super; font-family: Arial, Helvetica, 'Lucida Sans Unicode', 'Microsoft Sans Serif', 'Segoe UI Symbol', STIXGeneral, 'Cambria Math', 'Arial Unicode MS', sans-serif; line-height: 0; ">40Ar–<sup style="border-top-width: 0px; border-right-width: 0px; border-bottom-width: 0px; border-left-width: 0px; border-style: initial; border-color: initial; font-size: 0.75em; font-weight: 100; margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; padding-top: 0px; padding-right: 0px; padding-bottom: 0px; padding-left: 0px; vertical-align: super; font-family: Arial, Helvetica, 'Lucida Sans Unicode', 'Microsoft Sans Serif', 'Segoe UI Symbol', STIXGeneral, 'Cambria Math', 'Arial Unicode MS', sans-serif; line-height: 0; ">39Ar ages of 5.6 to 1.3 Ma for lavas from the fossil Phoenix Ridge in the Drake Passage show that magmatism continued for at least 2 Ma after the cessation of spreading at 3.3 ± 0.2 Ma. The Phoenix Ridge lavas are incompatible element-enriched relative to average MORB and show an increasing enrichment with decreasing age, corresponding to progressively decreasing degrees of partial melting of spinel peridotite after spreading stopped. The low-degree partial melts increasingly tap a mantle source with radiogenic Sr and Pb but unradiogenic Nd isotope ratios implying an ancient enrichment. The post-spreading magmas apparently form by buoyant ascent of enriched and easily fusible portions of the upper mantle. Only segments of fossil spreading ridges underlain by such enriched and fertile mantle show post-spreading volcanism frequently forming bathymetric highs. The Phoenix Ridge lavas belong to the Pacific, rather than the Atlantic, mantle domain in regional Sr–Nd–Pb space. Our new data show that the southern Pacific Ocean mantle is heterogeneous containing significant enriched portions that are preferentially tapped at low melt fractions. Isotopic mapping reveals that Pacific-type upper mantle flows eastward through Drake Passage and surrounds the subducting Phoenix Plate beneath the Bransfield Basin.
UnivIS-Import:2015-03-09:Pub.2010.nat.dgeo.IGM.legeo.magmat
Keywords: Basalt; Incompatible elements; Mantle upwelling; Mid-ocean ridges; Partial melting

Magmatic Evolution of the Fossil Melanesian Island Arc: Evidence From Lower Miocene Lavas of Malekula Island (Vanuatu) - Haase, Karsten; Schneider, K. P.; Pelletier, B.; Ishizuka, O. (Geochemistry Geophysics Geosystems, 2024)
The subduction zones in the SW Pacific Ocean are some of the most dynamic plate boundaries on Earth with changes in subduction polarity and subduction initiation processes. The New Hebrides island arc formed some 10 million years ago after the Melanesian island arc was abandoned due to the cessation of subduction of the Pacific Plate after collision of oceanic plateaus with the island arc. Parts of the Melanesian island arc occur within the New Hebrides island arc and we show that Miocene volcanic rocks exposed on Malekula island in the New Hebrides island arc consist of island arc tholeiites to alkaline basalts with variable slab contribution. The lava erupted between 22.5 and 16.3 Ma, similar to the Wainimala Group lavas on Fiji representing the eastern portion of the Melanesian island arc. Partial melts from subducted sediments affected a Pacific MORB-type mantle, but we do not find evidence for a slab component derived from the Ontong Java Plateau or for assimilation of continental crust. Thus, no Miocene subduction of the Ontong Java Plateau occurred beneath Malekula and the basement of the island probably does not consist of continental crust rifted from Australia. The Malekula lava succession resembles that of other portions of the Miocene Melanesian island arc between New Britain and Fiji, indicating continuous subduction of the Pacific plate along this arc.
CRIS-Team Scopus Importer:2024-03-08
Keywords: Hf-Nd isotope ratios; island arc evolution; New Hebrides island arc; polarity reversal; subduction; Vitiaz island arc

Magmatic evolution of the migrating central Urumieh–Dokhtar arc, Iran: implications for magma production - Babazadeh, Shahrouz; Haase, Karsten; Ghalamghash, Jalil; Regelous, Marcel; Poujol, Marc; Raeisi, Davood; Zhao, Miao (International Journal of Earth Sciences, 2023)
The Cenozoic Avaj volcano-plutonic rocks in central Urumieh-Dokhtar magmatic arc (UDMA) encompass gabbro, and basalt to rhyolite, chemically akin to those from continental arcs. U–Pb geochronology on zircon yielded ages of 23.69 ± 0.48 Ma, 24.71 ± 0.38 Ma, 20.92 ± 0.14 Ma, and 19.25 ± 0.13 Ma for gabbro, basalt, trachyandesite, and rhyolite, respectively. εHf(t) values for zircon grains are ranging from − 1.4 to + 6.2. The data display narrow ranges of initial Pb isotopic ratios and εNd(t) values, implying a fairly homogeneous source. Moderate 206Pb/204Pb, 207Pb/204Pb, and 208Pb/204Pb, high 143Nd/144Nd ratios of the mafic samples highlight the role of mantle components. The isotopic ratios–incompatible trace elements modelings reveal 2% of the melt come from the melting sediments in the petrogenesis of Avaj igneous rocks. The central UDMA with ages ranging from 42–38 Ma and 25–18 Ma, respectively, must have experienced two relatively brief periods of important magma production separated by 14–15 M.y. The early period of magma production correlates with the Middle Eocene Climatic Optimum (MECO), while the second magmatic period of the central UDMA is not associated with increasing CO2 contents in the atmosphere. The plutons of the older group are generally located to the east of those from the younger group suggesting a SW-directed migration of the arc following slab rollback. No systematic change of source compositions and magma formation is observed between the older and younger rocks implying similar magma sources and subduction input from the Eocene to Miocene. The potential effect of the UDMA magmatic activity on the global climate apparently does not reflect decreasing subduction of carbonate.
CRIS-Team Scopus Importer:2023-05-19
Keywords: Global climate; Oligocene to Miocene; Sr–Nd–Hf–Pb isotopes; Urumieh–Dokhtar magmatic arc; U–Pb zircon ages

Magmatic evolution of the Schiel Alkaline Complex, Bushveld large igneous province, South Africa - Höß, Alica; Klemd, Reiner; Bolhar, Robert; Haase, Karsten; Ramos, Joshua; Geiger, Elena; Brandt, Sönke; Graupner, Torsten (Lithos, 2024)
The Paleoproterozoic Schiel Alkaline Complex (SAC) in the Limpopo Belt is a composite pluton that coevally formed with the layered intrusion of the Bushveld large igneous province. The SAC is mainly composed of alkaline felsic rocks, pyroxenite, gabbro, syenodiorite/−gabbro, and minor carbonatite and gabbroic dikes. Here we present a new geochemical, geochronological, and isotopic study of the felsic and (ultra)mafic rock suites of the western SAC. The whole rock Sm[sbnd]Nd isotope study of the felsic rocks revealed εNd2059 Ma values between −6.5 and − 3.8, while those of the syenodiorite/−gabbros and gabbros vary from −7.9 to −8.8, and − 4.3 to +1.1, respectively. The pyroxenites have εNd2059 Ma values of +7.4 to +2.7. The Lu[sbnd]Hf isotope study displays εHf2059 Ma values of −15.9 to −9.0 for the syenites, alkali granites and syenodiorite/−gabbros, and significantly higher εHf2059 Ma of −3.1 to +3.4 for the gabbros. LA-SF-ICPMS U[sbnd]Pb zircon dating yields 2079 ± 10 Ma and 2088 ± 30 Ma for the syenodiorite/−gabbros, and 2086 ± 51 Ma and 2107 ± 30 Ma for the gabbros. In conjunction with published data from the eastern SAC, we propose a close petrogenetic link between the mafic and felsic rocks of the SAC. The positive εNd and εHf values of the pyroxenite and gabbro favor a depleted mantle source, while variable εNd and εHf values, and trace element ratios of the gabbros are ascribed to crustal contamination during magma ascent. The felsic rocks, however, mainly formed by fractional crystallization from the gabbros as revealed by major and trace element correlation trends, isotopic data and thermodynamic modelling.
CRIS-Team Scopus Importer:2024-01-05
Keywords: Alkaline complex; Bushveld LIP; Crustal assimilation; Fractional crystallization; Nd-Hf isotope compositions; Rare earth elements

Magmatic evolution of the South Shetland Islands, Antarctica, and implications for continental crust formation - Haase, Karsten; Beier, Christoph; Fretzdorff, Susanne; Smellie, John; Garbe-Schönberg, Dieter (Contributions To Mineralogy and Petrology, 2012)
Lavas from the South Shetland Islands volcanic arc (northern Antarctic Peninsula) have been investigated in order to determine the age, petrogenesis and compositional evolution of a long-lived volcanic arc constructed on 32-km-thick crust, a thickness comparable with average continental crust. New Ar- Ar ages for the volcanism range between 135 and 47 Ma and, together with published younger ages, confirm a broad geographical trend of decreasing ages for the volcanism from southwest to northeast. The migration pattern breaks down in Palaeogene time, with Eocene magmatism present on both Livingston and King George islands, which may be due to a change in both subduction direction and velocity after c. 60 Ma. The lavas range from tholeiitic to calc-alkaline, but there is no systematic change with age or geographic location. The compositions of lavas from the north-eastern islands indicate magma generation in a depleted mantle wedge with relatively low Sr and high Nd isotopic compositions and low U/Nb, Th/Nd and Ba/Nb ratios that was metasomatized by hydrous fluids from subducted basaltic oceanic crust. Lavas from the south-western islands show an additional sedimentary influence most likely due to fluid release from subducted sediments into the mantle wedge. Although magmatic activity in the South Shetland arc extended over c. 100 m. y., there is no evolution towards more enriched or evolved magmas with time. Few South Shetland arc lavas are sufficiently enriched with incompatible elements to provide a potential protolith for the generation of average continental crust. We conclude that even long-established subduction zones with magmatic systems founded on relatively thick crust do not necessarily form continental crustal building blocks. They probably represent only the juvenile stages of continental crust formation, and additional re-working, for example during subsequent arc-continental margin collision, is required before they can evolve into average continental crust. © 2012 Springer-Verlag.
Keywords: Fractionation; Geochemistry; Magmatism; Subduction zone

Magmatic PGE sulphide mineralization in clinopyroxenite from the platreef, bushveld complex, South Africa - Klemd, Reiner; Beinlich, Andreas; Kern, Matti; Junge, Malte; Martin, Laure; Regelous, Marcel; Schouwstra, Robert (Minerals, 2020)
The Platreef, at the base of the northern limb of the Bushveld Complex in South Africa, hosts platinum-group element (PGE) mineralization in association with base-metal sulphides (BMS) and platinum-group minerals (PGM). However, whilst a magmatic origin of the stratiform mineralization of the upper Platreef has been widely confirmed, the processes responsible for the PGE and BMS mineralization and metasomatism of the host rocks in the Platreef are still under discussion. In order to contribute to the present discussion, we present an integrated petrographical, mineral-chemical, whole-rock trace-and major-element, sulphur-and neodymium-isotope, study of Platreef footwall clinopyroxenite drill core samples from Overysel, which is located in the northern sector of the northern Bushveld limb. A metasomatic transformation of magmatic pyroxenite units to non-magmatic clinopyroxenite is in accordance with the petrography and whole-rock chemical analysis. The whole-rock data display lower SiO2, FeO, Na2O and Cr (<1700 ppm), and higher CaO, concentrations in the here-studied footwall Platreef clinopyroxenite samples than primary magmatic Platreef pyroxenite and norite. The presence of capped globular sulphides in some samples, which display differentiation into pyrrhotite and pentlandite in the lower, and chalcopyrite in the upper part, is attributed to the fractional crystallization of a sulphide liquid, and a downward transport of the blebs. In situ sulphur (V-CDT) isotope BMS data show isotopic signatures (δ34S = 0.9 to 3.1 ‰; ∆33S = 0.09 to 0.32‰) close to or within the pristine magmatic range. Elevated (non-zero) ∆33S values are common for Bushveld magmas, indicating contamination by older, presumably crustal sulphur in an early stage chamber, whereas magmatic δ34S values suggest the absence of local crustal contamination during emplacement. This is in accordance with the εNd (2.06 Ga) (chondritic uniform reservoir (CHUR)) values, of −6.16 to −6.94, which are similar to those of the magmatic pyroxenite and norite of the Main Zone and the Platreef in the northern sector of the northern Bushveld limb. Base-metal sulphide textures and S–Se-ratios give evidence for a secondary S-loss during late-to post-magmatic hydrothermal alteration. The textural evidence, as well as the bulk S/Se ratios and sulphide S isotopes studies, suggest that the mineralization in both the less and the pervasively hydrothermally altered clinopyroxenite samples of Overysel are of magmatic origin. This is further supported by the PPGE (Rh, Pt, Pd) concentrations in the BMS and mass-balance calculations, in both of which large proportions of the whole-rock Pd and Rh are hosted by pentlandite, whereas Pt and the IPGE (Os, Ir, Ru) were interpreted to mainly occur in discrete PGM. However, the presence of pentlandite with variable PGE concentrations on the thin section scale may be related to variations in the S content, already at S-saturation during magmatic formation, and/or post-solidification mobilization and redistribution.
CRIS-Team Scopus Importer:2020-07-10
Keywords: Bushveld Complex; Clinopyroxenite; Fluid–rock interaction; Metasomatism; Platreef

Magmatism in the Bransfield Basin: Rifting of the South Shetland Arc? - Fretzdorff, Susanne; Worthington, Tim; Haase, Karsten; Hékinian, Roger; Keller, Randy; Stoffers, Peter (Journal of Geophysical Research D: Atmospheres, 2004)
Bransfield Basin is an actively extending marginal basin separating the inactive South Shetland arc from the northern Antarctic Peninsula. Rift-related volcanism is widespread throughout the central Bransfield Basin, but the wider eastern Bransfield Basin was previously unsampled. Lavas recovered from the eastern subbasin form three distinct groups: (1) Bransfield Group has moderate large-ion lithophile element (LILE) enrichment relative to normal mid-ocean ridge basalt (NMORB), (2) Gibbs Group has strong LILE enrichment and is restricted to a relic seamount interpreted as part of the South Shetland arc, and (3) fresh alkali basalt was recovered from the NE part of the basin near Spanish Rise. The subduction-related component in Bransfield and Gibbs Group lavas is a LILE-rich fluid with radiogenic Sr, Nd, and Pb isotope compositions derived predominantly from subducting sediment. These lavas can be modeled as melts from Pacific MORB source mantle contaminated by up to 5% of the subduction-related component. They further reveal that Pacific mantle, rather than South Atlantic mantle, has underlain Bransfield Basin since 3 Ma. Magma productivity decreases abruptly east of Bridgeman Rise, and lavas with the least subduction component outcrop at that end. Both the eastward decrease in subduction component and occurrence of young alkali basalts require that subduction-modified mantle generated during the lifetime of the South Shetland arc has been progressively removed from NE to SW. This is inconsistent with previous models suggesting continued slow subduction at the South Shetland Trench but instead favors models in which the South Scotia Ridge fault has propagated westward since 3 Ma generating transtension across the basin. Copyright 2004 by the American Geophysical Union.
UnivIS-Import:2015-03-09:Pub.2004.nat.dgeo.IGM.legeo.magmat
Keywords: Back-arc basin; Bransfield Basin; Geochemistry; Volcanic arc

Magnesium quantification in calcites (Ca,Mg)CO_3_ by Rietveld-based XRD analysis: Revisiting a well-established method - Titschack, Jürgen; Götz-Neunhoeffer, Friedlinde; Neubauer, Jürgen (American Mineralogist, 2011)
Mg-calcites commonly occur in natural environments, with Mg-contents ranging between about 0 and 32 mol% (referring to MgCO3). Often, different Mg-calcite phases occur within the same sample. The Mg-content in calcites permits the classification of the diagenetic environment (marine vs. meteoric), or the reconstruction of paleotemperatures from skeletal remains. Since the 1960s, there have been published various calibrations for Mg determination in calcites based on XRD measurements. Recently, this method has come to be superseded by wet chemical, laser ablation, and microprobe analysis, due to their higher accuracy and/or higher sample resolution of these latter methods.This study presents a new calibration for the Mg determination in calcites using XRD measurements analyzed by means of the Rietveld refinement method. The calibration is based on lattice parameters and exhibits a reliable Mg-determination accuracy of more than 0.8 mol% between 0 and 15.5 mol%. The incorporation of the calibration into the Rietveld refinement software TOPAS permits a fast, standardized workflow. This, in turn, enhances the user-friendliness and the reproducibility of results, as well as allows the simultaneous analysis of multiple Mg-calcites in a sample. Mixtures of two Mg-calcites were analyzed using this new method. The Mg-content of two co-occurring Mg-calcite phases can be reliably quantified providing the Mg-calcites differ by at least 4.9 mol% and the minor Mg-calcite phase makes up more than 2.7 wt%. If the Mg-calcite phases differ by 3.4 mol% or less, the reliable identification of different Mg-calcite phases is questionable, due to the fact that differences involved here are too small. If such XRD patterns are refined with only one Mg-calcite phase, then the systematic misfit between measured and refined pattern can be used for the identification of a second Mg-calcite phase down to a difference in the Mg-content of about 3 mol%. However, a reliable phase quantification for these patterns cannot be achieved.
UnivIS-Import:2015-03-09:Pub.2011.nat.dgeo.IGM.LM.magnes

Magnetic characteristics of the Ság-hegy volcanic complex, little Hungerian Plain. - de Wall, Helga; et al. (Physical geology of subvolcanic systems: Laccoliths, Sills, and Dykes. Portree, Isle of Skye, Scotland, 2006)
UnivIS-Import:2015-04-16:Pub.2006.nat.dgeo.IGM.c3tekt.magnet

Magnetic fabric analysis in a mesoscopic fold - Mamtani, M. A.; Chadima, Martin; de Wall, Helga; Greiling, R. O. (International Journal of Earth Sciences, 2012)

Magnetic Supraparticles Capable of Recording High‐Temperature Events - Wolf, Andreas; Sauer, Julian; Hurle, Katrin; Müssig, Stephan; Mandel, Karl (Advanced Functional Materials, 2024)
Superparamagnetic iron oxide nanoparticles (SPIONs) are prone to oxidation at elevated temperatures (>300 °C) and lose their magnetizability upon transition from magnetite/maghemite (γ-Fe2O3 / Fe3O4) to hematite (α-Fe2O3). Silica (SiO2) shells can effectively prevent this undesired effect up to ≈1000 °C. Herein, the study shows how to utilize SPIONs with varying SiO2 shell thickness and thus, different oxidation susceptibility, and how to combine them in micrometers sized assemblies – so-called supraparticles (SPs), to create a structurally emerging magnetic temperature recording functionality. The desired oxidation of non or weakly-protected SPIONs within SPs upon temperature events reduces dipole–dipole interactions of well-protected SPIONs in the confined SP entity. The resulting change of magnetic interactions therefore contains information on the thermal history of the SP, which can be spectrally read out via magnetic particle spectroscopy within seconds. Their working range can be tuned from 400 to 1000 °C on two independent structural hierarchy levels, namely the SiO2 shell thickness and the freely selectable ratios of different building blocks in the SP. The application of such SPs as particulate additives for magnetic recording of high-temperature events, especially relevant in metal, alloy, and ceramic processing, representing a yet unexplored and optically-independent option for bulk temperature recording is proposed.<br
Keywords: high-temperature events; magnetic particle spectroscopy; magnetic recorders; smart additives; supraparticles

Magnetic susceptibility measurements for the petrographic characterization of Granitoids: Comparison of field and laboratory measurements in the Saghro region of the anti-Atlas of Morocco Magnetische Suszeptibilitätsmessungen zur petrographischen Charakterisierung von Granitoiden - Vergleich von Feld-undlabormessungen (Saghro-Gebiet, Anti-Atlas, Marokko) - de Wall, Helga; et al. (Zeitschrift für Angewandte Geologie, 2000)

Magnetic susceptibility variations in carbonates of the La Vid Group (Cantabrian Zone, NW-Spain) related to burial diagenesis - de Wall, Helga; et al. (Sedimentary Geology, 2004)
Keywords: Burial diagenesis; Fe-carbonate cements; Fe-chlorite; La Vid section; Magnetic susceptibility; Pyrite

Magnetic susceptibility zonation of the melilititic Riedheim dyke (Hegau volcanic field, Germany): Evidence for multiple magma pulses? - de Wall, Helga; et al. (Journal of Volcanology and Geothermal Research, 2004)
Keywords: Anisotropy of magnetic susceptibility; Magnetic susceptibility; Magneto-petrology; Riedheim dyke; Titanomagnetite

Magnetische Suszeptibilitätsmessungen an Gängen vom Ostrand des Hauzenberger Granitplutons Bayerischer Wald. - de Wall, Helga; et al. (11. Symposium "Tektonik, Struktur- und Kristallingeologie", 2006)
UnivIS-Import:2015-04-16:Pub.2006.nat.dgeo.IGM.c3tekt.magnet_9

Magnetostratigraphy and 40Ar-39Ar geochronology of the Malwa Plateau region (Northern Deccan Traps), central western India: Significance and correlation with the main Deccan Large Igneous Province sequences - Schöbel, Stefan; de Wall, Helga; Ganerod, Morgan; Pandit, Manoj K.; Rolf, Christian (Journal of Asian Earth Sciences, 2014)
Keywords: Ar-Ar geochronology; Deccan LIP; Deccan tectonomagmatic history; Eruption rate; Magnetostratigraphy; Malwa plateau

Manganous water column in the Tethys Ocean during the Permian-Triassic transition - Müller, Johann; Sun, Yadong; Yang, Fen; Regelous, Marcel; Joachimski, Michael (Global and Planetary Change, 2023)
Ocean anoxia was one of the key killing mechanisms responsible for the end-Permian mass extinction ( 252 Ma). However, the temporal evolution and the triggering mechanisms of the end-Permian anoxia are controversial, with the current view being that the water column deoxygenation was a spatially and temporally heterogeneous event. Here, we use cerium-anomalies, uranium contents and rare earth element and yttrium (REY) compositions measured on the carbonate fraction of samples from two marine sections in Armenia and South China to constrain the evolution of end-Permian marine anoxia. In particular, we attempt to identify intervals of manganous redox conditions (i.e., Mn2+-rich water column). These are characterized by the reduction of Mn(IV)-oxides at a redox potential lower than of nitrate and higher than of Fe(III)-oxide reduction. Most of our samples yield REY patterns with seawater characteristics suggesting the dominance of hydrogenous REYs. While decreasing U concentrations in the C. yini Zone suggest an overall intensification of global marine anoxia in the latest Permian, Ce-anomalies shift from negative to positive above the C. yini Zone, implying a deterioration in the oxygen content of the local water columns. Highly positive Ce-anomalies (Ce/Ce* > 1.3) are firstly reported for the P-T interval, indicating enrichment of Ce in the water column and the establishment of manganous redox conditions at both locations. This change coincided globally with climatic warming, the onset of the marine extinction interval as well as locally with the disappearance of sponge spicules and radiolarians (South China) and the appearance of microbialites (Armenia).<br

Manitouscolex a new palaescolecidan genus from the Lower Ordovician of Colorado - Lehnert, Oliver; Kraft, Petr (Journal of Paleontology, 2006)
UnivIS-Import:2015-03-09:Pub.2006.nat.dgeo.IGM.LG.manito

Mantle dynamics, element re-cycling, and magma genesis beneath the Kermadec ArcHavre Trough. - Haase, Karsten; Worthington, Tim; Garbe-Schönberg, Dieter; Stoffers, Peter; Wright, Ian (Geochemistry Geophysics Geosystems, 2002)
UnivIS-Import:2015-03-09:Pub.2002.nat.dgeo.IGM.legeo.mantle

Mantle heterogeneity controls on small-volume basaltic volcanism - Mcgee, Lucy E.; Millet, Marc-Alban; Beier, Christoph; Smith, Ian E. M.; Lindsay, Jan M. (Geology, 2015)
Eruptions of basaltic material in small-scale volcanic fields located in intraplate settings display a very diverse range in physical and chemical characteristics. Despite its relevance to the understanding of volcanic hazards, the relationship between physical properties of eruptions (explosivity, volume, location) and chemical composition of erupted products has, to date, not been investigated. Here we present a relationship between mantle heterogeneity and extents of partial melting, and both erupted volumes and eruptive style from the Auckland Volcanic Field (New Zealand), and we suggest that this provides a general model for smallscale "monogenetic" magmatic systems globally. Small volcanic centers consistently take the form of nephelinitic tuff rings and scoria cones, whereas larger centers are produced from effusive eruptions of less alkalic magmas. Nephelinitic melts are generated by melting of a deep, carbonated source, whereas less alkalic melts are the products of melting of a shallower, noncarbonated source. U-Th-Ra isotope data from eruptions closely paired in space and time show that mixing between magmas is extremely limited as a consequence of different ascent mechanisms due to differential segregation of melts from varying sources (early, carbonated melts ascending by higher porosity channels, and later, uncarbonated melts by a more diffusive regime). This suggests that extraction of melt is nearly instantaneous in these environments. Our results stress the importance of melting and magma dynamics in determining the size and style of eruptions in small volcanic fields, and suggest that mantle controls should be an important consideration in volcanic hazard assessment.

Mantle plume and rift-related volcanism during the evolution of the Rio Grande Rise - Hoyer, Patrick; Haase, Karsten; Regelous, Marcel; O'Connor, John; Homrighausen, Stephan; Geissler, Wolfram; Jokat, Wilfried (Communications Earth & Environment, 2022)
The Rio Grande Rise in the western South Atlantic Ocean has been interpreted as either an oceanic plateau related to the Tristan-Gough mantle plume, or a fragment of detached continental crust. Here we present new major and trace element data for volcanic rocks from the western and eastern Rio Grande Rise and the adjacent Jean Charcot Seamount Chain. The eastern Rio Grande Rise and older parts of the western Rio Grande Rise are comprised of tholeiitic basalt with moderately enriched trace element compositions and likely formed above the Tristan-Gough mantle plume close to the southern Mid-Atlantic Ridge. Younger alkalic lavas from the western Rio Grande Rise and the Jean Charcot Seamount Chain were formed by lower degrees of melting beneath thicker lithosphere in an intraplate setting possibly during rifting of the plateau. There is no clear geochemical evidence that remnants of continental crust are present beneath the Rio Grande Rise.<br

Mantle sources and magma evolution of the Rooiberg lavas, Bushveld Large Igneous Province, South Africa - Günther, Thomas; Haase, Karsten; Klemd, Reiner; Teschner, Claudia (Contributions To Mineralogy and Petrology, 2018)
Keywords: Assimilation fractional crystallization; Kaapvaal craton; Bushveld Complex; Sub-continental lithospheric mantle (SCLM); Large igneous province (LIP)

Mantle sources and magma evolution of the Rooiberg lavas, Bushveld Large Igneous Province, South Africa - Günther, Thomas; Haase, Karsten; Klemd, Reiner; Teschner, Claudia (Contributions To Mineralogy and Petrology, 2018)
We report a new whole-rock dataset of major and trace element abundances and Sr-87/Sr-86-Nd-143/Nd-144 isotope ratios for basaltic to rhyolitic lavas from the Rooiberg continental large igneous province (LIP). The formation of the Paleoproterozoic Rooiberg Group is contemporaneous with and spatially related to the layered intrusion of the Bushveld Complex, which stratigraphically separates the volcanic succession. Our new data confirm the presence of low- and high-Ti mafic and intermediate lavas (basaltic-andesitic compositions) with > 4 wt% MgO, as well as evolved rocks (andesitic-rhyolitic compositions), characterized by MgO contents of < 4 wt%. The high- and low-Ti basaltic lavas have different incompatible trace element ratios (e.g. (La/Sm)(N), Nb/Y and Ti/Y), indicating a different petrogenesis. MELTS modelling shows that the evolved lavas are formed by fractional crystallization from the mafic low-Ti lavas at low-to-moderate pressures ( 4 kbar). Primitive mantle-normalized trace element patterns of the Rooiberg rocks show an enrichment of large ion lithophile elements (LILE), rare-earth elements (REE) and pronounced negative anomalies of Nb, Ta, P, Ti and a positive Pb anomaly. Unaltered Rooiberg lavas have negative epsilon Nd-i (- 5.2 to - 9.4) and radiogenic epsilon Sr-i (6.6 to 105) ratios (at 2061 Ma). These data overlap with isotope and trace element compositions of purported parental melts to the Bushveld Complex, especially for the lower zone. We suggest that the Rooiberg suite originated from a source similar to the composition of the B1-magma suggested as parental to the Bushveld Lower Zone, or that the lavas represent eruptive successions of fractional crystallization products related to the ultramafic cumulates that were forming at depth. The Rooiberg magmas may have formed by 10-20% crustal assimilation by the fractionation of a very primitive mantle-derived melt within the upper crust of the Kaapvaal Craton. Alternatively, the magmas represent mixtures of melts from a primitive, sub-lithospheric mantle plume and an enriched sub-continental lithospheric mantle (SCLM) component with harzburgitic composition. Regardless of which of the two scenarios is invoked, the lavas of the Rooiberg Group show geochemical similarities to the Jurassic Karoo flood basalts, implying that the Archean lithosphere strongly affected both of these large-scale melting events.
Keywords: Bushveld Complex; Large igneous province (LIP); Sub-continental lithospheric mantle (SCLM); Assimilation fractional crystallization; Kaapvaal craton

