No (Cambrian) explosion and no (Ordovician) event: A single long-term radiation in the early Palaeozoic - Servais, Thomas; Cascales-Miñana, Borja; Harper, David A.T.; Lefebvre, Bertrand; Munnecke, Axel; Wang, Wenhui; Zhang, Yuandong (Palaeogeography, Palaeoclimatology, Palaeoecology, 2023)
The Cambrian ‘Explosion’, located by many authors between 540 and 520 million years ago (Ma), is considered to be an abrupt appearance in the fossil record of most animal phyla, with a sudden increase of complex morphologies across metazoan groups. In a few recent papers, the Great Ordovician Biodiversification ‘Event’ (GOBE) has similarly been restricted to a single dramatic biodiversification ‘event’ in the Darriwilian Stage of the Middle Ordovician Series, between 470 and 455 Ma, although historically the biodiversification is considered as an aggregation of radiation ‘events’ capturing a large and complex increase of taxonomic diversity of marine invertebrates covering the entire Ordovician. A review of biodiversity curves of marine organisms during the early Palaeozoic, including some based on data in the Paleobiology Database (PBDB) and the Geobiodiversity Database (GBDB), points towards a single, large-scale, long-term early Palaeozoic radiation of life that already started in the late Precambrian. An abrupt ‘explosion’ of diversity in the Cambrian or a significant ‘event’ in the Ordovician are not visible in our biodiversity studies, because they are either regional, or only reflect a single group of organisms. It is evident that the datasets remain incomplete, in particular those for many geographical areas and for several fossil groups, that are not covered by the PBDB and GBDB; also, such areas remain so far poorly or entirely unstudied. Some recently published biodiversity curves have to be considered with care, as the truly global diversity estimates of marine organisms during the early Palaeozoic remain elusive. Here, we argue that published curves of taxonomic richness, which show distinct periods of diversification, cannot sufficiently be disentangled from biases. We therefore question the existence of a distinct Cambrian ‘Explosion’ and global Ordovician ‘Event’ in the global datasets. Both terms, Cambrian ‘Explosion’ and Great Ordovician Biodiversification ‘Event should be used as conceptional terms only. The first represents the appearance of almost all animal phyla during the late Precambrian and early Cambrian, whereas the second term embraces the numerous and complex radiations that occurred during the entire Ordovician.
CRIS-Team Scopus Importer:2023-05-26
Keywords: Biodiversity; Cambrian Explosion; Geobiodiversity Database; Great Ordovician Biodiversification Event; Paleobiology Database; Radiation

No chemical change during high-T dehydration and re-hydration reactions: Constraints from Erzgebirge HP and UHP eclogite - Schmädicke, Esther; Will, Thomas M. (Lithos, 2021)
Meta-basaltic eclogite occurs in the Erzgebirge in three high-pressure (HP) units (Unit 1, 2, and 3) as numerous lenses within high-grade felsic rocks. Units 2 and 3 are common HP units with quartz eclogite, and Unit 1 is an ultra-high pressure (UHP) unit with coesite eclogite, garnetite (metarodingite) and garnet peridotite. The conditions of peak metamorphism increase from Unit 3 (600–650 °C, 20–22 kbar), to Unit 2 (670–730 °C, 24–26 kbar) and Unit 1 (840–920 °C, ≥30 kbar), correlating with a decreasing abundance of hydrous minerals (from >10 vol% in Unit 3 to 0 vol% in Unit 1). In all units, the dominating eclogite type is dark-colored with a composition typical of MORB. A subordinate light type is chemically more variable and has higher contents of Mg, Al, Ca, Cr, Ni, and large ion lithophile elements as well as lower Fe, Zr, Y, and rare earth element concentrations than dark eclogite. Light eclogite formation is interpreted by plagioclase accumulation in a MOR magma chamber. No compositional difference is visible between well-preserved eclogite and samples with variable degrees of post-eclogitic overprint. In addition, dark eclogite from all units is compositionally indistinguishable, implying that prograde dehydration reactions did not modify major and trace element concentrations. This conclusion applies to all reactions in the temperature interval between c. 600 °C (peak T in Unit 3) and c. 900 °C (peak T in Unit 1), including prograde breakdown of calcic amphibole, zoisite, paragonite, and phengite. Together with previous studies on dehydration reactions in blueschist and eclogite at <600 °C (Spandler et al., 2003; Spandler et al., 2004), the present results imply that de-volatilization of the basaltic portion of subducting slabs plays only a minor, if any, role for the enrichment of fluid-mobile elements in the mantle wedge. We infer that most, if not all, of the H2O produced by dehydration reactions between 600 and 900 °C is preserved in eclogite due to the pressure-enhanced capability of garnet and omphacite to incorporate structural water. Incorporation of H2O, produced during the final dehydration stage (c. 800 ± 50 °C, 25–30 kbar), in nominally anhydrous minerals may explain why partial melting obviously did not occur in eclogite.
CRIS-Team Scopus Importer:2021-02-05
Keywords: Eclogite; Element mobility; Erzgebirge; Geochemistry; Mantle wedge; Meta-basalt

Norithamnium madoniensis Senowbari-Daryan, Keupp, Abate & Vartis-Matarangas, 2002 in the Anisian reef boulders from Karaburun Peninsula, Turkey - Senowbari-Daryan, Baba; Link, Michael (Journal of alpine geology, 2007)
From the Anisian reef boulders embedded within the Gerence Formation in Karaburun Peninsula, Turkey the species Norithamnium madoniensis (Corallinales, Rhodophyta) is described. The genus was known until now from the Norian-Rhaetian reef limestones of Sicily, Greece, and Austria. The Anisian of Karaburun is the fourth locality and probably the oldest occurrence.
UnivIS-Import:2015-04-14:Pub.2007.nat.dgeo.IGM.LP.norith
Keywords: Algae; Corallinales; Rhodophyta; Norithamnium; Anisian; Karaburun; Turkey

Normal giants? Temporal and latitudinal shifts of Palaeozoic marine invertebrate gigantism and global change - Klug, Christian; de Baets, Kenneth; Kröger, Björn; Bell, Mark Alan; Korn, Dieter; Payne, Jonathan Louis; de Baets, Kenneth (Lethaia, 2015)
During and after the Cambrian explosion, very large marine invertebrate species have evolved in several groups. Gigantism in Carboniferous land invertebrates has been explained by a peak in atmospheric oxygen concentrations, but Palaeozoic marine invertebrate gigantism has not been studied empirically and explained comprehensively. By quantifying the spatiotemporal distribution of the largest representatives of some of the major marine invertebrate clades (orthoconic cephalopods, ammonoids, trilobites, marine eurypterids), we assessed possible links between environmental parameters (atmospheric or oceanic oxygen concentrations, ocean water temperature or sea level) and maximum body size, but we could not find a straightforward relationship between both. Nevertheless, marine invertebrate gigantism within these groups was temporally concentrated within intervals of high taxonomic diversity (Ordovician, Devonian) and spatially correlated with latitudes of high occurrence frequency. Regardless of whether temporal and spatial variation in sampled diversity and occurrence frequency reflect true biological patterns or sampling controls, we find no evidence that the occurrences of giants in these groups were controlled by optimal conditions other than those that controlled the group as a whole; if these conditions shift latitudinally, occurrences of giants will shift as well. It is tempting to attribute these shifts to contemporary changes in temperature, oxygen concentrations in the atmosphere and the oceans as well as global palaeogeography over time, but further collection-based studies are necessary on finer stratigraphic and phylogenetic resolution to corroborate such hypotheses and rule out sampling or collection biases.
Keywords: Arthropoda; Cephalopoda; macroecology; mass extinctions; palaeodiversity; palaeogeography; Palaeozoic

North Atlantic intermediate water variability over the past 20,000 years - Yasuhara, Moriaki; deMenocal, Peter B.; Dwyer, Gary S.; Cronin, Thomas M.; Okahashi, Hisayo; Huang, Huai-Hsuan (Geology, 2019)
North Atlantic intermediate-water temperature variations based on ostracod Mg/Ca ratios from Ocean Drilling Program (ODP) Hole 1055B document a series of multi-centennial-scale abrupt warming events throughout the last deglaciation and Holocene (up to 3 °C). These events are coherent with abrupt climate reversals including Heinrich event 1, the Younger Dryas-Intra-Allerød cold period, and Holocene North Atlantic Deep Water (NADW) reduction periods. Deglacial-Holocene warm events were likely related to reduction in the strength of the upper NADW (Labrador Sea Water). We also found a long-term cooling trend in the ODP 1055 Mg/Ca record indicating continuous Labrador Sea Water strengthening throughout the Holocene. Our results help to better understand deglacial-Holocene upper NADW dynamics that remain poorly understood but can be important for regional and global climates.
CRIS-Team Scopus Importer:2019-07-09

Northeastern Atlantic cold-water coral reefs and climate - Frank, Norbert; Freiwald, André; López Correa, Matthias; Wienberg, Claudia; Eisele, Markus; Hebbeln, Dierk; van Rooij, David; Henriet, Jean-Pierre; Colin, Christophe; van Weering, Tjeerd; de Haas, Henk; Buhl-Mortensen, Pål; et al. (Geology, 2011)
U-series age patterns obtained on reef framework-forming cold-water corals collected over a nearly 6000-km-long continental margin sector, extending from off Mauritania (17°N; northwest Africa) to the southwestern Barents Sea (70°N; northeastern Europe), reveal strong climate infl uences on the geographical distribution and sustained development of these ecosystems. Over the past three glacial-interglacial cycles, framework-forming cold-water corals (Lophelia pertusa and Madrepora oculata) seem to have predominantly populated reefs, canyons, and patches in the temperate East Atlantic and the Mediterranean Sea. Above 50°N corals colonize reefs in the northern East Atlantic primarily during warm climate periods with the biogeographic limit advancing from 50°N to 70°N. We propose that north-south oscillations of the biogeographic limit of reef developments are paced by ice ages and may occur synchronously with north-south displacement of cold nutrient-rich intermediate waters and surface productivity related to changes of the polar front. © 2011 Geological Society of America.
UnivIS-Import:2015-03-09:Pub.2011.nat.dgeo.IGM.LP.northe

Notes on Palaeontological Societies - Reich, Mike; Gehler, Alexander; Roden, Vanessa (Jahrestagung der Paläontologischen Gesellschaft. 8.-10. September 2008, Erlangen, 2008)

Novel evaluations of sources and sinks of dissolved oxygen via stable isotopes in lentic water bodies - Dordoni, Marlene; Seewald, Michael; Rinke, Karsten; Schmidmeier, Jakob; Barth, Johannes (Science of the Total Environment, 2022)
Dissolved oxygen (DO) dynamics of a temperate drinking water reservoir in the Harz Mountains (Germany) were investigated over a time period of 18 months. Via depth profiles in a fortnightly sampling resolution we were able to trace DO and temperature dynamics including the formation and breakdown of a Metalimnetic Oxygen Minimum (MOM) by means of DO concentration, saturation patterns and stable isotope ratios of dissolved oxygen (expressed as δ18ODO). Over the evaluation period, 19.4 % of the samples collected had δ18ODO values compatible with atmospheric equilibration (+24.6 ‰ ± 0.4 ‰). With values smaller and larger than this threshold, the remaining δ18ODO values showed that 40.8 % of our samples were dominated by photosynthesis and 39.8 % by respiration. From December to April the reservoir was mixed and DO consumption by respiration exceeded production via photosynthesis. During stratification period, quantification of respiration/photosynthesis rates (R/P) confirmed the epilimnion as a photosynthetic (i.e. net-autotrophic) environment while the hypolimnion was heterotrophic and dominated by respiration at various degrees. Samples of the MOM zone showed the highest R/P ratios and had among the most positive δ18ODO signals caused by respiration. This study showed that combinations of DO concentrations and their isotope ratios are promising to quantify critical zones of respiration and photosynthesis in aquatic environments.
CRIS-Team Scopus Importer:2022-07-01
Keywords: Atmospheric influence; Lentic water bodies; Metalimnetic Oxygen Minimum (MOM); Photosynthesis; R/P ratios; Respiration

Numerical modeling and inverse parameter estimation of the large-scale mass movement Gradenbach in Carinthia (Austria) - Meier, Joerg; Moser, Michael; Datcheva, Maria; Schanz, Tom (Acta Geotechnica, 2013)
Keywords: Parameter identification; Mathematical optimization; Statistic parameter analysis

Numerical Modelling of Seismic Site Effects Incorporating Non-linearity and Groundwater Level Changes - Ehret, Dominik; Rohn, Joachim; Hannich, Dieter; Grandas, Carlos; Huber, Gerhard (Journal of Earth Science, 2010)
In the past decades, the necessity for detailed earthquake microzonation studies was recognized worldwide. Therefore, different approaches were established and applied. Unfortunately, the majority of these approaches are not based on pre-existing field data but require extensive seismic measurements and investigations. Furthermore, these approaches incorporate non-linearity inadequately and cannot take groundwater level changes into account. For this purpose, notably numerical models are most suitable. These models require a good knowledge of the local geological conditions (especially of the uppermost unconsolidated units), information about the geotechnical parameters of these units, and a hydrogeological model of the investigated area. Most of this information can be obtained from geotechnical investigations and surveys that have already been carried out in most densely populated areas. In a case study for Bucharest City, non-linear analyses were performed using software that is based on the visco-hypoplastic constitutive law. The results indicate that groundwater level changes have an important influence on duration and amplitude of ground response and thus should be considered for seismic microzonation studies. This approach can be used to display site effects and to identify different microzones taking different earthquake magnitudes and groundwater levels into account. © 2010 China University of Geosciences and Springer-Verlag Berlin Heidelberg.
UnivIS-Import:2015-03-09:Pub.2010.nat.dgeo.IGM.profes_3.numeri
Keywords: Bucharest; microzonation; non-linearity; Romania; site effect; visco-hypoplasticity