Mapping intrashell variation in Mg/Ca of brachiopods to external growth lines: Mg enrichment corresponds to seasonal growth slowdown - Müller, Tamás; Tomašových, Adam; López Correa, Matthias; Mertz-Kraus, Regina; Mikuš, Tomáš (Chemical Geology, 2022)
Determining secular changes in seawater temperature and Mg/Ca ratio is of high importance in paleooceanographic, paleoenvironmental and paleoecological studies. On the one hand, intra-shell variation in Mg/Ca in brachiopod shells is used to reconstruct historical changes in temperature and in seasonality. On the other hand, intra-shell analyses show a weak relationship between Mg/Ca and δ18O, but a positive correlation between Mg/Ca and Sr/Ca, and an increase of Mg/Ca at growth lines, indicating that Mg/Ca does not simply track seawater temperature alone. Internal growth lines are rarely visible in brachiopod shells, and the relation between growth lines that mark growth slowdown or cessation and Mg/Ca fluctuation is thus not properly understood. Here, using four species of extant brachiopods from the NE Pacific and the SW Pacific, from environments with low seasonality in seawater temperature (<5 °C), and two species of Late Triassic brachiopods (Western Carpathians), we measure intra-shell ontogenetic variation in Mg/Ca, S/Ca and Sr/Ca with laser ablation ICP-MS and electron microprobe. In contrast to previous studies, we map variation in Mg, S, and Sr to external growth lines. We find that, first, zones of Mg/Ca enrichment in the secondary layer form 10–50 μm-thick discrete bands or clusters of micrometric bands that consistently terminate at major external, predominantly annual growth lines that are associated with distinct notches that correspond to mantle retractions in most species. These bands generate distinct peaks in Mg/Ca that stand above low, more uniformly distributed background Mg/Ca values along laser-ablation and microprobe transects. The magnitude of Mg/Ca in these bands is comparable to Mg/Ca in the primary layer, exceeding background values of Mg/Ca in the secondary layer by 5–20 mmol/mol (by a factor of two to five). Second, Mg enrichment in discrete bands is closely associated with an increase in S concentrations in the secondary layer. Therefore, even when Mg and S uptake is expected to be highest under fast precipitation rate, these empirical observations show that Mg and S enrichment occur in the zones that were precipitated at times of a significant growth reduction (e.g., in cold-temperate brachiopods studied here during winters when primary productivity is low). The mechanisms for this paradox are unclear but can be related to uptake of Mg by amorphous calcium carbonate (ACC) to delay the transformation of ACC to calcite during the formation of growth lines. Therefore, intra-shell variation in Mg/Ca in brachiopods with major growth lines is primarily determined by seasonal decline or cessation in shell growth and not by seasonal changes in seawater temperature.
Keywords: Brachiopoda; Biomineralization; Mg/Ca ratio; S/Ca ratio; Sr/Ca ratio; Growth rate; Seasonality

Mapping of Very Shallow Geothermal Potentials in Rural Areas: a Case Study of Bavaria (Germany) - Bertermann, David; Jocic, Nikola; Rammler, Mario; Schwarz, Hans; Wagner, Jan (Alternative Energy Sources, Materials and Technologies (AESMT’21), 2021)
Shallow geothermal energy is a renewable source for heating and cooling systems and buildings, by which a significant part of the arising energy demand could be covered if it is in widespread use. Especially in rural areas (very) shallow geothermal systems are well applicable due to the availability of spacious unsealed areas. The aim of the study was the examination of geothermal potential maps for utilization of very shallow horizontal applications in the rural areas of Bavaria (Germany). These potential maps should bring a more facilitated access to this issue for heating engineers and planners and with that a more common use of shallow geothermal energy. To develop these potential maps, the relevant parameters were implemented as areal data in a geographical information system (GIS). As database serves a soil map of Bavaria (scale 1:5000) which includes crucial parameters such as soil texture. Additionally, climate data based on degree-day numbers for characteristic regions were implemented. Soil and climate data provided the basis to develop an algorithm for calculation of (very) shallow geothermal potentials. Results are presented in two categories – thermal conductivity on the one hand, and heat extraction on the other. Thermal conductivity is the general parameter which describes local geothermal potentials, dependent on soil texture, bulk density and water content, while heat extraction is given as a system-specific characteristic. This research focused on four different shallow geothermal systems – horizonal ground heat collectors, capillary tube mats, geothermal baskets, and trench collectors. These geothermal potentials were processed in a GIS project enabling the output as potential maps. For validation of the very shallow geothermal potential maps soil data from selected case study municipalities were consulted. Therefore, data from geotechnical surveys and sampled and analysed soils were used. As a result, these maps revealing the very shallow geothermal potential can serve as handy tool for heating engineers and planners for an appropriate design of these horizontal geothermal applications. Afterall, the compilation process is easy to transfer to other regions, just by using respective soil maps and climatic dat
Keywords: Very shallow geothermal potential (vSGP); thermal conductivity; heat extraction; geothermal potential maps; GIS; rural areas

Mapping paleocoastlines and continental flooding during the Phanerozoic - Kocsis, Ádám; Scotese, Christopher R. (Earth-Science Reviews, 2021)
Sea levels shape the face of the Earth, define processes of sedimentation, and influence the evolution of life via the distribution of habitats. Ancient topographies can be reconstructed using the history and understanding of tectonic processes, lithological evidence, and present-day topographies. Paleogeographic reconstructions must accommodate ever newer sources of geological data, so we can refine and improve our model of ancient topography and bathymetry. Here, we assess the accuracy of a set of Phanerozoic digital paleogeographic maps by testing the proposed distribution of flooded shallow seas and land using fossil occurrence data from the Paleobiology Database. After noting a moderate match, we modified the positions of the coastlines and continental margins of these topographic models to reflect times of maximum transgression. Using the updated paleogeographic maps, we outline the changes of land and shallow marine areas over time and suggest ways they can be used for further investigations of our planet's history.
CRIS-Team Scopus Importer:2021-01-08
Keywords: Coastlines; Continental flooding; Fossils; Global; Paleogeography; Phanerozoic; Reconstruction

Mapping the elemental and crystalline phase distribution in Cu2+ doped 45S5 bioactive glass upon crystallization - Nawaz, Qaisar; De Pablos-Martin, Araceli; Berthold, Lutz; De Souza E Silva, Juliana Martins; Hurle, Katrin; Boccaccini, Aldo R. (CrystEngComm, 2021)
Bioactive glasses (BGs) incorporating metallic ions to impart antibacterial activity and stimulation of osteogenesis and angiogenesis are promising candidates for bone tissue engineering. Silicate BGs of the 45S5 composition (45 SiO2, 24.5 Na2O, 24.5 CaO, 6 P2O5, (wt%)) crystallize readily during the high temperature processing of porous scaffolds. The crystallization slightly suppresses the bioactivity and dissolution of the glass. Structural changes during the high-temperature processing of metal ion-doped 45S5 BGs are challenging since metal ions may affect the formation of crystalline phases during thermal treatment. In this study, we investigated the effect of Cu on structural changes during the sintering of Cu doped 45S5 BG (Cu-45S5). The Cu-45S5 BG was sintered at 900 degrees C and 1050 degrees C for 1 hour, and the resultant microstructures were investigated using X-ray diffraction (XRD) analysis, transmission electron microscopy (TEM), including elemental distribution mappings from energy-dispersive X-ray spectroscopy (EDXS), and X-ray nano-computed tomography (nano-CT). XRD patterns of thermally treated samples indicate the formation of combeite and rhenanite as crystalline phases. Besides the crystalline fraction, a residual glassy phase is also present, which is enriched with Na and P ions. The results reveal that the crystallinity of Cu-45S5 glass-ceramics can be adjusted over a range of 70-78% by applying appropriate heat treatment profiles. Moreover, the size of the crystals increases with increasing temperature under the investigated conditions. Cu is found to be localized in the residual glassy phase, together with Si and Na, which has an effect on the release of Cu ions in physiological environments.
CRIS-Team WoS Importer:2021-12-10

Mapping the techno-economic potential of closed-loop geothermal systems: A Europe-tested method - Perego, Rodolfo; Pera, Sebastian; Galgaro, Antonio; Dalla Santa, Giorgia; Cultrera, Matteo; de Carli, Michele; Emmi, Giuseppe; Bertermann, David; Müller, Johannes; Mendrinos, Dimitrios; Karytsas, Constantine; Vercruysse, Jacques; et al. (Swiss Geoscience Meeting 2018, 2018)

Marine benthic invertebrates from the Upper Jurassic of northern Ethiopia and their biogeographic affinities - Kießling, Wolfgang; Pandey, Dhirendra; Schemm-Gregory, Mena; Mewis, Heike; Aberhan, Martin (Journal of African Earth Sciences, 2011)
We present the first modern description of corals, brachiopods and bivalves from the Antalo Limestone in the Mekele Outlier of northern Ethiopia. This fauna is largely of Oxfordian age and lived in shallow subtidal environments and in small patch reefs. In combining our new data with fossil occurrence data from the Paleobiology Database, we conducted multidimensional scaling analyses to assess biogeographic patterns and the delineation of the Ethiopian Province for the Callovian to Kimmeridgian stages. Results suggest that an Ethiopian Province is indeed evident for our focal groups, but this is more confined than traditionally assumed. The so defined Ethiopian Province includes Tunisia, the Levant, Arabia and much of East Africa, but excludes Tanzania and India. The special status of India and Tanzania is perhaps due to latitudinal gradients in faunal composition. © 2010 Elsevier Ltd.
UnivIS-Import:2015-03-09:Pub.2011.nat.dgeo.IGM.LP.marine
Keywords: Biogeography; Bivalves; Brachiopods; Corals; Ethiopia; Jurassic

Marine Biodiversity and Geographic Distributions Are Independent on Large Scales - Antell, Gwen S.; Kießling, Wolfgang; Aberhan, Martin; Saupe, Erin E. (Current Biology, 2020)
Fundamental ecological and evolutionary theories, such as community saturation and diversity-dependent diversification, assume that biotic competition restricts resource use, and thus limits realized niche breadth and geographic range size [1–3]. This principle is called competitive exclusion. The corollary (ecological release) posits that, after competitors disappear from a region, species that were previously excluded will invade. Hundreds of field experiments have demonstrated ecological release in living populations. However, few of these studies were conducted in marine environments, and almost no work extended beyond 10 years and 1,000 km2 [4, 5]. In limited investigation of marine taxa at larger spatiotemporal scales, macroecologists and paleobiologists have observed little evidence of competitive exclusion [6–9]. Here, we quantified spatial trends in the rich and densely sampled fossil history of brachiopods and bivalves, while accounting for inconsistent sampling coverage through time using a new method of spatial standardization. The number of potential competitors in a region did not explain the geographic distribution of constituent species or genera. Furthermore, although ecological release predicts species to expand after extinction events, survivors of intervals with net species loss expanded as rarely as species in other intervals. Regression model estimates indicated different spatial responses of brachiopods and bivalves, and of habitat specialists and generalists, but no effect from changes in number of potential competitors. Biotic competition may control the distribution of populations, but, on larger spatiotemporal scales, non-competitive factors may have driven biogeographic patterns of brachiopods and bivalves. Long-standing ecological and evolutionary theories assume that competition between individuals controls the cumulative resource use and geographic ranges of species. Antell et al. demonstrate that spatial distributions of marine invertebrates are incongruent with this expectation throughout the last 485 million years.
CRIS-Team Scopus Importer:2020-01-07
Keywords: bivalves; brachiopods; competition; diversity-dependent diversification; ecological release; fossil record; macroecology; niche partitioning; spatial scale; species distributions

Marine carbonate facies in response to climate and nutrient level: The Upper Carboniferous and Permian of central Spitsbergen (Svalbard). - Buggisch, Werner; Joachimski, Michael; et al. (Facies, 2001)
Carbonate-dominated successions of the Gipsdalen and Tempelfjorden Groups from Svalbard record a significant shift from Photozoan to Heterozoan particle associations in neritic settings during the late Palaeozoic. During the Bashkirian, benthic particle associations which included photoautotrophs such as phylloid algae (Chloroforam Association) characterised shallow subtidal environments. Most depositional settings which endured siliciclastic terrestrial input exhibited poorly diversified associations dominated by brachiopods, bryozoans and siliceous sponges (Bryonoderm Association). During the Moscovian to Asselian, highly diversified associations typified by various calcareous green algae, Palaeoaplysina, Tubiphytes, fusulinids, smaller and encrusting foraminifers (Chloroforam Association) prevailed in carbonate sediments from supratidal to shallow subtidal environments. During the Sakmarian and Early Artinskian, oolitic carbonate sands (Chloroforam Association) typified intertidal flats, whereas shallow subtidal environments were occupied by moderately diversified associations with fusulinids, smaller foraminifers, echinoderms and bryozoans (Bryonoderm-extended Association) and poorly diversified associations with echinoderms, brachiopods and bryozoans (Bryonoderm Association). During the Late Artinskian to Kazanian, poorly diversified associations characterised by brachiopods, echinoderms and bryozoans (Bryonoderm Association), and sponge-dominated associations (Hyalosponge Association) reigned within siliceous carbonates of intertidal and shallow subtidal environments. This trend is interpreted as a result of climatic cooling and fluctuations of prevailing levels of trophic resources within shallow-water settings during the studied time period. While raised nutrient levels were restricted to near-shore settings during the Bashkirian, steady mesotrophic conditions arose from the Sakmarian onward and increased to late Permian times.
UnivIS-Import:2015-03-09:Pub.2001.nat.dgeo.IGM.LG.marine_7
Keywords: Climate; Microfacies; Northern pangaea; Permian; Photozoan and heterozoan caronates; Spitsbergen (Svalbard); Trophic resources; Upper carboniferous

Marine carbonate facies of arid to temperate humid climates: Upper Carboniferous to Permian strata from Billefjorden Trough and Nordfjorden Block, Svalbard. - Buggisch, Werner; Joachimski, Michael; et al. (Facies, 2001)

Marine clade sensitivities to climate change conform across timescales - Reddin, Carl James; Nätscher, Paulina; Kocsis, Ádám; Pörtner, Hans Otto; Kießling, Wolfgang (Nature Climate Change, 2020)
Rapid climate change is postulated to cause marine extinctions, especially among climate-sensitive clades, traits and regions1–6. This premise is based on two hypotheses: (1) known individual physiological sensitivities scale up to macroecological selectivity patterns4,7,8 and (2) ancient hyperthermal events are appropriate models to anticipate ecological winners and losers of anthropogenic climate change9. Yet these hypotheses have largely escaped quantitative appraisal. Here we show that experimental responses of modern marine ectotherms to single and combined climate-related stressors (such as seawater warming, hypoxia and acidification) align with Phanerozoic fossil extinction regimes across clades and functional traits. Of climate-related stressors, the synergistic interaction between warming and hypoxia10, encumbering aerobic metabolism, has the greatest potency as a proximate driver of extinction. All else being equal8, this synergy particularly imperils modern warm-water organisms. Modern–fossil agreement is strongest at intermediate–high extinction intensities and hyperthermal events but may fail at extreme extinction events, perhaps due to rising prominences of, and interactions among, additional biotic and abiotic stressors. According to results from marine ectotherms, clade-based sensitivity of individuals to climate-related stressors scales up from subannual experiments and decadal range-shift response magnitudes11, to extinction selectivity patterns at ancient climate-related stressor events and the Phanerozoic durations of genera.
CRIS-Team Scopus Importer:2020-02-25

Marine invertebrate migrations trace climate change over 450 million years - Reddin, Carl James; Kocsis, Ádám; Kießling, Wolfgang (Global Ecology and Biogeography, 2018)
Aim Poleward migration is a clear response of marine organisms to current global warming but the generality and geographical uniformity of this response are unclear. Marine fossils are expected to record the range shift responses of taxa and ecosystems to past climate change. However, unequal sampling (natural and human) in time and space biases the fossil record, restricting previous studies of ancient migrations to individual taxa and events. We expect that temporal changes in the latitudinal distribution of surviving taxa will reveal range shifts to trace global climate change. Location Global. Time period Post‐Cambrian Phanerozoic aeon. Major taxa studied Well‐fossilized marine benthic invertebrates comprising stony corals, bivalves, gastropods, brachiopods, trilobites and calcifying sponges. Methods We track deviations in the latitudinal distribution of range centres of age boundary crossing taxa from the expected distribution, and compare responses across latitudes. We build deviation time series, spanning hundreds of million years, from fossil occurrences and test correlations with seawater temperature estimates derived from stable oxygen isotopes of fossils. Results Seawater temperature and latitudinal deviations from sampling are positively correlated over the post‐Cambrian Phanerozoic. Simulations suggest that sampling patterns are highly unlikely to drive this putative signal of range shifts. Systematically accounting for known sampling issues strengthens this correlation, so that climate is capable of explaining nearly a third of the variance in ancient latitudinal range shifts. The relationship is stronger in low latitude taxa than higher latitude taxa, and in warm ages than cool ages. Main conclusions Latitudinal range shifts occurred in concert with climate change throughout the post‐Cambrian Phanerozoic. Low latitude taxa show the clearest climate‐migration signal through time, corroborating predictions of their shift in a warming future.
Keywords: d18O; fossil; latitude; out of the tropics; Paleobiology Database; Phanerozoic; sampling bias; time series

Marine sepiolite in Middle Permian carbonates of South China: implications for secular variation of Phanerozoic seawater chemistry. - Yan, Jiaxin; Munnecke, Axel; Steuber, Thomas; Carlson, E.H.; Xiao, Yilin (Journal of Sedimentary Research, 2005)
t is now widely accepted that the composition of seawater varied significantly during the Phanerozoic, and that the Mg/Ca ratio of seawater is a major factor in synchronized secular oscillations in the mineralogical composition of marine evaporites and nonskeletal as well as biogenic carbonates. However, the nature of the Mg sink is still subject to debate. We describe early diagenetic sepiolite from the Chihsia Formation (middle Permian) of South China. The Mg incorporated in sepiolite likely was furnished by stabilization of high-Mg calcite, and silica was derived from siliceous fossils. Two factors facilitated the accumulation of sepiolite in the Chihsia Formation. The first is a Chihsian depositional environment of an intra-oceanic carbonate platform that lacked detrital terrestrial input, which enhanced the availability of biogenic silica for sepiolite formation. The second is the chemical composition of Permian seawater, as the precipitation of high-Mg calcite was aided by a high Mg/Ca ratio associated with an aragonite sea. The formation of sepiolite is significant in constraining the recycling flux of Mg during recrystallization of carbonate sediments with a high proportion of high-Mg calcite (periods of aragonite seas). Worldwide, major occurrences of marine sepiolite and palygorskite in the Phanerozoic correlate with periods of aragonite seas. This temporal distribution implies that minerals of the sepiolite-palygorskite group play an important role in the geochemical recycling of Mg, and that major sepiolite and palygorskite deposits indicate episodes of high Mg concentrations in seawater. The formation of sepiolite also was probably related to an abundance of silica-secreting organisms, which interacted with the chemical evolution of Phanerozoic seawater. In addition, authigenic sepiolite and palygorskite are not indicators of arid and semiarid climate
Keywords: Sepiolite; China; Permian; Seawater chemistry

Mass and hyperconcentrated flow deposits record dune damming and catastrophic breakthrough of ephemeral rivers, Skeleton Coast Erg, Namibia. - Svendsen, Johan; Stollhofen, Harald; Krapf, Carmen; Stanistreet, Ian G. (Sedimentary Geology, 2003)
Channel-shaped deposits of well sorted sand with only 2–4% fine-grained material, being either massive and structureless or upward fining with basal lag, are found interbedded with aeolian sand in the Skeleton Coast Erg, Namibia. Detailed analyses of the channel-shaped deposits suggest that they are formed as hyperconcentrated flows within the erg. Grain-size analysis and whole rock geochemical modeling revealed that some of the fluvial sediments contain up to 70% aeolian sand, interpreted as a result of dune collapse into the fluvial system. In certain cases, this instantaneous supply of sand resulted in generation of sandy mass flows with laminar flow behaviour. The presence of smectite as dominant clay mineral proved to be of crucial importance in formation of mass flow deposits. These mass flows had no erosional capacity, and drape the palaeotopography. They are comparable to those generated by catastrophic collapse of dunes, described in the literature. This paper suggests that all these deposits should be termed intra-erg mass flows, as several of them carry little, if any debris. Based on their origin, intra-erg mass flows can be divided into two groups: (1) Attached intra-erg mass flows, which are formed and found attached to the dune that sourced the flow; (2) Detached intra-erg mass flows, which are not found adjacent to the dune sourcing the flow, and often carry material sourced outside the dune field. A five-stage model is proposed, involving dune damming to explain the observed deposits and the degree of reworking. When the flood basin behind the erg overtops the threshold area, water pours into the erg, giving rise to a complex fluvio aeolian setting. The setting in the Skeleton Coast erg is comparable to recent as well as ancient settings, and reveals valuable information for reservoir characterization and hazard assessment.
UnivIS-Import:2015-03-09:Pub.2003.nat.dgeo.IGM.LG.hyperc

Mass extinctions and clade extinctions in the history of brachiopods: Brief review and a post-paleozoic case study - Vörös, Attila; Kocsis, Ádám; Pálfy, József (Rivista Italiana Di Paleontologia E Stratigrafia, 2019)
Brachiopods are a key group in Phanerozoic marine diversity analyses for their excellent fossil record and distinctive evolutionary history. A genus-level survey of raw diversity trajectories allows the identification of the Brachiopod Big Five, episodes of major genus losses in the phylum which are compared with the established Big Five mass extinctions of Phanerozoic marine invertebrates. The two lists differ in that the end-Cretaceous extinction appears subdued for brachiopods, whereas the mid-Carboniferous is recognized as an event with significant loss of brachiopod genera. At a higher taxonomic level, a review of temporal ranges of rhynchonelliform orders reveals episodes of synchronous termination of multiple orders, here termed clade extinctions. The end-Ordovician, Late Devonian and end-Permian events are registered as both mass extinctions and clade extinctions. The Late Cambrian and the Early Jurassic are identified as the other two clade extinction events. Coincident with the Early Toarcian oceanic anoxic event, the last clade extinction of brachiopods is defined by the disappearance of the last two spire-bearing orders, Athyridida and Spiriferinida. Their diversity trajectory through the recovery after the end-Permian crisis parallels that of the extant terebratulides and rhynchonellides until a Late Triassic peak but diverge afterwards. The end-Triassic diversity decline and Toarcian vanishing of spire-bearers correspond with contraction in their spatial distribution. The observed patterns and extinction selectivity may be explained both ecologically and physiologically. The specialized adaptation of morphologically diverse spire-bearers, as well as their fixed lophophore and passive feeding put them at a disadvantage at times of environmental crises, manifest in their end-Triassic near-extinction and Toarcian demise. Similar analyses of other clade extinctions may further improve our understanding of drivers and processes of extinction.
CRIS-Team Scopus Importer:2019-10-08
Keywords: Biotic crises; Diversity; End-triassic; Rhynchonelliformea; Spire-bearers; Toarcian

Massive corals in Paleocene siliciclastic sediments of Chubut (Patagonia, Argentina) - Kießling, Wolfgang; et al. (Facies, 2005)
UnivIS-Import:2015-03-09:Pub.2005.nat.dgeo.IGM.LP.massiv

Massive volcanism at the Permian-Triassic boundary and its impact on the isotopic composition of the ocean and atmosphere - Korte, Christoph; Pande, Prabhas; Kalia, P.; Kozur, Heinz W.; Joachimski, Michael; Oberhaensli, Hedi (Journal of Asian Earth Sciences, 2010)
Bulk carbonate and conodonts from three Permian-Triassic (P-T) boundary sections at Guryul Ravine (Kashmir), Abadeh (central Iran) and Pufels/Bula/Bulla (Italy) were investigated for δ13C and δ18O. Carbon isotope data highlight environmental changes across the P-T boundary and show the following features: (1) a gradual decrease of ∼4‰ to more than 7‰ starting in the Late Permian (Changhsingian) C. bachmanni Zone, with two superimposed transient positive excursions in the C. meishanensis-H. praeparvus and the M. ultima-S. ? mostleri Zones; (2) two δ13C minima, the first at the P-T boundary and a higher, occasionally double-minimum in the lower I. isarcica Zone. It is unlikely that the short-lived phenomena, such as a breakdown in biological productivity due to catastrophic mass extinction, a sudden release of oceanic methane hydrates or meteorite impact(s), could have been the main control on the latest Permian carbon isotope curve because of its prolonged (0.5 Ma) duration, gradual decrease and the existence of a >1‰ positive shift at the main extinction horizon. The P-T boundary δ13C trend matches in time and magnitude the eruption of the Siberian Traps and other contemporaneous volcanism, suggesting that volcanogenic effects, such as outgassed CO2 from volcanism and, even more, thermal metamorphism of organic-rich sediments, as the likely cause of the negative trend. © 2009 Elsevier Ltd. All rights reserved.
UnivIS-Import:2015-03-09:Pub.2010.nat.dgeo.IGM.LG.massiv
Keywords: Abadeh; Carbon isotopes; Guryul Ravine; Oxygen isotopes; Permian-Triassic boundary; Pufels/Bula/Bulla; Volcanism

Mass movement investigation in the Xiangxi Catchment, Three Gorges Reservoir Area - Ehret, Dominik; Rohn, Joachim; Dumperth, Christian; Eckstein, Susan; Ernstberger, Stefanie; Otte, Karel; Rudolph, Rene; Wiedenmann, Johannes; Wei, Xiang; Renneng, Bi (Schriftenreihe der Deutschen Gesellschaft für Geowissenschaften, 2010)
UnivIS-Import:2015-03-09:Pub.2010.nat.dgeo.IGM.profes_3.massmo

Mass occurrence of the large solitary rugose coral Phaulactis angusta at the boundary Lower/Upper Visby Formation in the Silurian of Gotland, Sweden: palaeoecology and depositional implications - Adomat, Friederike; Munnecke, Axel; Kido, Erika (GFF, 2016)
The boundary between the Lower and Upper Visby formations on Gotland (Sweden), which roughly correlates with the Llandovery–Wenlock boundary, is characterised by a mass occurrence of the large solitary rugose coral Phaulactis angusta. This coral-rich layer can be followed for some 50 km along the north-west coast of Gotland. The mass occurrence coincides with the onset of a pronounced, globally recognised δC and δO excursions in the lower Sheinwoodian. Altogether 31 specimens of P. angusta from eight localities were examined. We demonstrate that the corals preferred to grow in an upright position. Attachment structures were not observed, and therefore a liberosessile life strategy is suggested. Some corallites show an abrupt change in growth direction accompanied by a decrease in diameter. These features mostly occur in later growth stages and may be explained by disturbances in the growth due to toppling or tilting of the corals. Many specimens were able to change their growth axes, but finally died after such an event. Most specimens in the outcrops show a flattened upper surface, which is interpreted as a result of post-mortem abrasion. Epibiontic bryozoan encrustation took place mostly while the corals where alive, whereas stromatoporoid encrustation and Trypanites borings occurred post-mortem. The repeated growth, tilting and erosion of the corallites of P. angusta demonstrate that the Phaulactis layer represents a condensed interval, characterised by multiple pulses of sediment accumulation and erosio
Keywords: Gotland; Ireviken event; rugose corals; Silurian

Matera building stones: Chemical, mineralogical and petrophysical characterization of the calcarenite di gravina formation - Bonomo, A. E.; Lezzerini, M.; Prosser, G.; Munnecke, Axel; Koch, Roman; Rizzo, G. (2019 IMEKO TC4 International Conference on Metrology for Archaeology and Cultural Heritage, MetroArchaeo 2019, 2019)
Matera (Basilicata, southern Italy) was awarded the World Heritage Site status by the UNESCO since 1993, and has been named the European Capital of Culture in 2019. It is one of the most ancient towns in the world, whose historical centre was totally built by a weakly lithified and highly porous lower Pleistocene sedimentary building stone, known as Gravina Calcarenite. This easily workable rock was quarried since prehistoric times, and it was used for building different kinds of constructions from the rupestrian settlement to gorgeous historic palaces during the XVIII century. Calcarenite, however, can be an extremely heterogeneous building material depending on the composition of the particles and their characteristics. After a geological survey, it was possible to recognize two main varieties of this building stone, which were in turn subdivided into six lithofacies (corresponding to sub-typologies of building stones). As a first approach, we have characterized, in terms of building stone quality, six lithofacies: basal bioclastic calcarenite, calcirudite-microconglomerate lithofacies, lithoclastic calcarenite, large bivalve bioclastic calcarenite, rhodolith bioclastic calcarenite, and fine bioclastic calcarenite. We focused on the three typologies that were mainly used as building stone (lithoclastic calcarenite, large bivalve bioclastic calcarenite, and fine bioclastic calcarenite). Mineralogical, petrographical and petrophysical analyses have been carried out according to European standard rules to highlight the main characteristics of the different calcarenite types when used as building stones. These three lithofacies show different petrophysical behavior indicating that large bivalve calcarenite and lithoclastic calcarenite lithofacies have slightly different but characteristic mechanical properties related to the primary influence of grain composition, early cementation and micrite contents. Moreover, fine bioclastic calcarenite lithofacies results to be the worst building stone because it is intensely heterogeneous in porosity, cementation and general petrophysical features because of its intense bioturbation.
CRIS-Team Scopus Importer:2021-04-20
Keywords: Building stone; Cultural heritage; Petrographic characterization; Petrophysical properties

Matera building stones: Comparison between bioclastic and lithoclastic calcarenites - Bonomo, Agnese Emanuela; Lezzerini, Marco; Prosser, Giacomo; Munnecke, Axel; Koch, Roman; Rizzo, Giovanna (Building Materials, Materials Design and Applications, 2019)
Matera (Basilicata, southern Italy) was awarded World Heritage Site status by the UNESCO since 1993, and it will be the European Capital of Culture in 2019. It is one of the most ancient towns in the world, whose historical centre was totally built by only a moderately lithified and highly porous sedimentary building stone, known as Gravina Calcarenite. This easily workable rock was quarried since prehistoric times, and it was used for building different kind of constructions from the rupestrian settlement to the gorgeous historic palace during the XVIII century. Calcarenite, however, can be an extremely heterogeneous building material depending on the composition of the particles and their characteristics. After a geological survey, it was possible to recognize two main varieties of this building stone, which were in turn subdivided into six sub-typologies. As a first approach, we have characterized, in terms of building stone quality, the two main varieties: the bioclastic calcarenite and the lithoclastic calcarenite, sampled in the quarrying area to the North of Matera. The bioclastic calcarenite is from a new quarry in the upper part of the Calcarenite Formation, while the lithoclastic calcarenite is from an old quarry, inactive since 1965, in the lower part of the same formation. Mineralogical, petrographic and petrophysical tests have been carried out according to European Standards rules to highlight the main characteristics of different calcarenite types when used as building stone. Despite of their compositional differences, the bioclastic and lithoclastic calcarenite are both pure limestones with slightly different amounts of non-carbonates (silt quartz, clay minerals). The slightly different but characteristic mechanical properties clearly characterize the primary influence of grain composition, early cementation and micrite contents.
CRIS-Team Scopus Importer:2019-11-12
Keywords: Building stone; Italian Unesco site; Petrographic characterization; Physical and mechanical properties