Numerical Simulation of Qiaotou Landslide Deformation Caused by Drawdown of the Three Gorges Reservoir, China - Jiang, Jiwei; Ehret, Dominik; Xiang, Wei; Rohn, Joachim; Huang, Ling; Yan, Shaojun; Bi, Renneng (Environmental Earth Sciences, 2011)
Landslides located beside reservoirs tend to be unstable or are characterized by large deformation during the drawdown process. This has been accepted by many experts. In this paper, we use Qiaotou Landslide, which is located beside the Three Gorges Reservoir (TGR), as a typical case study to investigate and predict the deformation mechanism during the drawdown process of TGR in detail. According to field investigation, the landslide mass is mainly composed of thick, loose silt and clay mixed with fragments of rock. Bedrock is mainly composed of silty sandstone. Field and laboratory tests indicate that the landslide mass has a high permeability coefficient. If the water level declines fast, intense seepage force may result. Based on these data, we establish a three-dimensional geological model of Qiaotou Landslide by FLAC3D and perform a numerical simulation using the saturated-unsaturated fluid-solid coupling theory. For the simulation, we assume that the drawdown from 175 to 145 m takes place with a speed of 25 cm/day, which is based on the extreme water level regulation program of TGR. The simulation shows that this causes a significant deformation in the landslide mass and that the maximum displacement within the landslide is 24.2 cm. During the drawdown process, the maximum displacement zone is shifting from the upper part of the landslide where bedrock surface is steeper and thickness of loose deposits is less to the middle part of the landslide where bedrock surface is less steep and thickness of loose deposits is higher. The deformation mechanism indicates that in the early stage of the drawdown the deformation of the landslide mass is mainly caused by seepage and in the later stage mainly by consolidation. © 2010 Springer-Verlag.
UnivIS-Import:2015-03-09:Pub.2011.nat.dgeo.IGM.profes_3.numeri
Keywords: Deformation prediction of landslide; Numerical simulation; Reservoir drawdown; Saturated-unsaturated seepage; Three Gorges Reservoir

Nuptial feeding is reflected in tissue nitrogen isotope ratio in female katydids - Joachimski, Michael; et al. (Functional Ecology, 2006)
1. During copulation male katydids transfer a protein-rich nuptial gift to females, which is ingested by the female. We hypothesized that female katydids are built at least partly from proteins assimilated from nuptial gifts. 2. We measured the ratio of nitrogen isotopes (δ15N) in the diet and tissue of sexually reproducing Isophya kraussii and obligate parthenogenetically reproducing Poecilimon intermedius. We used the δ15N of muscles as an indicator of the most recent diet and the δ15N of the cuticula as an indicator of the larval diet. 3. In free-ranging I. kraussi, muscular and cuticular δ15N of adult males was low, suggesting a plant diet. Cuticular δ15N did not differ between sexes, indicating that immatures of both sexes fed on similar diets. Female muscles were significantly more enriched in nitrogen-15 than female cuticula and also than male muscles, suggesting that adult females incorporated animal proteins and immature females plant material. 4. Female I. kraussii that were kept with males in captivity had higher δ15N in muscular tissue than in cuticula. Muscular δ15N of these females was also higher than that of muscle and cuticula of females held isolated from males, suggesting that incorporated nitrogen originated from nuptial gifts. 5. In parthenogenetically reproducing P. intermedius muscular and cuticular δ15N was almost identical, suggesting no additional uptake of insect proteins in the absence of nuptial gifts. 6. We therefore conclude that female I. kraussii substantially assimilate spermatophylax compounds for both egg production and body homeostasis. © 2006 The Authors.
UnivIS-Import:2015-03-09:Pub.2006.nat.dgeo.IGM.LG.nuptia
Keywords: Homeostasis; Isophya; Nitrogen source; Spermatophore; Stable isotopes

Oases of biodiversity: Early Devonian palaeoecology of Hamar Laghdad, Morocco - Klug, Christian; Samankassou, Elias; Pohle, Alexander; de Baets, Kenneth; Franchi, Fulvio; Korn, Dieter (Neues Jahrbuch für Geologie und Paläontologie-Abhandlungen, 2018)
The mudmound locality of Hamar Laghdad (Tafilalt Platform) contains possibly the greatest palaeobiodiversity, both horizontally in the surrounding sediments and stratigraphically through the Devonian sedimentary succession of the Moroccan eastern Anti-Atlas. From the Ordovician to the Devonian, sediments of the Hamar Laghdad region and their fossil contents tend to differ slightly from those in time-equivalent strata of other parts of the Tafilalt Platform. Our research provides a description of the sedimentological and palaeontological record of Hamar Laghdad covering the Lochkovian to Givetian interval. We use alpha-diversity data based on macrofossils from selected fossiliferous strata and compare the results with the relative abundance of bioclasts in polished sections. We show that the palaeobiodiversity of Hamar Laghdad was similar to that of the southern Tafilalt with a normal diversity during the Pragian, i.e. prior to mudmound initiation and growth. By contrast, the layers covering the massive mudmound carbonates (e.g., when their activity had ceased) show a high diversity during the latest Emsian with a trophic nucleus comprising 36 species. This fauna, here exemplified by the ‘Red Fauna’ (from the Red Cliff), is dominated by benthic suspension feeders (corals, brachiopods and crinoids) and cephalopods. The shift in biodiversity is most likely related to the local occurrence of a favourable environmental setting, characterized by a temporally and spatially varying topography. It is assumed that this setting was influenced by sea-level fluctuations, currents and nutrient availabilit

Oberflächennah bis kilometertief – Lehre und Forschung zur Geothermie an der FAU Erlangen - Stollhofen, Harald; Bauer, Wolfgang; Bertermann, David; Drews, Michael; Fazlikhani, Hamed (Geothermische Energie, 2018)
Geothermie-Forschung am GeoZentrum Nordbayern (GZN) der Friedrich-Alexander-Universität (FAU) ist auf die integrierte fazielle, petrographische, petrophysikalische und geomechanische Charakterisierung von Reservoirgesteinen und deren Exploration ausgerichtet. Zudem werden pedologische bzw. geophysikalische Systemzusammenhänge im Bereich der oberflächennahen Geothermie analysiert. Ein neuer Masterstudiengang "GeoThermie/GeoEnergie" zielt auf die Vermittlung eines ganzheitlichen Systemverständnisses.

Oberflächennahste Geothermiesysteme als Quelle für kalte Nahwärmenetze - Bertermann, David; Wienke, Jeannette; Müller, Johannes; Böck, Sebastian; Lach, Gerald; Steinhäuser, Harry (bbr - Leitungsbau, Brunnenbau, Geothermie, 2019)

Oblique magnetic fabric in siderite-bearing pelitic rocks of the Upper Carboniferous Culm Basin, SW England: An indicator for palaeo-fluid migration? - de Wall, Helga; Warr, Laurence N. (2004)

Obsidian clasts as sintered remnants of agglutination processes in volcanic conduits, evidence from the Pepom tephras (Sete Cidades), São Miguel, Azores - Ellis, B. S.; Pimentel, A.; Cortes-Calderon, E. A.; Moser, Z.; Baumann, Nils; Bachmann, O.; Wadsworth, F. B. (Chemical Geology, 2023)
The youngest explosive eruptions of the Sete Cidades volcano, São Miguel, Azores, are recorded by a series of relatively small-volume (<0.03 to 0.13 km3 DRE) trachytic pyroclastic deposits termed the Pepom tephra deposits. While dominated by crystal-poor to crystal-moderate (<10%) pumice clasts, these deposits also contain a suite of dense glassy clasts of broadly similar crystallinity. The obsidian clasts from a single deposit vary in texture from entirely dense to those that are moderately vesicular and typically single clasts will contain multiple textural domains. The majority (∼71%) of these dense clasts have compositions both from bulk rock and in-situ glass measurements that are identical to those of the pumice clasts within the same deposit. We interpret these dense clasts to reflect sintering of previously fragmented magma at shallow levels in the conduit prior to being re-entrained and erupted with the vesicular magma, in agreement with recent studies focussing on textural observations. Notably, across the exposed volcanic stratigraphy of São Miguel obsidian domes, flows/coulees are not preserved, arguing against the idea that the dense glass clasts within the Pepom tephras are sourced from existing surficial rocks. In contrast, the neighbouring island of Terceira exhibits domes and coulees with large obsidian bands that cut through the crystalline groundmass. Most silicic rocks of Santa Bárbara and Pico Alto volcanoes on Terceira are peralkaline, comenditic to pantelleritic in composition, and at similar conditions (e.g., temperature and water content) have lower viscosities than the trachytic Pepom obsidian clasts. However, the Santa Bárbara silicic lavas on Terceira (the less peralkaline suite) have more obsidian than the more peralkaline Pico Alto domes and coulees indicating that while peralkalinity, developed during magmatic evolution in the crust, may play a role, sintering occurring at shallow levels within the conduit likely is more important in producing obsidian.
CRIS-Team Scopus Importer:2023-09-29
Keywords: Azores; Geochemistry; Obsidian; Sintering; Trachyte

Occurrence and fate of perfluorinated compounds in sewage sludge from Spain and Germany - Gomez-Canela, Cristian; Barth, Johannes; Lacorte, Silvia (Environmental Science and Pollution Research, 2012)

Ocean and Coastal Ecosystems and their Services, in: Climate Change 2022: Impacts, Adaptation and Vulnerability. Working Group II Contribution to the IPCC Sixth Assessment Report - Cooley, Sarah; Schoeman, David; Bopp, Laurent; Boyd, Philip; Donner, Simon; Ghebrehiwet, Dawit Yemane; Ito, Shin-Ichi; Kießling, Wolfgang; Martinetto, Paulina; Ojea, Elena; Racault, Marie-Fanny; Rost, Björn; et al. (Climate Change 2022: Impacts, Adaptation and Vulnerability. Working Group II Contribution to the IPCC Sixth Assessment Report, 2022)
Anthropogenic climate change has exposed ocean and coastal ecosystems to conditions that are unprecedented over millennia (high confidence2), and this has greatly impacted life in the ocean and along its coasts (very high confidence). Fundamental changes in the physical and chemical characteristics of the ocean acting individually and together are changing the timing of seasonal activities (very high confidence), distribution (very high confidence), and abundance (very high confidence) of oceanic and coastal organisms, from microbes to mammals and from individuals to ecosystems, in every region. Evidence of these changes is apparent from multi-decadal observations, laboratory studies and mesocosms, as well as meta-analyses of published data. Geographic range shifts of marine species generally follow the pace and direction of climate warming (high confidence): surface warming since the 1950s has shifted marine taxa and communities poleward at an average (mean ± very likely range) of 59.2 ± 15.5 km per decade (high confidence), with substantial variation in responses among taxa and regions. Seasonal events occur 4.3 ± 1.8 to 7.5 ± 1.5 days earlier per decade among planktonic organisms (very high confidence) and on average 3 ± 2.1 days earlier per decade for fish (very high confidence). Warming, acidification and deoxygenation are altering ecological communities by increasing the spread of physiologically sub-optimal conditions for many marine fish and invertebrates (medium confidence). These and other responses have subsequently driven habitat loss (very high confidence), population declines (high confidence), increased risks of species extirpations and extinctions (medium confidence) and rearrangement of marine food web
Keywords: anthropogenic; climate; change; geographic range shifts; range; shifts; marine; species; warming; acidification; deoxygenation; invertebrates; fish; extinctions; rearrangement

Oceanic island biogeography through the lens of the general dynamic model: Assessment and prospect - Borregaard, Michael K.; Amorim, Isabel R.; Borges, Paulo A. V.; Cabral, Juliano S.; Fernandez-Palacios, Jose M.; Field, Richard; Heaney, Lawrence R.; Kreft, Holger; Matthews, Thomas J.; Olesen, Jens M.; Price, Jonathan; Rigal, Francois; et al. (Biological Reviews, 2017)
The general dynamic model of oceanic island biogeography (GDM) has added a new dimension to theoretical island biogeography in recognizing that geological processes are key drivers of the evolutionary processes of diversification and extinction within remote islands. It provides a dynamic and essentially non-equilibrium framework generating novel predictions for emergent diversity properties of oceanic islands and archipelagos. Its publication in 2008 coincided with, and spurred on, renewed attention to the dynamics of remote islands. We review progress, both in testing the GDM's predictions and in developing and enhancing ecological–evolutionary understanding of oceanic island systems through the lens of the GDM. In particular, we focus on four main themes: (i) macroecological tests using a space-for-time rationale; (ii) extensions of theory to islands following different patterns of ontogeny; (iii) the implications of GDM dynamics for lineage diversification and trait evolution; and (iv) the potential for downscaling GDM dynamics to local-scale ecological patterns and processes within islands. We also consider the implications of the GDM for understanding patterns of non-native species diversity. We demonstrate the vitality of the field of island biogeography by identifying a range of potentially productive lines for future research.
Keywords: Archipelago; Diversity theory; General dynamic model; Island biogeography; Island evolution; Trait evolution; Volcanic islands

Ocean temperatures through the Phanerozoic reassessed - Grossman, Ethan; Joachimski, Michael (Scientific Reports, 2022)
The oxygen isotope compositions of carbonate and phosphatic fossils hold the key to understanding Earth-system evolution during the last 500 million years. Unfortunately, the validity and interpretation of this record remain unsettled. Our comprehensive compilation of Phanerozoic δ18O data for carbonate and phosphate fossils and microfossils (totaling 22,332 and 4615 analyses, respectively) shows rapid shifts best explained by temperature change. In calculating paleotemperatures, we apply a constant hydrosphere δ18O, correct seawater δ18O for ice volume and paleolatitude, and correct belemnite δ18O values for 18O enrichment. Similar paleotemperature trends for carbonates and phosphates confirm retention of original isotopic signatures. Average low-latitude (30° S–30° N) paleotemperatures for shallow environments decline from 42.0 ± 3.1 °C in the Early-to-Middle Ordovician to 35.6 ± 2.4 °C for the Late Ordovician through the Devonian, then fluctuate around 25.1 ± 3.5 °C from the Mississippian to today. The Early Triassic and Middle Cretaceous stand out as hothouse intervals. Correlations between atmospheric CO2 forcing and paleotemperature support CO2’s role as a climate driver in the Paleozoic.<br

OH 83: A new early modern human fossil cranium from the Ndutu beds of Olduvai Gorge, Tanzania - Reiner, Whitney B.; Masao, Fidelis; Sholts, Sabrina B.; Songita, Agustino Venance; Stanistreet, Ian; Stollhofen, Harald; Taylor, R. E.; Hlusko, Leslea J. (American Journal of Physical Anthropology, 2017)
Objective: Herein we introduce a newly recovered partial calvaria, OH 83, from the upper Ndutu Beds of Olduvai Gorge, Tanzania. We present the geological context of its discovery and a comparative analysis of its morphology, placing OH 83 within the context of our current understanding of the origins and evolution of Homo sapiens. Materials and methods: We comparatively assessed the morphology of OH 83 using quantitative and qualitative data from penecontemporaneous fossils and the W.W. Howells modern human craniometric dataset. Results: OH 83 is geologically dated to ca. 60–32 ka. Its morphology is indicative of an early modern human, falling at the low end of the range of variation for post-orbital cranial breadth, the high end of the range for bifrontal breadth, and near average in frontal length. Discussion: There have been numerous attempts to use cranial anatomy to define the species Homo sapiens and identify it in the fossil record. These efforts have not met wide agreement by the scientific community due, in part, to the mosaic patterns of cranial variation represented by the fossils. The variable, mosaic pattern of trait expression in the crania of Middle and Late Pleistocene fossils implies that morphological modernity did not occur at once. However, OH 83 demonstrates that by ca. 60–32 ka modern humans in Africa included individuals that are at the fairly small and gracile range of modern human cranial variation.
Keywords: evolution; paleoanthropology; paleontology; pleistocene; variation