Matera’s Old Quarries: Geological and Historical Archives That Need Protection and Valorization - Bonomo, A. E.; Acito, A. M.; Prosser, G.; Rizzo, G.; Munnecke, Axel; Koch, Roman; Bentivenga, M. (Geoheritage, 2019)
The Sassi of Matera, UNESCO site since 1993, represents a human settlement completely integrated in the natural landscape. There, the development of the community is closely connected to the geology since prehistoric times. The Calcarenite di Gravina, a Pleistocene poorly lithified limestone onlapping a large area of the Apulian foreland in southern Italy, is the building stone that people used to carve their houses inside, and build the town outside. The use of calcarenite for housing began in the prehistory with the first human settlement, deepening natural caves which served as dwellings, while the mining activity began in the third century B.C., increasing until the nineteenth century in connection with the urban development of Matera. The calcarenite was carved out on site and used to build houses. In the eighteenth century, the great urban development of the city gave way to large mining activities in the northern area of Matera. Geomorphological analysis through aerial photographs and a geological survey in this area have been carried out to investigate the historical quarrying activities. In the present study, six quarry areas along the Appia Antica road are valuated: the Madonna delle Vergini topographic high; Cava della Palomba; Parco Scultura–Cava Paradiso; Cava del Sole, the Monumental Quarry Remains; Via Ridola inside the Piano, the highest area of Sassi. They represent peculiar and important examples to be safeguarded and valued. Their geomorphological, geostratigraphical and palaeontological elements provide useful information for understanding the territory evolution in the last two millennia.
CRIS-Team Scopus Importer:2019-11-19
Keywords: Geo-valorization; Geological itinerary; Mining activities; Reused quarries; Soft limestone

Maximizing Cache Memory Usage for Multigrid Algorithms - Douglas, Craig C.; Hu, Jonathan; Iskandarani, Mohamed; Kowarschik, Markus; Rüde, Ulrich; Weiß, Christian (Numerical Treatment of Multiphase Flows in Porous Media. Proc. of the Int. Workshop held at Beijing, China, August 2–6, 1999, 2000)
<p class="Para" style="border: 0px; font-stretch: inherit; font-size: 13px; line-height: 1.6; font-family: 'Helvetica Neue', Arial, Helvetica, sans-serif; margin: 0px; padding: 0px; vertical-align: baseline; outline: 0px; width: 580px; color: rgb(51, 51, 51);"> Computers today rely heavily on good utilization of their cache memory subsystems. Compilers are optimized for business applications, not scientific computing ones, however. Automatic tiling of complex numerical algorithms for solving partial differential equations is simply not provided by compilers. Thus, absolutely terrible cache performance is a common result. <p class="Para" style="border: 0px; font-stretch: inherit; font-size: 13px; line-height: 1.6; font-family: 'Helvetica Neue', Arial, Helvetica, sans-serif; margin: 0.5em 0px 0px; padding: 0px; vertical-align: baseline; outline: 0px; width: 580px; color: rgb(51, 51, 51);"> Multigrid algorithms combine several numerical algorithms into a more complicated algorithm. In this paper, an algorithm is derived that allows for data to pass through cache exactly once per multigrid level during a V cycle before the level changes. This is optimal cache usage for large problems that do not fit entirely in cache. The numerical techniques and algorithms discussed in this paper can be easily applied to numerical simulation of fluid flows in porous media.
UnivIS-Import:2015-04-16:Pub.2000.tech.IMMD.lsinfs.maximi
Keywords: multigrid; cache; threads; sparse matrix; iterative methods; domain decomposition; compiler optimization

Maximum rates of climate change are systematically underestimated in the geological record - Kießling, Wolfgang; Kemp, David B.; Eichenseer, Kilian (Nature Communications, 2015)
Recently observed rates of environmental change are typically much higher than those inferred for the geological past. At the same time, the magnitudes of ancient changes were often substantially greater than those established in recent history. The most pertinent disparity, however, between recent and geological rates is the timespan over which the rates are measured, which typically differ by several orders of magnitude. Here we show that rates of marked temperature changes inferred from proxy data in Earth history scale with measurement timespan as an approximate power law across nearly six orders of magnitude (102 to >107 years). This scaling reveals how climate signals measured in the geological record alias transient variability, even during the most pronounced climatic perturbations of the Phanerozoic. Our findings indicate that the true attainable pace of climate change on timescales of greatest societal relevance is underestimated in geological archives.
UnivIS-Import:2017-01-09:Pub.2015.nat.dgeo.IGM.LP.maximu

Measurements and analysis of the thermal properties of a sedimentary succession in Yangtze plate in China - Luo, Jin; Qiao, Yu; Xiang, Wei; Rohn, Joachim (Renewable Energy, 2020)
A geological stratum is a rock or soil layer that has internally consistent characteristics and is distinguishable from adjacent layers. A stratigraphic section contains reference information for the strata of an associated sedimentary area. In this paper, the thermal properties of 36 rock formations in a succession of the Yangtze plate in China are studied. Thermal properties are analyzed with an emphasis on rock formations, rock lithological types and dry/saturated conditions. The results show that thermal conductivity varies dramatically with different rock lithological types, which range from 0.72 W m−1 K−1 to 4.49 W m−1 K−1. The analysis of biochemical sedimentary rocks shows that silicate has the highest thermal conductivity, followed by dolomite and limestone; this variation is due to the differences in rock-forming minerals. The thermal conductivity of the clastic rocks is mainly determined by the type of minerals, the porosity and the water content. Compared to dry samples, the thermal conductivity and volumetric heat capacity of saturated samples are higher. Moreover, the thermal conductivity data of nine other locations in the Yangtze plate are compared with the stratigraphic data. This analysis shows that thermal conductivity matches very well for most of the geological formations, with the exception of sandstone, which exhibits a significant deviation across formations. Finally, the thermal properties for the Yangtze plate are mapped for insight on their spatial distribution.
CRIS-Team Scopus Importer:2019-12-10
Keywords: Geothermal energy; Sedimentary succession; Thermal properties; Yangtze plate

Mechanical improvement of calcium carbonate cements by: In situ HEMA polymerization during hardening - Myszka, Barbara; Hurle, Katrin; Zheng, Kai; Wolf, Stephan; Boccaccini, Aldo R. (Journal of Materials Chemistry B, 2019)
Calcium carbonate cements are a promising alternative for calcium phosphate cements. Due to the higher solubility of calcium carbonate compared to apatite, it is expected to have an improved biodegradation rate; a clear advantage for prospective biomedical applications in a clinical context. As of yet, the poor mechanical performance of calcium carbonate cements precludes their exploitation as a bioceramic. Herein, we report a mechanically enhanced calcium carbonate cement, formulated of vaterite and magnesium-doped amorphous calcium carbonate, which was strengthened by in situ polymerization of incorporated 2-hydroxyethylmethacrylate (HEMA) during setting in simulated body fluid (SBF). This approach allowed us to generate a pronouncedly strengthened polymer-ceramic composite whose mechanical properties can be tuned by the monomer fraction. Varying cement compositions were characterized with respect to their mechanical performance, morphology, and quantitative phase composition. HEMA polymer reinforcement strengthened the calcium carbonate cement distinctly in four-point bending test while, in stark contrast, the brittleness of the polymer-free cement simply made such tests impossible. Our results demonstrate that the chosen polymer-enforcement strategy is an efficient and straightforward approach and allows for tuning the mechanical properties of an otherwise brittle and thus unusable calcium carbonate cement towards biomedical application.
CRIS-Team Scopus Importer:2019-06-25

Mechanically activated alite: New insights into alite hydration - Bergold, Sebastian; Neubauer, Jürgen; Götz-Neunhoeffer, Friedlinde (Cement and Concrete Research, 2015)
For superior understanding of alite hydration an investigation of mechanically activated alite (M3 modification) was performed by XRD and heat flow calorimetry. Activation resulted in reduced particle size, a decreased mean crystallite size and partial amorphization. For the samples of activated alite a significantly accelerated and intensified hydration was observed and complete conversion of alite was found after 24 h. The enthalpy of reaction for crystalline alite was determined to be - 548 J/g from measured heat of hydration after 24 h. The enthalpy of reaction of amorphous "alite" was found to be less exothermic (- 386 J/g). The main hydration period is controlled by nucleation of C-S-H, while the transition from acceleration to deceleration period takes place after consumption of the small alite particles. XRD amorphous C-S-H phase is indicated to precipitate in considerable amount even in the highest activated alite before "long-range ordered", XRD detectable C-S-H was observed.
Keywords: Acceleration (A); Amorphous material (B); Ca3SiO5 (D); Calcium-Silicate-Hydrate (C-S-H) (B); Hydration (A)

Mechanisms and drivers of belemnite body-size dynamics across the Pliensbachian–Toarcian crisis - Costa Rita, Patrícia; Nätscher, Paulina; Duarte, Luís V.; Weis, Robert; de Baets, Kenneth (Royal Society Open Science, 2019)
Body-size reduction is considered an important response to current climate warming and has been observed during past biotic crises, including the Pliensbachian–Toarcian crisis, a second-order mass extinction. However, in fossil cephalopod studies, the mechanisms and their potential link with climate are rarely investigated and palaeobiological scales of organization are not usually differentiated. Here, we hypothesize that belemnites reduce their adult size across the Pliensbachian–Toarcian boundary warming event. Belemnite body-size dynamics across the Pliensbachian–Toarcian boundary in the Peniche section (Lusitanian Basin, Portugal) were analysed based on the newly collected field data. We disentangle the mechanisms and the environmental drivers of the size fluctuations observed from the individual to the assemblage scale. Despite the lack of a major taxonomic turnover, a 40% decrease in rostrum volume is observed across the Pliensbachian–Toarcian boundary, before the Toarcian Oceanic Anoxic Event where belemnites go locally extinct. The pattern is mainly driven by a reduction in adult size of the two dominant species, Pseudohastites longiformis and Passaloteuthis bisulcata. Belemnite-size distribution is best correlated with fluctuations in a palaeotemperature proxy (stable oxygen isotopes); however, potential indirect effects of volcanism and carbon cycle perturbations may also play a role. This highlights the complex interplay between environmental stressors (warming, deoxygenation, nutrient input) and biotic variables (productivity, competition, migration) associated with these hyperthermal events in driving belemnite body-siz
Keywords: cephalopods; Lilliput effect; Pliensbachian–Toarcian boundary event; Toarcian oceanic anoxic event; climate warming; computed tomography

Mechanisms of early ettringite formation in ternary CSA-OPC-anhydrite systems - Wolf, Julian; Jansen, Daniel; Götz-Neunhoeffer, Friedlinde; Neubauer, Jürgen (Advances in Cement Research, 2019)
Ternary systems on the basis of calcium sulfoaluminate (CSA), ordinary Portland cement (OPC) and anhydrite are known for their rapid setting and hardening properties, which are mainly attributed to the formation of ettringite. Ettringite is the major hydrate phase precipitated in the early stages of hydration in these systems and may be formed by three different main reaction pathways. To investigate the process of these mechanisms, the hydration of four different ternary blends were examined by means of heat flow calorimetry, in situ X-ray diffraction, and thermogravimetric analysis. For the CSA-rich mixes, it was found that hydration in the first 48 h is only subject to the behaviour of ye'elimite and anhydrite dissolution and the resulting formation of ettringite. In the system with the highest OPC proportion, the initial hydration kinetics were found to be more rapid, leading to very high ettringite quantities in the first couple of hours. With the dissolution of the anhydrous OPC phases, more ettringite is formed by the hydration of C(3)A and the consumption of AH(3) stemming from the hydration of ye'elimite and calcium provided by the dissolution of C3S. In the OPC-rich mixes, more than 50% of the formed ettringite can be attributed to this coupled reaction pathway.
CRIS-Team WoS Importer:2019-04-12

Mechanistic insight on the chemistry of potential Pt antitumor agents as revealed by collaborative research performed in Kragujevac and Erlangen - Petrović, Biljana; Jovanović, Snezana; Puchta, Ralph; van Eldik, Rudi (Inorganica Chimica Acta, 2019)
This personal account reports on the mechanistic insight gained on the chemistry of potential Pt antitumor agents based on the collaborative research between the groups of Živadin Bugarčić in Kragujevac (Serbia) and Rudi van Eldik in Erlangen (Germany). The work focuses on different mononuclear Pt(II) and Pt(IV), as well as dinuclear Pt(II) complexes, the tuning of their lability through steric and electronic (σ-donor and π-acceptor) effects, their interaction with sulfur- and nitrogen-donor bio-relevant nucleophiles, the elucidation of structure-reactivity relationships, and DFT calculations on ground, transition and product state complexes. It presents an overview of the investigated systems and reveals mechanistic information on the basis of spectroscopic and kinetic measurements.
CRIS-Team Scopus Importer:2019-06-21
Keywords: DFT calculations; Di-nuclear Pt(II) complexes; Kinetics; Mechanism; Pt(II) complexes; Pt(IV) complexes

Mechanistic neutral models show that sampling biases drive the apparent explosion of early tetrapod diversity - Dunne, Emma; Thompson, Samuel E.D.; Butler, Richard J.; Rosindell, James; Close, Roger A. (Nature Ecology & Evolution, 2023)
Estimates of deep-time biodiversity typically rely on statistical methods to mitigate the impacts of sampling biases in the fossil record. However, these methods are limited by the spatial and temporal scale of the underlying data. Here we use a spatially explicit mechanistic model, based on neutral theory, to test hypotheses of early tetrapod diversity change during the late Carboniferous and early Permian, critical intervals for the diversification of vertebrate life on land. Our simulations suggest that apparent increases in early tetrapod diversity were not driven by local endemism following the ‘Carboniferous rainforest collapse’. Instead, changes in face-value diversity can be explained by variation in sampling intensity through time. Our results further demonstrate the importance of accounting for sampling biases in analyses of the fossil record and highlight the vast potential of mechanistic models, including neutral models, for testing hypotheses in palaeobiology.
CRIS-Team Scopus Importer:2023-08-11

Mediate relation between electrical and thermal conductivity of soil - Schwarz, Hans; Bertermann, David (Geomechanics and Geophysics for Geo-Energy and Geo-Resources, 2020)
Thermal conductivity is a key parameter for many soil applications, especially for dimensioning shallow and very shallow geothermal systems based on the possible heat extraction rate and for modelling heat transfer processes around high voltage underground cables. Due to the limited purview of direct thermal conductivity measurements, for an investigation of extensive areas, usually other geophysical methods like electrical resistivity tomography measurements are applied. To derive thermal conductivity of soil from geoelectrical measurements a relation between electrical and thermal conductivity is needed. Until now only few approaches worked on a direct correlation between both conductivities. Due to the difficulties of a direct relation, within this study a modular approach of a mediate correlation between electrical and thermal conductivity was investigated. Therefore, a direct relationship between a corrected electrical conductivity and water content as well as the standard and simple thermal conductivity model of Kersten (Bull of the Univ Minnesota 28:1–227, 1949) was used. To develop this concept soil types of sand, silt loam and clay were investigated where different saturation steps and pressure loads were applied. For each configuration electrical and thermal conductivity as well as water content and bulk density was determined. To refine the results of the calculated water content a corrective factor was applied. Furthermore, bulk density as an inlet parameter of the Kersten equation was also derived based on electrical conductivity. The suggested proceeding enables the determination of thermal conductivity solely based on electrical conductivity without prior soil property information.
CRIS-Team Scopus Importer:2020-08-07
Keywords: Bulk density; ERT; Heat transfer; Kersten model; Water content

Meeresschildkrötenschutz - Schulbert, Christian; Römheld, Julia (Vogelschutz, 2007)
UnivIS-Import:2015-03-09:Pub.2007.nat.dgeo.IGM.LP.meeres

Meiobenthos and ocean acidification: Effects on meiobenthic communities inhabiting Mediterranean cold shallow CO2-vents - Cocozza di Montanara, A.; Baldrighi, E.; López Correa, Matthias; Chianese, E.; Appolloni, L.; Simoncini, N.; Sandulli, R.; Zeppilli, D.; Semprucci, F.; Gambi, M. C.; Ferrigno, F.; Donnarumma, L. (Estuarine Coastal and Shelf Science, 2024)
Ocean acidification is causing major changes in marine ecosystems, with varying levels of impact, depending both on the habitat and the studied organisms. Here, we investigated for the first time the meiobenthos and nematode fauna inhabiting the sediments around Castello Aragonese (Ischia, Italy), characterized by variable pH values due to coastal volcanic CO2 venting. In this scenario, nematode functional diversity changed according to different pH levels and grain size: maturity index was higher at most acidic stations and trophic composition spanned from the dominance of predators in the acidic stations, to the high abundance of non-selective deposit feeders and epistrate feeders in the ambient-pH stations. Overall, the present study revealed a relatively high tolerance of meiobenthos and nematodes to lower pH conditions. However, an in-depth analysis of nematode fauna showed differences in their assemblages at different pH levels with few nematode genera rather adapted to the extreme environmental conditions at the acidic stations.
CRIS-Team Scopus Importer:2024-04-05
Keywords: CO; Community composition; Functional diversity; Ischia vents; Mediterranean sea; Meiofauna; Nematodes

Melt generation beneath Arctic Ridges: Implications from U decay series disequilibria in the Mohns, Knipovich, and Gakkel Ridges - Elkins, Lynne; Sims, Ken W.W.; Prytulak, Julie; Blichert-Toft, Janne; Elliott, Tim; Blusztajn, Jerzy; Fretzdorff, Susanne; Reagan, Mark; Haase, Karsten; Humphris, Susan; Schilling, Jean-Guy (Geochimica Et Cosmochimica Acta, 2014)
We present new U-Th-Ra-Pb, U-Pa, and Nd, Sr, Hf, and Pb isotope data for the slow- to ultraslow-spreading Mohns, Knipovich, and Gakkel Ridges. Combined with previous work, our data from the Arctic Ridges cover the full range of axial depths from the deep northernmost Gakkel Ridge shallowing upwards to the Knipovich, Mohns, and Kolbeinsey Ridges north of Iceland. Age-constrained samples from the Mohns and Knipovich Ridges have (Th/U) activity ratios ranging from 1.165 to 1.30 and 1.101 to 1.225, respectively. The high Th excesses of Kolbeinsey, Mohns, and Knipovich mid-ocean ridge basalts (MORB) are erupted from ridges producing relatively thin (Mohns, Knipovich) to thick (Kolbeinsey) oceanic crust with evidence for sources ranging from mostly peridotite (Kolbeinsey) to eclogite-rich mantle (Mohns, Knipovich). Age-constrained lavas from 85°E on the Gakkel Ridge, on the other hand, overlie little to no crust and range from small ( 5%) Th excesses to small U excesses ( 5%). The strong negative correlation between (Th/U) values vs. axial ridge depth among Arctic ridge basalts is controlled not only by solidus depth influence on U-Th disequilibria, but also by variations in mantle source lithology and depth to the base of the lithosphere, which is expected to vary at ultra-slow spreading ridges. Small Pa excesses (65% excess) in age-constrained basalts support the presence of eclogite in the mantle source for this region. Conversely, the ultraslow-spreading Gakkel Ridge basalts are homogeneous, with Sr, Nd, and Hf radiogenic isotopic signatures indicative of a long time-averaged depleted mantle source. The Gakkel samples have minimum (Ra/Th) ratios ranging from 3.07 to 3.65±3%, which lie along and extend the global negative correlation between Ra and Th excesses observed in MORB. The new Th-Ra data support a model for global MORB production in which deep melts record interaction with shallower materials. This scenario requires either mixing with shallow-derived melts, or melt-rock reaction with shallower rocks in the lithosphere or crust. © 2013 Elsevier Ltd.

Melting versus contamination effects on 238U-230Th-226Ra and 235U-231Pa disequilibria in lavas from São Miguel, Azores - Prytulak, Julie; Avanzinelli, Riccardo; Koetsier, Govert; Kreissig, Katharina; Beier, Christoph; Elliott, Tim (Chemical Geology, 2014)
The island of São Miguel, Azores piques geochemical interest due to a strikingly large range in the long-lived radiogenic isotope ratios of its lavas. The 'enriched' signatures (e.g., radiogenic Sr/Sr and unradiogenic Nd/Nd) observed in lavas found in the east of the island have been proposed to originate from recycled crustal components in their mantle sources. Such fertile lithologies should have higher melt productivities (amount of melt generated per decrement in pressure) than peridotitic mantle and this heritage ought to be evident in the U-series signatures of melts derived from such materials. Specifically, combined U-Th and U-Pa disequilibria in erupted lavas should identify significant differences in the melting rate and/or the mineralogical makeup of their sources (e.g., the amount of garnet). To this end, new U-Th-Ra and U-Pa disequilibria are presented for sixteen mafic lavas (<50wt.% SiO) that encompass the full range of São Miguel's long-lived radiogenic isotope variability. However, primary U-series signatures of mafic lavas can be influenced by assimilation of more differentiated products. Notably, syenite nodules and cumulate alkali feldspar xenocrysts have been identified in São Miguel basalts. We argue that secondary contamination of basalts is most evident in the hugely variable Th-Ra disequilibria ( 18% deficits to >300% excesses of Ra) that strongly correlate with Ba/Th ratios. The longer-lived U-series nuclides are only slightly perturbed in a number of the more enriched lavas, resulting in increased noise in the dataset. In apparently uncontaminated samples, isotopically depleted lavas from the west of São Miguel display slightly higher Th and Pa excesses than the enriched samples from the east. The U-series signature of the enriched lavas can be modeled with a combination of higher absolute values of D-UU and D-Th, coupled with higher melting rates compared to the depleted western source. These parameters are consistent with a peridotite source enriched with contributions from more fusible lithologies such as eclogite and/or pyroxenite in the eastern source, but not with direct derivation from such fusible lithologies. The only subtle variations in U-series isotopes coupled with large, systematic variations in radiogenic isotope compositions suggest that enriched components and/or their melts are well-mixed with mantle peridotite, thus masking their distinctive melting behavior. Finally, basalts from Sete Cidades volcano in the west of São Miguel have very similar long-lived isotope compositions and U-series disequilibria to basalts from the island of Pico, Azores. The geochemical similarity of lavas from islands at the center and periphery of the archipelago argue against systematic differences in melting behavior related to sampling different portions of an underlying plume structure. © 2014 Elsevier B.V.
Keywords: Contamination; Dynamic melting; Pyroxenite/eclogite; São Miguel; U-series

Melts from hydrous depleted back-arc mantle at a young boninitic volcano on the flank of Valu Fa Ridge (Lau basin, SW Pacific) - Myeong, Bora; Regelous, Marcel; Haase, Karsten; Lim, Hoseong; Park, Jongkyu (Contributions To Mineralogy and Petrology, 2023)
Volcano S3 is a young seamount located 5 km east of the Valu Fa Ridge (VFR) in the Lau Basin, which has erupted boninitic lavas. We present new data for whole-rock compositions, minerals and olivine‐hosted melt inclusions, and propose a new model for low-Si boninite (LSB) petrogenesis in a subduction-related setting. The whole-rock compositions reflect mixing of less primitive melt with variable amounts ( 30%) of minerals, whereas quenched glass compositions result from ( 60%) crystal fractionation of a primitive boninitic magma which is preserved as melt inclusions hosted in olivine crystals. The compositions of primitive olivine and spinel from S3 are more refractory than those from MORB and back-arc basin (BAB) lavas. Lower Fe8 and Na8 values of S3 than those of BAB lavas reflect melting of relatively depleted mantle at high temperature and low pressure. The mantle beneath S3, and the adjacent VFR and Ata is more depleted than those of BAB located further from the arc, and S3 and Ata lavas have similar slab input ( 1%). The geochemical differences between S3 and BAB lavas imply that the boundary between dry and wet mantle is located beneath VFR. We suggest that a vertical mantle flow beneath VFR brings depleted mantle containing slab components from deeper within the wedge. This depleted and wet mantle probably experienced a high degree of partial melting at low pressure to form LSB magmas beneath S3. The LSB lavas can be formed at back-arc spreading centers which are located close enough to an active arc.
CRIS-Team Scopus Importer:2023-09-29
Keywords: Crustal thickness; Low-Si boninite; Off-axis seamount; Partial melting; Refractory mantle; Subduction input

Melts of sediments in the mantle wedge of the Oman ophiolite - Haase, Karsten; Freund, Sarah; Koepke, Jürgen; Hauff, Folkmar; Erdmann, Martin (Geology, 2015)
The rocks in the crustal section of the Oman ophiolite show an increasing input of a subduction component with time, most likely reflecting the generation of the ophiolite above a subducting slab. Field relations, new geochemical data, and Nd-Hf isotope data for felsic to mafic intrusive rocks in the mantle harzburgite from the Haylayn block in the Oman ophiolite suggest late magmatic events in a mantle wedge shortly before obduction of the ophiolite. Incompatible element contents and low ε and ε of the felsic rocks exclude differentiation from mafic magmas, but are consistent with an origin by partial melting of pelagic sediments similar to leucogranites in continental collision zones. These melts apparently mixed with mafic magmas resembling enriched late-stage lavas from the ophiolite. The leucogranitic intrusions into the mantle wedge confirm the transfer of melts of sediments from the subducted plate into the mantle at subduction zones. We suggest that the enrichment of Rb, K, and Pb observed in the Oman boninites is caused by addition of melts of sediments similar to those from the Haylayn block to the boninite source in the mantle wedge.

Mesoproterozoic continental arc magmatism and crustal growth in the eastern Central Tianshan Arc Terrane of the southern Central Asian Orogenic Belt: Geochronological and geochemical evidence - He, Zhenyu; Klemd, Reiner; Zhang, Zeming; Zong, Keqing; Sun, Li-Xin; Tian, Zuolin; Huang, Bo-Tao (Lithos, 2015)
Numerous microcontinents are known to occur in the Central Asian Orogenic Belt (CAOB), one of the largest accretionary orogens and the most significant area of Paleozoic crustal growth in the world. The evolution of the Precambrian crust in these microcontinents is central to understanding the accretionary and collisional tectonics of the CAOB. Here, we present systematic zircon U–Pb dating and Hf isotope studies of Mesoproterozoic gneissic granitoids from the eastern Central Tianshan Arc Terrane (CTA) of the southern CAOB. The investigated intermediate to felsic (SiO2 = 60.48–78.92 wt.%) granitoids belong to the calcic- to calc-alkaline series and usually have pronounced negative Nb, Ta and Ti anomalies, relative enrichments of light rare earth elements (LREEs) and large ion lithophile elements (LILEs) while heavy rare earth elements (HREEs) and high field strength elements (HFSEs) are depleted, revealing typical active continental margin magmatic arc geochemical characteristics. These spatially-distant rocks show consistent zircon U–Pb crystallization ages from ca. 1.45 to 1.40 Ga and thus constitute a previously unknown Mesoproterozoic continental magmatic arc covering hundreds of kilometers in the eastern segment of the CTA. Furthermore the high and mainly positive zircon εHf(t) values between − 1.0 and + 8.6 and the zircon Hf model ages of 1.95 to 1.55 Ga, which are slightly older than their crystallization ages, suggest that they were mainly derived from rapid reworking of juvenile material with a limited input of an ancient crustal component. Therefore, the formation of these granitoids defines an extensive Mesoproterozoic intermediate to felsic, subduction-related intrusive magmatic arc activity that was active from at least 1.45 to 1.40 Ga, involving significant juvenile continental growth in the eastern segment of the CTA. Furthermore the zircon U–Pb and Hf isotopic data challenge the common belief that the CTA was part of the Tarim Craton during Paleo- to Mesoproterozoic times. However, the southern Beishan microcontinents and the CTA have similar zircon U–Pb and Hf isotopic signatures, indicating a similar Precambrian tectonothermal evolution for both. This finding provides new and important constraints on the Precambrian crustal evolution of the microcontinents in the southern CAOB.<br
Keywords: Zircon U–Pb geochronology and Hf isotopes; Crustal growth; Mesoproterozoic continental magmatic arc; Chinese Eastern Tianshan; Central Asian Orogenic Belt

Mesoproterozoic dyke swarms in foreland and nappes of the central Scandinavian Caledonides: structure, magnetic fabric, and geochemistry - de Wall, Helga; et al. (Geological Magazine, 2007)
As an example of microstructural and magnetic fabric evolution, and geochemistry of mafic dykes during a Subsequent orogenic overprint, a major Mesoproterozoic dyke complex in Scandinavia, the Vasterbotten complex of the Central Scandinavian Dolerite Group, is traced westwards into the crystalline nappes of the early Phanerozoic Caledonian orogen. Using geophysical, field, microscopic, magnetic and geochemical information, dykes and sills are characterized, and their overprint during Caledonian orogeny documented. The Vasterbotten complex is composed of sets of dykes, trending NE-SW, NW-SE and WNW-ESE, respectively. Similar dykes are exposed in allochthonous positions (Lower and Middle allochthons) in the Caledonian fold-and-thrust belt. The autochthonous dykes are generally undeformed and retain both their primary texture and mineralogy Chilled margins are well preserved. In the Caledonian Lower and Middle allochthons, similar dykes in crystalline basement rocks are progressively faulted and sheared when proceeding from the marginal to the interior parts of the orogen. Dyke margins are more likely to be sheared than the interior parts of dykes. In the Lower Allochthon, under very low- and low-grade metamorphic conditions, dykes are distinctly less competent than granitic host rocks. Thick dykes are more competent than gneisses; thin dykes do not show such competence contrasts. In the Middle Allochthon, metre-scale dykes with patches of altered plagioclase phenocrysts can still be discerned in low-strain domains. Highly sheared dykes are drawn out to thin layers of centimetre thickness. Dykes are deformed together with the crystalline country rocks under greenschist-grade metamorphic conditions without major competence contrasts. Magnetic fabrics show an evolution similar to the silicate mineral fabrics. The magnetic fabrics in the dykes are transformed successively from ferromagnetic-magmatic in the Autochthon to ferromagnetic deformational in the Lower Allochthon and, finally, paramagnetic deformational in the Middle Allochthon. As a consequence, the magnetic susceptibility decreases for several orders of magnitude. Geochemically, the dykes are dominantly sub-alkaline basalts typical for continental tholeiites and can be distinguished from the Neoproterozoic dykes in the Sarv-Nappe equivalents (highest part of the Middle Allochthon), which show a more MORB-like (E-MORB) magmatic signature. Preliminary age information from a dyke in the Lower Allochthon of the Borgefiell area and the Middle Allochthon is consistent with the assumption that these dykes are time equivaient with the Central Scandinavian Dolerite Group. Therefore, the studied dykes may represent an extension of the Vasterbotten complex or a new complex of the Central Scandinavian Dolerite Group. According to section restorations, the Caledonian allochthons were situated further WNW relative to their present position, and, originally, the mafic dykes cut across all of the Fennoscandian lithosphere, at least to the present Atlantic margin and the earlier passive margin of the Baltica terrane. As a consequence, these dykes may provide a link for pre-Caledonian and pre-Grenvillian plate reconstructions.
Keywords: dykes; microstructure; magnetic anisotropy; geochemistry; dolerite; Caledonides; Scandinavia

Mesoproterozoic juvenile crust in microcontinents of the Central Asian Orogenic Belt: evidence from oxygen and hafnium isotopes in zircon - He, Zhenyu; Klemd, Reiner; Yan, Li-Li; Lu, Tianyu; Zhang, Zeming (Scientific Reports, 2018)
We report in situ O and Hf isotope data of zircon grains from coeval Mesoproterozoic (ca. 1.4 Ga) igneous metamafic (amphibolite) and granitic rocks of the Chinese Central Tianshan microcontinent (CTM) in the southern Central Asian Orogenic Belt (CAOB). Zircon grains from amphibolite have mantle-like δ18OVSMOW values of 4.7–5.6‰ and juvenile Hf isotopic compositions (εHf(t) = 8.4–15.3; TDMC = 1.57–1.22 Ga), whereas those from granitic rocks have δ18OVSMOW values of 5.6–7.0‰ and evolved Hf isotopic compositions (εHf(t) = −1.0–8.2; TDMC = 2.09–1.62 Ga). Zircon O–Hf isotopic compositions of the metamafic and granitic rocks provide evidence for Mesoproterozoic (ca. 1.4 Ga) crustal growth and a substantial Palaeoproterozoic supracrustal component in the CTM. These findings and previous studies, reporting ca. 1.4 Ga magmatic rocks from other microcontinents of the CAOB, suggest that a large belt of Mesoproterozoic (ca. 1.4 Ga) juvenile continental crust formed in a continental terrane, fragments of which now occur over a distance of more than a thousand kilometres in the southern CAOB.<br
Keywords: Geochemistry; Petrology; Precambrian geology

Mesoscopic-scale structure and dynamics near the morphotropic phase boundary of (1-x)PbTiO3-xBiScO3 - Datta, Kaustuv; Richter, Andreas; Göbbels, Matthias; Neder, Reinhard; Mihailova, Boriana (Physical Review B - Condensed Matter and Materials Physics, 2015)
A range of compelling information on the local structure and dynamics of the ferroelectric perovskite-type (ABO3) system (1-x)PbTiO3-xBiScO3 has been revealed through analyzing room-temperature x-ray pair distribution functions and temperature-dependent Raman scattering data for compositions ranging across the morphotropic phase boundary (MPB). Raman scattering data have provided exclusive evidence for distinct dynamical responses from the A-site Pb/Bi and the B-site Ti/Sc cations as a function of composition and temperature. Both pair distribution function and Raman scattering analyses indicate improved coherence between the A-site and B-site off-center displacements for x above the MPB composition. The distinguishable dynamical features were spotted between two sets of compositional range from which x=0.34 could be assigned as a critical composition of "local" MPB: the composition at which the pathway of mesoscopic-scale temperature-driven coupling and transformation processes changes. This differs from the previous reports based on the analysis of the average structure, suggesting the response function of a system may not necessarily follow the evolution of the average structure from which however the MPB has so far been ascribed for a particular system. The individual features of the cations revealed here will further help in understanding the structure-property correlations for similar ferroelectric solid solutions.