OH point defects in olivine from Pakistan - Schmädicke, Esther; et al. (Mineralogy and Petrology, 2010)

Okorusu tailings – Part II: REE mineralisation, and oxygen and carbon isotope variations - Lohmeier, S.; Machleidt, Jakob; Klemd, Reiner; Ellmies, R. (South African Journal of Geology, 2023)
The Okorusu carbonatite complex and the mine’s tailings dump constitute a potential resource of rare earth elements meaning lanthanides and yttrium (REY). Small (≤100 μm), hydrothermal REE fluorcarbonates (bastnäsite, parisite, röntgenite and synchysite) are the principal light REE carriers while the heavy REE and Y are primarily hosted in magmatic apatite, magmatic-hydrothermal carbonates (calcite, dolomite, ankerite) and hydrothermal fluorite. Bastnäsite and röntgenite occur as individual, liberated crystals in the tailings albeit syntaxial intergrowths of acicular parisite-synchysite-röntgenite are more common. There is a clear trend of decreasing REY contents in the magmatic carbonates over the early hydrothermal carbonates to the late hydrothermal carbonates. The lower total REY abundance in the hydrothermal carbonates is interpreted to be mainly a consequence of their limited redistribution during hydrothermal activity following the breakdown of the primary magmatic minerals and precipitation of REE fluorcarbonates. During this process hydrothermal fluids changed the isotopic composition of the Okorusu carbonatites by shifting δ13C-δ18O pairs of magmatic carbonatite (δ13C:-6.5‰ to-5.4‰; δ18O: +6.4‰ to +11.2‰) to higher values of hydrothermally modified carbonatite (δ13C:-4.2 to-2.2; δ18O: +12.0‰ to +17.5‰). The preferential presence of REY in the magmatic carbonates and to a minor degree in the hydrothermal carbonates in the Okorusu carbonatite and tailings is an important exploration tool for primary magmatic REY mineralisations. The recovery of REE fluorcarbonates can be considered in the development of the flowsheet for the planned recycling of the tailings material as a potential REY by-product.
CRIS-Team Scopus Importer:2023-11-03

Oldest known Stereospondylous amphibian from the Early Permian of Namibia. - Stollhofen, Harald; et al. (PalArch's Journal of Vertebrate Palaeontology, 2001)
UnivIS-Import:2015-03-09:Pub.2001.nat.dgeo.IGM.LG.oldest

Olduvai's oldest Oldowan - Stollhofen, Harald; Stanistreet, Ian G.; Toth, Nicholas; Schick, Kathy D.; Rodriguez-Cintas, Agata; Albert, Rosa M.; Farrugia, Paul; Njau, Jackson K.; Pante, Michael C.; Herrmann, Edward W.; Ruck, Lana; Bamford, Marion K.; et al. (Journal of Human Evolution, 2021)
Previously, Olduvai Bed I excavations revealed Oldowan assemblages <1.85 Ma, mainly in the eastern gorge. New western gorge excavations locate a much older similar to 2.0 Ma assemblage between the Coarse Feldspar Crystal Tuff (similar to 2.015 Ma) and Tuff IA (similar to 1.98 Ma) of Lower Bed I, predating the oldest eastern gorge DK assemblage below Tuff IB by similar to 150 kyr. We characterize this newly discovered fossil and artifact assemblage, adding information on landscape and hominin resource use during the similar to 2.3-2.0 Ma period, scarce in Oldowan sites. Assemblage lithics and bones, lithofacies boundaries, and phytolith samples were surveyed and mapped. Sedimentological facies analysis, tephrostratigraphic and sequence stratigraphic principles were applied to reconstruct paleoenvironments and sedimentary processes of sandy claystone (lake), sandstone (fluvial), and sandy diamictite (debris flow) as principal lithofacies. Artifacts, sized, weighed, categorized, were examined for petrography, retouch, and flake scar size. Taxonomic classifications and taphonomic descriptions of faunal remains were made, and phytoliths were categorized based on reference collections. Lithics are dominantly quartzite, mainly debitage and less frequently simple cores, retouched pieces, and percussors. Well-rounded spheroids and retouched flakes are rare. Identifiable taxa, Ceratotherium cf. simum (white rhinoceros) and Equus cf. oldowayensis (extinct zebra), accord with nearby open savanna grasslands, inferred from C-3 grass, mixed and/or alternating with C-4 grass-dominated phytolith assemblages. Palms, sedges, and dicots were also identified from phytoliths. Diatoms and sponge spicules imply nearby freshwater. The assemblage accumulated at the toe of a Ngorongoro Volcano-sourced fan-delta apron of stacked debris flows, fluvials, and tuffs, preserving fossil tree stumps and wooded grassland phytoliths farther upfan. It formed after the climax of Ngorongoro volcanic activity during a Paleolake Olduvai lowstand and was then buried and preserved by lacustrine clays, marking the first of two lake transgressions, signifying wetter climates. Orbital precessional lake cycles were superposed upon multimillennial (similar to 4.9 kyr) lake fluctuations. (C) 2020 Elsevier Ltd. All rights reserved.
CRIS-Team WoS Importer:2021-01-15

Olivine from spinel peridotite xenoliths: Hydroxyl incorporation and mineral composition - Schmädicke, Esther; et al. (American Mineralogist, 2012)
Keywords: Olivine; Nominally anhydrous minerals; Trace elements; Spinel peridotite; Water content

On- and off-axis chemical heterogeneities along the South Atlantic Mid-Ocean-Ridge (5-11°S): Shallow or deep recycling of ocean crust and/or intraplate volcanism? - Hoernle, Kaj; Hauff, Folkmar; Kokfelt, Thomas; Haase, Karsten; Garbe-Schönberg, Dieter; Werner, Reinhard (Earth and Planetary Science Letters, 2011)
The Mid-Atlantic Ridge between the Ascension and Bode Verde Fracture Zones exhibits anomalous crustal thickness and geochemical compositions, which could reflect the presence of either small, enriched heterogeneities in the upper mantle or a weak, diffuse mantle plume. We report new trace element (106 samples) and Sr, Nd and Pb (double spike) isotope data from 72 ridge axis samples and 9 off-axis seamount samples between 5 and 11°S, as well as U-Th-Ra disequilibria data for the seamounts. The U-series data constrain the age of one sample from Seamount D, furthest (120km) east of the shallowest part of the ridge, to be <10,000yrs old and the samples from the other three seamounts closer to the ridge to be younger than 240,000yrs. As can be most clearly discerned on a diagram of Pb/Pb vs. Nd/Nd, at least four distinct components are required to explain the geochemical variations along the ridge: 1) a common depleted (D-MORB-like) component in samples near and north of the Ascension Fracture Zone (4.8-7.6°S), representing the most depleted compositions sampled thus far along the mid-Atlantic ridge, 2) an enriched component upwelling beneath Ascension Island and the northern A1 ridge segment (segment numbers increase from A1 to A4 going south from the Ascension Fracture Zone), 3) an enriched component upwelling beneath the A2 ridge segment, and 4) an enriched component upwelling beneath the line of seamounts east of the A3 segment and the A3 and A4 segments. The A1 and the A3+A4 segment lavas form well-defined mixing arrays, which extend from Ascension Island and the A3 seamounts respectively to the depleted D-MORB component, interpreted to reflect local ambient mantle. We propose that the enriched components represent different packages of subducted ocean crust and/or ocean island basalt (OIB) type volcanic islands and seamounts that have either been recycled through 1) the shallow mantle, upwelling passively beneath the ridge system or 2) the deep mantle via an actively upwelling heterogeneous mantle plume that interacts with the ridge system. © 2011 Elsevier B.V.
Keywords: Ascension hotspot; Mantle plume-ridge interaction; Southern Atlantic Mid-Ocean Ridge; Trace element and Sr-Nd-Pb isotope geochemistry; U-series age dating

One-Year Monitoring of a Ground Heat Exchanger Using the In Situ Thermal Response Test: An Experimental Approach on Climatic Effects - Suft, Oliver; Bertermann, David (Energies, 2022)
The use of renewable energies, and of geothermal energy in particular, is increasingly being applied in Germany and Europe for the development of new residential districts. The use of geothermal borehole heat exchangers (BHE), in combination with ground-source heat pumps (GSHP), represents an important part of shallow geothermal systems, which are used, among other systems, in urban areas due to their small space requirements. Over the course of planning BHE systems, performance must be determined via the parameters of thermal conductivity, thermal capacity, undisturbed ground temperature, and borehole thermal resistance. These can be identified by the experimental approach known as thermal response testing (TRT). The thermal parameters change due to the influences of the seasonal temperature fluctuations that take place in the ground. In this paper, a pilot double-U BHE heat exchanger field with a depth of 120 m was investigated from this perspective. TRT was carried out using monthly measurements taken over the period of one year using an electrically powered mobile TRT device. The evaluation of the individual tests was carried out using the line-source, moving-line-source, and cylinder-source theories. Our results show that the season in which TRT was implemented had an influence on the determined thermal parameters, with better thermal conditions being obtained in winter months. This is especially visible for thermal conductivity, with monthly deviations of 0.1 W/(m∙K), independent of the evaluation approaches used.<br

On Paleozoic platycerate gastropods - Nützel, Alexander; Ebbestad, Jan Ove; Seuß, Barbara; Munnecke, Axel; Mapes, Royal H.; Cook, Alex G. (Zitteliana, 2023)

Onshore equivalents of the main Kudu gas reservoir in Namibia. - Stanistreet, Ian G.; Stollhofen, Harald (The oil and gas habitats of the South Atlantic, 1999)
Radiometric dates of Jurassic and Cretaceous flood basalts of the southern South Atlantic maritimes have thrown the stratigraphic contexts of Karoo and post-Karoo sequences into considerable question. Central to the problem is the status of volcano-sedimentary units, characterized by aeolian-related sedimentary interlayers, containing evaporites and other lacustrine elements. The main Kudu gas reservoir ('Lower Gas Sand') offshore Namibia, interleaved with undated flood basalts, is a prime example. A previously proposed onshore correlate is the fluvio-aeolian Etjo Sandstone, with a central Namibian type area, and comparisons have been made, particularly with units traditionally classified as Etjo Sandstone, near the Etendeka Plateau base in northwest Namibia, now recognized to be of younger age. We time-correlate the main Kudu Sandstone reservoir, however, with evaporitic fluvio-lacustrine and aeolian interlayers beneath and interleaved with Early Jurassic Kalkrand flood basalts of southern Namibia, situated onshore almost directly opposite the Kudu Field. The main Kudu Sandstone reservoir is transitional in palaeoenvironmental setting between Early Jurassic onshore analogues. Main Kudu reservoir geometries and associated lithologies can be better constrained with knowledge derived from Kalkrand sedimentary interlayers and their tectonic and volcanic controls. Kalkrand interlayer thicknesses are controlled primarily by down-to-the-east extensional fault system half-graben geometries, antithetic to an inferred down-to-the-west master detachment. Within resulting sub-basinal accommodation space, lava topography controlled thickness variation. When Kalkrand insights are taken into account with radiometric dating and biostratigraphy, a Namibian Mesozoic framework fixes Kudu reservoirs and analogues into a southern Gondwanan context. At least in its type area in central Namibia, the Etjo Formation is Early Jurassic, discounting a previously proposed widespread <100 Ma hiatus along a sub-Etjo disconformity. Instead, sequence boundary hiatuses of Permian-Triassic, Early Jurassic and Middle Jurassic-Early Cretaceous ages represent time-stratigraphic gaps, relating to major faulting episodes, recording extensional events associated with continental margin evolution. Understanding onshore analogues and refining the Namibian Mesozoic framework should help constrain seismic analysis of the Namibian margin and hydrocarbon reservoir geometries. Consequently, exploration focus should widen to include Karoo sequences beneath the basal Early Cretaceous transgression.
UnivIS-Import:2015-04-20:Pub.1999.nat.dgeo.IGM.LG.onshor

On the assignment of quartz-like LiAlSi2O6 - SiO2 solid solutions in dental lithium silicate glass-ceramics: Virgilite, high quartz, low quartz or stuffed quartz derivatives? - Hurle, Katrin; Lubauer, Julia; Belli, Renan; Lohbauer, Ulrich (Dental Materials, 2022)
Objectives: Here we aim to provide a background on X-Ray Diffraction analysis of quartz-like crystal structures with varying amounts of Al3+ and Li+ substitution, existing confusions on their nomenclature and its implications for novel lithium silicate glass-ceramics. Methods: We reviewed the literature dealing with modifications of the quartz crystal structure and their stuffed LiAlSi2O6 derivates, LiAlSi2O6 – SiO2 solid solutions, the terminology of such phases and criteria used to define the structure known as virgilite. Based on this information, we attempted to allocate the quartz-like phases found in CEREC TesseraTM, InitialTM LiSi Block and Amber® Mill in the range of LiAlO2 - SiO2 solid solutions. For this purpose, their lattice parameters obtained from Rietveld refinement were compared with the lattice parameters of members of the corresponding solid solutions with defined SiO2 molar fraction found in the literature. Results: Based on the lattice parameters available for low quartz, high quartz and its stuffed derivatives, including LiAlSi2O6 and the mineral virgilite, a plot of the a- and c-parameters vs. the mol% SiO2 related to LiAlO2 was constructed with the literature data and the data found for the three dental lithium silicates. As per the definitions of virgilite as either LixAlxSi3-xO6, with 0.5 < x < 1 or especially as members of the LiAlSi2O6 – SiO2 solid-solution series with more than 50 mol% LiAlSi2O6, the crystal structures in CEREC TesseraTM, InitialTM LiSi Block and Amber® Mill failed to fall within the ranges of mol% SiO2 confined for virgilite. Significance: Based on available literature and definitions, the quartz-like phases found in the three dental lithium silicates should be addressed as stuffed (probably low) quartz solid solutions instead of “virgilite”. However determined by mineralogical practices, the term “virgilite” for parts of the LiAlSi2O6 – SiO2 solid solution is ambiguous and can be considered as arbitrary.
CRIS-Team Scopus Importer:2022-08-12
Keywords: Crystal; Glass-ceramics; Lithium silicate; Quartz; Virgilite; X-ray diffraction