Mesozoic–Cenozoic bioevents - Kießling, Wolfgang; Lazarus, David; Zeller, Ulrich (Palaeogeography, Palaeoclimatology, Palaeoecology, 2004)
Keywords: Biodiversity; Evolution; Extinctions

Metal-induced malformations in early Palaeozoic plankton are harbingers of mass extinction - Vandenbroucke, Thijs R.A.; Emsbo, Poul; Munnecke, Axel; Nuns, Nicolas; Duponchel, Ludovic; Lepot, Kevin; Quijada, Melesio; Paris, Florentin; Servais, Thomas; Kießling, Wolfgang (Nature Communications, 2015)
Glacial episodes have been linked to Ordovician-Silurian extinction events, but cooling itself may not be solely responsible for these extinctions. Teratological (malformed) assemblages of fossil plankton that correlate precisely with the extinction events can help identify alternate drivers of extinction. Here we show that metal poisoning may have caused these aberrant morphologies during a late Silurian (Pridoli) event. Malformations coincide with a dramatic increase of metals (Fe, Mo, Pb, Mn and As) in the fossils and their host rocks. Metallic toxins are known to cause a teratological response in modern organisms, which is now routinely used as a proxy to assess oceanic metal contamination. Similarly, our study identifies metal-induced teratology as a deep-time, palaeobiological monitor of palaeo-ocean chemistry. The redox-sensitive character of enriched metals supports emerging 'oceanic anoxic event' models. Our data suggest that spreading anoxia and redox cycling of harmful metals was a contributing kill mechanism during these devastating Ordovician-Silurian palaeobiological event
Keywords: Metal-induced; Mass extinction; Silurian; Palaeozoic plankton; Palaeobiological events

Metallogenesis of the Zhibo and Chagangnuoer volcanic iron oxide deposits in the Awulale Iron Metallogenic Belt, Western Tianshan orogen, China - Zhang, Xi; Klemd, Reiner; Gao, Jun; Dong, Lian-Hui; Wang, Xin-Shui; Haase, Karsten; Jiang, Tuo; Qian, Qing (Journal of Asian Earth Sciences, 2014)
The Zhibo and Chagangnuoer iron ore deposits occur at the same volcanic edifice and are situated along the eastern segment of the Awulale Iron Metallogenic Belt in the Western Tianshan orogen of China. The former deposit is exposed near the caldera and the latter lies on the northwestern flank of the volcanic structure. The ore mineralization, the ore texture, the ore bodies structures, the trachytic to trachy andesitic host rocks and the geological characteristics of the Zhibo and Chagangnuoer deposits indicate a magmatic source for the iron oxide mineralization. This is supported by the observation that the vast majority of the Zhibo and Chagangnuoer magnetites have δ18O values between >+0.9‰ and <+4.00‰ consistent with a precipitation from 'normal' subduction type intermediate to felsic magmas or high-temperature magmatic fluids. However some magnetites with low δ18O values (<+0.9‰) are thought to have formed in equilibrium with a low to moderate temperature hydrothermal fluid as is evidenced by pervasive and vein-type controlled (skarn-type) alteration of the ore and host volcanic rocks. Furthermore, the trace element composition of the equilibrium ortho-magmatic magnetites was reset during this hydrothermal alteration event. Major and trace element characteristics indicate that the volcanic rocks, the granitoids and the iron ore bodies were formed in a continental arc setting during the Early Carboniferous. The ore-hosting volcanic rocks probably originated from melting of a mantle wedge that was metasomatized during subduction. Laser ablation-ICPMS (LA-ICPMS) U-Pb zircon ages of 350 ± 2 Ma and 361 ± 7 Ma were obtained for zircon from the trachy andesitic host rock of the iron ore exposed near the caldera of the volcano and the highly altered fine grained garnet-dominated host rock on the flank of the volcano, respectively. A U-Pb zircon age of 321 ± 2 Ma was gained for the rhyolite overlying the ore bodies at the Chagangnuoer deposit, which were intruded by a granitic pluton with a U-Pb zircon age of 319 ± 2 Ma. Furthermore, the minerals of the skarn-type alteration zone at the Chagangnuoer deposit yield an Sm-Nd isochron age of 313 ± 7 Ma (Grt-Act-Epi-whole rock). Considering previous geochronological studies, a 350-330 Ma age range as observed in the host rocks of the Zhibo mine is believed to display a period of continuous volcanic activity and associated ortho-magmatic, high-temperature iron oxide mineralization during subduction. The iron oxide mineralization in both deposits is thought to have been derived from the same magma source, as the ore-hosting volcanic rocks are similar to 'Kiruna-type' iron oxide ores. Subsequently, the volcanic host rocks and the iron ore bodies were variably hydrothermally altered during subduction (ca. 319-313 Ma). The alteration zones were probably facilitated by the infiltration of hydrothermal fluids along faults, which were created by the intrusion of a granitic pluton. © 2014 Elsevier Ltd. All rights reserve
UnivIS-Import:2015-03-09:Pub.2014.nat.dgeo.IGM.c3geoc.metall
Keywords: Magmatic iron oxide ore deposits; Magnetite trace elements and O-isotopes; Metallogenesis; Tianshan; U-Pb zircon ages

Metallogenesis of the Zhibo and Chagangnuoer volcanic iron oxide deposits in the Awulale Iron Metallogenic Belt, Western Tianshan orogen, China - Zhang, Xi; Klemd, Reiner; Gao, Jun; Dong, Lian-Hui; Wang, Xin-Shui; Haase, Karsten; Jiang, Tuo; Qian, Qing (Journal of Asian Earth Sciences, 2015)
The Zhibo and Chagangnuoer iron ore deposits occur at the same volcanic edifice and are situated along the eastern segment of the Awulale Iron Metallogenic Belt in the Western Tianshan orogen of China. The former deposit is exposed near the caldera and the latter lies on the northwestern flank of the volcanic structure. The ore mineralization, the ore texture, the ore bodies structures, the trachytic to trachy andesitic host rocks and the geological characteristics of the Zhibo and Chagangnuoer deposits indicate a magmatic source for the iron oxide mineralization. This is supported by the observation that the vast majority of the Zhibo and Chagangnuoer magnetites have δ18O values between >+0.9‰ and <+4.00‰ consistent with a precipitation from ‘normal’ subduction type intermediate to felsic magmas or high-temperature magmatic fluids. However some magnetites with low δ18O values (<+0.9‰) are thought to have formed in equilibrium with a low to moderate temperature hydrothermal fluid as is evidenced by pervasive and vein-type controlled (skarn-type) alteration of the ore and host volcanic rocks. Furthermore, the trace element composition of the equilibrium ortho-magmatic magnetites was reset during this hydrothermal alteration event. Major and trace element characteristics indicate that the volcanic rocks, the granitoids and the iron ore bodies were formed in a continental arc setting during the Early Carboniferous. The ore-hosting volcanic rocks probably originated from melting of a mantle wedge that was metasomatized during subduction. Laser ablation-ICPMS (LA-ICPMS) U–Pb zircon ages of 350 ± 2 Ma and 361 ± 7 Ma were obtained for zircon from the trachy andesitic host rock of the iron ore exposed near the caldera of the volcano and the highly altered fine grained garnet-dominated host rock on the flank of the volcano, respectively. A U–Pb zircon age of 321 ± 2 Ma was gained for the rhyolite overlying the ore bodies at the Chagangnuoer deposit, which were intruded by a granitic pluton with a U–Pb zircon age of 319 ± 2 Ma. Furthermore, the minerals of the skarn-type alteration zone at the Chagangnuoer deposit yield an Sm-Nd isochron age of 313 ± 7 Ma (Grt-Act-Epi-whole rock). Considering previous geochronological studies, a 350–330 Ma age range as observed in the host rocks of the Zhibo mine is believed to display a period of continuous volcanic activity and associated ortho-magmatic, high-temperature iron oxide mineralization during subduction. The iron oxide mineralization in both deposits is thought to have been derived from the same magma source, as the ore-hosting volcanic rocks are similar to ‘Kiruna-type’ iron oxide ores. Subsequently, the volcanic host rocks and the iron ore bodies were variably hydrothermally altered during subduction (ca. 319–313 Ma). The alteration zones were probably facilitated by the infiltration of hydrothermal fluids along faults, which were created by the intrusion of a granitic pluton.<br
Keywords: Metallogenesis; Magmatic iron oxide ore deposits; Magnetite trace elements and O-isotopes; U–Pb zircon ages; Tianshan

Metamorphic and Structural Evolution of the Southern Shackleton Range during the Ross Orogeny. - Buggisch, Werner; Kleinschmidt, Georg; Kreuzer, Hans; Krumm, Stefan (Polarforschung, 1994)
UnivIS-Import:2015-03-05:Pub.1994.nat.dgeo.IGM.LG.metamo

Metamorphic evolution of (ultra)-high-pressure subduction-related transient crust in the South Tianshan Orogen (Central Asian Orogenic Belt): Geodynamic implications - Klemd, Reiner; Gao, Jun; Li, Jilei; Meyer, Melanie (Gondwana Research, 2015)
The study of subduction-related high-pressure- and ultra-high-pressure metamorphic rocks exposed in orogenic belts is critical for unraveling the tectonothermal evolution of an orogen. The South Tianshan Orogen of the southwestern Central Asian Orogenic Belt, one of the world's largest accretionary orogens, contains several Paleozoic (ultra-)high-pressure ((U)HP) metamorphic terranes. (U)HP eclogites, blueschists and associated (U)HP metasedimentary rocks of continental and oceanic origin were reported from two localities in the Northern Tianshan (NTS) of Kazakhstanand Kyrgyzstan, namely from the Ordovician Aktyuz and Makbal metamorphic terranes. Furthermore Lower Carboniferous (U)HP eclogites and blueschists of oceanic origin are located in the Southern Tianshan Accretionary Complex (STAC) of southern Kyrgyzstan (Atbashi) and northwestern China (Akeyazi). The continentally-derived Aktyuz eclogite is considered to have experienced a continuous clockwise prograde P–T path with peak metamorphic conditions of ca. 1.6–2.1 GPa at 610–670 °C, corresponding to a burial depth of about 70 km. A peak metamorphic Lu–Hf garnet isochron age of 474 ± 2 Ma for the retrogressed eclogite of continental origin is in accordance with a Sm–Nd garnet isochron age of 462 ± 7 Ma interpreted as time of cooling and decompression of the metamorphic rock assemblage below 650 to 600 °C. Quantitative P–T pseudosection modeling for peripheral Makbal HP garnet amphibolites of continental origin also revealed a continuous clockwise P–T path with peak-metamorphic conditions of ca. 1.4 GPa at ca. 620 °C followed by an isothermal uplift to ca. 0.7 GPa. Furthermore, prograde P–T paths of oceanically-derived central Makbal high-pressure metabasic rocks revealed peak metamorphic conditions between 520 °C and 560 °C at 2.2 GPa to 2.5 GPa with subsequent isothermal decompressions. The metamorphic (P–T) evolution of a garnet–chloritoid–talc schist is exhibited by a P–T trajectory starting ca. 480 °C at 2.5 GPa, followed by peak pressures of ca. 2.85 GPa at 525 °C and peak temperatures of ca. 580 °C at 2.4 GPa. A Lu–Hf peak metamorphic age of 470.1 ± 2.5 Ma for a peripheral garnet amphibolite is in accordance with a garnet-growth Sm–Nd age of 475 ± 4 Ma of the UHP garnet–chloritoid–talc schist. Different and variable P–T paths show that former oceanic and continental crust at Makbal was subducted to different maximum depths (HP versus UHP conditions). The (U)HP metamorphism of oceanic and continental mafic rocks from the Aktyuz and Makbal metamorphic terranes is assumed to have occurred in a similar time frame of between 500 and 460 Ma. The proposed geodynamic model for the HP Aktyuz metamorphic terrane incorporates the deep northeast-directed subduction of NTS continental crust under the Ankrakhai block of Paleo-Kazakhstan subsequent to the closure of the Djalair–Naiman Basin. At Makbal the final consumption of the oceanic crust of the Terskey Ocean to the northeast was immediately followed by the deep subduction of a (thinned) passive continental margin of the Central Tianshan Arc Terrane (CTA). Both scenarios are in accordance with continental-type subduction geodynamics producing the subduction-related (U)HP rocks during continental–continental collision processes. The exhumation of detached oceanic material by channel flow may have been initiated by the transient subduction of oceanic and subsequent continental crust. The Lower Carboniferous (U)HP metamorphic terranes (Atbashi and Akeyazi) in the Southern Tianshan Accretionary Complex are mainly composed of metasediments which host some lenses and boudins of oceanically-derived blueschists and eclogites. Most eclogites, blueschists and metasediments have experienced peak high-pressure metamorphism (480–580 °C at 1.4–2.1 GPa), while some slices display UHP-conditions (2.7–3.3 GPa at 570–630 °C). Multi-point Lu–Hf and Sm–Nd isochrons from several eclogite and blueschist samples from the Atbashi and Akeyazi metamorphic terranes revealed consistent ages of ca. 320–315 Ma for the peak of metamorphism, thereby confirming that (U)HP metamorphism occurred during a single subduction event. The highly variable peak metamorphic conditions displayed by the (U)HP rocks imply that metamorphism of the metasediments and the various metabasic rocks occurred in different depths of the subduction zone. (U)HP metabasites and metasediments exhibit different P–T paths, which is consistent with the chaotic incorporation in a subduction channel resulting in the eventual exhumation as a mélange. This scenario is much in agreement with initial subduction of oceanic crust and accretionary wedge sediment removal by subduction erosion and thus is similar to accretionary-type subduction terranes, although, with higher peak P–T conditions than previously recorded. The absence of significant melting, in combination with the variable peak pressure metamorphic conditions and the intimate interlayering of high- and ultrahigh-pressure rocks, suggests that the (U)HP rocks were derived from varying depths within the subduction zone and then juxtaposed during exhumation in the subduction channel. This is in accordance with exhumation of the (U)HP rocks by channel flo
Keywords: South Tianshan Orogen; (Ultra-)high-pressure metamorphism; Geochronology; Accretionary- and continental-type subductions; Channel flow exhumation

Metamorphic evolution of (ultra)-high-pressure subduction-related transient crust in the South Tianshan Orogen (Central Asian Orogenic Belt): Geodynamic implications - Klemd, Reiner; Gao, Jun; Li, Ji-Lei; Meyer, Melanie (Gondwana Research, 2015)
UnivIS-Import:2015-03-09:Pub.2015.nat.dgeo.IGM.c3geoc.metamo

Metamorphic petrology of a high-T/low-P granulite terrane (Damara belt, Namibia) – Constraints from pseudosection modelling and high-precision Lu–Hf garnet-whole rock dating - Jung, Stefan; Brandt, Sönke; Bast, Rebecca; Scherer, Erik E.; Berndt, Jasper (Journal of Metamorphic Geology, 2019)
Migmatites comprise a minor volume of the high-grade part of the Damara orogen of Namibia that is dominated by granite complexes and intercalated metasedimentary units. Migmatites of the Southern Central Zone of the Damara orogen consist of melanosomes with garnet+cordierite+biotite+K-feldspar, and leucosomes, which are sometimes garnet- and cordierite-bearing. Field evidence, petrographic observations, and pseudosection modelling suggest that, in contrast to other areas where intrusion of granitic magmas is more important, in situ partial melting of metasedimentary units was the main migmatite generation processes. Pseudosection modelling and thermobarometric calculations consistently indicate that the peak-metamorphic grade throughout the area is in the granulite facies ( 5 kbar at 800°C). Cordierite coronas around garnet suggest some decompression from peak-metamorphic conditions and rare andalusite records late, near-isobaric cooling to <650°C at low pressures of 3 kbar. The inferred clockwise P–T path is consistent with minor crustal thickening through continent–continent collision followed by limited post-collisional exhumation and suggests that the granulite facies terrane of the Southern Central Zone of the Damara orogen formed initially in a metamorphic field gradient of 35–40°C/km at medium pressures. New high-precision Lu–Hf garnet-whole rock dates are 530 ± 13 Ma, 522.0 ± 0.8 Ma, 520.8 ± 3.6 Ma, and 500.3 ± 4.3 Ma for the migmatites that record temperatures of 800°C. This indicates that high-grade metamorphism lasted for c. 20–30 Ma, which is compatible with previous estimates using Sm–Nd garnet-whole rock systematics. In previous studies on Damara orogen migmatites where both Sm–Nd and Lu–Hf chronometers have been applied, the dates (c. 520–510 Ma) agree within their small uncertainties (0.6–0.8% for Sm–Nd and 0.1–0.2% for Lu–Hf). This implies rapid cooling after high-grade conditions and, by implication, rapid exhumation at that time. The cause of the high geothermal gradient inferred from the metamorphic conditions is unknown but likely requires some extra heat that was probably added by intrusion of magmas from the lithospheric mantle, i.e., syenites that have been recently re-dated at c. 545 Ma. Some granites derived from the lower crust at c. 545 Ma are the outcome rather than the cause of high-T metamorphism. In addition, high contents of heat-producing elements K, Th, and U may have raised peak temperatures by 150–200°C at the base of the crust, resulting in the widespread melting of fertile crustal rocks. The continuous gradation from centimetre-scale leucosomes to decametre-scale leucogranite sheets within the high-grade metamorphic zone suggests that leucosome lenses coalesced to form larger bodies of anatectic leucogranites, thereby documenting a link between high-grade regional metamorphism and Pan-African magmatism. In view of the close association of the studied high-T migmatites with hundreds of synmetamorphic high-T granites that invaded the terrane as metre- to decametre-wide sills and dykes, we postulate that crystallization of felsic lower crustal magma is, at least partly, responsible for heat supply. Late-stage isobaric cooling of these granites may explain the occurrence of andalusite in some samples.
CRIS-Team Scopus Importer:2019-10-11
Keywords: Damara orogen; granulite facies metamorphism; Lu–Hf garnet dating; migmatites; Namibia

Metamorphic P–T–t evolution of mafic HP granulites in the northeastern segment of the Tarim Craton (Dunhuang block): Evidence for early Paleozoic continental subduction - He, Zhenyu; Zhang, Zeming; Zong, Keqing; Xiang, Hua; Klemd, Reiner (Lithos, 2014)
The Dunhuang block, which constitutes the northeastern segment of the Tarim Craton, is located between the Central Asian Orogenic Belt (CAOB) to the north and the Altyn-Qilian Orogenic Belt to the south. The present study reveals that the early Paleozoic HP mafic granulites from the Dunhuang block underwent four stages of metamorphism: prograde amphibolite-facies (M1), peak high-pressure (HP) granulite-facies (M2) and two late stages of amphibolite-facies retrograde metamorphism. Based on phase equilibrium modeling, P-T conditions of the four stages of metamorphism are estimated at 720-750. °C and 11-13. kbar, 760-800. °C and 14-16. kbar, 690-720. °C and 8-8.5. kbar, and at <. 6. kbar and <. 640. °C respectively. Peak granulite-facies metamorphism is characterized by a low geothermal gradient of ca. 16. °C/km. Zircon U-Pb dating shows that the HP granulite-facies metamorphism occurred at ca. 431. Ma and the early retrograde amphibolite-facies overprint at ca. 403. Ma. Thus the investigated mafic rocks here reveal a clockwise P-T-t path involving burial heating before peak granulite-facies metamorphism and subsequent decompression-cooling with an uplift rate of ca. 0.8. km/Ma. This, together with a continental affinity of the HP metamorphic rocks, indicates that the Dunhuang block experienced a collisional orogenesis during the early Paleozoic. © 2014 Elsevier B.V.
UnivIS-Import:2015-03-09:Pub.2014.nat.dgeo.IGM.c3geoc.metamo
Keywords: Beishan orogenic collage; CAOB; Dunhuang block; Early Paleozoic; HP granulite; P-T-t path

Metamorphic Response to Alpine Thrusting of a Crustal-scale Basement Nappe in Southern Calabria (Italy) - Brandt, Sönke; Schenk, V. (Journal of Petrology, 2020)
Structural, geophysical and age data indicate that the tilted cross-section of the Variscan continental crust exposed in the Serre of southern Calabria forms the uppermost Alpine nappe ('Serre nappe') of three Variscan basement slices derived from the southern European margin. This Alpine nappe stack is a fragment of the western Mediterranean Alps and rests now, after Miocene emplacement, on top of the Apennine carbonate platform. We report for the first time a P-T path for prograde Alpine metamorphism, which is restricted to the two lower nappes (Castagna and Bagni nappes) that are squeezed between cooler tectonic units, the Serre nappe above and the Apennine platform below. Therefore, we attribute their metamorphism to tectonic loading and concomitant shear heating during Eocene south-directed overthrusting of the crustal-scale Serre nappe. In the underlying Castagna nappe, Alpine metamorphism is only locally recorded, mainly by new growth of garnet, forming at the expense of retrogressed Variscan biotite dated at 43 Ma. The local existence of Alpine besides relict Variscan mineral assemblages in the strongly but heterogeneously overprinted rocks allows for characterization of metamorphic evolutions during both the Alpine and Variscan orogeneses in the former intermediate level of the Variscan crust of Calabria. The metamorphic evolutions have been reconstructed through P-T pseudosection modelling for Al-rich metasediments. In the Castagna nappe, rarely preserved Variscan garnet-sillimanite-biotite-ilmenite-plagioclase-quartz (+/- K-feldspar Si-poor white mica) assemblages formed under amphibolite-facies subsolidus conditions (650 +/- 60 degrees C, 4.0 +/- 0.5 kbar). During subsequent decompression and cooling to greenschist-facies conditions garnet was replaced by biotite-sillimanite and later by white mica-chlorite intergrowths. Retrogression of Variscan biotite is evidenced by the exsolution of ilmenite along grain boundaries and cleavages, textures that were subsequently overgrown by Alpine garnet coexisting with Si-rich white mica, rare chloritoid (in metapelites), and hornblende (in metagreywackes). Alpine garnet shows prograde zoning and is Ca-rich, and thus is distinct from unzoned and Ca-poor Variscan garnet porphyroblasts. Estimated conditions (520 +/- 40 degrees C, 8.0 +/- 1.0 kbar) record elevated pressures during Alpine lower amphibolite-facies metamorphism. In the lowermost Bagni nappe, rare prograde-zoned, Ca-rich garnet in strongly retrogressed mylonitic quartz-phyllites allows isopleth thermobarometry, which indicates lower amphibolite-facies conditions (555 +/- 10 degrees C, 7.4 +/- 0.3 kbar) resembling those for Alpine garnet growth in the Castagna nappe. The similar clockwise P-T paths for prograde Alpine metamorphism and the consistent peak pressures of 7-9 kbar in the Castagna and Bagni nappes point to a joint short-lived metamorphism during overthrusting of the crustal-scale Serre nappe within the south European margin during the north-directed subduction of the Alpine Tethys. South-directed overthrusting of the now tilted Variscan crustal section of the Serre along the up to 500 m thick mylonite horizon of the Curinga-Girifalco Line is in agreement with seismic data indicating an extended, few kilometres thick low-velocity zone (Bagni and Castagna nappes and mylonites of the Curinga-Girifalco Line) below the exposed lower crustal section of the Serre nappe.
CRIS-Team WoS Importer:2021-05-14

Meteoritic Molybdenum and Ruthenium Isotopic Abundances Document Nucleosynthetic p-process Components - Marti, Kurt; Fischer-Gödde, Mario; Proksche, Carina (Astrophysical Journal, 2023)
Anomalies in isotopic abundances of Mo and Ru in solar system matter were found to document variable contributions of the nucleosynthetic s-process component. We report isotopic relations of ϵ 92Mo versus ϵ 100Ru in meteorites from chondritic parent bodies, iron meteorites, and achondrites that reveal deviations from expected s-process abundance variations. We show that two p-process isotopes 92Mo and 94Mo require the presence of distinct p-process components in meteoritic materials. The nucleosynthetic origin of abundant magic (N = 50) p-process nuclides, covering the mass range of Zr, Mo, and Ru, has long been an enigma, but contributions by several recognized pathways, including alpha and νp-antineutrino reactions on protons, may account for the observed relatively large solar system abundances. Specific core-collapse supernovae explosive regions may carry proton-rich matter. Since Mo and Ru isotopic records in solar system matter reveal the presence of more than one nucleosynthetic p-process component, these records are expected to be helpful in documenting different explosive synthesis pathways and the implied galactic evolution of p-nuclides.
CRIS-Team Scopus Importer:2023-11-03

Metre-scale effective flow properties of heterogeneous fine-grained sediments - Kurtev, Kuncho; Drews, Michael; Ma, Jingsheng; Aplin, Andrew (EAGE Shale Workshop 2010: Shale - Resource and Challenge, 2010)

Miaolingian (Cambrian) trilobite biostratigraphy and carbon isotope chemostratigraphy in the Tingskullen drill core, Öland, Sweden - Ahlberg, Per; Lundberg, Frans; Calner, Michael; Lehnert, Oliver; Dahlqvist, Peter; Joachimski, Michael (Estonian Journal of Earth Sciences, 2021)
The Cambrian succession of the Tingskullen drill core from northern Öland comprises Cambrian Series 2 and Miaolingian (Wuliuan Stage) siliciclastic strata. The major portion of the succession is represented by the Miaolingian Borgholm Formation, which, in ascending order, is subdivided into the Mossberga, Bårstad and Äleklinta members. The Äleklinta Member is barren of body fossils, whereas the Mossberga and Bårstad members are moderately to highly fossiliferous and biostratigraphically reasonably well constrained. Trilobites and agnostoids from the Bårstad Member are indicative of the Acadoparadoxides pinus Zone. The Mossberga Member has not yielded any zonal guide fossils but is tentatively assigned to the Eccaparadoxides insularis Zone. A δ13Corg curve throughout the Borgholm Formation shows a general positive trend up-section without any distinctive excursion, suggesting that the Wuliuan Acadoparadoxides (Baltoparadoxides) oelandicus Superzone (the ‘Oelandicus beds’) of Öland is younger than the negative Redlichiid–Olenellid Extinction Carbon isotope Excursion (ROECE), which is known from near the top of Stage 4 and close to the traditional ‘Lower–Middle Cambrian boundary’ in several parts of the world.<br

Microbial bioerosion of erratic sub-fossil Nautilus shells in a karstic cenote (Lifou, Loyalty Islands, New Caledonia) - Seuß, Barbara; Wisshak, Max; Mapes, Royal H.; Hembree, Daniel I.; Landman, Neil; Lignier, Vincent (Ichnos-An International Journal For Plant and Animal Traces, 2016)
UnivIS-Import:2016-06-01:Pub.2016.nat.dgeo.IGM.LP.microb
Keywords: Bioerosion; Cenote; Holocene; Ichnocoenosis; Karst; Nautilus; New Caledonia; Taphonomy

Microbially induced wrinkle structures in Middle Devonian siliciclastics from the Prague Basin, Czech Republic - Vodrážková, Stanislava; Vodrážka, Radek; Munnecke, Axel; Franců, Juraj; Al‐Bassam, Khaldoun; Halodová, Patricie; Tonarová, Petra (Lethaia, 2018)
The occurrence of wrinkle structures in Middle Devonian deep‐water siliciclastic sequences of the Prague Basin (Roblín Member, Srbsko Formation, Givetian) is reported and interpreted to be microbially induced. Current and/or gravitational forces are considered the simplest explanation of the origin of these structures. Taking into account the tectonic activity linked with ongoing Variscan orogeny, the wrinkle structures could also be interpreted as soft sediment deformation structures originating due to exposure of mat‐bearing sediment to seismic shocks. The distribution of n‐alkanes and isoprenoids suggests two types of prevailing biological sources, namely phytoplankton, representing organic material from the water column, and benthic bacteria. Judging from the sedimentary facies and lack of petrographic characteristics suggestive of light competition, the microbial mats are interpreted to be formed by non‐autotrophic bacteri

Microbioerosion in Tahitian reefs: A record of environmental change during the last deglacial sea-level rise (IODP 310) - Heindel, Katrin; Wisshak, Max; Westphal, Hildegard (Lethaia, 2008)
The main motivation for Integrated Ocean Drilling Program Expedition 310 to the Tahitian Archipelago was the assumption that the last deglacial sea-level rise is precisely recorded in the coral reefs of this far-field site. The Tahitian deglacial succession typically consists of coral framework subsequently encrusted by coralline algae and microbialites. The high abundance of microbialites is uncommon for shallow-water coral reefs, and the environmental conditions favouring their development are still poorly understood. Microbioerosion patterns in the three principal framework components (corals, coralline algae, microbialites) are studied with respect to relative light availability during coral growth and subsequent encrustation, in order to constrain the palaeobathymetry and the relative timing of the encrustation. Unexpectedly for a tropical, light-flooded setting, ichnotaxa typical for the deep-euphotic to dysphotic zone dominate. The key ichnotaxa for the shallow euphotic zone are scarce in the analysed sample set, and are restricted to the base of the deglacial succession, thus reflecting the deglacial sea-level rise. At the base of the deglacial reef succession, the ichnocoenoses present in the corals indicate shallower bathymetries than those in the encrusting microbialites. This is in agreement with radiocarbon data that indicate a time gap of more than 600 years between coral death and microbialite formation. At the top of the deglacial reef succession, in contrast, the microbioerosion patterns in the three framework components indicate a uniform palaeobathymetry, and radiocarbon ages imply that encrustation took place shortly after coral demise. An enigma arises from the fact that the ichnocoenoses imply photic conditions that appear very deep for zooxanthellate coral growth. During the deglacial sea-level rise increased nutrients and fluvial influx may have led to (seasonal?) eutrophication, condensing the photic zonation. This would have exerted stress on the coral ecosystem and played a significant role in initiating microbialite development.