On the potential for ocean acidification to be a general cause of ancient reef crises - Kießling, Wolfgang; Simpson, Carl (Global Change Biology, 2011)
Anthropogenic rise in the carbon dioxide concentration in the atmosphere leads to global warming and acidification of the oceans. Ocean acidification (OA) is harmful to many organisms but especially to those that build massive skeletons of calcium carbonate, such as reef corals. Here, we test the recent suggestion that OA leads not only to declining calcification of reef corals and reduced growth rates of reefs but may also have been a trigger of ancient reef crises and mass extinctions in the sea. We analyse the fossil record of biogenic reefs and marine organisms to (1) assess the timing and intensity of ancient reef crises, (2) check which reef crises were concurrent with inferred pulses of carbon dioxide concentrations and (3) evaluate the correlation between reef crises and mass extinctions and their selectivity in terms of inferred physiological buffering. We conclude that four of five global metazoan reef crises in the last 500 Myr were probably at least partially governed by OA and rapid global warming. However, only two of the big five mass extinctions show geological evidence of OA. © 2010 Blackwell Publishing Ltd.
UnivIS-Import:2015-03-09:Pub.2011.nat.dgeo.IGM.LP.onthep
Keywords: Climate change; Mass extinctions; Ocean acidification; Phanerozoic; Reefs

Optical dating of alluvial deposits at the orogenic front of the Andean Precordillera (Mendoza, Argentina) - Schmidt, Silke; Tsukamoto, Sumiko; Salomon, Eric; Frechen, Manfred; Hetzel, Ralf (Geochronometria, 2012)
Well constrained numerical ages of alluvial fan sediments are key to understanding the chronology of alluvial episodes and tectonic activity at the front of the Andean Precordillera. We tested the application of radiocarbon and optically stimulated luminescence (OSL) dating in the distal part of an alluvial fan five kilometers north of Mendoza. For OSL dating a large number of aliquots (n > 70) - each composed of similar to 50 quartz grains - were measured in order to obtain reliable burial ages despite scattered dose distributions. Owing to a feldspar contamination in all samples, an infrared stimulation was inserted before each OSL measurement, which reduced the feldspar OSL signal successfully. By using the minimum age model we obtained stratigraphically consistent burial ages of alluvial deposits in a depth profile. The uppermost similar to 1 m of sediment is composed of debris flow deposits buried 770 +/- 76 years ago. Three plant remnants used for radiocarbon dating from the same layer, however, yielded ages younger than 350 years, which are interpreted to underestimate the depositional age. Underneath the debris flow, a major unconformity cuts a series of distal alluvial fan sediments with interstratified floodplain deposits, which are composed of sandy and calciterich silt layers, respectively. Three samples from this unit which were distributed over one meter of sediment thickness yielded statistically concordant OSL ages of 12.3 +/- 1.2 ka, 12.3 +/- 1.2 ka, and 11.7 +/- 1.1 ka. The deposition of these sediments during the latest Pleistocene coincides with a phase of cool and humid climate, which occurred before the alluvial fan propagated farther into the foreland. The overlying debris flow sediments are associated with alluvial fan incision during the arid Late Holocene.
Keywords: OSL dating; alluvial fan sediments; incomplete bleaching; minimum age model; Andean Precordillera

Optimization of instrument setup and post-run corrections for oxygen and hydrogen stable isotope measurements of water by isotope ratio infrared spectroscopy (IRIS) - van Geldern, Robert; Barth, Johannes (Limnology and Oceanography-Methods, 2012)

Optimizing sampling approaches along ecological gradients - Schweiger, Andreas H.; Irl, Severin D. H.; Steinbauer, Manuel; Dengler, Juergen; Beierkuhnlein, Carl (Methods in Ecology and Evolution, 2016)
Natural scientists and especially ecologists use manipulative experiments or field observations along gradients to differentiate patterns driven by processes from those caused by random noise. A well-conceived sampling design is essential for identifying, analysing and reporting underlying patterns in a statistically solid and reproducible manner, given the normal restrictions in labour, time and money. However, a technical guideline about an adequate sampling design to maximize prediction success under restricted resources is lacking. This study aims at developing such a solid and reproducible guideline for sampling along gradients in all fields of ecology and science in general. We conducted simulations with artificial data for five common response types known in ecology, each represented by a simple function (no response, linear, exponential, symmetric unimodal and asymmetric unimodal). In the simulations, we accounted for different levels of random and systematic error, the two sources of noise in ecological data. We quantified prediction success for varying total sample size, number of locations sampled along a spatial/temporal gradient and number of replicates per sampled location. The number of replicates becomes more important with increasing random error, whereas replicates become less relevant for a systematic error bigger than 20% of total variation. Thus, if high levels of systematic error are indicated or expected (e.g. in field studies with spatial autocorrelation, unaccountable additional environmental drivers or population clustering), continuous sampling with little to no replication is recommended. In contrast, sampling designs with replications are recommended in studies that can control for systematic errors. In a setting that is characteristic for ecological experiments and field studies strictly controlling for undeterminable systematic error (random error ≥10% and systematic error ≤10% of total variation), prediction success was best for an intermediate number of sampled locations along the gradient (10–15) and a low number of replicates per location (3). Our findings from reproducible, statistical simulations will help design appropriate and efficient sampling approaches and avoid erroneous conclusions based on studies with flawed sampling design, which is currently one of the main targets of public criticism against science.
Keywords: ANOVA; Curve fitting; Ecological experiment; Experimental design; Model selection; Regression analysis; Replication; Sampling design; Simulation

Ordination analysis in sedimentology, geochemistry and palaeoenvironment-Background, current trends and recommendations - Bialik, Or M.; Jarochowska, Emilia; Grossowicz, Michal (Depositional Record, 2021)
Ordination is the name given to a group of methods used to analyse multiple variables without preceding hypotheses. Over the last few decades, the use of these methods in Earth science in general, and notably in analyses of sedimentary sources, has dramatically increased. However, with limited resources oriented towards Earth scientists on the topic, the application of ordination analysis is at times suboptimal and misuse by authors can occur. This text was written for researchers with little to no experience with ordination with the aim of exposing them to the utility and the pitfalls of this branch of exploratory statistics. To do so, a detailed review of three ordination methods is offered: principal component analysis, non-metric multidimensional scaling and detrended correspondence analysis. A survey of 163 publications in Earth science is presented, in which these ordination methods were used together with a summary of how, why and on what type of data ordination was used. With common mistakes outlined and misuses in those publications identified. Notably, issues were found with reproducibility, documentation, data set dimensions and transformations. Based on this survey, a recommended workflow is offered for Earth scientists who wish to apply ordination. Additionally, this article is accompanied by highly annotated R scripts for novice users to use these methods.
CRIS-Team WoS Importer:2021-09-24

Ordovician and Silurian sea-water chemistry, sea level, and climate: A synopsis - Munnecke, Axel; Calner, Michael; Harper, David A.T.; Servais, Thomas (Palaeogeography, Palaeoclimatology, Palaeoecology, 2010)
Following the Cambrian Explosion and the appearance in the fossil record of most animal phyla associated with a range of new body plans, the Ordovician and Silurian periods witnessed three subsequent major biotic events: the Great Ordovician Biodiversification Event, the end-Ordovician extinction (the first animal extinction and second largest of the five mass extinctions of the Phanerozoic), and the Early Silurian post-extinction recovery. There are currently no simple explanations for these three major events. Combined extrinsic (geological) and intrinsic (biological) factors probably drove the biodiversifications and radiations, and the appearance and disappearance of marine habitats have to be analysed in the frame of changing palaeogeography, palaeoclimate and sea-water chemistry. The present paper reviews the relationships of the three biotic events to chemical and physical processes occurring in the ocean and atmosphere during the Ordovician and Silurian, including sea-level changes, geochemical proxies (δC, δO, Sr/Sr) of the ocean waters, and the evolution of the atmosphere (oxygen and carbon dioxide content). © 2010 Elsevier B.
Keywords: Climate; Ordovician; Sea level; Silurian; Stable isotopes

Ordovician paleokarst, quartz sand and climate - Keller, Martin; Lehnert, Oliver (Palaeogeography, Palaeoclimatology, Palaeoecology, 2010)
UnivIS-Import:2015-03-09:Pub.2010.nat.dgeo.IGM.LG.ordovi

Ordovician stable carbon isotope stratigraphy in the Tarim Basin, NW China - Zhang, Yuandong; Munnecke, Axel (Palaeogeography, Palaeoclimatology, Palaeoecology, 2016)
The Tarim Basin, located in NW-China, represents one of China's major palaeoplates. Its palaeogeographic position in the Ordovician, however, is debated. In this study we present biostratigraphically controlled stable carbon isotope data from some 600 samples spanning almost the entire Ordovician in order to provide a tool that can be used for future chemostratigraphic correlations. The data correlate well with results from South China, and several major global δC excursions such as the MDICE (Dw2/3), SAICE (Sa2), GICE (Ka1), and Whitewater excursion (Ka4) are documented for the first time from the Tarim Basin. Major sedimentary gaps are detected in the lower Floian between the Penglaiba and Yinshan formations, in the upper Darriwilian to lower Sandbian between the Dawangou and Saergan (or Kanling) formations, and in the latest Sandbian between the Kanling and Qilang formations as well as between the Tumuxiuke and Lianglitag formations. Three scenarios for the depositional history of the late Darriwilian to early Sandbian Saergan Formation, which represents an important hydrocarbon source rock in the Tarim Basin, are discussed with respect to their bio- and chemostratigraphic implications. The mid-upper Ordovician rocks recording high δC values have been deposited during transgressive or highstand intervals, whereas the regressive intervals are mostly missing. This results in a stacking of several positive excursions, and thus chemostratigraphic correlation without biostratigraphic control might produce misleading results, especially for shallow-water carbonates.
Keywords: Chemostratigraphy; Ordovician; Source rocks; Stable carbon isotope; Tarim

Ordovician stratigraphy and sedimentary facies of the Stumsnäs 1 core from the southern Siljan Ring, central Sweden. - Lehnert, Oliver; Meinhold, Guido; Arslan, Arzu; Ebbestad, Jan Ove; Calner, Mikael (Gff, 2013)
UnivIS-Import:2015-03-09:Pub.2013.nat.dgeo.IGM.LG.ordovi

Organic-walled microfossils incertae sedis from the Ordovician of the Argentine Precordillera and Bohemia - Heuse, Thomas; Lehnert, Oliver; Kraft, Petr (Acta Universitatis Carolinae - Geologica, 1997)

Origin, age and stratigraphic significance of distal fallout ash tuffs from the Carbonifereous-Permian continental Saar-Nahe Basin (SW-Germany) - Königer, Stephan; Lorenz, Volker; Stollhofen, Harald; Armstrong, Richard A. (International Journal of Earth Sciences, 2002)
Thin, widespread, fallout tuff layers interbedded within fluvio-lacustrine successions of the Carboniferous–Permian Saar–Nahe Basin provide important tephrostratigraphic markers. In addition, radiogeochronometric data derived from the tuffs serve as calibration points for the adjustment to regional chronostratigraphy and to numerical time scales. The Pappelberg-Tuff in the Meisenheim Formation (Glan Group) has been dated by U/Pb zircon SHRIMP technique at 297.0±3.2 Ma. Taking the Carboniferous/Permian boundary at 296 Ma, the Meisenheim Formation coincides approximately with this boundary. Consequently, underlying strata, lithostratigraphically regarded as the basal part of the ‘Rotliegend’, chronostratigraphically belong to the Upper Carboniferous. Bed thicknesses, grain size and sorting characteristics of the tuffs and the absence of contemporaneously emplaced volcanics within the Saar–Nahe Basin point to an extrabasinal derivation of the wind-drifted volcanic ash. Decreasing grain sizes of juvenile pyroclastic particles towards the north suggest source areas south of the basin within 300 km distance. The majority of the tuffs are rhyolitic to rhyodacitic and indicate petrographic and geochemical affinities to Moldanubian S-type granitoids, in particular to highly differentiated two-mica granites, and related volcanic effusives. Within the time frame considered here, such potential source rocks were emplaced in the northern and central Black Forest (SW Germany) and the northern Vosges (E France) at 100–150 km distance south of the Saar–Nahe Basin.
UnivIS-Import:2015-03-09:Pub.2002.nat.dgeo.IGM.LG.origin
Keywords: Distal fallout ash tuffs · Saar–Nahe Basin · ‘Lower Rotliegend’; Glan Group; Meisenheim Formation; Variscan volcanism; SHRIMP U/Pb zircon ages; Chronostratigraphy; Carboniferous/Permian boundary

Origin and geodynamic significance of the early Mesozoic Weiya LP and HT granulites from the Chinese Eastern Tianshan - Mao, Ling-Juan; He, Zhenyu; Zhang, Zeming; Klemd, Reiner; Xiang, Hua; Tian, Zuolin; Zong, Keqing (Lithos, 2015)
The Chinese Tianshan in the southwestern part of the Central Asian Orogenic Belt (CAOB) is characterized by a variety of high-grade metamorphic rocks, which provide critical constraints for understanding the geodynamic evolution of the CAOB. In this paper, we present detailed petrological and zircon U–Pb geochronological studies of the Weiya low-pressure and high-temperature (LP-HT) granulites of the Chinese Eastern Tianshan. These granulites were previously considered to be a product of a regional metamorphic orogenic event. Due to different bulk-rock chemistries the Weiya granulites, which occur as lenses within the contact metamorphic aureole of the Weiya granitic ring complex, have a variety of felsic–pelitic and mafic granulites with different textural equilibrium mineral assemblages including garnet–cordierite–sillimanite-bearing granulites, cordierite–sillimanite-bearing granulites, cordierite–orthopyroxene-bearing granulites, and orthopyroxene–clinopyroxene-bearing granulites. Average P–T thermobarometric calculations and conventional geothermobarometry indicates that the Weiya granulites underwent early prograde metamorphism under conditions of 600–650 °C at 3.2–4.2 kbar and peak metamorphism of 750–840 °C at 2.9–6.3 kbar, indicating a rather high geothermal gradient of ca. 60 °C/km. Zircon U–Pb LA–ICP–MS dating revealed metamorphic ages between 244 ± 1 to 237 ± 3 Ma, which are in accordance with the crystallization age of the Weiya granitic ring complex. We suggest that the formation of the Weiya granulites was related to contemporaneous granitic magmatism instead of a regional metamorphic orogenic event. In addition, a Late Devonian metamorphic age of ca. 380 Ma was recorded in zircon mantle domains from two pelitic samples which is consistent with the metamorphic age of the Xingxingxia metamorphic complex in the Chinese Eastern Tianshan. This suggests that the mantle domains of the zircon grains of the Weiya granulites probably formed during the Late Devonian regional metamorphism and were overprinted by the Early Triassic contact metamorphism. Therefore, Early Triassic geodynamic models for the southwestern part of the CAOB, which are based on a previously suggested regional metamorphic orogenic event of the Weiya granulites, need to be viewed with caution.<br
Keywords: Central Asian Orogenic Belt; Chinese Eastern Tianshan; Weiya granulites; Early Triassic; Contact metamorphism; Geodynamic setting

Origination and dispersal dynamics of Cenozoic marine plankton - Raja, Nussaïbah Begum; Kießling, Wolfgang (Annual Meeting of the Paleontological Society (Paläontologische Gesellschaft) 2019, 2019)

Origin of discordant ultramafic pegmatites in the Bushveld Complex from externally-derived magmas - Cawthorn, Grant; Latypov, Rais; Klemd, Reiner; Vuthuza, Andisiwe (South African Journal of Geology, 2018)
Coarse-grained, discordant, mainly ultramafic, bodies cut the layered succession of the Bushveld Complex. Previous models have subdivided them into magnesian dunite, considered to have been emplaced upward, and more ironrich wehrlite (± oxides), referred to as iron-rich ultramafic pegmatites (IRUP), emplaced downward. We have studied a number of these IRUP bodies in an open pit on Marikana Mining Operations platinum mines property, near Rustenburg, as well as other samples from different levels in the intrusion. A compilation of our and previously published compositions for olivine and clinopyroxene suggests that there are not two discrete suites and processes, but that all bodies originated from multiple magmas with a similar source, resulting in formation of magnesian olivine followed by progressively more iron-rich olivine and clinopyroxene in a fractionating system. In fact, more evolved compositions of discordant pegmatitic gabbro mineralogy exist that have been largely ignored in the past, but are considered here to be cogenetic with the ultramafic bodies. These rocks are all cumulates, based on their simple mineralogy and extreme deficiency in incompatible trace elements in whole-rock compositions. We question the previous models. The first involved fluid replacement. We question from where the high TiO2 content of these bodies originated and to where the high Al2O3 (from the replaced plagioclase) went, noting that TiO2 and Al2O3 are typically the most refractory of oxides. The second involved highly evolved or immiscible liquids or products of disequilibrium melting, generated within the intrusion, considered to have penetrated downward (kms) displacing a succession of cumulate rocks. We question the mechanism by which a downward penetrating magma could displace pre-existing cumulates, presumably returning them back up the same conduit without any interaction between the two. We suggest that initial upward penetration of magmas, not generated within the layered succession, replaced the existing cumulates initially by infiltration. Subsequently, vertical central channels developed and large volumes of magma flowed through, precipitating cumulus minerals. The removed components and the residual liquids from formation of these discordant cumulate bodies were expelled upward. The composition of the proposed liquid for these bodies is considered to have affinities with sub-alkaline basalt (ankaramite), which occurs in many large igneous provinces, and whose distinctive features are the dominance of olivine and clinopyroxene and absence of plagioclase, and have a high CaO/Al2O3compared to tholeiitic magmas. Support for this conclusion is based in part on the clinopyroxene compositions in IRUP, which are enriched in the wollastonite component and do not plot near to the tholeiite or Bushveld trend in the pyroxenite quadrilateral. They contain no exsolution which is abundant in all layered rocks in the Bushveld Complex. Examples of such sub-alkaline rocks related to the Bushveld Complex have been previously reported. One (Schoongezicht intrusion), distal from, and at a much deeper stratigraphic level (base of the Ventersdorp Supergroup) than, the complex, is dominated by dunite, wehrlite and magnetitite, comparable to the IRU
Keywords: Africa; Bushveld Complex; chain silicates; clinopyroxene; dunite; feldspar group; framework silicates; granites; ICP mass spectra; igneous rocks; magmas; magnetite; mass spectra; mineral composition; nesosilicates; olivine group; oxides pegmatite; plutonic rocks; peridotites; plagioclase; pyroxene group; silicates; South Africa; Southern Africa; trace metals; ultramafics; wehrlite

Origin of Erzgebirge ultrahigh-pressure garnetite: Formation from a basaltic protolith by serpentinization-assisted metasomatism? - Schmädicke, Esther; Will, Thomas M. (Journal of Metamorphic Geology, 2023)
Erzgebirge ultrahigh-pressure (UHP) garnet peridotite includes scarce layers of garnet pyroxenite, nodules of garnetite and, very rarely, of eclogite. Peridotite-hosted eclogite shows the same subalkali-basaltic bulk rock composition, mineral assemblage and peak conditions as gneiss-hosted eclogite present in the same UHP unit. Garnetite has considerably more Mg, moderately enhanced Ca and Fe and significantly lower contents of Na, Ti, P, K and Si than eclogite, whereas Al is very similar. In addition, the compatible trace elements (Ni, Co, Cr, V) are elevated and most incompatible elements (Zr, Hf, Y, Sr, Rb and rare Earth elements [REE]) are depleted in garnetite relative to eclogite. In contrast to other large ion lithophile elements (LILEs), Pb (+121%) and Ba (+83%) are strongly enriched. The REE patterns of garnetite are characterized by depletion of light and heavy REE and a medium REE hump indicative of metasomatism, features being absent in eclogite. An exceptional garnetite sample shows an REE distribution similar to that of eclogite. Garnetite is interpreted to have formed from the same, but metasomatically altered, igneous protolith as eclogite. Except for Ba and Pb, the chemical signature of garnetite is explained best by metasomatic changes of its basaltic protolith caused by serpentinization of the host peridotite. Garnetite is chemically similar to basaltic rodingite/metarodingite. Although rodingite is commonly more enriched in Ca, there are also examples with moderately enhanced Ca matching the composition of Erzgebirge garnetite. Limited Ca metasomatism is attributed to the preservation of Ca in peridotite during hydrous alteration. This can be explained by incomplete serpentinization favouring metastable survival of the original clinopyroxene. In this case, most Ca is retained in peridotite and not available for infiltration and metasomatism of the garnetite protolith. This inescapable consequence is supported by the fact that clinopyroxene is part of the garnet peridotite UHP assemblage, which would not be the case if Ca had been removed from the protolith prior to high-pressure metamorphism. The enrichment of compatible elements in garnetite is attributed to decomposition of peridotitic olivine (Ni, Co) and spinel (Cr, V) during serpentinization. Enrichment of Ba and Pb contrasts the behaviour of other LILEs and is ascribed to dehydration of the serpentinized peridotite (deserpentinization). This requires two separate stages of metasomatism: (1) intense chemical alteration of the basaltic garnetite precursor, together with serpentinization of peridotite at the ocean floor or during incipient subduction; and (2) prograde metamorphism and dehydration of serpentinite during continued subduction, thereby releasing Pb–Ba-rich fluids that reacted with associated metabasalt. Finally, subduction to >100 km and UHP metamorphism of all lithologies led to formation of garnetite, eclogite and garnet pyroxenite hosted by co-facial garnet peridotite as observed in the Erzgebirge.
CRIS-Team Scopus Importer:2023-11-17
Keywords: Erzgebirge; garnetite; rodingitization; serpentinization; UHP metamorphism

Origin of magnetic anomalies in volcaniclastic units of the Messel maar-diatreme (Germany). In Goth, K. & Suhr, P. (eds.): Geophysics of maars and diatremes - de Wall, Helga; et al. (Zeitschrift der Deutschen Gesellschaft für Geowissenschaften, 2006)
UnivIS-Import:2015-03-09:Pub.2006.nat.dgeo.IGM.c3tekt.origin

Origin of particulate organic carbon in the upper St. Lawrence: Isotopic constraints - Barth, Johannes; et al. (Earth and Planetary Science Letters, 1998)

Origin of planktotrophy - evidence from early molluscs: a response to Freeman and Lundelius. - Nützel, Alexander; Lehnert, Oliver; Fryda, Jiri (Evolution & Development, 2007)
UnivIS-Import:2015-03-09:Pub.2007.nat.dgeo.IGM.LG.origin

Origin of planktotrophy - evidence from early molluscs - Nützel, Alexander; Lehnert, Oliver; Fryda, Jiri (Evolution & Development, 2006)
The size of early ontogenetic shells (protoconchs) of ancient benthic molluscs suggests that feeding larvae occurred at about 490 myr (approximately, transition from Cambrian to Ordovician). Most studied Ordovician protoconchs were smaller than Cambrian ones, indicating smaller Ordovician eggs and hatchlings. This suggests substitution of nutritious reserve matter such as yolk by plankton as an energy source for larvae. The observed size change represents the first direct empiric evidence for a late Cambrian to Ordovician switch to planktotrophy in invertebrate larvae. It corroborates previous hypotheses about a possible polyphyly of planktotrophy. These hypotheses were primarily based on molecular clock data of extant clades with different types of larva, change in the overall body size, as well as increasing predation pressure on Early Paleozoic sea floors. The Early Ordovician is characterized by an explosive radiation of benthic suspension feeders and it was suggested that planktotrophy would prolongate escape from benthic predation on hatchlings. This biological escalation hypothesis does not fully explain why planktotrophy and suspension feeding became important at the same time, during a major biodiversification. An additional factor that probably included availability of nutrients must have played a role. We speculate that an increasing nutrient supply and availability of photoautotrophic plankton in world oceans have facilitated both planktotrophy and suspension feeding, which does not exclude a contemporaneous predation-driven escalation. It is very likely that the evolution of planktotrophy as well as increasing predation contributed to the Ordovician radiation. © 2006 The Author(s).
UnivIS-Import:2015-03-09:Pub.2006.nat.dgeo.IGM.LP.assess_9

Origin of s-, a-and i-type granites: Petrogenetic evidence from whole rock th/u ratio variations - Regelous, Anette; Scharfenberg, Lars; de Wall, Helga (Minerals, 2021)
The origin and evolution of granites remain a matter of debate and several approaches have been made to distinguish between different granite types. Overall, granite classification schemes based on element concentrations and ratios, tectonic settings or the source rocks (I-, A-, S-type) are widely used, but so far, no systematic large-scale study on Th/U ratio variations in granites based on their source or tectonic setting has been carried out, even though these elements show very similar behavior during melting and subsequent processes. We therefore present a compiled study, demonstrating an easy approach to differentiate between S-, A-and I-type granites using Th and U concentrations and ratios measured with a portable gamma ray spectrometer. Th and U concentrations from 472 measurements in S-and I-type granites from the Variscan West-Bohemian Massif, Germany, and 78 measurements from Neoproterozoic A-type Malani granites, India, are evaluated. Our compendium shows significant differences in the average Th/U ratios of A-, I-and S-type granites and thus gives information about the source rock and can be used as an easy classification scheme. Considering all data from the studied A-, I-and S-type granites, Th/U ratios increase with rising Th concentrations. A-type granites have the highest Th/U ratios and high Th concentrations, followed by I-type granites. Th/U ratios in S-to I-type granites are lower than in A-type and I-type granites, but higher than in S-type granites. The variation of Th/U ratios in all three types of granite cannot be explained by fractional crystallization of monazite, zircon and other Th and U bearing minerals alone, but are mainly due to source heterogeneities and uranium mobilization processes.
CRIS-Team Scopus Importer:2021-07-02
Keywords: Continental crust; Granites; Petrogenesis; Thorium; Uranium

Origin of Silicic Magmas at Spreading Centres-an Example from the South East Rift, Manus Basin - Beier, Christoph; Bach, Wolfgang; Turner, Simon; Niedermeier, Dominik; Woodhead, Jon; Erzinger, Joerg; Krumm, Stefan (Journal of Petrology, 2015)
There has been much recent interest in the origin of silicic magmas at spreading centres away from any possible influence of continental crust. Here we present major and trace element data for 29 glasses (and 55 whole-rocks) sampled from a 40 km segment of the South East Rift in the Manus Basin that span the full compositional continuum from basalt to rhyolite (50-75 wt % SiO2). The glass data are accompanied by Sr-Nd-Pb, O and U-Th-Ra isotope data for selected samples. These overlap the ranges for published data from this part of the Manus Basin. Limited increases in Cl/K ratios with increasing SiO2, La-SiO2 and Yb-SiO2 relationships, and the oxygen isotope data rule out models in which the more silicic lavas result from partial melting of altered oceanic crust or altered oceanic gab-bros. Rather, the data form a coherent array that is suggestive of closed-system fractional crystallization and this is well simulated by MELTS models run at 0.2 GPa and QFM (quartz-fayalite-magnetite buffer) with 1 wt % H2O, using a parental magma chosen from the basaltic glasses. Although some assimilation of altered oceanic crust or gabbro cannot be completely ruled out, there is no evidence that this plays an important role in the origin of the silicic lavas. The U-series disequilibria are dominated by U-238 and Ra-226 excesses that limit the timescale of differentiation to less than a few millennia. Overall, the data point to rapid evolution in relatively small magma lenses located near the base of thick oceanic crust; we speculate that this was coupled with relatively low rates of basaltic recharge. A similar model may be applicable to the generation of silicic magmas elsewhere in the ocean basins.
Keywords: silicic lavas; differentiation; oceanic spreading centre; South East Rift; Manus Basin