Microfacies analysis and 3D reconstruction of bioturbated sediments in the calcarenite di Gravina formation (southern Italy) - Bonomo, Agnese Emanuela; Munnecke, Axel; Schulbert, Christian; Prosser, Giacomo (Marine and Petroleum Geology, 2021)
The Calcarenite di Gravina is a poorly lithified, heterogeneous bio-lithoclastic Plio-Pleistocene limestone formed in a temperate shallow-water setting. Since prehistoric times it has been used for construction, as witnessed by the “Sassi”, the old city center of Matera (southern Italy). Here, the relatively distal, fine-grained bioclastic grain-packstone is characterized by large bioturbation structures of crustaceans. The aim of this work is to understand how bioturbation controls texture, porosity, permeability, and the cementation of the calcarenite. Crustaceans such as Callianassa are known to produce vertical burrows and sort grains. A bioturbated calcarenite level, outcropping in the Parco Scultura- Cava Paradiso in La Palomba (Matera northern area), has been selected as case study. Large rock samples including fossil traces and surrounding rocks have been analysed. Optical microscope and SEM observations show a close connection between sediment sorting and cementation, and 3D analyses by means of CT scans indicate that the internal structure and the connected porosity of the samples is a function of the cementation. Moreover, the porosity network is reconstructed in 3D in order to derive the real connected porosity variations and their implications for the evolution in terms of diagenesis and alteration of the rocks. Indeed, a cementation gradient from the external lining of the burrows to the internal part of the trace fossil is observed. Cementation is less pronounced outside of the trace fossil. Cluster analysis of point-counting results allows to identify four sub-facies characterized by differences in composition, cementation and porosity. One of them is present in the interior of the burrows while the other two characterize the external lining (crust) and storage chamber of crustacean burrows. The last sub-facies occurs in the area surrounding the trace fossils and shows a weaker cementation. The presence of a cementation gradient inside the trace fossil is explained through a diagenetic model that considers the contribution of different factors. The geochemical environments allow the CaCO3 precipitation inside the burrows starting from the lining to the internal area thanks to the microbial actions, water circulation and relative oxygenation of fluids. Dissolution of aragonitic components probably represents the principal source of CaCO3. Variation in cementation and porosity are quite moderate, but capable of generating major differences in the resistance to weathering. From this study it emerges how the diagenetic processes lead to significant changes in the bioturbated fabric, making the burrows less permeable than the surrounding sediment. This is confirmed by the selective erosion that brings to light very well-preserved traces of Callianassidae even on building stones.
CRIS-Team Scopus Importer:2021-01-08
Keywords: 3D porosity; Bioturbation; Diagenesis; microCT-scan modelling

Microfacies and carbon isotope records of Mississippian carbonates from the isolated Bama Platform of Youjiang Basin, South China: Possible responses to climate-driven upwelling - Liu, Chao; Jarochowska, Emilia; Du, Yuansheng; Vachard, Daniel; Munnecke, Axel (Palaeogeography, Palaeoclimatology, Palaeoecology, 2015)
Changes in Mississippian global paleogeography derived from the reconfiguration of the continents have been suggested to result in a change in oceanic circulation, carbon cycling, as well as in global cooling. Here, integrated δC chemostratigraphy and foraminiferal biostratigraphy across the Mississippian (late Tournaisian, Visean, early Serpukhovian; MFZ6-MFZ16 foraminiferal biozones) of the Gongchuan section located in the isolated Bama Platform in the Youjiang Basin, South China, are presented. The δC trend shows an abrupt decline during late Visean (Asbian-early Brigantian; MFZ13-14). This decline is also observed in subequatorial western Euramerica, whereas coeval sections in subequatorial eastern Euramerica show consistently elevated δC values across the entire Visean. The δC decline in western Euramerica and the South China Block (eastern Paleo-Tethys) coincides with a global regression with a suggested glacioeustatic origin, the onset of high-frequency climate and sea-level oscillations, and the closure of the Rheic seaway between Euramerica and Gondwana. We propose a model explaining the divergence of δC records resulting from the closure of the Rheic seaway and development of upwelling zones in the western margin of Euramerica and the eastern Paleo-Tethys realm. Quantitative microfacies analysis across the Mississippian succession in the Gongchuan section shows facies-independent disappearance of corals and increased proportion of cortoids and filter-feeding organisms at the onset of the Asbian δC decline, which may support an increase in nutrient level that can be expected as a result of upwellin
Keywords: Euramerica; Foraminiferal zones; Late Paleozoic Ice Age; Paleo-Tethys; Point-counting; Visean

Microfacies, depositional environments and meter-scale cycles of the middle jurassic Tuwaiq Mountain formation, central Saudi Arabia - El-Yamani, Mahmoud Samir; Al-Ramadan, Khalid; Munnecke, Axel; Cantrell, Dave; Abdulghani, Waleed; Reub, Lukas (Journal of African Earth Sciences, 2018)

Microplastic contamination of the drilling bivalve Hiatella arctica in Arctic rhodolith beds - Teichert, Sebastian; Löder, Martin; Pyko, Ines; Mordek, Marlene; Schulbert, Christian; Wisshak, Max; Laforsch, Christian (Scientific Reports, 2021)
There is an increasing number of studies reporting microplastic (MP) contamination in the Arctic environment. We analysed MP abundance in samples from a marine Arctic ecosystem that has not been investigated in this context and that features a high biodiversity: hollow rhodoliths gouged by the bivalve Hiatella arctica. This bivalve is a filter feeder that potentially accumulates MPs and may therefore reflect MP contamination of the rhodolith ecosystem at northern Svalbard. Our analyses revealed that 100% of the examined specimens were contaminated with MP, ranging between one and 184 MP particles per bivalve in samples from two water depths. Polymer composition and abundance differed strongly between both water depths: samples from 40 m water depth showed a generally higher concentration of MPs and were clearly dominated by polystyrene, samples from 27 m water depth were more balanced in composition, mainly consisting of polyethylene, polyethylene terephthalate, and polypropylene. Long-term consequences of MP contamination in the investigated bivalve species and for the rhodolith bed ecosystem are yet unclear. However, the uptake of MPs may potentially impact H. arctica and consequently its functioning as ecosystem engineers in Arctic rhodolith bed

Microplastic pollution as a possible threat for an arctic reef system and its association of ecosystem engineers - Pyko, Ines; Löder, Martin; Schulbert, Christian; Wisshak, Max; Laforsch, Christian; Munnecke, Axel; Teichert, Sebastian (54th European Marine Biology Symposium, 2019)
The coralline red alga Lithothamnion glaciale forms rigid frameworks of magnesium calcite. The shelfs around the high arctic Svalbard archipelago (northern Norway) are intensely covered by these so-called rhodoliths. Drilled by boring mussels of the species Hiatella arctica , many rhodoliths become hollow ecospheres, inhabited by a great variety of benthic taxa. Thereby, these rhodolith communities can be regardedas arctic reef structures and increase the local biodiversity significantly, comparable to corals in the tropics. They also provide a possible nursery ground for fish. We report the first findings of microplastic ingested by individuals of H. arctica. Altogether, we identified eight different types of polymers via F-spectroscopy within the rhodolith-colonizing bivalves. The potential consequences for the bivalves can be manifold, including a negative impact on their function as an ecosystem-engineering organism. This would also affect the complete ecosystem of the Svalbard Shelf and its biodiversity.
Keywords: Arctic; biodiversity; ecosystem engineers; microplastic

Microproblematic organisms from the Norian-Rhaetian reefal carbonates of Saklikent, Taurus Mountains, southern Turkey - Senowbari-Daryan, Baba; Link, Michael (Facies, 2018)
UnivIS-Import:2018-09-05:Pub.2018.nat.dgeo.IGM.LP.microp

Microstructural evolution during initial stages of static recovery and recrystallization: New insights from in-situ heating experiments combined with electron backscatter diffraction analysis - Bestmann, Michel; et al. (Journal of Structural Geology, 2005)
Keywords: Electron backscatter diffraction; Grain boundary migration; In-situ heating; Microstructure; Rocksalt

Microstructure and fluid flow in the vicinity of basin bounding faults in rifts – The Dombjerg Fault, NE Greenland rift system - Salomon, Eric; Rotevatn, Atle; Kristensen, Thomas Berg; Grundvåg, Sten-Andreas; Henstra, Gijs Allard (Journal of Structural Geology, 2021)
Faults commonly form loci for high fluid flux in sedimentary basins, where fluids, rocks and deformation processes frequently interact. Here, we elucidate the interaction of fluid flow, diagenesis and deformation near basin-bounding faults in sedimentary basins through a study in the vicinity (0–3.5 km) of the Dombjerg Fault in the NE Greenland rift system. Due to fault-controlled fluid circulation, fault-proximal syn-rift clastics underwent pervasive calcite cementation, whereas uncemented clastics at some distance from the fault remained highly porous and friable. Correspondingly, two distinct deformation regimes developed to accommodate continued deformation: discrete brittle fractures formed in calcite cemented rocks, whereas cataclastic deformation bands formed in uncemented deposits. We show that low-permeable deformation bands forming in highly porous rocks were associated with localized host rock alteration, and chemical reduction of porosity along bands. In rocks with cementation-induced low porosity, brittle fractures created new pathways for fluids, but were subsequently filled with calcite. Occasionally, veins comprise multiple generations of microcrystalline calcite, likely precipitated from rapidly super-saturated fluids injected into the fractures. This suggests cemented deposits sealed uncemented compartments, where fluid overpressure developed. We conclude that compartmentalized flow regimes may form in fault-bounded basins, which has wide implications for assessments of potential carbon storage, hydrocarbon, groundwater, and geothermal sites.
CRIS-Team Scopus Importer:2021-10-29
Keywords: Syn-rift; Fluid flow; Fault evolution; Structural diagenesis; Fracturing; Cementation

Microstructures of modern sea pen axes – a tool for the systematics of fossil pennatulaceans (Octocorallia) - Roden, Vanessa; Reich, Mike (Terra Nostra 2012/3, 2012)

Middle Ordovician sea-level changes and the evolution of the Ordovician conodont genus Cahabagnathus Bergström, 1983. - Leslie, Stephen Andrew; Lehnert, Oliver (Journal of Paleontology, 2005)
UnivIS-Import:2015-03-09:Pub.2005.nat.dgeo.IGM.LG.middle

Middle to Late Ordovician carbon isotope chemostratigraphy of the Lower Yangtze Platform: Implications for global correlation - Gong, Fangyi; Joachimski, Michael; Yan, Guanzhou; Li, Lixia; Wei, Xin; Wu, Rongchang (Geological Journal, 2021)
Middle to Late Ordovician carbonates were collected in South China (Anhui Province) from the Kuniutan, Datianba, and Pagoda formations in the Dingxiang and Daling sections and analysed for high‐resolution carbon isotope chemostratigraphy. An increase by 0.4‰ in δ13Ccarb is observed in the upper part of the Kuniutan Formation (Eoplacognathus pseudoplanus Biozone), representing the rising limb of the Middle Darriwilian Isotopic Carbon Excursion (MDICE). In the upper part of the Datianba Formation, positive shifts of ca. 1‰ are recorded in the studied section which compare with the carbon shifts reported in North America and Baltoscandia. A pronounced positive δ13Ccarb excursion of ca. 1.5‰ from the lower part of the Pagoda Formation can be correlated with the global Guttenberg Isotopic Carbon Excursion (GICE). The documentation of three carbon isotope shifts in this study provides new evidence for changes in the global carbon cycle from Darriwilian to Early Katian which could have been influenced by changes in global climate and primary productivity.<br

Middle to Upper Jurassic bivalves of the southwestern Morondava Basin (Madagascar) - Fürsich, Franz; Ayoub-Hannaa, Wagih; Heinze, Michael (Zitteliana, 2019)

Mid-ocean ridge basalt generation along the slow-spreading, South Mid-Atlantic Ridge (5-11°S): Inferences from 238U- 230Th- 226Ra disequilibria - Turner, Simon P.; Kokfelt, Thomas; Hauff, Folkmar; Haase, Karsten; Lundstrom, Craig; Hoernle, Kaj; Yeo, Isabel; Devey, Colin (Geochimica Et Cosmochimica Acta, 2015)
U-series disequilibria have provided important constraints on the physical processes of partial melting that produce basaltic magma beneath mid-ocean ridges. Here we present the first 238U-230Th-226Ra isotope data for a suite of 83 basalts sampled between 5°S and 11°S along the South Mid-Atlantic Ridge. This section of the ridge can be divided into 5 segments (A0-A4) and the depths to the ridge axis span much of the global range, varying from 1429 to 4514m. Previous work has also demonstrated that strong trace element and radiogenic isotope heterogeneity existed in the source regions of these basalts. Accordingly, this area provides an ideal location in which to investigate the effects of both inferred melt column length and recycled materials. 226Ra-230Th disequilibria indicate that the majority of the basalts are less than a few millennia old such that their 230Th values do not require any age correction. The U-Th isotope data span a significant range from secular equilibrium up to 32% 230Th excess, also similar to the global range, and vary from segment to segment. However, the (230Th/238U) ratios are not negatively correlated with axial depth and the samples with the largest 230Th excesses come from the deepest ridge segment (A1). Two sub-parallel and positively sloped arrays (for segments A0-2 and A3 and A4) between (230Th/238U) and Th/U ratios can be modelled in various ways as mixing between melts from peridotite and recycled mafic lithologies. Despite abundant evidence for source heterogeneity, there is no simple correlation between (230Th/238U) and radiogenic isotope ratios suggesting that at least some of the trace element and radiogenic isotope variability may have been imparted to the source regions > 350kyr prior to partial melting to produce the basalts. In our preferred model, the two (230Th/238U) versus Th/U arrays can be explained by mixing of melts from one or more recycled mafic lithologies with melts derived from chemically heterogeneous peridotite source regions.

Migration of Arc Magmatism Above Mantle Wedge Diapirs With Variable Sediment Contribution in the Aegean - Schaarschmidt, Anna; Haase, Karsten; Voudouris, Panagiotis C.; Melfos, Vasilios; Klemd, Reiner (Geochemistry Geophysics Geosystems, 2021)

Migration von Weichmachern und Beschichtungen während der extrakorporalen Perfusion in der Kardiotechnik - Münch, Frank; Göen, Thomas; Schulbert, Christian; Cesnjevar, Robert; Ihlenburg, Katharina Susanne (Abstracts der 40. Internationalen Jahrestagung der DGfK und 3. Fokustagung Herz, 2011)
UnivIS-Import:2017-12-18:Pub.2011.nat.dgeo.IGM.LP.migrat

Mineralization of autochthonous particulate organic carbon is a fast channelof organic matter turnover in Germany's largest drinking water reservoir - Dordoni, Marlene; Seewald, Michael; Rinke, Karsten; Friese, Kurt; van Geldern, Robert; Schmidmeier, Jakob; Barth, Johannes (Biogeosciences, 2022)
Turnover of organic matter (OM) is an essential ecological function in inland water bodies and relevant for water quality especially for the potential of dissolved organic carbon (DOC) removal as well as due to emissions of CO2. We investigated various sources of OM including DOC, autochthonous particulate organic carbon (allo-POC), allochthonous particulate organic carbon (allo-POC), and sedimentary matter (SED) in a temperate drinking water reservoir (Rappbode Reservoir, Germany) with respect to carbon isotope ratios and concentration dynamics. For this purpose, we focused on the metalimnion and the hypolimnion, where respiratory turnover is expected to be dominant and hardly disturbed by atmospheric exchange. The observation period of nine months covered a complete stratification period of the water body. Dissolved inorganic carbon (DIC) concentrations and its isotopes (delta C-13(DIC)) were considered together with isotope data of DOC and POC (delta C-13(DOC) and delta C-13(POC)) as input parameters for mass balances. DIC concentrations ranged between 0.30 and 0.53 mmol L-1 , while delta C-13(DIC) values were between -15.1 and -7.2 parts per thousand versus the VPDB (Vienna PeeDee Belemnite) standard. Values of delta(13)C(DOC )and delta C-13(auto-POC) ranged between -28.8 and -27.6 parts per thousand and between -35.2 and -26.8 parts per thousand, respectively. Isotope compositions of sedimentary material and allochthonous POC were inferred from the literature with average values of delta C-13(SED) = -30.7 parts per thousand, and delta C-13(allo-POC) = -31.8 parts per thousand. Comparison of DIC concentration gains and stable isotope mass balances showed that autochthonous POC from primary producers was the main contributor to DIC increases, while contributions from DOC, ExtPOC and SED played a minor role. OM turnover rates, i.e. the conversion of organic carbon towards DIC, calculated with our isotope approach were within the range for oligotrophic water bodies (0.01 to 1.3 mu mol L(-1 )d(-1)). Some higher values in the metalimnion are likely due the availability of settling POC from the photic zone. Samples from a Metalimnetic Oxygen Minimum (MOM) showed a clear dominance of respiration over photosynthesis through bacterial degradation of autochthonous POC. These high turnover rates further highlight a close link with planktonic biological assemblages. Our work shows that respiration in temperate lentic water bodies largely depends on autochthonous POC production as a major carbon source
CRIS-Team WoS Importer:2022-12-09

MINERALOGICAL, BIB-SEM AND PETROPHYSICAL DATA IN SEAL ROCK ANALYSIS: A CASE STUDY FROM THE VIENNA BASIN, AUSTRIA - Misch, D.; Siedl, W.; Drews, Michael; Liu, B.; Klaver, J.; Pupp, M.; Sachsenhofer, R. F. (Journal of Petroleum Geology, 2021)
The Vienna Basin is a major hydrocarbon province with a long exploration history. Within the basin, secondary migration from Upper Jurassic source rocks into stacked Middle Miocene (Badenian) sandstone reservoirs was formerly considered to have occurred almost entirely along major fault zones. However recent exploration data has suggested that in areas where no major faults are present, oil may have migrated vertically through the sandy mudstone intervals separating individual reservoir units, which are therefore imperfectly sealed. In order to investigate possible secondary migration through the semi-permeable mudstones, this study links variations in gross depositional environment (GDE) to variations in mudstone properties (e.g. mineralogy and pore size distribution). The study focussed on the mudstones which seal reservoir sandstones referred to locally as the “8.TH” and “16.TH” units. The bulk mineralogical composition of 56 mudstone and sandy mudstone (and minor intercalated muddy sandstone) samples from seal layers in 22 wells was studied by X-ray diffraction analysis, broad ion beam – scanning electron microscopy (BIB-SEM), mercury intrusion porosimetry (MICP) and N2 adsorption. These data are interpreted in the context of GDE maps of the Vienna Basin which were previously established using seismic and well log data. Results indicate that the gross depositional environment strongly controlled the pore space characteristics of the mudstones. The sandy mudstones in the NW part of the study area were influenced by a complex eastward-prograding deltaic system which deposited coarse detritus into a major palaeo depression (“Zistersdorf Depression”) located in the centre of the basin. Higher overall porosity and a dominance of larger pore size classes, probably resulting in reduced seal quality, were observed for sandy mudstones from well locations within feeder channels and also from within the Zistersdorf Depression. Similarly, sandy mudstones from locations associated with the long-term input of coarser sediments in shoreline, coastal and proximal offshore settings in the NW and central parts of the study area are considered to be of lower sealing quality compared to fine-grained mudstones deposited in distal, open-marine settings which prevailed in the SE part of the study area throughout the Middle Miocene. In general, pore geometries were influenced by mineralogical composition; quartz- and detrital carbonate-rich samples show equidimensional pores, while more elongated pores (with a higher average aspect ratio) characterize clay-rich samples. Furthermore, matrix mesopores (2-50 nm) determined by N2 sorption are more abundant in clay-rich versus quartz-rich samples, and show a pronounced positive trend with increasing percentage of illite-smectite mixed-layer clay minerals. This study shows that regional-scale mudstone seals in the Vienna Basin have been influenced by variations in sedimentation associated with lateral variations in gross depositional environment during the Middle Miocene. The observed pore characteristics will serve as input data for future models of secondary migration.
CRIS-Team Scopus Importer:2020-12-25
Keywords: Austria; BIB-SEM; cap rocks; gas adsorption; hydrocarbon migration; MICP; Miocene; sandstone reservoirs.; seal capacity; Vienna Basin

Mineralogical characteristics of Ettringites synthesized from solutions and suspensions - Neubauer, Jürgen; Götz-Neunhoeffer, Friedlinde; Schwesig, Peter (Cement and Concrete Research, 2006)
Due to the wide technical importance of Ettringite (3CaO•Al 2O3•3CaSO4•32H2O) in hydrated cement based systems, four different synthesis methods were applied to get a better overview on how and under what favoring conditions Ettringite can be formed. In the first step different precipitation methods resulting in Ettringite were established. For all methods Al3+ was supplied by aqueous CO2-free solution of Al2(SO4) 3•18H2O. As a source of CaO-supply a clear solution and otherwise a Ca(OH)2-suspension was utilized. Four synthesis routes with and without sucrose were employed. Variation of reaction parameter like temperature, time of reaction, pH-value of synthesis solution and influence of additional Gypsum were investigated. The qualitative phase analysis was performed by X-ray diffraction method (XRD). Morphological aspects of some synthesis products were studied by scanning electron microscopy (SEM). Finally lattice and structural parameter of the Ettringites were determined by refinement of XRD-pattern using the Rietveld-Method. © 2005 Elsevier Ltd. All rights reserved.
UnivIS-Import:2015-03-09:Pub.2006.nat.dgeo.IGM.LM.minera
Keywords: Characterization; Ettringite; SEM; X-ray diffraction

Mineralogical, compositional and isotope characterization of human kidney stones (urolithiasis) in a Sri Lankan population - Chandrajith, Rohana; Weerasingha, Anushka; Premaratne, Kusala M.; Gamage, Dhanushke; Abeygunasekera, Anuruddha M.; Joachimski, Michael; Senaratne, Atula (Environmental Geochemistry and Health, 2019)
Keywords: FTIR; Hydroxylapatite; Calcium oxalate monohydrate; Carbon isotopes; Trace elements; Urinary stones

Mineralogical constraints on the potassic and sodic-calcic hydrothermal alteration and vein-type mineralization of the maronia porphyry cu-mo ± re ± au deposit in NE greece - Melfos, Vasilios; Voudouris, Panagiotis; Melfou, Margarita; Sánchez, Matías G.; Papadopoulou, Lambrini; Filippidis, Anestis; Spry, Paul G.; Schaarschmidt, Anna; Klemd, Reiner; Haase, Karsten; Tarantola, Alexandre; Mavrogonatos, Constantinos (Minerals, 2020)
The Maronia Cu-Mo ± Re ± Au deposit is spatially related to a microgranite porphyry that intruded an Oligocene monzonite along the Mesozoic Circum-Rhodope belt in Thrace, NE Greece. The magmatic rocks and associated metallic mineralization show plastic and cataclastic features at the south-eastern margin of the deposit that implies emplacement at the ductile-brittle transition, adjacent to a shear zone at the footwall of the Maronia detachment fault. The conversion from ductile to brittle deformation caused a rapid upward magmatic fluid flow and increased the volume of water that interacted with the host rocks through high permeable zones, which produced extensive zones of potassic and sodic-calcic alteration. Potassic alteration is characterized by secondary biotite + K-feldspar (orthoclase) + magnetite + rutile + quartz ± apatite and commonly contains sulfides (pyrite, chalcopyrite, pyrrhotite). Sodic-calcic alteration consists of actinolite + sodic-calcic plagioclase (albite/oligoclase/andesine) + titanite + magnetite + chlorite + quartz ± calcite ± epidote-allanite. The high-oxidation state of the magmas and the hydrothermal fluid circulation were responsible for the metal and sulfur enrichments of the aqueous fluid phase, an increase in O2 gas content, the breakdown of the magmatic silicates and the production of the extensive potassic and sodic-calcic alterations. Brittle deformation also promoted the rapid upward fluid flow and caused interactions with the surrounding host rocks along the high temperature M-, EB-, A-and B-type veins.
CRIS-Team Scopus Importer:2020-03-06
Keywords: Greece; Maronia; Porphyry deposit; Potassic alteration; Sodic-calcic alteration; Vein-types

Mineralogical features of Ettringites synthesized from solutions and suspensions - Götz-Neunhoeffer, Friedlinde; Neubauer, Jürgen; Schwesig, Peter (Proceedings of the 24th International Conference on Cement Microscopy, 2002)
UnivIS-Import:2015-03-09:Pub.2002.nat.dgeo.IGM.LM.minera

Mineralogical, geochemical and isotopic features of tuffs from the CFDDP drill hole: hydrothermal activity in the eastern side of the Campi Flegrei volcano (southern Italy). - Mormone, A.; Troise, Claudia; Piochi, M.; Balassone, G.; Joachimski, Michael; De Natale, Giuseppe (Journal of Volcanology and Geothermal Research, 2015)
A 506. m drill-hole has been recently drilled in the framework of the Campi Flegrei Deep Drilling Project (CFDDP) and the International Continental Scientific Drilling Program (ICDP) with the intention of coring the subsurface in the eastern sector of the Campi Flegrei caldera. The borehole, located in the western district of the Neapolitan city (Bagnoli Plain) 3. km to the east of the most active volcanic area and about 5. m above sea level, is now targeted for monitoring purposes.This paper reports the results obtained from the analysis of two short cores collected at depths of -443 and -506m below the ground level. The cores sampled two pre-caldera tuffs. Observations performed by optical and scanning electron microscopy, energy dispersive spectroscopy and powder X-ray diffraction were used to achieve data on the primary lithology, both primary and secondary mineralogical assemblages, and the relationship between texture and secondary mineralization. Sr isotope ratios were determined on selected primary feldspars, whereas δ13C and δ18O analyses were performed on carbonates from veins and filled-voids in tuffs.Our results provide information on the hydrothermal system in the eastern sector of the caldera that was not among the goals in the previous drilling programs. Secondary mineralization suggests a saline hydrothermal environment characterized by fluids that progressively evolved from boiling toward more alkaline and cooler conditions. A paleo-temperature of ca. 160. °C has been inferred from authigenic mineral occurrences and calculated on the basis of equilibria between cored calcites and fluids presently emitted at the surface, by using carbon and oxygen isotope data. The temperature measured at the bottom of the drilling is about 80. °C.
UnivIS-Import:2015-07-08:Pub.2015.nat.dgeo.IGM.LG.minera
Keywords: Campi Flegrei; Core samples; Geothermal field; Hydrothermal activity; Pilot-hole

Mineralogical, microstructural and magnetic studies on natural pyrrhotite from a 260°C section at the KTB Drilling Site /Germany - Kontny, Agnes; de Wall, Helga; Sharp, Thomas G.; Pósfai, Mihály (American Mineralogist, 2000)
UnivIS-Import:2015-03-09:Pub.2000.nat.dgeo.IGM.c3tekt.minera

Mineralogische Charakterisierung synthetischer Ettringite - Schwesig, Peter; Neubauer, Jürgen (European Journal of Mineralogy, 2000)
UnivIS-Import:2015-03-09:Pub.2000.nat.dgeo.IGM.LM.minera_8

Mineralogy and elemental geochemistry of pyrite coal-balls, Datong Coalfield, Shanxi Province, China: Implications for differentiation mechanism - Hao, Huidi; Huang, Wenhui; Hao, Ruilin; Mu, Nana; Wen, Long; Yu, Chunlan (Ore Geology Reviews, 2023)
The pyrite coal-balls found in No.9 coal of Taiyuan Formation in Dongzhouyao Mine of Datong Coalfield were selected to investigate its mineralogy and elemental geochemistry using optical microscope observation, scanning electron microscopy combined with an energy-dispersive X-ray spectrometer (SEM-EDX), inductively coupled plasma mass spectrometry analysis (ICP-MS), laser ablation inductively-coupled plasma mass spectrometry (LA-ICP-MS), and electron probe micro-analysis (EPMA). Due to the high content of pyrite, the major-element oxides in the coal-ball samples were mainly Fe2O3, with an average of 62.68 %. LA-ICP-MS results showed that coal-balls were enriched in Tl (CC = 32.79), Pb (CC = 9.22), and Mo (CC = 2.07), while the coals in the same layer were enriched in Ga (CC = 5.31), Tl (CC = 3.66), and Li (CC = 2.27). Affinities to S or Fe and the variation of elemental concentration in the environment during the formation of coal-balls were the primary factor of the elemental differentiation between coals and coal-balls, as well as within coal-balls. The coal-balls formed in four stages in a marine-continental transition environment, with Fe from terrestrial sources and S from marine phases, and its physical origin is basically consistent with that of some Carboniferous-Permian coals in the Datong Coalfield. According to the formation sequence and geochemical characteristics, four periods of pyrite coal-balls evolution have been proposed.
CRIS-Team Scopus Importer:2023-06-30
Keywords: Coal-balls; Datong Coalfield; Formation mechanism; Geochemical characteristics; Mineralogical characteristics