Origin of the Cretaceous olistostromes in the Oman mountains (Sultanate of Oman): Evidence from clay minerals - Mattern, Frank; Scharf, Andreas; Pracejus, Bernhard; Al Shibli, Issa S. A.; Al Kabani, Bader M. S.; Al Qasmi, Waleed Y. A.; Kießling, Wolfgang; Callegari, Ivan (Journal of African Earth Sciences, 2022)
Mid- to Late Cretaceous olistostrome generation ensued sequentially, linked to progressive southwest-directed thrusting of the Semail Ophiolite towards and over Arabia - at first in the northeastern part of the oceanic Hawasina Basin (Umar Sub-Basin) and then in its southwestern part (Hamrat Duru-Sub-Basin). Thrusting steepened slopes, causing seismic tremors, which destabilized slope sediments and triggering olistostrome formation. Ophiolite thrusting over Arabia created the Aruma Foreland Basin. Olistostrome formation in the foredeep ensued last and on the flank of the uplifting forebulge. As olistoliths, Olistostrome 1 contains radiolarian limestone, plain micrite, allodapic limestone, basalt, amygdaloidal basalt, radiolarian chert and coarse, massive limestone with crystalline texture (Oman Exotics). These olistoliths "float" in shale, containing illite/muscovite, vermiculite and kaolinite. Olistostrome 1 formed in the Umar Sub-Basin. Olistostrome 2 is associated with the Late Albian to Coniacian Nayid Formation of the Hamrat Duru Sub-Basin. It is characterized by olistoliths of graded limestones (calc-turbidites) with angular shelfal limestone lithoclasts. The olistoliths are embedded in shale with unidentifiable clay minerals. Olistostrome 2 formed in the Hamrat Duru Sub-Basin, postdating Olistostrome 1. Olistostrome 3 is associated with the Upper Cretaceous Aruma Foreland Basin and characterized by olistoliths, like lithoclastic packstone (calcarenite), dolomitic limestone, and sandstone with carbonate lithoclasts. The matrix of the olistoliths is a pyrophyllite- and kaolinite-bearing shale. Olistostrome 3 formed in the foredeep as the youngest olistostrome. The different clay mineralogy of Olistostrome 1 and Olistostrome 3, reflects their different basinal origin. Shale samples taken from conventional sediments (no olistostromes) of the syn-tectonic and post-tectonic Aruma units show some resemblance in their clay mineralogy as they contain detritus from the Oman Mountains. Olistolith types of both Hawasina olistostromes differ significantly. The reviewed and novel data may serve as a guideline for future olistostrome studies in the Oman Mountains and may be particularly helpful in identifying the basinal origin of olistostromes in case of fault-bounded olistostromes, unexposed olistostrome contacts and inconclusive olistoliths. Evaluating matrix shales of olistostromes leads to important decision criteria, such as color, oxygenation state and clay mineralogy, to determine the paleogeographic basin position.
CRIS-Team WoS Importer:2022-06-24

Osmium and lithium isotope evidence for weathering feedbacks linked to orbitally paced organic carbon burial and Silurian glaciations - Sproson, Adam D.; Pogge von Strandmann, Philip A.E.; Selby, David; Jarochowska, Emilia; Frýda, Jiří; Hladil, Jindřich; Loydell, David K.; Slavík, Ladislav; Calner, Mikael; Maier, Georg; Munnecke, Axel; Lenton, Timothy M. (Earth and Planetary Science Letters, 2022)
The Ordovician (∼487 to 443 Ma) ended with the formation of extensive Southern Hemisphere ice sheets, known as the Hirnantian glaciation, and the second largest mass extinction in Earth History. It was followed by the Silurian (∼443 to 419 Ma), one of the most climatically unstable periods of the Phanerozoic as evidenced by several large scale (>5‰) carbon isotope (δ13C) perturbations associated with further extinction events. Despite several decades of research, the cause of these environmental instabilities remains enigmatic. Here, we provide osmium (187Os/188Os) and lithium (δ7Li) isotope measurements of marine sedimentary rocks that cover four Silurian δ13C excursions. Osmium and Li isotope records resemble those previously recorded for the Hirnantian glaciation suggesting a similar causal mechanism. When combined with a new dynamic carbon-osmium-lithium biogeochemical model we suggest that astronomical forcing of the marine organic carbon cycle, as opposed to a decline in volcanic arc degassing or the rise of early land plants, resulted in drawdown of atmospheric CO2, triggering continental scale glaciation, intense global cooling and eustatic sea-level lows recognised in the geological record. Lower atmospheric pCO2 and temperatures during the Hirnantian and Silurian glaciations suppressed CO2 removal by silicate weathering, driving 187Os/188Os and δ7Li variability, supporting the existence of climate-regulating feedbacks.
CRIS-Team Scopus Importer:2021-11-12
Keywords: eccentricity and precession; Hirnantian glaciation; orbital obliquity; osmium (; silicate weathering; Silurian palaeoclimate

Osteogenic lithium-doped brushite cements for bone regeneration - Hurle, Katrin; Maia, F. R.; Ribeiro, V. P.; Pina, S.; Oliveira, J. M.; Götz-Neunhoeffer, Friedlinde; Reis, R. L. (Bioactive Materials, 2022)
This study investigated the osteogenic performance of new brushite cements obtained from Li+-doped β-tricalcium phosphate as a promising strategy for bone regeneration. Lithium (Li+) is a promising trace element to encourage the migration and proliferation of adipose-derived stem cells (hASCs) and the osteogenic differentiation-related gene expression, essential for osteogenesis. In-situ X-ray diffraction (XRD) and in-situ 1H nuclear magnetic resonance (1H NMR) measurements proved the precipitation of brushite, as main phase, and monetite, indicating that Li+ favored the formation of monetite under certain conditions. Li+ was detected in the remaining pore solution in significant amounts after the completion of hydration. Isothermal calorimetry results showed an accelerating effect of Li+, especially for low concentration of the setting retarder (phytic acid). A decrease of initial and final setting times with increasing amount of Li+ was detected and setting times could be well adjusted by varying the setting retarder concentration. The cements presented compressive mechanical strength within the ranges reported for cancellous bone. In vitro assays using hASCs showed normal metabolic and proliferative levels. The immunodetection and gene expression profile of osteogenic-related markers highlight the incorporation of Li+ for increasing the in vivo bone density. The osteogenic potential of Li-doped brushite cements may be recommended for further research on bone defect repair strategies.
CRIS-Team Scopus Importer:2022-01-21
Keywords: Alkaline phosphatase activity; Bone regeneration; Brushite cements; Collagen expression; Lithium doping; Osteogenic expression; β-tricalcium phosphate

Osteological revision of the holotype of the Middle Jurassic sauropod dinosaur Patagosaurus fariasi Bonaparte, 1979 (Sauropoda: Cetiosauridae) - Holwerda, Femke Marleen; Rauhut, Oliver W. M.; Pol, Diego (Geodiversitas, 2021)
Middle Jurassic sauropod taxa are poorly known, due to a stratigraphic bias of localities yielding body fossils. One such locality is Cerro Condor North, Canadon Asfalto Formation, Patagonia, Argentina, dated to latest Early-Middle Jurassic. From this locality, the holotype of Patagosaurus fariasi Bonaparte 1986 is revised. The material consists of the axial skeleton, the pelvic girdle, and the right femur. Patagosaurus is mainly characterised by a combination of features mainly identified on the axial skeleton, including the following: 1) cervical centra with low Elongation Index; 2) high projection of the postzygodiapophyseal lamina; 3) deep anterior pleurocoels that are sometimes compartmentalized in cervicals; 4) high projection of the neural arch and spine in dorsal vertebrae and anterior(most) caudal vertebrae; 5) deep pneumatic foramina in posterior dorsals which connect into an internal pneumatic chamber, and 6) anterior caudal vertebrae with 'saddle' shaped neural spines. Diagnostic features on the appendicular skeleton include: 1) a transversely wide and anteroposteriorly short femur; 2) a medial placement of the fourth trochanter on the femur; and 3) an anteroposteriorly elongated ilium with a rounded dorsal rim, with hook-shaped anterior lobe. The characters that are diagnostic for Patagosaurus are discussed, and the osteology of Patagosaurus is compared to that of Early and Middle Jurassic (eu)sauropods from both Laurasia and Gondwana.
CRIS-Team WoS Importer:2021-10-01

Ostracod eye size: A taxonomy-free indicator of the Paleocene-Eocene Thermal Maximum sea level - Tian, Skye Yunshu; Yasuhara, Moriaki; Robinson, Marci M.; Huang, Huai-Hsuan (Marine Micropaleontology, 2021)
Deep-time sea-level changes associated with the Paleocene-Eocene Thermal Maximum (PETM) are of great interest to paleoceanographers and paleontologists, especially in shallow marine settings, like the Atlantic Coastal Plain PETM sections of the Eastern North American Continental Shelf. Accurate paleo-water depth reconstruction is essential to properly interpret and contextualize any PETM-associated paleoceanographic and paleoecological changes that are depth-dependent. In addition, our understanding on eustatic sea-level changes in the greenhouse world without polar ice sheets remains limited. Despite this importance of an accurate and robust paleodepth reconstruction, all water depth estimation methods applied for the shallow marine PETM sections suffer from uncertainties and intrinsic/logical flaws. It is therefore important to develop and apply an independent water depth proxy to complement and validate paleodepth estimates derived from the traditional estimation methods based on sedimentary fossil components and lithological features. Here we present the relative eye size of sighted ostracods as a taxonomy-free water depth proxy and apply it to shallow-marine PETM paleodepth reconstruction of the Mattawoman Creek-Billingsley Road (MCBR) core in Maryland, eastern USA. We identified a significant and rapid reduction in water depth of 40 m within the carbon isotope excursion (CIE) onset consistent with the previous estimation based on benthic foraminifer species associations. This ostracod-eye-based paleodepth reconstruction improves current understanding on the regional paleobathymetry of the Salisbury Embayment and facilitates future studies on continental shelf paleoceanography and paleoecology during the PETM, a rapid, extreme global warming event under long-term greenhouse conditions, which possibly parallels the ongoing anthropogenic warming.
CRIS-Team Scopus Importer:2021-06-11
Keywords: Ostracod relative eye size; Paleocene-Eocene Thermal Maximum; Paleodepth reconstruction; Salisbury Embayment

Outcrop scale mixing enhanced by permeability variations: the role of stationary and travelling waves of high saturation indices - Köhn, Daniel; Kelka, Ulrich; Toussaint, Renaud; Siegel, Coralie; Mullen, Gary; Boyce, Adrian; Piazolo, Sandra (Geological Magazine, 2022)
To study the ore mineralization at the outcrop scale we merge an advection-diffusion simulation with the geochemical software iphreeqc to model the mixing of two realistic fluids. We simulate the infiltration of a metal-rich fluid into a rock that is saturated with pore fluid. We test the feedback effects with a number of scenarios based on an outcrop-scale 5 x 5 m model consisting of two high-permeable vertical faults within a low-permeable host rock that lead into a permeable layer. The hot metal-rich fluid enters the model through the faults from below. We solve the advection-diffusion equation for 12 chemical species and temperature, and use iphreeqc to determine the resulting properties of local fluid domains as well as related saturation indices for minerals. The faults in the model act as pathways for the metal-rich fluid, with the infiltrating fluid displacing the pore fluid. Mixing in the model takes place as a function of advection along permeable faults coupled with diffusion of chemical species at the interface between two fluids, while heat diffusion is fast enough (10(3) times faster) to equilibrate temperature. Simulations show a high saturation index of mixing-derived minerals such as barite at the interface between the two fluids as a result of fluid mixing. Fast fluid pathways (i.e. faults) show travelling waves of high saturation indices of barite, while low-permeability zones such as fault walls and areas below less permeable layers experience stationary waves of high saturation indices. Our results show that, depending on the dominant transport process (advection or diffusion), mineralization will localize next to permeability contrasts in zones where local diffusion dominates.
CRIS-Team WoS Importer:2022-11-11

Out of the extratropics: the evolution of the latitudinal diversity gradient of Cenozoic marine plankton - Raja, Nussaïbah Begum; Kießling, Wolfgang (Proceedings of the Royal Society of London, Series B: Biological Sciences, 2021)
Many ecological and evolutionary hypotheses have been proposed to explain the latitudinal diversity gradient, i.e. the increase in species richness from the poles to the tropics. Among the evolutionary hypotheses, the ‘out of the tropics’ (OTT) hypothesis has received considerable attention. The OTT posits that the tropics are both a cradle and source of biodiversity for extratropical regions. To test the generality of the OTT hypothesis, we explored the spatial biodiversity dynamics of unicellular marine plankton over the Cenozoic era (the last 66 Myr). We find large-scale climatic changes during the Cenozoic shaped the diversification and dispersal of marine plankton. Origination was generally more likely in the extratropics and net dispersal was towards the tropics rather than in the opposite direction, especially during the warmer climates of the early Cenozoic. Although migration proportions varied among major plankton groups and climate phases, we provide evidence that the extratropics were a source of tropical microplankton biodiversity over the last 66 Myr.<br
Keywords: macroevolution; biodiversity; marine plankton; climate change; biogeography

Overcoming the coupled climate and biodiversity crises and their societal impacts - Pörtner, H. O.; Scholes, R. J.; Arneth, A.; Barnes, D. K.A.; Burrows, M. T.; Diamond, S. E.; Duarte, C. M.; Kießling, Wolfgang; Leadley, P.; Managi, S.; McElwee, P.; Midgley, G.; et al. (Science, 2023)
Earth's biodiversity and human societies face pollution, overconsumption of natural resources, urbanization, demographic shifts, social and economic inequalities, and habitat loss, many of which are exacerbated by climate change. Here, we review links among climate, biodiversity, and society and develop a roadmap toward sustainability. These include limiting warming to 1.5°C and effectively conserving and restoring functional ecosystems on 30 to 50% of land, freshwater, and ocean "scapes." We envision a mosaic of interconnected protected and shared spaces, including intensively used spaces, to strengthen self-sustaining biodiversity, the capacity of people and nature to adapt to and mitigate climate change, and nature's contributions to people. Fostering interlinked human, ecosystem, and planetary health for a livable future urgently requires bold implementation of transformative policy interventions through interconnected institutions, governance, and social systems from local to global levels.
CRIS-Team Scopus Importer:2023-04-28

Overpressure Prediction and its implications for well planning in the Bavarian Foreland Molasse Basin. - Drews, Michael; Bauer, Wolfgang (Praxisforum Geothermie.Bayern 2017, 2017)

Oversimplification risks too much: A response to 'How predictable are mass extinction events?' - Reddin, Carl J.; Aberhan, Martin; Dimitrijević, Danijela; Dowding, Elizabeth; Kocsis, Ádám; Mathes, Gregor; Nätscher, Paulina; Patzkowsky, Mark E.; Kießling, Wolfgang (Royal Society Open Science, 2023)
CRIS-Team Scopus Importer:2023-09-15

Oxide Minerals - Nadoll, Patrick (Encyclopedia of Geochemistry - A Comprehensive Reference Source on the Chemistry of the Earth, 2018)
CRIS-Team WoS Importer:2019-07-30