Mineralogy and magnetic behavior of pyrrhotite from a 260°C section at the KTB drilling site, Germany - de Wall, Helga; et al. (American Mineralogist, 2000)

Mismatches of threat status and actual extinctions in Quaternary reef corals - Raja, Nussaïbah Begum; Lauchstedt, Andreas; Pandolfi, John M.; Kim, Sun W.; Budd, Ann F.; Kießling, Wolfgang (GSA 2020 Connects Online, 2020)
Species traits and spatial distributions influence the extinction risk of species as a result of abiotic and biotic change. We performed a comparative assessment of the relationship between traits and extinction risk of reef corals in the modern oceans against Plio-Pleistocene reef corals. We chose the Plio-Pleistocene as most of the corals during this time are still present today and their traits are thus comparable to those of modern corals. As such, the regional extinctions of reef corals during this time, attributed to climate change, may shed light on which traits contribute to the resilience or vulnerability of reef building corals in the face of contemporary ocean warming. We applied predictive modelling using two morphological and two distributional traits of 585 extant reef coral species together with data on extinction risk as reported by the International Union for Conservation of Nature (IUCN). This model was then validated against the fossil corals. Although our model performed well in the prediction of the extinction risk of modern corals (82% match), the match between our modelled extinction risk and observed extinction during the Plio-Pleistocene was not better than random. This suggests that either 1) the IUCN status for reef corals may not reflect true extinction risk, or 2) the drivers of extinction during the Plio-Pleistocene may be considerably different from the conditions currently observed in the oceans. This underlines the need to incorporate fossil data when assessing the vulnerability of extant species to climate chang

Mississippian d13Ccarb and conodont apatite d18O records - Their relation to the Late Palaeozoic Glaciation - Buggisch, Werner; Joachimski, Michael; Sevastopulo, George; Morrow, Jared R. (Palaeogeography, Palaeoclimatology, Palaeoecology, 2008)
UnivIS-Import:2015-03-09:Pub.2008.nat.dgeo.IGM.LG.missis

Mistelgau - Schulbert, Christian (2010)
Keywords: Tongrube; Unterer Jura; Mittlerer Jura; Mistelgau

Mixing and transport of water in a karst catchment: A case study from precipitation via seepage to the spring - Barth, Johannes; et al. (Hydrology and Earth System Sciences, 2009)

Mobility, turnover and storage of pollutants in soils, sediments and waters: Achievements and results of the EU project AquaTerra. A review - Barth, Johannes; Grathwohl, P.; Fowler, H. J.; Bellin, Alberto; Gerzabek, M. H.; Lair, G. J.; Barcelo, D.; Petrovic, Mira; Navarro, A.; Negrel, Ph.; Petelet-Giraud, E.; Darmendrail, D.; et al. (Agronomy For Sustainable Development, 2009)

Mobility, turnover and storage of pollutants in soils, sediments and waters: Achievements and results of the EU project AquaTerra - A review - Barth, Johannes; Grathwohl, P.; Fowler, H. J.; Bellin, Alberto; Gerzabek, M. H.; Lair, G. J.; Barcelo, D.; Petrovic, Mira; Navarro, A.; Negrel, Ph.; Petelet-Giraud, E.; Darmendrail, D.; et al. (2009)

Model for economic evaluation of closed-loop geothermal systems based on net present value - Xiao, Dong; Liu, Mingjie; Li, Li; Cai, Xinhui; Qin, Shan; Gao, Ruoyu; Liu, Jianhong; Liu, Xiantao; Tang, Haijun; Li, Gao (Applied Thermal Engineering, 2023)
Closed-loop geothermal systems (CGSs) represent an effective means of extracting low-grade thermal energy from hot dry rock (HDR). Thus far, there has been much debate on whether they can be profitable because no economic evaluation model has been available. This study highlights the profitability of geothermal projects by developing a techno-economic coupling model for economic evaluation of CGSs based on net present value (NPV) for the first time. The proposed model was applied and analyzed in the case of the Gonghe Basin, Qinghai, China. The results indicate the following conclusions. (1) The technical model was extremely accurate, and the results were consistent with experimental results and the results of calculations using other classical models (the relative errors were all less than 9.8 %). (2) In terms of the heat extraction effect, the heat extraction power of U-shaped closed-loop geothermal systems (UCGSs) is ∼ 1.3 times that of coaxial closed-loop geothermal systems (CCGSs). The heat extraction power for direct heating is ∼ 1.1 times that for electricity generation. (3) Increasing the rate of the one-off government subsidy to 30 %, increasing the heat price by 30 %, and reducing the drilling cost by 30 % can make a CGS profitable within a production time of 50 years. This study will serve as a theoretical foundation for policymakers and engineers to develop HDR resources using CGSs.
CRIS-Team Scopus Importer:2023-07-07
Keywords: Closed-loop geothermal system; Economic evaluation; Hot dry rock; Net present value; Techno-economic coupling model

Modeling and experiments on energy loss in horizontal connecting pipe of vertical ground source heat pump system - Luo, Jin; Bayer, Manfred; Prieß, Anna; Rohn, Joachim (Applied Thermal Engineering, 2013)
Keywords: Energy loss; Ground source heat pump system; Horizontal connecting pipe; Pipe burial depth Heat carrier fluid; Pipe insulation

Modeling the carbon and sulfur isotope compositions of marine sediments: climate evolution during the Devonian. - Buggisch, Werner; Joachimski, Michael; et al. (Chemical Geology, 2007)
A model of global biogeochemical cycles coupled to an energy-balance climatic model (modified after the COMBINE model; [Goddéris, Y., Joachimski, M.M., 2004. Global change in the Late Devonian: modeling the Frasnian-Famennian short-term carbon isotope excursions. Palaeogeogr. Palaeoclimatol. Palaeoecol. 202, 309-329]) is used to calculate the short-term evolution of atmospheric pCO2 during the Devonian. The geochemical cycles for carbon, alkalinity, phosphorus, sulfur and oxygen are included in this model, with also 13C and 34S cycles. High-resolution records of δ13C of marine carbonates and δ34S of marine sulfates are used as forcing parameters of the geochemical cycles in an inverse modeling. Atmospheric pCO2 and pO2 at the end of the Silurian are calculated to have been 3000 ppmv and 0.165 bar (0.75 PAL), respectively. A long-term decrease in pCO2 is modeled for almost the entire Devonian. Short-term lowering of pCO2 to concentrations around 2000 ppmv is calculated for the Silurian-Devonian transition and the Pragian. Contents around 900 ppmv are modeled for the Eifelian-Givetian, Givetian-Frasnian and Frasnian-Famennian boundaries as a consequence of enhanced organic carbon burial during deposition of Lochkovian, Eifelian, and Frasnian grey and black shales. Organic carbon burial is enhanced by the increase of phosphorus delivery to the ocean triggered by short-term sea-level falls. The corresponding short-term global climatic cooling at the Silurian-Devonian boundary, at the end of the Pragian, and the Givetian-Frasnian as well as Frasnian-Famennian boundaries reached 2 °C at the equator. The rapid colonization of continental surface by land plants during the Middle and Late Devonian, increasing chemical alteration of the continents and CO2 consumption by silicate weathering, is assumed to have caused cooling of surface seawater, as suggested by the δ18O values of biogenic apatites. © 2007 Elsevier B.V. All rights reserved.
UnivIS-Import:2015-03-09:Pub.2007.nat.dgeo.IGM.LG.modeli
Keywords: Carbon; Carbon dioxide; Devonian; Isotope ratios; Modeling; Sulfur

Modelle zur Kinetik der Hydratation von Calciumaluminatzement mit Calciumsulfat aus kristallchemischer und mineralogischer Sicht - Götz-Neunhoeffer, Friedlinde (Universitätsbund Erlangen-Nürnberg, 2006)
Zur Klärung der Phasenentwicklung während der Hydratation von Calciumaluminatzement bei 23 °C wurden Röntgenbeugungsaufnahmen von hydratisierenden Pasten ausgewertet. Der Verlauf der Phasenbildung kann damit in situ dokumentiert werden. Die Pasten wurden innerhalb eines Zeitraumes von 24 h in kurzen Abständen wiederholt röntgenbeugungsanalytisch untersucht. Das Ergebnis der quantitativen Phasenanalyse der Calciumaluminatzementpasten in Kombination mit den zeitabhängigen Daten der Wärmeflusskalorimetrie ermöglicht Modelle zur Hydratation von Calciumaluminatzement bei Anwesenheit von Calciumsulfat, Li+ und Weinsäure zu entwickeln.
UnivIS-Import:2015-04-02:Pub.2006.nat.dgeo.IGM.LM.modell_8

Modelling an induced thermal plume with data from electrical resistivity tomography and distributed temperature sensing: a case study in northeast Italy - Cultrera, Matteo; Boaga, Jacopo; Di Sipio, Eloisa; Dalla Santa, Giorgia; De Seta, Massimiliano; Galgaro, Antonio (Hydrogeology Journal, 2017)
Groundwater tracer tests are often used to improve aquifer characterization, but they present several disadvantages, such as the need to pour solutions or dyes into the aquifer system and alteration of the water’s chemical properties. Thus, tracers can affect the groundwater flow mechanics and data interpretation becomes more complex, hindering effective study of ground heat pumps for low enthalpy geothermal systems. This paper presents a preliminary methodology based on a multidisciplinary application of heat as a tracer for defining the main parameters of shallow aquifers. The field monitoring techniques electrical resistivity tomography (ERT) and distributed temperature sensing (DTS) are noninvasive and were applied to a shallow-aquifer test site in northeast Italy. The combination of these measurement techniques supports the definition of the main aquifer parameters and therefore the construction of a reliable conceptual model, which is then described through the numerical code FEFLOW. This model is calibrated with DTS and validated by ERT outcomes. The reliability of the numerical model in terms of fate and transport is thereby enhanced, leading to the potential for better environmental management and protection of groundwater resources through more cost-effective solutions
Keywords: Electrical resistivity tomography . Numerical modeling . Tracer tests . Thermal response test . Distributed temperature sensing

Modelling multiseasonal preferential transport of dissolved organic carbon in a shallow forest soil: Equilibrium versus kinetic sorption - Dusek, Jaromir; Dohnal, Michal; Vogel, Tomas; Marx, Anne; Barth, Johannes (Hydrological Processes, 2019)
Parameterization of transformation and transport processes of dissolved organic carbon (DOC) in soils is challenging especially under variable hydrological conditions. In this study, DOC concentrations in stormflow were analysed with a physically based modelling approach. A one-dimensional dual-continuum vertical flow and transport model was applied to simulate subsurface processes in a macroporous forest hillslope soil over a period of 4.5 years. Microbially mediated transformations of DOC were assumed to depend primarily on soil moisture and soil temperature. Two conceptually different descriptions of the sorption of DOC to soil were examined with equilibrium and kinetic approaches. In order to quantify the uncertainties associated with the model parameterization, Monte Carlo analyses in conjunction with Latin hypercube sampling was performed. Despite the complexity of microbial transformations, the simulated temporal patterns of DOC concentrations in stormflow showed similar behaviour to those reflected in the observed DOC fluxes. Due to preferential flow, the hillslope DOC export (5.0 ± 0.5 g C · m−2 · year−1) was higher than the amounts usually reported in the literature. Overall DOC transport in hillslope scenarios could be described appropriately using the equilibrium sorption assumption. The performed analyses showed that the inclusion of the kinetic description of DOC sorption only slightly improved the predictions of the DOC hillslope export. Moreover, influences of seasonal hydro-climatological conditions on hillslope export of DOC could be observed. Reduced DOC transport during an extreme warm and dry summer was described with lower accuracy, thus indicating the difficulties in the representation of DOC transformations under dry conditions.
CRIS-Team Scopus Importer:2019-09-03
Keywords: dissolved organic carbon; DOC adsorption/desorption; dual-permeability model; hillslope discharge; kinetic sorption; Monte Carlo analysis; preferential transport; uncertainty

Modelling spatial permeability distributions in fine-grained sediments on a meter scale - Drews, Michael; Kurtev, Kuncho; Ma, Jingsheng; Aplin, Andrew; et al. (6th IMA Conference on Modelling Permeable Rocks, 2010)

Modelling Thermo-Hydraulic Coupled Phase Change Processes of BHE Induced Ground Freezing - Dalla Santa, Giorgia; Galgaro, Antonio; Farina, Zeno; Di Sipio, Eloisa; Anbergen, Hauke; Rühaak, Wolfram (EGC 2016- European Geothermal Congress Proceedings, 2016)
Keywords: Ground source heat pump; operating temperature; FEFLOW; freeze-thaw cycles; thermal conductivity; thermal plume

Modelling vSGPs (very shallow geothermal potentials) in selected CSAs (case study areas). - Bertermann, David; Klug, Hermann; Morper-Busch, Lucia; Bialas, Christian (Energy, 2014)
Very shallow geothermal energy resources are amongst the RES (renewable energy sources). They can be expressed as TC (thermal conductivity) (W/m*K) and VHC (volumetric heat capacity) (MJ/m3*K) of unconsolidated ground, and can be obtained from a depth of 10m below the Earth's surface. Utilising horizontal and vertical heat collector systems, these geothermal energy sources can be harnessed for heating and cooling purposes of residential and industrial buildings. To ensure proper prediction of available potentials at landscape or even local scale, downscaling of the already existing pan-European vSGP (very shallow geothermal potential) at a scale of 1:250,000 is required. Therefore, we applied an advanced methodology to 14 European CSAs (case study areas) from which we selected two German and one Austrian area for demonstration purposes. To ensure comparability across CSAs, national and case study related datasets were standardised and harmonised. Standards and unified spatial data processing methods across CSAs ensure comparability and seamless visualisation. Laboratory investigations on TC demonstrate valid modelling results for three depth layers, visualised in a publicly available WebGIS. © 2014 Elsevier Ltd.
UnivIS-Import:2015-03-09:Pub.2014.nat.dgeo.IGM.LG.modell
Keywords: Heat transfer; Particle-size fraction; Soil water content; Spatial analysis; TC (thermal conductivity); VHC (volumetric heat capacity); Geologie; erneuerbare Energiequelle; Bodenkunde

Modern brackish bryostromatolites (“bryoliths”) from Zeeland (Netherlands) - Harrison, G. William M.; Claußen, Anna Lene; Schulbert, Christian; Munnecke, Axel (Palaeobiodiversity and Palaeoenvironments, 2021)
Bryostromatolites are found in stressed environments from the Paleozoic to the Recent. They are formed by alternating layers of bryozoans and microbes. This study investigates recent bryostromatolites in brackish ponds in the Netherlands to better understand ancient analogues and the environments which hosted them. They formed a fringing reef at the site Ronde Weel and a barrier reef at Kaaskenswater. The ponds had low biodiversity with only one bivalve species, two gastropod species, one ostracod species, and three diatom species comprising most of the easily fossilizable taxa; one isopod species, one decapod species, and two polychaete species were also present. Observations of microbial layers and cementation practices indicate that an alternation of bryozoan-favouring conditions and microbe-favouring conditions is essential to forming bryostromatolites. The collected bryostromatolites only had tiny living bryozoan patches. Water tests confirmed a brackish environment but with enriched arsenic and titanium concentrations and periodic euxinia. The extreme environment explains the lack of biodiversity and may provide information about the environments in which past bryostromatolites formed.<br
Keywords: Bryozoan; Bryostromatolite; Reef

Modularity explains large-scale reef booms in Earth’s history - Raja, Nussaïbah Begum; Pandolfi, John M.; Kießling, Wolfgang (Facies, 2023)
Drivers of reef decline are well known both today and in the geological past. Considerably less is known about the preconditions for a pantropical expansion of coral reefs. The geological record of reef building is characterised by considerably long intervals with very limited reef expansion and geologically brief (< 20 million years) episodes of prolific, pantropical reef growth. Here, we propose a new "co-occurrence hypothesis" (COH), which posits that reefs thrive when fast-growing hypercalcifiers co-occur with encrusting organisms such as calcifying microbes or coralline algae to construct wave-resistant structures. While there is little evidence of the effect of abiotic drivers on reef proliferation, we find that positive co-occurrence patterns are significantly more common in reefal as compared to non-reefal communities, suggesting that biological interactions are more relevant in reefs than in non-reefs. Supporting COH, we also show that reefs after the end-Permian mass extinction became more modular in nature with limited membership in reef assemblages during reef booms than in typical periods of reef growth (background intervals). Modularity in reefs may have led to the stabilisation of reef ecosystems, giving them the ability to recover from small perturbations, promoting reefal carbonate accretion and prolific reef growth.
CRIS-Team Scopus Importer:2023-07-07
Keywords: Co-occurrence; Modularity; Palaeobiology; Reefs

Mo.nalis.a: a methodological approach to identify how to meet thermal industrial needs using already available geothermal resources - Bruno, Delia Evelina; Lombardo, Giuseppe; Di Sipio, Eloisa; Galgaro, Antonio; D' Arpa, Stefania; Destro, Elisa; Passarella, Giuseppe; Barca, Emanuele; Auricchio, Vito Felice; Manzella, Adele (Energy Efficiency, 2017)
Keywords: Energetic model; Geothermal heat; Groundwater and ground source heat pumps; Industrial thermal needs; Renewable energy

Monazite CHIME/EPMA dating of Erinpura granitoid deformation: Implications for Neoproterozoic tectono-thermal evolution of NW India - Just, Jana; Schulz, Bernhard; de Wall, Helga; Jourdan, Fred; Pandit, Manoj K. (Gondwana Research, 2011)
Keywords: Ar-Ar muscovite age; CHIME/EPMA monazite dating; Erinpura granite; NW India; Shear zone

Monitoring of cap-rock integrity during CCS from field data at the Ketzin pilot site (Germany): Evidence from gas composition and stable carbon isotopes - Barth, Johannes; Nowak, M. E.; Zimmer, M.; Norden, B.; van Geldern, Robert (International Journal of Greenhouse Gas Control, 2015)

Morphological characters and ontogenetic development of deep-sea species of the genus Caryophyllia - Vertino, Agostina; Stolarski, Jarosław; Schulbert, Christian (13th International Symposium onFossil Cnidaria and PoriferaModena, ABSTRACT BOOK, 2019)
The genus Caryophyllia is known from shallow- to deep-waters in all oceans and seas of the planet and itincludes 66 valid Recent species. Though frequently reported as fossil, at least since the Upper Jurassic, thedistribution of valid Caryophyllia species in the paleontological record is still unknown. Only consideringthe Neogene and Pleistocene deposits of the Mediterranean, over 100 species are mentioned in the ancientliterature but they have never been revised following modern taxonomic concepts. The diagnostic taxonomic character that distinguishes the genus Caryophyllia from the other genera ofthe family Caryophylliidae is the presence of pali before the penultimate, rarely the antepenultimate cycle ofsepta. Mitochondrial 16S rRNA phylogeny analyses of modern species support grouping Caryophyllia in oneclade, however, two other taxa included in this clade (Crispatotrochus rugosus and Dasmosmilia lymani) donot develop pali (Crispatotrochus) or develop structures called paliform lobes before all but the last septalcycle. The distinction between pali and paliform lobes remains ambiguous not only in Caryophyllia but inseveral other scleractinian taxa. For that reason, precise documentation of ontogenetic development of bothskeletal structures is of general importance for scleractinian coral researchers. This study aims at describing the morphological variability and ontogenetic development of deep-sea Caryophyllia species collected from Pleistocene deposits of southern Italy and from modern seafloors of theMediterranean and the NE Atlantic. By analysing SEM and micro-CT images, as well as polished and thinsections, particular attention has been devoted to (1) the micromorphology of the coral wall and calicularfeatures and (2) the arrangement and ontogenetic development of pal
Keywords: Corals; Cariophyllia; micro-CT; µCT; ontogeny

Morphological disparity and ontogeny of the endemic heteromorph ammonite genus Aegocrioceras (Early Cretaceous, Hauterivian, NW-Germany) - Hoffmann, René; Weinkauf, Manuel; Wiedenroth, Kurt; Goeddertz, Peter; de Baets, Kenneth (Palaeogeography, Palaeoclimatology, Palaeoecology, 2019)
Despite the fact that heteromorph ammonites often show a large range of intraspecific variation, that variation has rarely been quantified. Here, we quantify the intraspecific variation and ontogeny of 85 newly collected specimens of the Hauterivian endemic ammonite genus Aegocrioceras. All specimens were collected from concretions in the recently exposed bed 82 in the clay pit Resse in NW Germany (Lower Saxony Basin). Data for the conch morphology (diameter, whorl height, whorl interspace, rib spacing) were collected in 45° steps using the new software CONCH©. The CONCH© software will be made officially available with this publication. All ammonites were a priori identified as A. bicarinatum or A. semicinctum. An assessment of the intra- and interspecific variation as well as the ontogeny of this assemblage demonstrates the presence of just one species, i.e., A. bicarinatum. Comparison with the type material of A. bicarinatum and A. semicinctum reveals a large morphological overlap of different conch parameters and does not support a separation of both forms as distinct species. The analyzed assemblage of A. bicarinatum has a high variation in conch morphology including whorl interspace, umbilical width, and whorl expansion. Furthermore, the changes in intraspecific variation through ontogeny were quantified and the presence or absence of sexual dimorphism within the assemblage is discusse
Keywords: Aegocrioceras bicarinatum; Aegocrioceras semicinctum; Systematics; Sexual dimorphism; Morphometric measurement software CONCH©

Morphological response accompanying size reduction of belemnites during an Early Jurassic hyperthermal event modulated by life history - Nätscher, Paulina; Dera, Guillaume; Reddin, Carl J.; Rita, Patrícia; de Baets, Kenneth (Scientific Reports, 2021)
One of the most common responses of marine ectotherms to rapid warming is a reduction in body size, but the underlying reasons are unclear. Body size reductions have been documented alongside rapid warming events in the fossil record, such as across the Pliensbachian-Toarcian boundary (PToB) event ( 183 Mya). As individuals grow, parallel changes in morphology can indicate details of their ecological response to environmental crises, such as changes in resource acquisition, which may anticipate future climate impacts. Here we show that the morphological growth of a marine predator belemnite species (extinct coleoid cephalopods) changed significantly over the PToB warming event. Increasing robustness at different ontogenetic stages likely results from indirect consequences of warming, like resource scarcity or hypercalcification, pointing toward varying ecological tolerances among species. The results of this study stress the importance of taking life history into account as well as phylogeny when studying impacts of environmental stressors on marine organisms.
CRIS-Team Scopus Importer:2021-08-06

Morphological traits of reef corals predict extinction risk but not conservation status - Raja, Nussaïbah Begum; Lauchstedt, Andreas; Pandolfi, John M.; Kim, Sun W.; Budd, Ann F.; Kießling, Wolfgang (Global Ecology and Biogeography, 2021)
Aim The current assessment of extinction risk in reef corals by the International Union for Conservation of Nature (IUCN) has been criticized, because coral life-history traits associated with resilience are not reflected in the conservation status. We aimed to carry out a quantitative assessment of the link between reef coral traits and species extinction risk informed by extinctions of reef corals observed in the fossil record. Location Global. Time period Plio-Pleistocene and present day. Major taxa studied Scleractinian reef corals. Methods We used morphological traits, phylogenetic information and evidence of extinction during the Plio-Pleistocene to predict the extinction risk of contemporary reef corals. Our model was trained using 138 Caribbean fossil coral species and an automatic machine learning algorithm. We then used this model to predict the extinction risk of 674 modern coral species. Results Model validation confirmed 77% accuracy in predicting extinction risk of fossil corals. Extinction risk predicted by our model showed a near-random (57%) match with the IUCN conservation status. Our model also suggested that corals in the Least Concern or Near Threatened categories might be at higher risk of extinction than currently believed. Main conclusions Morphological traits of fossil corals linked to their extinction risk in the Plio-Pleistocene Caribbean Sea are known to reflect the vulnerability of extant corals. However, the results from our fossil-calibrated model do not match the IUCN assessment of reef corals, with increased overall extinction risk. This does not necessarily indicate near-future extinction risk, because fossil extinctions are spread over thousands of years. However, we show the applicability of using fossil data to inform the extinction risk of modern corals and recommend that future assessments of extinction risk of reef corals should consider incorporating the relationship between morphological traits and resilience, calibrated by fossil data, to maximize the utility of the extinction risk assessment. <br
Keywords: extinction risk; fossil record; predictive modelling; Red List; reef corals; traits

Morphological variability of peteinoid acritarchs from the Middle Ordovician of Öland, Sweden, and implications for acritarch classification - Kroeck, David M.; Eriksson, Mats E.; Lindskog, Anders; Munnecke, Axel; Dubois, Michel; Regnier, Sylvie; Servais, Thomas (Palynology, 2021)
Investigation of large populations of peteinoid acritarchs recovered from Middle Ordovician strata of the Hälludden and Horns Udde quarry sections (Öland, Sweden) allows for statistical analyses based on morphometric measurements. The results indicate the presence of assemblages with a continuous variability of morphotypes, thus a distinction of different peteinoid acritarch taxa in the sections proved to be impossible. This challenges the currently accepted classification based on a differentiation into the three genera Peteinosphaeridium, Cycloposphaeridium and Liliosphaeridium, and a multitude of different species; individual taxa are essentially arbitrary as morphotypes intergrade. Investigations on modern dinoflagellates show that these can develop variable cyst morphologies depending on environmental factors. By analogy, it can be hypothesised that the different morphologies observed among the peteinoid acritarchs from Öland are cysts produced by only very few phytoplanktic organisms (or even a single species) with high morphological variability.
CRIS-Team Scopus Importer:2021-06-04
Keywords: ecophenotypism; Palaeozoic Darriwilian; Phytoplankton; taxonomy

Morphology and fluvio-aeolian interaction of the tropical latitude, ephemeral braided-river dominated Koigab Fan, north-west Namibia. - Krapf, Carmen; Stanistreet, Ian G.; Stollhofen, Harald (Fluvial Sedimentology VII, 2005)
The Koigab Fan is the largest of the active fan systems formed by some of the west-south-west flowing ephemeral river systems of the Skeleton Coast area, north-west Namibia. Issuing from the volcanic Etendeka Plateau, the Koigab River flows towards the Atlantic Ocean across a considerable climatic gradient from semi-arid summer rainfall in the mountainous catchment, to hyperarid in the coastal depositional setting. The morphology of channels can be discerned over the whole fan surface (gradient 1.011), the majority of which appears as a vast deflation surface on which lithic and heavy mineral grains are concentrated by aeolian removal of fines. The Koigab catchment restricts source-rock lithologies to flood basalts and interleaved quartz latites of the Etendeka Plateau, so components that unequivocally relate to a volcanic source (e.g. volcanic lithics, Ti-magnetite, pyroxenes) indicate fluvial transport, whereas grains reflecting a metamorphic basement source (e.g. garnet, muscovite, staurolite) must be aeolian derived. Both heavy mineral and grain-size data were used to estimate the amount of fluvio-aeolian interaction at the Koigab Fan surface. This aspect is significant because it comprises not only winnowing of the fan surface and of ‘fresh’ sandy channel deposits but also fluvial recycling of aeolian material. The contribution of aeolian-derived grains to river deposits increases from 5% in the fan apex area to as much as 50% in the distal fan reaches. In the spectrum of fan types, the Koigab Fan takes an intermediate position both in size and in terms of the braided river style between debris flow and low sinuosity meandering fan systems. Within the braided fluvially dominated fan class itself the Koigab Fan is also intermediate in size, but its ephemeral channels contrast sharply with those of perennial glacial outwash fans previously described from the sub-Arctic. Within low-latitude fan systems, the Koigab also contrasts with other highly vegetated fans in the tropics, for example the subaerial portion of the Yallahs Fan-delta, Jamaica. Thus, the Koigab Fan is important as a potential analogue for Precambrian and early Palaeozoic low-latitude fan systems that lacked surface vegetation prior to the evolution of land plants.
UnivIS-Import:2015-03-09:Pub.2005.nat.dgeo.IGM.LG.morpho

Morphology and systematics of fossil and recent sea pens (Octocorallia: Pennatulacea) - Roden, Vanessa; Reich, Mike (12th International Symposium on Fossil Cnidaria and Porifera 2015 - Abstract Volume, 2015)

Morphotectonic analysis of basement and cover units in eastern Bavaria, SE Germany - insights into the deeper crustal architecture? - Eberts, Andreas; Schaarschmidt, Anna; Bauer, Wolfgang; Stollhofen, Harald; de Wall, Helga (GeoBonn 2018, 2018)
The topographic expression of landscapes directly depends on the interaction between exposed rock type, erosion and tectonic deformation. In areas where high rates of active deformation pre-vail, the effects of faulting and folding are often immediately transferred to the Earth’s surface. By contrast, in areas where ongoing, rapid deformation is absent, as it is assumed for large parts of eastern Bavaria, erosional processes need to utilize gradients in erodibility to uncover already existent tectonic structures. In that case, resulting topographic features are not visible as well-defined fault scarps but as linear to curvilinear river valleys, ridgelines or slope breaks. Because these lineaments outline structures that formed during ancient tectonic events, mapping of them yields important information about the general structural framework of the subsurface. Here, we present results from an integrated study, using high-resolution digital elevation models from airborne LiDAR surveys combined with gravity data to reveal the morphotectonic feature inventory of eastern Bavaria, SE Germany, and its relation to the underlying crustal architecture. The studied area comprises the western border zone of the Bohemian Massif, a region well known for hosting some of the largest fault zones existing in Central Europe, such as the Pfahl Fault Zone (PFZ) and Danube Fault Zone (DFZ). Post-Variscan to Alpine reactivation of earlier struc-tures led to a complex structural pattern along these faults and ultimately resulted in the uplifted and exposed basement complex of the Bohemian Massif. Our results show that the investigated area is segmented into several domains of different orders. 1st order domains, best delineated in gravity data, are thought to represent large crustal blocks which partly root into the upper mantle. These are assigned to the Saxothuringian, Teplá-Barran-dian and Moldanubian crustal units. In contrast, 2nd order domains additionally show distinct var-iations in the arrangement of topographic lineaments and in other DEM-specific parameters such as surface roughness indices and altitude distributions. In the Bavarian Forest, for example, a central domain of high gravity is also characterized by predominantly N-S oriented lineaments and an increased surface roughness. Furthermore, 2nd order domains are separated by large topographic lineaments, some of which situated in close vicinity to already known fault zones such as the PFZ and DFZ. However, our study also identifies previously unknown locations of ancient fault zones, ultimately indicating an even more complex structural evolution and crustal architecture of eastern Bavaria and the western border zone of the Bohemian Massif.<br

Mosses like it rough-growth form specific responses of mosses, herbaceous and woody plants to micro-relief heterogeneity - Leutner, Benjamin; Steinbauer, Manuel; Müller, Carina; Früh, Andrea; Irl, Severin; Jentsch, Anke; Beierkuhnlein, Carl (Diversity, 2012)
Micro-relief heterogeneity can lead to substantial variability in microclimate and hence niche opportunities on a small scale. We explored the relationship between plant species richness and small-scale heterogeneity of micro-relief on the subtropical island of La Palma, Canary Islands. Overall, we sampled 40 plots in laurel and pine forests at four altitudinal bands. Species richness was recorded separately for various growth forms (i.e., mosses, herbaceous and woody plants). Site conditions such as altitude, slope, aspect, and tree density were measured. Micro-relief heterogeneity was characterized by surface structure and a subsequently derived surface heterogeneity index. The effect of micro-relief heterogeneity on species richness was analysed by means of linear mixed effect models and variance partitioning. Effects of micro-relief heterogeneity on species richness varied considerably between growth forms. While moss richness was affected significantly by micro-relief heterogeneity, herbaceous and woody plants richness responded mainly to larger-scale site conditions such as aspect and tree density. Our results stress the importance of small-scale relief heterogeneity for the explanation of spatial patterns of species richness. This poses new challenges as small-scale heterogeneity is largely underrepresented, e.g. with regard to its application in species distribution models.
Keywords: Altitudinal gradient; Biodiversity; Bitterlich; Climate change; Habitat heterogeneity; Laurel forest; Micro-topography; Northernness; Species diversity; Topographic variability

Multidimensional Scaling of Varietal Data in Sedimentary Provenance Analysis - Vermeesch, P.; Lipp, A. G.; Hatzenbühler, D.; Caracciolo, Luca; Chew, D. (Journal of Geophysical Research F: Earth Surface, 2023)
Varietal studies of sedimentary provenance use the properties of individual minerals or mineral groups. These are recorded as lists of numerical tables that can be difficult to interpret. Multidimensional Scaling (MDS) is a popular multivariate ordination technique for analyzing other types of provenance data based on, for example, detrital geochronology or petrography. Applying MDS to varietal data would allow them to be treated on an equal footing with those other provenance proxies. MDS requires a method to quantify the dissimilarity between two samples. This paper introduces three ways to do so. The first method (“treatment-by-row”) turns lists of (compositional) data tables into lists of vectors, using principal component analysis. These lists of vectors can then be treated as “distributional” data and subjected to MDS analysis using dissimilarity measures such as the Kolmogorov-Smirnov statistic. The second method (“treatment-by-column”) turns lists of compositional data tables into multiple lists of vectors, each representing a single component of the varietal data. These multiple distributional data sets are subsequently subjected to Procrustes analysis or 3-way MDS. The third method uses the Wasserstein-2 distance to jointly compare the rows and columns of varietal data. This arguably makes the best use of the data but acts more like a “black box” than the other two methods. Applying the three methods to a detrital titanite data set from Colombia yields similar results. After converting varietal data to dissimilarity matrices, they can be combined with other types of provenance data, again using Procrustes analysis or 3-way MDS.
CRIS-Team Scopus Importer:2023-04-07
Keywords: apatite; provenance; sediment; statistics; titanite; zircon

Multiple ways of producing intermediate and silicic rocks within Thingmúli and other Icelandic volcanoes - Charreteur, Gilles; Tegner, Christian; Haase, Karsten (Contributions To Mineralogy and Petrology, 2013)
Major and trace element compositions of rocks and coexisting phenocrysts of the Thingmúli volcano suggest a revision of the existing models for the formation of intermediate and silicic melts in Iceland. The new data define two compositional tholeiitic trends with a significant gap between them. A high-iron trend (HFe) contains 6-14 wt% total FeO in silicic rocks with c. 1 wt% MgO, as well as sodic plagioclase and hedenbergite phenocrysts. A low-iron trend (LFe) contains 3-5 wt% FeO at c. 1 wt% MgO, which is typical of Iceland but higher than MORB compositions. The most evolved phenocrysts of the LFe trend do not reach iron-rich end members. The HFe trend is interpreted as a result of fractional crystallization; numerical modelling using the MELTS algorithm suggests that crystallization took place under redox conditions constrained to one-log unit below the fayalite-magnetite-quartz oxygen buffer (FMQ-1). The LFe trend is explained by a combination of mixing between rhyolite and ferrobasalt, assimilation of hydrated crust and fractional crystallization under higher redox conditions (FMQ). The two trends and the gap are best defined in a plot of Mg# versus SiO that is useful to unravel petrogenetic processes. For example, intermediate and silicic rocks of the Holocene volcanic systems of spreading rifts (e.g. Krafla), propagating rifts (e.g. Hekla) and off-rifts (Öræfajökull) also fall into high- and low-iron fields and outline a gap similar to Thingmúli. The identification of two compositional trends in erupted intermediate and silicic volcanic products shows that processes in the deep roots of single volcanic systems are highly diverse and likely controlled by local variations in the thermal gradients and the extend of hydrothermal alteration. Generalizations about the relationship between the compositions of intermediate and silicic rocks and plate tectonic setting, therefore, should be avoided. © 2013 Springer-Verlag Berlin Heidelberg.
Keywords: Basalt; Fractional crystallization; Iceland; Intermediate rocks; Magma mixing; Rhyolite; Thingmuli volcano

Multi-proxy approach involving ultrahigh resolution mass spectrometry and self-organising maps to investigate the origin and quality of sedimentary organic matter across a subtropical reservoir - Jeunon Gontijo, Erik Sartori; Herzsprung, Peter; Lechtenfeld, Oliver J.; Bueno, Carolina De Castro; Barth, Johannes; Rosa, Andre H.; Friese, Kurt (Organic Geochemistry, 2021)
Humic substances (HS) in sediments play an important role in carbon and nutrient biogeochemical cycles and fate of contaminants in the environment. However, information regarding HS quality and transformations that may affect their behaviour in reservoirs is still limited. The aim of this investigation was to track sources and changes in sedimentary HS across a subtropical reservoir, connecting them to in lake processes and land-use influences. Surface sediments were collected at seven sampling sites in Itupararanga Reservoir (Brazil). Humic (HA) and fulvic (FA) acids (components of HS) were extracted from the sediment samples followed by in-depth characterisation via UV/VIS, fluorescence spectroscopy, elemental (C, N) and isotopic analysis (delta C-13, delta N-15), nuclear magnetic resonance (C-13 NMR) and Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR-MS). All data were analysed by self organising maps. The results showed that samples from the upstream part of the reservoir were older and more decomposed. They likely originated from C3 land-plants (delta C-13 varied from -26.3 parts per thousand to -22.4 parts per thousand), having more aromatic, oxygen-poor (O/C < 0.5) and unsaturated compounds (H/C 1.1). In contrast, near-dam samples were younger and had larger contributions of autochthonous material. This was confirmed by oxygen-rich (O/C 0.5) and partly more unsaturated compounds for FA as well as oxygen poor and saturated compounds with H/C > 1.1 for HA. Self-organising maps pointed out these differences between upstream and dam areas and indicated that agriculture lands were related to microbiallyderived HS. Changes in HS composition revealed that internal reservoir processes may have influenced HS quality across the reservoir. (C) 2020 Elsevier Ltd. All rights reserved.
CRIS-Team WoS Importer:2021-03-12

Multiproxy approach to understanding the origin of Cretaceous pelagic limestone-marl alternations (DSDP site 391, Blake-Bahama Basin) - Westphal, Hildegard; Munnecke, Axel; Pross, Jörg; Herrle, Jens; Munnecke, Axel; Munnecke, Axel (Sedimentology, 2004)
Limestone-marl alternations are usually directly interpreted to reflect cyclic palaeoenvironmental signals. However, uncertainty in such interpretations stems from the differential diagenesis that most limestone-marl alternations have undergone. Differential diagenesis results in markedly different alterations between limestones and marls and in the loss of comparability of many measurable parameters. For an unequivocal interpretation of the origin of rhythmic alternations, diagenetically robust parameters or parameters that clearly indicate the degree of diagenetic bias are required. The present study uses a multiproxy approach (independent biotic, sedimentary and geochemical parameters) in order to unravel the palaeoenvironmental signal recorded in Valanginian (Early Cretaceous) limestone-marl alternations from the Blake-Bahama Basin (DSDP site 391). Using this approach, terrestrial and marine influences can be distinguished, changes in nutrient levels estimated and prediagenetic differences in the non-carbonate fraction constrained. Surprisingly, no systematic variations in any of these parameters were observed between limestone and marl layers, implying that none of these was directly responsible for the formation of the rhythmic alternation. Hence, none of the current models of sedimentary formation of limestone-marl rhythmites is applicable here. Calcareous nannofossils are equally well preserved in limestone and marl layers, ruling out their dissolution in marl layers as a source of the calcite cement in the limestone beds. Sr values of 700-900 p.p.m. indicate that aragonite may have been present in the original, pelagic sediment. The assumption of fine-grained sedimentary aragonite imported from nearby carbonate platforms as the source of the cement would explain a number of otherwise enigmatic features in these rhythmites, including the source of the calcite cement observed in the limestones, the equally good preservation of calcareous nannofossils in limestones and marls and the higher concentration of calcareous nannofossils in marl layers. The study demonstrates that examination of diagenetically inert parameters or parameters in which diagenetic effects can be filtered can yield unexpected results. Clearly, careful analysis of such parameters needs to be undertaken in order to make reliable palaeoenvironmental interpretations from rhythmite successions. © 2004 International Association of Sedimentologist
Keywords: Calcareous nannofossils; Cretaceous; Differential diagenesis; DSDP; Limestone-marl alternations; Palynomorphs

Multistage fluorite mineralization in the southern Black Forest, Germany: Evidence from rare earth element (REE) geochemistry - Hintzen, Robin; Werner, Wolfgang; Hauck, Michael; Klemd, Reiner; Fischer, Lennart A. (European Journal of Mineralogy, 2023)
The Black Forest hosts a wide range of hydrothermal mineralization, including fluorite-barite vein deposits. In a detailed investigation of the Finstergrund and Tannenboden deposits in the Wieden mining district (southern Black Forest), the diversity, geochemical evolution and relative chronology of multistage fluorite precipitation is tracked on the basis of rare earth element (REE) geochemistry, geologic field relationships and crystal zoning. Geochemical discrimination and mathematical λ coefficients suggest a total of seven fluorite REE groups, at least three distinguishable post-Variscan fluid mobilization events and independent formation histories for the deposits despite their spatial proximity. Fluorite vein mineralization at the Finstergrund deposit evolved over three fluid generations, was derived from gneissic source aquifers and comprises five distinct fluorite REE groups: the first fluid generation is characterized by fluorite precipitation above 200°C ("group III"), below 200°C ("group I") and after fractional crystallization ("group IV"); the second generation comprises remobilized fluorite ("group II"); and the third generation revealed fluorite precipitation by meteoric water mixing ("group V"). Fluorite vein formation at the Tannenboden deposit is associated with two distinct fluorite REE patterns derived from the same fluid generation: fluorite precipitation above 200°C ("group VII") and after cooling below 200°C ("group VI"). Its fluid source aquifer lithology best matches migmatites contrary to previous models that suggest either gneissic or granitic aquifer rocks for fluorite vein precipitation in the Black Forest. The decoupled formation history between the deposits is tectonically controlled as suggested by a new genetic model for the Wieden mining district. The model argues for a change in the local fluid percolation network and the termination of hydrothermal activity at the Tannenboden deposit after the first fluid mobilization event. The geochemical evolution of multistage fluorite mineralization, as exemplified by the Tannenboden and Finstergrund deposits in combination with other fluorite mineralizations in the Black Forest, provides unique insights into the lithospheric origin and precipitation behaviour of fluorite by various fluid-rock interaction processes occurring in large hydrothermal systems. The local diversity of REE patterns emphasizes the need for detailed investigations of individual hydrothermal vein deposits.
CRIS-Team Scopus Importer:2023-07-21

Multistratigraphy of condensed ammonoid beds of the Rappoltstein (Berchtesgaden, Southern Germany): unravelling palaeo-environmental conditions on Hallstatt deep swells during the Reingraben Event (late Lower Carnian) - Joachimski, Michael; et al. (Facies, 2007)
UnivIS-Import:2015-03-09:Pub.2007.nat.dgeo.IGM.LG.multis

Multi-system geochronology of North Dabie eclogite: Ineffective garnet ‘shielding’ on rutile inclusions under multi-thermal conditions - Zhou, Tian; Li, Qiuli; Klemd, Reiner; Shi, Yonghong; Tang, Xu; Li, Chaofeng; Liu, Yu (Lithos, 2020)
It has been shown that certain host minerals can robustly shield mineral inclusions and prevent loss of petrochronological information during subsequent thermal events. Rutile inclusions in garnet may crystallize under a wide range of metamorphic conditions and thus rutile is expected to be a useful geochronometer for constraining different stages of a metamorphic P-T path. Hence, it is important to ascertain whether rutile inclusions shielded by garnet retain the original crystallization age information despite later retrograde cooling or subsequent new thermal events. In this study, we test the “shielding effect” of garnet on rutile inclusions from the Baizhangya eclogite in the North Dabie Zone (China), which underwent a multi-stage thermal evolution. Secondary ion mass spectrometry (SIMS) U[sbnd]Pb dating of inherited zircon core domains constrains a Neoproterozoic formation age ( 770 Ma) of the eclogite protolith. SIMS U[sbnd]Pb dating of metamorphic zircon and complementary thermal-ionization mass spectrometry (TIMS) Sm[sbnd]Nd isochron dating of garnet revealed Triassic eclogite-facies metamorphic ages (245–210 Ma). An Early Cretaceous SIMS U[sbnd]Pb age of ca. 130 Ma, yielded by matrix rutile grains and rutile inclusions, suggests significant isotopic alteration since crystallization. This indicates that shielding was ineffective, since the U[sbnd]Pb ages derived from the rutile inclusions, although hermetically armored by garnet, were influenced by a subsequent Early Cretaceous tectono-thermal event. Further transmission electron microscope (TEM) analysis revealed the presence of hematite microlites along the garnet-rutile boundaries, which may have acted as a potential reservoir to store the expelled radiogenic Pb from rutile. This study suggests that newly formed minerals located along mineral boundaries seem to be crucial for understanding the shielding effect.
CRIS-Team Scopus Importer:2020-06-23
Keywords: Rutile inclusions; Secondary ion mass spectrometry; Shielding effect; Transmission electron microscope; U-Pb dating

Mustelids from Sackdilling Cave (Bavaria, Germany) and their biostratigraphic significance - Marciszak, Adrian; Ambros, Dieta Carola; Hilpert, Brigitte (Geobios, 2021)
Sackdilling Cave is a karst fissure filled with a fossiliferous breccia including abundant fossil remains, mostly snails and small mammals. The taxonomic status of mustelid remains from this cave was previously regarded as controversial and, consequently, different authors listed different species from the locality. A detailed revision of the material shows the presence of five mustelid species: Meles sp., Martes vetus, Mustela strandi, Mustela palerminea, and Mustela praenivalis. Among them, especially noteworthy is the presence of the type specimen of Martes vetus. The Sackdilling holotype resembles Martes foina and differs from that of Martes martes in a short and broad viscerocranium; wide and less extended forward incisor row; compressed, short and wide temporal region; large, strongly inflated and convex tympanic bullae; and narrow P3 with weak lingual bulge. Some dental characters are specific for Martes vetus and show some intermediate values between Martes foina than Martes martes. Among them are the P4 protocone length and the M1 trigon length. The revised material from Sackdilling Cave of Mustela palerminea and Mustela praenivalis was compared with that from other Early and early Middle Pleistocene sites of Europe and showed the presence of intermediate characters. Subsequently, based on the entire mustelid assemblage and other faunal elements (mainly rodents), the age of this fauna was estimated as ca. 0.9-0.7 Ma. (C) 2021 Elsevier Masson SAS. All rights reserved.
CRIS-Team WoS Importer:2021-11-19

Mythos Drache: Schwingen, Schuppen, Schwefeldämpfe. Ein studentisches Forschungsprojekt auf Spurensuche - Link, Michael (Skeptiker, 2003)
UnivIS-Import:2015-03-09:Pub.2003.nat.dgeo.IGM.LP.mythos

Natural Attenuation investigations of an abandoned landfill contaminated by chlorinated hydrocarbons - Rüttinger, Stefan; Breiter, Roman; Hirsch, Katharina; Salaices Avila, Manuel Alejandro; Tobschall, Heinz; Neeße, Thomas; Bayer, Manfred (Grundwasser, 2006)
The Natural Attenuation of chlorinated hydrocarbons leaking from an abandoned landfill was the focus of an investigation conducted within the framework of the Bavarian joint research project "Nachhaltige Altlastenbewaltigung unter Einbeziehung des naturlichen Reinigungsvermogens". The research focused on two contaminant plumes, one having a diffuse TCE/PCE source and the other a cis-DCE source. The TCE/PCE plume had a maximum concentration of 52 mu g/l total chlorinated hydrocarbons near the source area. Cis-DCE concentrations near the source of the second plume were up to 7,000 mu g/l. In addition, degradation products (VC and Ethylene) were detected in this region, which indicate reductive dechlorination of the cis-DCE, TCE or PCE pollutants. However, other investigations indicate that the natural attenuation potential of the site is low and that the reduction in concentration is dependant more on dilution and other unknown processes. Stemming from this research, a new approach was developed using Solid Phase Micro Extraction (SPME) and GC/FID analytical techniques for microcosm testing. Furthermore, an airtight column was developed that allows the detection of sorption of highly volatile substances in low concentrations within an aquifer material.

Natürliche Gammastrahlung von Graniten in der Oberpfalz (Nordost-Bayern) – Vergleich von aerogeophysikalischen und in situ gammaspektrometrischen Messungen - Scharfenberg, Lars; de Wall, Helga (Geologische Blätter für Nordost-Bayern und angrenzende Gebiete, 2016)
Das Oberpfalz- (Tirschenreuth-) Komposit-Massiv, das östlich der Fränkischen Linie liegt, bildet einen von verschiedenen variszischen Granitkomplexen im Grenzgebiet zwischen Deutschland und der Tschechischen Republik. Granitische Gesteine bedecken etwa 450 km² der Fläche des anstehenden Grundgebirges in der Oberpfalz. Während dem kontinentalen Tiefbohrprojekt (KTB) wurde 1991 im Rahmen einer helikoptergestützten geophysikalischen Messkampagne auch eine gammaspektrometrische Erkundung in der Umgebung von Windischeschenbach durchgeführt, welche Teile der granitischen Körper im Umkreis erfasste. Rohdaten dieser Erkundungen wurden genutzt, um Differentiationsmuster für die Granite abzuschätzen. In dieser Studie wurden in situ Erkundungen mit einem tragbaren Gerät durchgeführt, um die aus den luftgestützten Messungen gewonnenen Daten am Boden zu überprüfen. Unterschiede im Wertebereich zwischen den Messungen werden diskutiert. Die Granite in der Oberpfalz zeigen klare Unterschiede in ihren Uran- und Thorium-Konzentrationen zwischen und in den zwei Intrusionskomplexen, dem Älteren Intrusionskomplex und dem Jüngeren Intrusionskomplex. Ein beeinflussender Faktor ist die Differentiation des Magmas mit einer allgemeinen Verringerung der Thorium- und einem Anstieg der Uran-Konzentrationen, was vor allem in den jüngeren Granittypen einschließlich des Steinwald- und Flossenbürg-Granits ausgeprägt ist.
Keywords: Granite; Oberpfalz; Gammastrahlung

Nb-depleted andesites from the Pacific-Antarctic Rise as analogues for early continental crust. - Haase, Karsten; Stroncik, Nicole; Hékinian, Roger; Stoffers, Peter (Geology, 2005)
Sampling of the Pacific-Antarctic Rise close to the Foundation hotspot in the South Pacific reveals that silicic lavas erupt together with basalts on a 130-km-long part of this mid-oceanic ridge, representing the most extensive occurrence of andesites on the submarine spreading system. Most of these tholeiitic andesites and dacites have negative Nb and Ta anomalies, a signature that has so far been attributed only to subduction-related magmas and the continental crust. The silicic lavas formed by fractional crystallization from basalts and assimilation of melts from hydrothermally altered amphibolite in the oceanic crust. The presence of andesites with negative Nb and Ta anomalies on the Pacific-Antarctic Rise implies that such magmas are not restricted to subduction zones but can form at a plume-influenced mid-oceanic ridge. The andesites and dacites from the Pacific-Antarctic Rise may represent analogs to some Precambrian volcanic rocks and early continental crust. © 2005 Geological Society of America.
UnivIS-Import:2015-03-09:Pub.2005.nat.dgeo.IGM.legeo.nbdepl
Keywords: Crust formation; Geochemistry; Mantle plume; Silicic lavas

Nb–Ta fractionation by partial melting at the titanite–rutile transition - John, Timm; Klemd, Reiner; Klemme, Stephan; Pfaender, Joerg A.; Hoffmann, J. Elis; Gao, Jun (Contributions To Mineralogy and Petrology, 2011)
During the evolution of the Earth, distinct geochemical reservoirs with different Nb/Ta ratios have developed. Archean granitoids of the tonalite-trondhjemite-granodiorite (TTG) suite, which represent the Earth's early continental crust, show larger Nb/Ta variations than any other Earth reservoir. This implies that significant Nb-Ta fractionation must have occurred during early crust formation, while the underlying mechanism behind is still unclear. Here, we present a new model on how Nb may be fractionated from Ta during partial melting of subducted oceanic crust. Our data show that Nb/Ta ratios in melts derived from rutile- and titanite-bearing eclogite are largely controlled by the modal relative abundances of rutile and titanite in the source. High modal ratios of titanite over rutile generate melts with very high Nb/Ta (>60), whereas low modal titanite/rutile produces melts with much lower Nb/Ta (≤30). Very low Nb/Ta (<16) occur when all Ti-phases are consumed at very high degrees of melting. As the modal ratio of titanite to rutile is a function of pressure, the Nb/Ta of melts is a function of melting depth. Our new model helps to explain the extreme variation of Nb/Ta observed in many TTGs and thus how Nb and Ta were fractionated during the early evolution of the Earth. Furthermore, the model also indicates that simple one-stage melting models for mafic crust are not sufficient to explain the formation of TTGs. © 2010 Springer-Verlag.
UnivIS-Import:2015-03-09:Pub.2011.nat.dgeo.IGM.c3geoc.nbtafr
Keywords: Crustal evolution; Eclogite; Nb-Ta; Partial melting; Rutile; Subduction zone; Titanite

Neodymium isotopes of central Mediterranean phosphatic hardgrounds reveal Miocene paleoceanography - Cornacchia, Irene; Brandano, Marco; Agostini, Samuele; Munnecke, Axel (Geology, 2022)
Understanding the causes of the formation of hardgrounds provides insights on the oceanographic evolution of a basin. Phosphate-rich hardground formation interrupted carbonate ramp deposition in the Mediterranean during the Miocene. We analyzed the epsilon(Nd) record of three central Mediterranean hardgrounds to identify the origin of the phosphate-rich waters that formed them within the frame of Mediterranean Miocene paleoceanographic evolution. The Nd isotopes suggest that eastern Mediterranean deep waters were controlled by runoff, in contrast to Atlantic and Indian Ocean waters. This Nd isotope record attests to the weakening of Mediterranean circulation during the Miocene due to closure of the Indian Gateway. Limited exchange with Atlantic shallow seawater led to long residence times for deep waters in the basin. This record indicates the role of upwelling in formation of phosphate hardgrounds and shows the influence of global climate change and local paleoceanographic conditions.
CRIS-Team WoS Importer:2022-06-24

Neon and helium isotopes as tracers of mantle reservoirs and mantle dynamics. - Stroncik, Nicole; Niedermann, Samuel; Haase, Karsten (Earth and Planetary Science Letters, 2007)
He isotopes are usually used as tracers for the identification of mantle reservoirs and mantle dynamics. High 3He/ 4He ratios are thought to represent deep mantle material, whereas ratios around 8 R A (R A stands for the atmospheric 3He/ 4He ratio of 1.39 × 10 - 6) are thought to be representative of the upper mantle. Based on He, Ne and Ar fusion data from fresh, submarine volcanic glasses of several Mid-Atlantic Ridge off-axis seamounts we show that He isotopes can be susceptible to interferences during melt formation and evolution resulting in the decoupling of He from other elements, such as e.g. Ne or Pb. All obtained He data are indistinguishable from that of the MORB range. In contrast, Ne isotopic compositions are much more primitive than MORB. Combined He, Ne and Ar systematics show that the source region of these seamounts has experienced a preferential loss of He compared to Ne and Ar. This He loss, combined with subsequent 4He production, resulted in the decoupling of the He isotope systematics from Ne and Pb. Thus, when considering He and Ne, only Ne has preserved the evidence that a primitive mantle component contributed to the formation of the investigated seamounts. As these seamounts are not fed from a mantle plume being derived from the deep mantle, the primitive Ne component resides within the upper mantle, implying that primitive noble gases are not necessarily indicative of deep mantle material. © 2007 Elsevier B.V. All rights reserved.
UnivIS-Import:2015-03-09:Pub.2007.nat.dgeo.IGM.legeo.neonan
Keywords: decoupling; mantle sources; mantle tracer; neon

Neoproterozoic geodynamics in NW India–evidence from Erinpura granites in the South Delhi Fold Belt - de Wall, Helga; Regelous, Anette; Schulz, Bernhard; Hahn, Gregor; Bestmann, Michel; Sharma, Kamal Kant (International Geology Review, 2021)
Erinpura Granites form the basement for the Neoproterozoic Malani Igneous Suite in NW India. Based on this study, the Erinpura granites can be divided into Erinpura-East (gneissic fabric), a belt parallel to the southern sector of the South Delhi Fold Belt, and Erinpura-West (magmatic fabrics). EPMA dating on monazites gives a time frame of 890 to 860 Ma for crystallization of both types. The geochemically homogeneous peraluminous S-type granites with εNd values of −2.1 to −10.8 are interpreted as melting products of Archaean crust. REE pattern follows the pattern of the average continental crust, but Erinpura-East samples are more fractionated with steeper HREE depletion indicating melting in a deeper crustal level. A thermal pulse between 835 and 820 Ma constrains the timing of deformation in granite-gneisses during uplift along thrust planes, coeval with shear-bound exhumation of high-grade metamorphic rocks and initiated by delamination of the lower crust in this southern sector of the South Delhi Fold Belt. This is in contrast to the northern sector of the SDFB with arrested orogenic development and without considerable delamination or erosion of the lower crust. Latest movement related to the 200 Ma tectono-magmatic history overlaps with initiation of rifting during the Malani igneous event. A change from S-type to A-type granites and shift of isotopic signatures to εNd values of −2.8 to −1.7 indicate substantial contribution of asthenospheric material in the Malani melting process.
CRIS-Team Scopus Importer:2021-06-04
Keywords: delhi orogeny; epma dating; granite petrogenesis; Neoproterozoic magmatism; sr-nd isotopes

Neptunian dykes in the Devonian carbonate buildup Aferdou El Mrakib (eastern Anti-Atlas, Morocco) and implications for its growth - Tessitore, Lorena; Naglik, Carole; de Baets, Kenneth; Galfetti, Thomas; Klug, Christian (Neues Jahrbuch für Geologie und Paläontologie-Abhandlungen, 2016)
Aferdou El Mrakib is the largest single carbonate buildup in the eastern Anti-Atlas, Morocco. Its sediments are intersected by several Neptunian dykes. Herein, we compare their facies, spatial arrangement and the associated fauna to that of Neptunian dykes from other mound localities in Morocco and elsewhere in order to assess their origin as well as that of the mound. One of the studied dykes is filled with pisoids. Its facies suggests some kind of seep origin, but the carbon and oxygen isotopic values have only slightly negative signatures, which might be diagenetic, thus prohibiting further interpretation. Nevertheless, the unique occurrence of pisoids at a depth of c. 50 metres below the mound surface within a dyke is herein interpreted as supporting the presence of a source with a considerable discharge.
Keywords: Morocco; Devonian; Maider Basin; carbonate buildups; Neptunian dykes; pisoids

Net ecosystem production in the great lakes basin and its implications for the North American missing carbon sink: A hydrologic and stable isotope approach - Karim, A.; Veizer, J.; Barth, Johannes (Global and Planetary Change, 2008)

Neuaufschluss des berühmten Schwarzjura-Profils am historischen Ludwig-Donau-Main-Kanal bei Dörlbach/Mittelfranken - Arp, Gernot; Schulbert, Christian; Seuß, Barbara; Aiglstorfer, Manuela; Havlik, Philipe; Krause, Thorsten; Waltschew, Anton; Strobl, Christian (GMIT - Geowissenschaftliche Mitteilungen, 2011)
UnivIS-Import:2015-03-09:Pub.2011.nat.dgeo.IGM.LP.neuauf

New analytical possibilities for monitoring the phase development during the production of autoclaved aerated concrete - Schreiner, Jürgen; Jansen, Daniel; Ectors, Dominique; Götz-Neunhoeffer, Friedlinde; Neubauer, Jürgen; Volkmann, Stephan (Cement and Concrete Research, 2018)
This work presents improved analytical methods for both steps of the production process of autoclaved aerated concrete (AAC), the phase development during the hydration before autoclaving and during the autoclaving process itself. The improvement includes new insights into preparation methods of AAC samples for powder diffraction as well as Rietveld refinement strategies. For the first time a new implementation for calculating anisotropic crystal domain sizes is applied to major hydrate phases occurring during AAC production, namely portlandite during the hydration before autoclaving and tobermorite during the autoclaving process. The calculation of anisotropic domain size growth, which can be implemented in the Rietveld environment, is based on crystallographically and geometrically appropriate models. The implementation of calculating anisotropic domain sizes for the Rietveld software TOPAS 5.0 allows a superior Rietveld fit and a more accurate quantification of the phase development. Additionally it enables the tracking of growth mechanism of portlandite during hydration.<br
Keywords: Calcium silicate; Hydrothermal synthesis; silicate hydrate