Oxygen and carbon stable isotope records of the Lochkovian-Pragian boundary interval from the Prague Basin (Lower Devonian, Czech Republic) - Weinerová, Hedvika; Bábek, Ondřej; Slavík, Ladislav; Vonhof, Hubert; Joachimski, Michael; Hladil, Jindřich (Palaeogeography, Palaeoclimatology, Palaeoecology, 2020)
Climate changes close to the Lochkovian-Pragian Event are still widely discussed. Carbonate δ18O and δ13C and conodont apatite δ18O from medial to distal carbonate ramp sediments were analysed to provide further stable isotope data from the stratotype area in the Prague Basin. The uppermost Silurian to lower Emsian δ18O trends are put into an updated conodont biostratigraphy framework. Carbonate δ18O and δ13C are discussed in the context of facies-dependent diagenesis. The δ13C pattern measured from different sections enables the correlation of intervals with development of different facies inside the Prague Basin. Positive δ13C shifts are often coupled with trends of decreasing computed gamma-ray (CGR) values interpreted as regressions, whereas negative δ13C shifts commonly coincide with opposite trends in CGR. The Lochkovian-Pragian boundary interval coincided with an increase in carbonate δ13C and an increase in the δ18O of conodont apatite and carbonate, which we interpret as consequence of climate cooling. Generally, the Lochkovian was warmer than the Pragian and earliest Emsian.
CRIS-Team Scopus Importer:2020-10-09
Keywords: Barrandian area; Carbonate; Climate changes; Conodont apatite; Diagenesis; Palaeozoic

Oxygen and hydrogen stable isotopes in Earth’s hydrologic cycle - van Geldern, Robert; Barth, Johannes (Isotopic Landscapes in Bioarchaeology, 2016)

Oxygen and stable carbon isotopes from a nautiloid from the middle Pennsylvanian (Late Carboniferous) impregnation Lagerstätte "Buckhorn Asphalt Quarry" - Primary paleo-environmental signals versus diagenesis - Seuß, Barbara; Titschack, Jürgen; Seifert, Severin; Neubauer, Jürgen; Nützel, Alexander (Palaeogeography, Palaeoclimatology, Palaeoecology, 2012)

Oxygen and strontium isotopes from fossil shark teeth: environmental and ecological implications for Late Palaeozoic European basins. - Fischer, Jan; Schneider, Joerg W.; Voigt, Silke; Joachimski, Michael; Tichomirowa, Marion; Tuetken, Thomas; Goetze, Jens; Berner, Ulrich (Chemical Geology, 2013)
Fossil shark remains occur in both marine and nonmarine Late Palaeozoic deposits, therefore their palaeoecology is controversial. The oxygen and strontium isotopic composition of biogenic fluorapatite in 179 teeth, scales and spines predominantly of hybodontid (Lissodus) and xenacanthiform (Orthacanthus, Xenacanthus, Bohemiacanthus, Triodus) sharks from various Late Carboniferous (Moscovian) to Early Permian (Artinskian) basins of Europe are used as ecological tracers to decipher diadromous or obligate freshwater lifestyle of the investigated taxa. The δ18OP values of the different shark teeth range from 11.7 to 20.2‰ within the different basins with mean values of 16.9±0.5‰ for the Bohemian Massif, 16.2±0.8‰ for eastern Germany, 18.2±1.0‰ for southwestern Germany, 18.5±0.7‰ for southern-central Spain, 17.6±0.4‰ for Sardinia, and 16.6±0.5‰ VSMOW for the French Massif Central. The tooth δ18OP values from the basins are mostly depleted by 1-5‰ relative to those of shark teeth from contemporaneous marine settings. Oxygen isotope signatures of co-occurring taxa do not show systematic differences excluding habitat effects for different shark groups. However, distinctly higher δ18OP values from Puertollano and Saar-Nahe can be attributed to significant evaporative enrichment in 18O of the ambient water in the ancient lacustrine environments due to a warm and dry climate and sufficient residence time in the basins. The strontium isotopic composition of the teeth varies between 0.70824 and 0.71216 with a mean value of 0.71031. These 87Sr/86Sr ratios are always more radiogenic in comparison to the 87Sr/86Sr record of seawater of their stratigraphic age. Overall, the investigated tooth samples yield low δ18OP and high 87Sr/86Sr values deviating from bioapatite values expected for contemporaneous marine vertebrates and typical for freshwater settings. This indicates a fully freshwater adapted lifestyle for a variety of fossil shark taxa in Late Palaeozoic European basins. © 2013 Elsevier B.V.
UnivIS-Import:2015-03-09:Pub.2013.nat.dgeo.IGM.LG.oxygen
Keywords: Bioapatite; Carboniferous; Freshwater shark; Oxygen isotopes; Permian; Strontium isotopes

Oxygen isotope and trace element compositions of platiniferous dunite pipes of the Bushveld Complex, South Africa - Signals from a recycled mantle component? - Günther, Thomas; Haase, Karsten; Junge, Malte; Oberthür, Thomas; Wölki, Dominic; Krumm, Stefan (Lithos, 2018)
Platiniferous dunite pipes occur in the lower mafic/ultramafic portion of the Rustenburg layered Suite of the Bushveld large igneous province (LIP). Olivine compositions in these pipes range from forsterite (Fo) 80 to 35 mol% and suggest crystallization from variably evolved magmas at high temperatures (similar to 1200 degrees C). The most primitive olivines are from a stock unit and have the highest contents of Ni (>0.15 wt%) and lowest contents of Mn (<0.3 wt%). Fractional crystallization and partial melting of pyroxenite host rock play a significant role in the formation of the fayalitic olivines with its high Mn contents (>0.3 wt%). High delta O-18 values of olivine (5.7-7.0 parts per thousand) and pyroxene (6.7-7.4 parts per thousand) are akin to those of the Lower and Critical Zone of the Bushveld intrusion suggesting a common origin. The constant high O isotope ratios with variable Fo contents in the olivines are unlike trends observed in olivine phenocrysts in magmas forming by assimilation-fractional crystallization. We suggest that the high delta O-18 in the most primitive dunites reflect that of the primary melt of the Bushveld pipes, indicating either a bulk assimilation of crust prior to pipe formation or a contribution from recycled oceanic crust in the subcontinental lithospheric mantle (SCLM). The latter scenario is supported by the high Ni/Mn ratios in primitive pipe olivine that might be inherited from melting of a pyroxene-rich mantle source. (C) 2018 Elsevier B.V. All rights reserved.
Keywords: Bushveld Complex; Kaapyaal Craton; Large Igneous Province; Olivine; Trace elements; Oxygen isotopes

Oxygen isotope and trace element compositions of platiniferous dunite pipes of the Bushveld Complex, South Africa – Signals from a recycled mantle component? - Günther, Thomas; Haase, Karsten; Junge, Malte; Oberthür, Thomas; Wölki, Dominic; Krumm, Stefan (Lithos, 2018)

Oxygen isotope evidence for the formation of andesitic-dacitic magmas from the fast-spreading Pacific-Antarctic Rise by assimilation-fractional crystallisation - Freund, Sarah; Beier, Christoph; Krumm, Stefan; Haase, Karsten (Chemical Geology, 2013)
Andesitic to dacitic lavas occur along a 300km long portion of the Pacific-Antarctic Rise close to the intersection of the spreading axis with the Foundation seamount chain. The fresh silicic glasses have low δO isotope values between 5.6‰ and 5.1‰ whereas basaltic glasses from the same ridge section have normal MORB δO values. Additionally, two FeTi basaltic and all silicic glasses have high Cl (up to 1.1wt.%) and KO (up to 1.6wt.%) contents, indicating assimilation of hydrothermally altered material. Modelling suggests that the fractionating magma assimilated up to 30% of hydrothermally altered material after 57% fractional crystallisation of the basaltic magma in a melt lens at less than 2km depth. In contrast, the basaltic glasses show little assimilation and clinopyroxene-melt barometry indicates crystal fractionation in deeper melt sills. Relatively low HO/Ce and Li/Ce ratios as well as the low δO values and high Cl and K concentrations in the silicic glasses suggest assimilation of altered crustal rock rather than a brine. While some of the variability in highly incompatible element ratios is best explained by crystal fractionation processes of FeTi-oxides (e.g., decreasing Nb/U) others require a reaction of the melt with residual amphibole and clinopyroxene (Cl/K, Tb/Yb, Hf/Sm, Ce/Yb). The initial onset of FeTi oxide crystallisation is associated with a reduced oxygen fugacity causing sulphide saturation and significant loss of S, Cu, and Co from the evolved melts. This change to more reducing melts as a result of oxide crystallisation is supported by the strong development of a negative Eu anomaly in the andesites and dacites indicating stronger partitioning of Eu into plagioclase. Reverse mineral zoning in the evolved lavas also indicates that replenishment by mafic melts occurs in the shallow melt lens. © 2013 Elsevier B.V.
Keywords: Assimilation-fractional crystallisation; FeTi basalt; Magma evolution; Mid-ocean ridge; Oxygen isotopes; Silica-rich lava

Oxygen isotope evidence for the formation of silicic Kermadec island arc and Havre-Lau backarc magmas by fractional crystallization. - Haase, Karsten; Krumm, Stefan; Regelous, Marcel; Joachimski, Michael (Earth and Planetary Science Letters, 2011)
UnivIS-Import:2015-03-09:Pub.2011.nat.dgeo.IGM.LG.oxygen

Oxygen isotope evolution of biogenic calcite and apatite during the Middle and Late Devonian - Joachimski, Michael; Geldern, Robert; Breisig, Stephan; Buggisch, Walter; Day, Jed; van Geldern, Robert (International Journal of Earth Sciences, 2004)
Oxygen isotope ratios of well-preserved brachiopod calcite and conodont apatite were used to reconstruct the palaeotemperature history of the Middle and Late Devonian. By assuming an oxygen isotopic composition of -1‰ V-SMOW for Devonian seawater, the oxygen isotope values of Eifelian and early Givetian brachiopods and conodonts give average palaeotemperatures ranging from 22 to 25 °C. Late Givetian and Frasnian palaeotemperatures calculated from δO values of conodont apatite are close to 25 °C in the early Frasnian and increase to 32 °C in the latest Frasnian and early Famennian. Oxygen isotope ratios of late Givetian and Frasnian brachiopods are significantly lower than equilibrium values calculated from conodont apatite δO values and give unrealistically warm temperatures ranging from 30 to 40 °C. Diagenetic recrystallization of shell calcite, different habitats of conodonts and brachiopods, as well as non-equilibrium fractionation processes during the precipitation of brachiopod calcite cannot explain the O depletion of brachiopod calcite. Moreover, the O depletion of brachiopod calcite with respect to equilibrium δO values calculated from conodont apatite is too large to be explained by a change in seawater pH that might have influenced the oxygen isotopic composition of brachiopod calcite. The realistic palaeotemperatures derived from δO may suggest that biogenic apatite records the oxygen isotopic composition and palaeotemperature of Palaeozoic oceans more faithfully than brachiopod calcite, and do not support the hypothesis that the O/O ratio of Devonian seawater was significantly different from that of the modern ocean. © Springer-Verlag 2004.
Keywords: Brachiopod calcite; Conodont apatite; Devonian; Oxygen isotopes; Palaeotemperature

Oxygen Isotope fractionation in marine aragonite of coralline sponges. - Joachimski, Michael; et al. (Geochimica Et Cosmochimica Acta, 2000)
Oxygen isotope values of the extant Caribbean coralline sponge Ceratoporella nicholsoni are compared with published temperatures and δ18O of water calculated from salinities. The measured values from aragonitic sponge skeletons have a mean offset of 1.0 ± 0.1‰ from calculated calcite equilibrium values (α(aragonite-calcite) = 1.0010). This is in good agreement with published values from synthetic aragonite. They further agree with published near-equilibrium oxygen isotope values of temperate and cold water molluscs and foraminifera extrapolated to the temperature range of the coralline sponges. These results and the mode of skeleton formation of Ceratoporella nicholsoni suggest that these sponges precipitate aragonite close to isotopic equilibrium. The temperature dependence of oxygen isotopic fractionation between the aragonite of Ceratoporella nicholsoni and water is only roughly constrained by the available data, due to the narrow temperature range of the Caribbean reef sites. However, as the data suggest oxygen isotopic equilibrium, we can calculate a well constrained temperature equation combining temperate and cold water equilibrium values from molluscs and foraminifera with our sponge data: 103lnα(aragonite-water) = (18.45 ± 0.4) * 103/T(K) - (32.54 ± 1.5) and T (°C) = (20.0 ± 0.2) - (4.42 ± 0.10) * (δ(a) - δ(w)); for 3°< T < 28°. Copyright (C) 2000 Elsevier Science Ltd.
UnivIS-Import:2015-03-09:Pub.2000.nat.dgeo.IGM.LG.oxygen_20

Oxygen isotopes in the Azores islands: Crustal assimilation recorded in olivine - Genske, Felix; Beier, Christoph; Haase, Karsten; Turner, Simon P.; Krumm, Stefan; Brandl, Philipp (Geology, 2013)
Oxygen isotope ratios of olivine have become a widely used tool for the study of magmatic systems, especially in the interpretation of source heterogeneities in mantle plume-derived ocean island basalts. The underlying assumption is that fresh minerals provide a better guide to magma δO than bulk rock analyses and that olivine is also likely to be a major phenocryst phase in primitive magmas. However, distinctions between source compositions and the effects of subsequent magma evolution have not always been thoroughly scrutinized. For the Azores samples investigated here, we can demonstrate that the δO variation (+4.84‰ to +5.25‰ Vienna standard mean ocean water) observed in the olivine phenocryst population is closely linked to evolution in the host magmas during ascent to the surface. We observe a linear, positive correlation between forsterite (Fo) content and δO in all of the individual island lava suites. This forces us to conclude that the low oxygen isotope ratios result from combined assimilation and fractional crystallization processes, the assimilant being hydrothermally (temperature > 250 C) altered, lower oceanic crust. Linear regression of the measured δO olivine values to Fo suggests a homogeneous mantle source with δO = +5.2‰ ± 0.1‰. © 2013 Geological Society of America.