New biostratigraphic and chemostratigraphic data from the Chicotte Formation (Llandovery, Anticosti Island, Laurentia) compared with the Viki core (Estonia, Baltica) - Munnecke, Axel; Männik, Peep (Estonian Journal of Earth Sciences, 2009)
Due to the lack of biostratigraphically useful graptolites in the crinoidal and reefal Chicotte Formation on Anticosti Island (Québec, Canada), the precise chronostratigraphic position of the formation is not known. New stable carbon isotope and conodont data and a comparison with the detailed conodont distribution and δC development in the Viki core (Estonia) suggest an early Telychian age (Pterospathodus eopennatus to P. a. angulatus zones) for at least the lower half of the formation. This interval is characterized by a small but distinct positive excursion in δC, with peak values of + 3.2% and + 2.8% VPDB in the lowermost 10-15 m of the Chicotte Formation on Anticosti and in the Viki core, respectively.
Keywords: conodonts; stable carbon isotopes; Anticosti; Estonia; Llandovery; Telychian

New chemostratigraphic through the Middle Mulde Event interval (Silurian, Wenlock), Gotland, Sweden - Calner, Mikael; Lehnert, Oliver; Jeppsson, Lennart (Gff, 2012)
UnivIS-Import:2015-03-09:Pub.2012.nat.dgeo.IGM.LG.newche

New constraints on the last aragonite-calcite sea transition from early Jurassic ooids - Vulpius, Sara; Kießling, Wolfgang (Facies, 2018)
Calcite and aragonite seas are commonly distinguished based on the prevailing primary mineralogy of ooids and carbonate cements over time. Secular oscillations of these seas are usually attributed to changes in ocean chemistry and paleoclimate. While the veracity of such oscillations has been verified by independent data and modeling approaches, the timing of the transition from one ocean state to the other remains poorly resolved. Here, the timing of the last aragonite-calcite sea transition is estimated by assessing the preservation of Early Jurassic ooids from the Trento Platform in northern Italy. Point counting of ooid-bearing limestones from four distinct stratigraphic levels provides a contrasting pattern: Hettangian and Sinemurian ooids are all poorly preserved and were probably predominantly originally aragonitic, whereas Pliensbachian and Toarcian ooids are excellently preserved, suggesting a primary calcitic mineralogy. Although calcitic ooids may have already been common in the Late Triassic, it is proposed that the last aragonite-calcite sea transition occurred in the Early Jurassic between the Sinemurian and Pliensbachian, at least in this subtropical region. Therefore, the selective extinction of aragonite-secreting organisms at the end-Triassic mass extinction cannot be attributed to secular changes in ocean chemistry.
Keywords: Ooid; Calcite; Aragonite; Lower to Middle Jurassic; Italy; Northern Alps

New evidence for an old idea: Geochronological constraints for a paired metamorphic belt in the central European Variscides - Will, T. M.; Schmädicke, Esther; Ling, X. -X.; Li, X. -H.; Li, Q-L. (Lithos, 2018)
Keywords: Odenwald-Spessart basement; Paired metamorphic belt; Lu-Hf isotope data; U-Pb geochronology; Variscan orogeny

New excavations at the HWK EE site: Archaeology, paleoenvironment and site formation processes during late Oldowan times at Olduvai Gorge, Tanzania - de la Torre, Ignacio; Albert, Rosa M.; Arroyo, Adrián; Macphail, Richard; McHenry, Lindsay J.; Mora, Rafael; Njau, Jackson K.; Pante, Michael C.; Rivera-Rondón, Carlos A.; Rodríguez-Cintas, Ágata; Stanistreet, Ian G.; Stollhofen, Harald; et al. (Journal of Human Evolution, 2017)
his paper reports the results of renewed fieldwork at the HWK EE site (Olduvai Gorge, Tanzania). HWK EE is positioned across the boundary between Lower and Middle Bed II, a crucial interval for studying the emergence of the Acheulean at Olduvai Gorge. Our excavations at HWK EE have produced one of the largest collections of fossils and artefacts from any Oldowan site, distributed across several archaeological units and a large excavation surface in four separate trenches that can be stratigraphically correlated. Here we present the main stratigraphic and archaeological units and discuss site formation processes. Results show a great density of fossils and stone tools vertically through two stratigraphic intervals (Lemuta and Lower Augitic Sandstone) and laterally across an area of around 300 m2, and highlight the confluence of biotic and abiotic agents in the formation of the assemblage. The large size and diversity of the assemblage, as well as its good preservation, qualify HWK EE as a reference site for the study of the late Oldowan at Olduvai Gorge and elsewhere in Africa. In addition, the description of the stratigraphic and archaeological sequence of HWK EE presented in this paper constitutes the foundation for further studies on hominin behavior and paleoecology in Lower and Middle Bed II.
Keywords: Early Pleistocene; Early Stone Age; Oldowan-Acheulean transition; Paleoecology; Spatial analysis; Taphonomy

New excavations in the MNK Skull site, and the last appearance of the Oldowan and Homo habilis at Olduvai Gorge, Tanzania - de la Torre, Ignacio; Benito-Calvo, Alfonso; Martín-Ramos, Carmen; McHenry, Lindsay J.; Mora, Rafael; Njau, Jackson K.; Pante, Michael C.; Stanistreet, Ian G.; Stollhofen, Harald (Journal of Anthropological Archaeology, 2021)
MNK Skull is one of the most significant archaeological sites in Olduvai Gorge, particularly due to the previous discovery of human fossils referred to in the paper where the Homo habilis taxon was originally defined. An important archaeological assemblage is contained in the same horizon as the hominin fossils, constituting the last evidence of both Homo habilis remains and handaxe-free tool kits in the Olduvai Gorge sequence. Our excavations at the site are the first to be conducted since the original work in the 1960s, and sought to refine the archaeological context wherein the Homo habilis remains were discovered. Chronostratigraphic results place the MNK Skull sequence in Middle Bed II prior to deposition of Tuff IIB. The assemblage was deposited near the shoreline, as Palaeolake Olduvai withdrew into the basinal depocentre, and fossils and stone tools were subjected to significant post-depositional processes. The assemblage was affected by mudflow deposits that buried and preserved the assemblage but also entrained surficial bone and lithic elements into the flow. Rather than an occupation site as originally interpreted, the assemblage is better understood as a background deposit, possibly accumulated on an unconformity surface over a long period of time. The stone tool assemblage is typical of the Oldowan, with no technological elements announcing the appearance of the Acheulean, which is well attested to across the Olduvai sequence in post-Tuff IIB times. Our results highlight that, with an approximate age of circa 1.67 Ma, MNK Skull stands as a key site to understand the late Oldowan and the disappearance of Homo habilis in East Africa.
CRIS-Team Scopus Importer:2021-01-15
Keywords: Acheulean Origins; Early Homo; Early Stone Age; Lower Pleistocene

New exposure of the Ludwigskanal section near Dorlbach - a key section for the Lower Jurassic in the Franconian Alb, Southern Germany - Arp, Gernot; Aiglstorfer, Manuela; Havlik, Philipe; Krause, Thorsten; Schulbert, Christian; Seppelt, Stephan (Zeitschrift der Deutschen Gesellschaft für Geowissenschaften, 2014)
UnivIS-Import:2015-03-09:Pub.2014.nat.dgeo.IGM.LP.newexp

New geophysical knowledge of groundwater systems in complex estuarine environment - Di Sipio, Eloisa; Galgaro, Antonio; Zuppi, Gian Maria (Estuarine Coastal and Shelf Science, 2006)
Keywords: groundwater; salinization; Vertical Electrical Sounding; geochemistry; Venice Lagoon 1. Introduction The south sector of the Venice Lagoon mainland is bordered by the Venice Lagoon itself to the North; by the Adriatic Sea to the East and; for about 20 km; by the Adige River to the South; (Fig. 1). The land surface has been reclaimed from the lagoon and is subject to artificial pumping. Subsidence; due to human activities and natural processes; is a phenomenon present in the area (Benvenuti et al.; 1972; Carbognin et al.; 1997; Galgaro et al.; 2000; Ciavola et al.; 2002; Brambati et al.; 2003; Carbognin and Tosi; 2003; Comerlati et al.; 2004). The high electrical conductivity (EC) values detected in the surface water and shallow groundwater point to the existence of salt intrusion. Sea tidal oscillations and anthropic

New insights into the crystallization process of sol-gel–derived 45S5 bioactive glass - Nawaz, Qaisar; de Pablos-Martín, Araceli; Martins de Souza e Silva, Juliana; Hurle, Katrin; Jaimes, Altair T.Contreras; Brauer, Delia S.; Boccaccini, Aldo R. (Journal of the American Ceramic Society, 2020)
In this work the influence of thermal treatment conditions was evaluated in a sol-gel-derived 45S5 bioactive glass using DSC, XRD, TEM, EDX, and X-ray nanocomputed tomography (nano-CT). Temperature and time of the thermal treatment strongly influence the composition of the crystalline phases. At the onset of the glass transition temperature (600°C), combeite crystallizes as the main phase along with a calcium silicate-phosphate phase, which decomposes into rhenanite from 2 hours of thermal treatment at this temperature. At the crystallization temperature (700°C), combeite remains as the main crystalline phase. Additionally, Na2Ca2Si2O7 crystalline phase is formed. Our results provide a basic platform for tailoring the crystalline phases by controlling the nucleation and growth of crystalline phases via thermal treatments. Different morphologies (round particles, stacked layers, toothpick-like, and long features) were discerned by TEM as a function of temperature and time of treatment. It is the first time that bioactive glass is investigated by X-ray nanocomputed tomography (nano-CT) at laboratory scale. This novel technique enables the 3D visualization of features in the nanometer range, giving a suggestion of the distribution in the sample of the parts composing the sample.
CRIS-Team Scopus Importer:2020-05-02
Keywords: bioactive glasses; crystallization behavior; Sol-gel

Newly developed Sr-substituted alpha-TCP bone cements - Pina, Sandra; Torres, Paula M. C.; Götz-Neunhoeffer, Friedlinde; Neubauer, Jürgen; da Fonte Ferreira, José Maria (Acta Biomaterialia, 2010)
New bone cements made of Sr-substituted brushite-forming α-tricalcium phosphate (α-TCP) were prepared and characterized in the present work. The quantitative phase analysis and structural refinement of the starting powders and of hardened cements were performed by X-ray powder diffraction and the Rietveld refinement technique. Isothermal calorimetry along with setting time analysis allowed a precise tracing of the setting process of the pastes. The pastes showed exothermic reactions within the first 10-15 min after mixing and further release of heat after about 1 h. An apatitic phase formed upon immersion of the hardened cements in simulated body fluid for 15 and 30 days due to the conversion of brushite into apatite confirming their in vitro mineralization capability. The compressive strength of the wet cement specimens decreased with increasing curing time, being higher in the case of Sr-substituted CPC. The results suggest that the newly developed Sr-substituted brushite-forming α-TCP cements show promise for uses in orthopaedic and trauma surgery such as in filling bone defects. © 2009 Acta Materialia Inc.
UnivIS-Import:2015-03-09:Pub.2010.nat.dgeo.IGM.LM.newlyd
Keywords: Bone cement; Brushite; Rietveld refinement; Strontium; XRD

New monofunctional platinum(II) and palladium(II) complexes: Studies of the nucleophilic substitution reactions, DNA/BSA interaction, and cytotoxic activity - Cocic, Dugan; Jovanovic, Snaana; Radisavljevic, Snezana; Korzekwa, Jana; Scheurer, Andreas; Puchta, Ralph; Baskic, Dejan; Todorovic, Danijela; Popovic, Suzana; Matic, Sanja; Petrovic, Biljana (Journal of Inorganic Biochemistry, 2018)
Keywords: Kinetics; DNA; DFT; Cytotoxicity; Pd(II) and Pt(II) complexes; BSA

New Oldowan localities at high level within Kilombe Caldera, Kenya De nouvelles localités oldowayennes à un niveau élevé dans la caldeira de Kilombe, au Kenya - Gowlett, John A.J.; Stanistreet, Ian G.; Albert, Rosa M.; Blackbird, Sabena J.; Herries, Andy I.R.; Hoare, Sally; Kogai, Philip; Komboh, Caroline K.; Mark, Darren F.; Muriuki, Rebecca M.; Murphy, Hayley; Rucina, Stephen M.; et al. (Anthropologie, 2022)
New occurrences of early artefacts ascribed to the Oldowan tradition come from localities at high level within the caldera of the extinct Kilombe volcano, located in the central rift valley of Kenya. The trachyte cone and caldera of Kilombe volcano formed at ca. 2.5 Ma, and the record of >130 m of sediment-fill indicates that the caldera subsequently held a lake for long periods during the Early Pleistocene. The Oldowan artefact localities, dated by 40Ar/39Ar and palaeomagnetism to ∼1.78 Ma, lie east of the centre of the caldera, on the west side of an ancient small lake, which later drained away as a gorge formed on the east side of the mountain. The artefacts are dominantly made of Kilombe trachyte, and are associated with a fauna of large animals including Hippopotamus gorgops. These are the first Oldowan localities to be discovered in a new area of the Kenyan rift valley in the last thirty years, and their presence at high level in rugged landscape indicates that the associated hominins were exploiting a full range of environments.
CRIS-Team Scopus Importer:2022-02-25
Keywords: Argon-Argon (; Caldera; Oldowan; Rift Valley high-altitude

New Olduvai Basin stratigraphy and stratigraphic concepts revealed by OGCP cores into the Palaeolake Olduvai depocentre, Tanzania - Stanistreet, Ian G.; Stollhofen, Harald; Deino, Alan L.; McHenry, Lindsay J.; Toth, Nicholas P.; Schick, Kathy A.; Njau, Jackson K. (Palaeogeography, Palaeoclimatology, Palaeoecology, 2020)
The Olduvai Gorge Coring Project (OGCP) drilled four boreholes 1A, 2A, 3A, 3B at three sites into the central palaeolake of the Olduvai Basin depocentre. Previously known Beds I, II, III, IV, Masek Beds and Ndutu are identifiable in the upper part of the cores, and from these formations predominantly lacustrine facies associations are recognised. These are described and then interpreted in terms of their palaeoenvironmental significance. However, stratigraphy known from natural outcrop exposures is more than doubled by strata intersected below. For example, an extra 135 m of pre-Bed I stratigraphy in Core 2A records the entire volcanic history of a fan-delta sourced from Ngorongoro Volcano. Beneath that fan sequence is an interval of fluvio-lacustrine non-volcaniclastic sediments. For the latter the new stratigraphic term Naibor Soit Formation is introduced, because these strata were discovered for the first time in Boreholes 2A and 3A, to either side of Naibor Soit Inselberg, where they thus lap onto its basement topography. The volcanically sourced unit above is named Ngorongoro Formation, including Marker Tuffs CFCT (Coarse Feldspar Crystal Tuff) and the Naabi Ignimbrite within its topmost portion. Only the dominantly lacustrine sediments above the main Ngorongoro sourced fan body are now attributed to Lower Bed I. The Ngorongoro Formation defined here contains primary Tuff Markers NgA to NgQ, and volcaniclastic fan-delta deposits that interfinger with and overlie claystones and interbedded sandstones of the fluvio-lacustrine Naibor Soit Formation. Boreholes 1A and 2A intersect the Bed I Basalt, but not Borehole 3A, where the position of the lava is marked by three separated volcaniclastic sandstone layers, containing pebble-sized basalt scoriae, likely correlating to three complex basalt flows at Locality 9A and Orkeri and allowing assessment of syn-basalt sedimentation. Disconformities bounding Beds I, II, III, IV, Masek Beds and Ndutu Beds provide important stratigraphic markers for the novel application of sequence stratigraphic concepts, as they mark lowstands of Palaeolake Olduvai, guiding outcrop to core correlations. Major disconformities are identified in: (1) Core 1A, where the Lower Bed II Crocodile Valley Incision Surface cuts out Tuff IF; (2) Core 1A, where disconformities and facies within Beds II, III, IV, and Masek Beds are identified; (3) Cores 2A and 3A, where Tuff IF is identified below the Lower to Middle Bed II disconformity; and (4) Lower Bed I claystones and Tuff IA in Core 3A that correlate to similar sedimentary units from Locality 66e in the Western Gorge, but which are absent from Core 2A because of a newly identified major disconformity, which causes the Bed I lava to sit directly on top of the CFCT marker.
CRIS-Team Scopus Importer:2020-06-23
Keywords: Borehole core; Disconformity; Naibor Soit Formation; Ngorongoro Formation; Olduvai Beds

New Ordovician-Silurian drill cores from the Siljan impact structure in central Sweden - an integral part of the Swedish Deep Drilling Program - Lehnert, Oliver; Meinhold, Guido; Bergström, Stig M.; Calner, Mikael; Ebbestad, Jan Ove; Egenhoff, Sven; Frisk, Asa; Hannah, Judith L.; Högström, Annette E. S.; Huff, Warren D.; Juhlin, Christopher; Maletz, Jörg; et al. (Gff, 2012)
New drill cores from the largest known impact structure in Europe, the relict of the Siljan meteorite crater, provide new possibilities to reconstruct Early Palaeozoic marine environments and ecosystems, and to document changes in sedimentary facies, sea level and palaeoclimate in Baltoscandia. The impact crater is an important target of the project "Concentric Impact Structures in the Palaeozoic" within the framework of the "Swedish Deep Drilling Program". Two core sections, Mora 001 and Solberga 1, have been analysed. The sedimentary successions of these core sections include strata of late Tremadocian through late Wenlock ages. Our preliminary studies show not only that several of the classical Palaeozoic units of Sweden are represented in the area, but also that other significantly different facies are preserved in the Siljan district. An erosional unconformity representing a substantial hiatus occurs between Middle Ordovician limestone and a Llandovery-Wenlock (Silurian) shale succession in the western part of the Siljan structure and suggests an extended period of uplift and erosion. This may be related to forebulge migration due to flexural loading by the Caledonian thrust sheet to the west. Thus, this part of Sweden, previously regarded as a stable cratonic area, presumably was affected by the Caledonian collision between Baltica and Laurentia. © 2012 Copyright Geologiska Föreningen.
UnivIS-Import:2015-03-09:Pub.2012.nat.dgeo.IGM.LG.neword
Keywords: impact structure; Ordovician; Siljan district; Silurian; stratigraphy; Sweden

New Permian-Triassic conodont data from Selong (Tibet) and the youngest occurrence of Vjalovognathus - Wang, Lina; Wignall, Paul B.; Sun, Yadong; Yan, Chunbo; Zhang, Zaitian; Lai, Xulong (Journal of Asian Earth Sciences, 2017)
Keywords: Biostratigraphic correlation; Himalaya; Induan; Mass extinction; Vjalovognathus

New radiolarians from the earliest Cretaceous of the Sultanate of Oman (Wahrah Formation, Jebel Buwaydah) - Kießling, Wolfgang (Palaeontologische Zeitschrift, 1995)

New radiometric datings of different cave bear sites in Germany - results and interpretations - Rosendahl, Wilfried; Döppes, Doris; Joger, Ulrich; Laskowski, Rainer; López Correa, Matthias; Nielbock, Ralf; Wrede, Volker (Bulletin de la Société d'histoire naturelle de Toulouse, 2005)
New radiometric dates from seven cave bear sites in Germany were achieved during the last two years. The dates were obtained for four sites from bone samples, for one site from two stalagmites and from another site from charcoal and bones. The bones and the charcoal have been dated with the AMS 14C-method and the stalagmites with the TIMS-U/Th-method. Sites are briefly described and all dates with their analytic values are presented and discussed in methodological and paleoclimatic context. Radiocarbon ages were calibrated using calPal2004 (www.calPal.de) and paleoclimatic interpretation was made by correlation with the GISP2 ice core δ18O-curve (Stuiver & Grootes, 2000), GI = Greenland Interstadial of the GIPS2 ice core.
UnivIS-Import:2015-03-09:Pub.2005.nat.dgeo.IGM.LP.newrad
Keywords: cave bear

New records of early Middle Jurassic belemnites in the French Subalpine Basin and their paleobiogeographic significance - Mariotti, Nino; Weis, Robert; di Cencio, Andrea; Clément, Arnaud; de Baets, Kenneth (Geobios, 2012)
A biostratigraphic and systematic study based on belemnites collected along with ammonites was performed on four sections in the Subalpine Basin (SE France): Lac du Castillon and La Baurne (Castellane area), Galabrun and Grand Lara (Gap area). The specimens, originating from hemi-pelagic marllimestone alternations in the lower part of the "Calcaires a Zoophycos" Formation, are dated from Middle Aalenian (Murchisonae Zone) to Lower Bajocian (Humphriesianum Zone). Five belemnite taxa (Megateuthis elliptica, Holcobelus munieri, H. trauthi, Pachybelemnopsis roettingensis, Hibolithes sp.) have been identified, and two more taxa are reported in an open nomenclature (Belemnitida incertae sedis sp. 1 and sp. 2). The biostratigraphic range of the belemnite fauna is established. The new findings contribute to a more detailed understanding of the paleobiogeography of holcobelid belemnites that flourished at the northern margin of the Tethys Ocean and formed a distinct sub-Mediterranean fauna. The association herein described is similar to the fauna of the Calabro-Peloritani Arc (Calabria, Italy), a further hint for the supposed paleogeographic position of the latter during the Middle Jurassic. (C) 2012 Elsevier Masson SAS. All rights reserved.
Keywords: Holcobelidae; Megateuthididae; Mesohibolithidae; Middle Jurassic; Subalpine Basin; Biostratigraphy; Paleobiogeography

New SEM observations of keriothecal walls: Implications for the evolution of fusulinida - Vachard, Daniel; Munnecke, Axel; Servais, Thomas; Munnecke, Axel; Munnecke, Axel (Journal of Foraminiferal Research, 2004)
This study presents new scanning electron microscopy (SEM) observations of Paleozoic foraminifera. It focuses especially on the wall of three Fusulinida, Sakmarella moelleri, Paraskinnerella skinneri, and Taiyuanella furoni, that belong to the Schwagerinoidea, which are fusulinids with keriothecal test walls. In addition, Eostaffella sp. is investigated as an example of the microstructure of the microgranular imperforate tectum. The fillings of the keriothecal alveoles of Sakmarella, Paraskinnerella, and Taiyuanella yield diverse, characteristic flower-like structures that indicate a gradual evolution of the microstucture of the tests. Sakmarella and Paraskinnerella have flowers with a narrow center, and Taiyuanella has a larger center. The true keriothecal structure, described, for example, in Triticites, is distinguished from these structures by simply filled alveoles. The term "anthotheca" is introduced for the structure with narrow-centered flowers. It can be distinguished from the large-centered flower structure identified as Zhuang's (1989) stalactotheca. Following a literature review of previous work on keriothecal structures, several morphofunctional hypotheses are discussed, including the housing of symbiotic algae or cyanobacteria, which leads to the new interpretation that the flowers of the antho- and stalactothecal structures are induced by algal endosymbionts. In addition, we discuss the monophyly of keriothecal fusulinids. The transition from diaphanothecal to keriothecal forms recognized since Thompson (1964) is reinterpreted in terms of relationships with symbiotic algae or cyanobacteria. The Schwagerinoidea constitute an important group in understanding the evolution of larger foraminifera in the late Paleozoic.

New thermophysical data pool for NE-Bavaria reveals exceptionally high heat fluxes - Kämmlein, Marion; Bauer, Wolfgang; Stollhofen, Harald (German Geothermal Congress GGC 2017, 2017)
A geothermal anomaly in the Franconian Basin/NE Bavaria was already described in the 1980s and further specified in the 2000s. An undisturbed temperature log in a 1309 m deep well provided a geothermal gradient (gradT) of 4.8 K/100m. The enhanced geothermal gradients led to the development of several balneological facilities in the area. However, heat flux in the Franconian Basin has never been quantified. Only supra-regional heat flux densities for the Rhenohercynian and Saxothuringian of 65 – 85 mW/m2 were published, based on a few temperature data only from 50 – 300 m depths and literature derived thermal conductivity values. Within the framework of a study on the geothermal potential of NE Bavaria, a new dataset of statistically evident thermo-physical parameters of almost all stratigraphic units of the up to >1600 m thick sedimentary cover rocks of NE Bavaria was created. The newly established data pool comprises measurements of 932 core samples, 661 plug samples and 57 rock fragment samples. Thermal conductivity measurements were performed on dry and water saturated core samples and powder samples from rock fragments. For the determination of gradT, available temperature logs and BHT data of deep wells in NE Bavaria were evaluated. Temperature data were derived from log sections, which are not influenced by artesian upflow. For BHT correction different methods were tested. Heat flux density calculations were performed by the interval method, which is considering the thicknesses of the individual stratigraphic units and their key parameters. In total, temperature data of ten deep wells >500 m in the Franconian Basin were evaluated. Nine of these wells, which are located within the Basin, provide moderate to significantly enhanced geothermal gradients of 3.4 – 4.8 K/100m. Two of these wells do show enhanced gradT in the basement rocks. In contrast, one well at the outer edge of the basin and near the Franconian Line provides a below-normal gradT of 2.5 K/100m. By applying temperature corrected measured thermal conductivities and corrected underground temperatures, the area reveals significantly enhanced heat flux densities between 92 to 128 mW/m2. The deep well with the highest geothermal gradient of 4.8 K/100m provides heat flux densities of 128 mW/m2. The value distribution of heat flux density and geothermal gradients points to a local positive temperature anomaly within an area of about 80 x 50 km. The calculated heat flux densities lie in the order of magnitude of heat flux densities known from the Upper Rhine Rift, which provides heat flux densities around 110 mW/m2 and within the range of heat fluxes of other rift zones worldwide. The exceptionally high heat flux density value of 128 mW/m2 in the centre is based on an undisturbed temperature log which was measured 567 d after the shutdown of the drilling. This time after circulation is sufficient for thermal equilibrium in the borehole. The enhanced gradT in basement rocks of two wells points to a convective thermal regime, the heat source of which is most probably located in the deeper crust. Results of gravimetric modelling in the area, suggest the presence of local granite bodies within the basement rocks and calculations of radiogenic heat production of granitic outcrop analogues shows them sufficient to explain the enhanced gradT in the area.
Keywords: heat flux density; NE-Bavaria; thermal conductivity; thermophysical rock properties

New Tools to Support the Designing of Efficient and Reliable Ground Source Heat Exchangers: The Cheap-GSHPs Databases and Maps - Galgaro, Antonio; Dalla Santa, Giorgia; de Carli, Michele; Emmi, Giuseppe; Bertermann, David; Müller, Johannes; Castelruiz Aguirre, Amaia; Perego, Rodolfo; Pera, Sebastian; Mezzasalma, Giulia; Bernardi, Adriana (Geophysical Research Abstracts Vol. 21, EGU2019-17924, 2019, 2019)
The overall goal of the EU funded project CHEAP-GSHPs is the development of more efficient and safe shallow geothermal systems for building conditioning, and the reduction of their installation costs. New types of heat exchangers and installation techniques have been studied. In addition, in order to reduce the engineering costs of geothermal heat exchangers sizing, a Decision Support System (DSS) has been developed for the design of new geothermal systems. The DSS tools consider all aspects from the geological and drilling issues to the technical and economical ones, by starting from several possible design and operational solutions. They support the user in the selection of the most suitable heat exchanger, in the borehole field sizing and in the choice of the best installation technique. These tools are public and available on the web (http://cheap-gshp.eu/); they have been targeted at users with different levels of knowledge, so that they can be used by both expert and non-expert users. Several databases have been built up to feed the DSS: (I) a detailed Thermo-Geological Database indicating the thermo-physical parameters of a wide spectrum of european lithologies and unconsolidated sediments classes; in order to allow the correct evaluation of the heat exchange capacity of the subsoil where a new borehole field has to be installed. (II) an European Superficial Geological Map, that represents the variability of the subsoil conditions in Europe; this is used associated to the Thermo-Geological database as well as to suggest the best drilling technique for the local geological setting; (III) a pan-european Climatic Database; (IV) a standard temporal profiles database of the heating and cooling requirements for several standardized typologies of buildings, by taking into account also several thermal insulation levels. The detailed Thermo-Geological database has been built in order to identify the most appropriate values of physical and thermal parameters to be assigned to the local geological context. The database consolidates a wide amount of data present in the international guidelines and scientific literature (it is based on more than 60 references) integrated with more than 400 experimental measurements performed on samples of rocks and sediments sampled in several european countries. The Database include 29 categories of rocks and 10 classes of unconsolidated sediments. The Thermo-Geological Database merges the thermal conductivity ranges exposed in literature with the values acquired by the direct measurements; in addition, the reference values of density and thermal diffusivity for each category are indicated. Finally, a method to map the techno-economic potential of closed-loop shallow geothermal systems (expressed as €/kW) has been developed. It merges all geological, climatic and energetic data collected in the Databases in order to quantify the geothermal potential for different locations and the feasibility of shallow geothermal systems. The method has been successfully applied in some test sites representative of main European contexts. The new web tools and the developed mapping method support the design and the installation of new shallow geothermal systems, by taking into account all the involved aspects from the geological to the economical ones. <br

New tools to support the designing of efficient and reliable ground source heat exchangers: the Cheap-GSHPs databases and maps - Galgaro, Antonio; Della Santa, Giorgia; de Carli, Michele; Emmi, Giuseppe; Zarrella, Angelo; Müller, Johannes; Bertermann, David; Castelruiz Aguirre, Amaia; Noyé, Sarah; Perego, Rodolfo; Pera, Sebastian; Poletto, Fabio; et al. (Advances in Geosciences, 2019)

Noble guests in organic cages–encapsulation of noble gases by cryptophane - Ćoćić, Dušan; Puchta, Ralph; van Eldik, Rudi (Journal of Coordination Chemistry, 2020)
With the application of DFT calculations (ωB97XD/def2-SVP/SVPfit), the ability and mechanism of noble gas encapsulation by cryptophane was investigated. Based on the applied model reaction, by monitoring geometric changes and investigating the non-covalent interactions between the studied hosts and the noble gases, the size of the host did not necessarily play a decisive role in the selective encapsulation of the guests. Rather the adjustment of the host’s interior and functionalization of its “gates” can be significant in tuning the affinity of cryptophanes.
CRIS-Team Scopus Importer:2020-10-02
Keywords: cryptophane; DFT; host-guest chemistry; Noble gases