Oxygen isotopes of bovid teeth: archives of palaeoclimatic variations in archaeological deposits of Ganga Plain. - Joachimski, Michael; et al. (Quaternary Research, 2004)
UnivIS-Import:2018-09-05:Pub.2004.nat.dgeo.IGM.LG.oxygen

Oxygen isotopes of bovid teeth as archives of paleoclimatic variations in archaeological deposits of the Ganga plain, India - Joachimski, Michael; et al. (Quaternary Research, 2004)
UnivIS-Import:2015-03-09:Pub.2004.nat.dgeo.IGM.LAG.oxygen

Oxygen Isotope Stratigraphy - Grossman, Ethan; Joachimski, Michael (Geological Timescale 2020, 2020)

Oxygen mobility in the perovskite SrTi1-xFexO3-ð (x = 0.8) - Mashkina, Elena; Magerl, Andreas; Ollivier, Jacques; Göbbels, Matthias; Seifert, Friedrich (Physical Review B - Condensed Matter and Materials Physics, 2006)
The dynamics of long range translation and local motions of oxygen in SrTi0.2 Fe0.8 O3-δ have been studied by electrical conductivity and quasielastic neutron scattering. The activation energy of the translational ionic diffusion measured by electrical conductivity is 0.97 eV for T>900°C. Both quasielastic linewidths and quasielastic intensities in neutron scattering show the presence of two motions. The Q independences indicate a localized character for these oxygen diffusion modes with activation energies of 0.43 and 0.27 eV for the "fast" and the "slow" local jumps, respectively. A model for the local oxygen motion is proposed involving oxygen jumps in the (0 k 0) plane either directly to the next unit cell or performing detours combining two and two site jumps resulting in the same final momentum transfer. © 2006 The American Physical Society.
UnivIS-Import:2015-03-09:Pub.2006.nat.dgeo.IGM.LM.oxygen

Oyster-dominated macrobenthic associations in the Cenomanian of Djebel Bouarif (Aures Mountains, Northeastern Algeria) - Aouissi, Riadh; Abdelhady, Ahmed Awad; Martinez, Sergio; Ahmed, Mohamed S.; Hannaa, Wagih; Jain, Sreepat; Salmi-Laouar, Sihem (Cretaceous Research, 2023)
In the Batna area of Algeria, the Cenomanian is represented by the Smail Marls Formation, a highly fossiliferous unit with a diverse benthic macrofauna (mainly of ostreid bivalves). A total of 1090 specimens belonging to 65 macrobenthic species were identified from 19 stratigraphic samples. The macrofaunal communities were quantitively analyzed using the hierarchical clustering (HC), nonmetric multidimensional scaling (NMDS), and permutational analysis of variance (PERMANOVA). Five distinct associations are recognized: 1) Costagyra olisiponensis, 2) Rhynchostreon suborbiculatum, 3) Aspidiscus cristatus, 4) Rhynchostreon suborbiculatum-Mecaster ameliae, and 5) Pycnodonte vesicularis. Data suggests that during the Cenomanian, the dominance of high-energy opportunistic oyster species within the soft marly sediments are related to their adaptive strategies. The changes noted in the community structure are attributed to sea-level fluctuations, rate of sedimentation and the prevailing hydrodynamics. Towards the uppermost Cenomanian and the Cenomanian–Turonian boundary, the oysters become rare due to eustatic sea-level rise and this decline coincides with increasing predation intensity on oysters and the destruction of their shallower habitats.
CRIS-Team Scopus Importer:2023-06-30
Keywords: Benthic associations; Bivalves; North Africa; Paleoenvironmental reconstruction; Upper Cretaceous

Palaeobotryllus and friends: Cambro-Ordovician record of probable ascidian tunicates - Lehnert, Oliver; Miller, James F.; Cochrane, Karen (Acta Universitatis Carolinae - Geologica, 1999)

Palaeoclimate reconstructions of the Middle Jurassic of Kachchh (western India): An integrated approach based on palaeoecological, oxygen isotopic, and clay mineralogical data - Fürsich, Franz; Singh, Indabir; Joachimski, Michael; Krumm, Stefan; Schlirf, M; Schlirf, S. (Palaeogeography, Palaeoclimatology, Palaeoecology, 2005)
The Middle Jurassic sedimentary succession of the Kachchh Basin shows significant changes in lithology, faunal content and diversity across the Bathonian-Callovian boundary. The change in lithology from predominantly carbonates in the Middle and Late Bathonian to siliciclastics in the Callovian is accompanied by a drop in species diversity from high to moderate. Characteristic faunal elements of the Bathonian (corals, sponges, the bivalves Eligmus and members of the Opinae) are absent or rare in the Callovian. In contrast, Callovian sediments contain comparatively high proportions of nuculid bivalves. The clay mineral assemblage reveals prominent variations in the smectite vs. kaolinite abundance, especially during the Bathonian to Callovian transition. From the Bajocian to the Middle Bathonian, smectite becomes the dominant clay mineral and is nearly exclusively present in the Late Bathonian. Towards the Middle Callovian, its content gradually decreases and kaolinite becomes the dominant clay mineral. Illite generally is only a minor component throughout the Middle Jurassic. Based on these results, the Bajocian to Middle Bathonian time interval is interpreted to represent subtropical climatic conditions with seasonal droughts and a moderate supply of terrigenous clastics to the basin. The Late Bathonian was a period with a semi-arid climate, hot seasonal droughts and a minor input of terrigenous clastics. The increase in kaolinite contents in the Callovian suggests a subtropical humid climate with less prominent seasonal droughts and a higher input of siliclastics into the basin accompanied by a higher nutrient influx. Oxygen isotope ratios measured on Bathonian to early Callovian brachiopod shells give palaeotemperatures of 19-24°C. Callovian to Oxfordian paleotemperatures calculated from oxygen isotopes measured on belemnite rostra range from 11 to 21°C. The lower palaeotemperatures estimated from the oxygen isotopic composition of belemnite calcite are explained by assuming that the belemnites spent most of their life span in colder regions of the Malagassy Gulf and migrated into the warmer subtropical waters of the Kachchh Basin. Combining these various lines of evidence, the changes in lithology and faunal composition taking place in the Kachchh Basin during the Middle Jurassic appear to reflect largely a change towards increasing humidity rather than a distinct decrease in water temperature. © 2004 Elsevier B.V. All rights reserved.
Keywords: Clay mineralogy; India; Jurassic; Kachchh Basin; Oxygen isotopes; Palaeoclimate; Palaeoecology

Palaeoecology of Late Triassic conodonts: Constraints from oxygen isotopes in biogenic apatite. - Rigo, Manuel; Joachimski, Michael (Acta Palaeontologica Polonica, 2010)
The oxygen isotopic composition of conodont apatite derived from the Late Triassic (Carnian to lower Norian), Pignola 2 and Sasso di Castalda sections in the Lagonegro Basin (Southern Apennines, Italy) was studied in order to constrain the habitat of Late Triassic conodont animals. Oxygen isotope ratios of conodonts range from 18.5 to 20.8‰ V-SMOW, which translate to palaeotemperatures ranging from 22 to 31°C, assuming a δ 18O of Triassic subtropical sea water of -0.12‰ V-SMOW. These warm temperatures, which are well comparable to those of modern subtropical-tropical oceans, along with the body features of the conodont animal suggest that conodont 1 δ8O values reflect surface water temperatures, that the studied conodont taxa lived in near-surface waters, and that δ 18O values of Late Triassic conodonts can be used for palaeoclimatic reconstructions.
UnivIS-Import:2015-03-09:Pub.2010.nat.dgeo.IGM.LG.palaeo_4
Keywords: Conodonta; Late Triassic; Oxygen isotope; Palaeoecology; Palaeotemperatures; Tethys

Palaeoecology of tropical marine invertebrate assemblages from the Late Triassic of Misurina, Dolomites, Italy - Hausmann, Imelda M.; Nuetzel, Alexander; Roden, Vanessa; Reich, Mike (Acta Palaeontologica Polonica, 2021)
Two marine invertebrate fossil assemblages from the Late Triassic Cassian Formation (Dolomites, northern Italy) were examined to assess their diversity and palaeoecology. Surface and bulk samples from the localities Misurina Landslide and Lago Antorno were taken and analysed separately. Both benthic assemblages are relatively similar in taxonomic composition. Gastropods form the most abundant and diverse group, followed by bivalves. Disarticulated echinoderm ossicles are also common in the bulk sample from Misurina Landslide, but they are rare at Lago Antorno. The Misurina Landslide outcrop has yielded two echinoderm Palaeozoic holdovers, the ophiocistioid Linguaserra triassica and plates of putative proterocidarids, supporting the earlier hypothesis that such basins acted as refugia. The gastropod species Coelostylina conica, Prostylifer paludinaris, and Ampezzopleura hybridopsis are characteristic elements of both assemblages. The gastropod Jurilda elongata, however, is the most abundant species at Misurina Landslide, whereas juveniles of the gastropod species Dentineritaria neritina dominate the assemblage from Lago Antorno. Newly described gastropod taxa are Angulatella bizzarinii Nützel and Hausmann gen. et sp. nov., Bandellina compacta Nützel and Hausmann sp. nov., and Ampezzogyra angulata Nützel and Hausmann sp. nov. Fifty-seven invertebrate species were found in the bulk sample from Misurina Landslide and 26 species were recovered from the bulk sample from Lago Antorno. However, sample size from Lago Antorno was much smaller than that from Misurina. Diversity indices (Shannon, Simpson, Berger-Parker) show similar moderate diversities in both assemblages. Rarefaction curves and rank-abundance distributions also point to very similar diversities and ecological structures of the fossil assemblages. Both assemblages are autochthonous or parautochthonous, stemming from basinal, soft-bottom habitats. Their taxonomic composition differs significantly from that of other faunas known from the Cassian Formation. The tropical marine Cassian palaeoecosystem was highly complex and its diversity is still far from being fully explored.
CRIS-Team Scopus Importer:2021-03-05
Keywords: Alps; Carnian; Cassian Formation; Diversity; Echinodermata; Ladinian; Mollusca; Small body size

Palaeoenvironments of the late Triassic Rhaetian Sea: Implications from oxygen and strontium isotopes of hybodont shark teeth - Fischer, Jan; Voigt, Silke; Franz, Matthias; Schneider, Joerg W.; Joachimski, Michael; Tichomirowa, Marion; Goetze, Jens; Furrer, Heinz (Palaeogeography, Palaeoclimatology, Palaeoecology, 2012)
The oxygen and strontium isotopic composition of 125 teeth of the hybodont sharks Lissodus and Hybodus from various late Triassic (Rhaetian) bone bed localities in the Central European Basin are used as environmental and ecological tracers for the shallow epicontinental Rhaetian Sea. The preservation of tooth enameloid was ascertained by cathodoluminescence microscopy. Mean δ 18O P values differ regionally across the Rhaetian Sea with values of 18.6±0.6‰ near the western gate, 16.1±0.8‰ in the east, 15.4±0.6‰ in the southeast, and 17.7±0.9‰ in the south. The δ 18O P values in the eastern Rhaetian Sea are 4-5‰ lower relative to Tethyan seawater, while teeth from the southern and western parts close to the marine gates are less fractionated. The strontium isotopic composition of teeth from most localities is more radiogenic in comparison to late Triassic seawater. The observed spatial δ 18O P trend in the Rhaetian Sea indicates a shift from marine to brackish conditions in the south and west towards extensively brackish conditions with salinities of less than 16‰ in the east, thus confirming the existence of two marine gates. Brackish conditions persisted throughout early Rhaetian times, and were maintained by increased fluvial discharge from the Vindelician-Bohemian and Fennoscandian Highs as a result of enhanced atmospheric moisture availability in the course of the Rhaetian transgression. The δ 18O P values of Lissodus and Hybodus indicate euryhaline behaviour of Rhaetian hybodonts by exceeding modern shark intraspecific variability. The lack of accordance in δ 18O P values between different isotopically conspicuous localities in the Rhaetian Sea contradicts a basin-wide migration pattern. Differences between co-site taxa might indicate some degree of niche partitioning. © 2012 Elsevier B.V.
UnivIS-Import:2015-03-09:Pub.2012.nat.dgeo.IGM.LG.palaeo
Keywords: Hybodont sharks; Oxygen isotopes; Palaeoecology; Rhaetian; Salinity; Strontium isotopes

Palaeokarst evidence for widespread regression and subaerial exposure in the middle Katian (Upper Ordovician) of Baltoscandia: significance for global climate. - Calner, Mikael; Lehnert, Oliver; Nolvak, Jaak (Palaeogeography, Palaeoclimatology, Palaeoecology, 2010)
We report on widespread and contemporary palaeokarst in the middle Katian (Upper Ordovician) of Sweden, Estonia and Latvia, the first major palaeokarst horizon to be reported from the Ordovician of Baltoscandia. The solution features occur within a few metres of thick zone of limestone immediately below the widespread Fjäcka Shale and are related to an unconformity with preserved palaeorelief in the Slandrom Limestone in Sweden and the time-equivalent Saunja Formation in Estonia and Latvia. Facies evidence for a karst origin comes from several outcrops and core sections and includes 1) frequent karren-like morphologies interpreted as 'Swiss-cheese' karst [. sensu Baceta et al., 2001], 2) local occurrences of solution/collapse breccia, 3) presence of bladed pseudospar crystals in solution cavities, and 4) carbon isotope values indicating meteoric influence to the succession. These findings are herein put in context with previously reported, large-scale erosional channels that may cut down several tens of metres below the Fjäcka Shale in the subsurface Baltic Sea area, and with regional, anomalous thickness variations in the Slandrom Limestone and Saunja Formation, all together forming strong support for regional exposure of the Baltoscandian continent in the middle Katian. High-resolution stable isotopic data show that the regression and lowstand of sea-level overlap with the Waynesville carbon isotope excursion. It resulted in basin-wide cessation of carbonate production near the Amorphognathus superbus and A. ordovicicus conodont zonal boundary. The contemporary development of palaeokarst in different confacies belts of the basin suggests that this was an extraordinary sea-level lowstand, herein interpreted as reflecting a middle Katian glaciation. © 2009 Elsevier B.V.
UnivIS-Import:2015-03-09:Pub.2010.nat.dgeo.IGM.LG.palaeo
Keywords: Baltoscandia; Fjäcka Shale; Katian; Ordovician; Palaeokarst; Saunja Formation; Slandrom Limestone

Palaeontological and facial features of the Upper Jurassic Hochstegen Marble (Tauern Window, Eastern Alps) - Kießling, Wolfgang (Terra Nova, 1992)

Palaeoproterozoic to Palaeozoic magmatic and metamorphic events in the Shackleton Range, East Antarctica: Constraints from zircon and monazite dating, and implications for the amalgamation of Gondwana - Schmädicke, Esther; et al. (Precambrian Research, 2009)
Keywords: Gondwana assembly; East Antarctica; Zircon and monazite U-Pb and Th-U-Pb dating; Shackleton Range

Palaeosalinity and palaeoclimatic geochemical proxies (elements Ti, Mg, Al) vary with Milankovitch cyclicity (1.3 to 2.0 Ma), OGCP cores, Palaeolake Olduvai, Tanzania - Stanistreet, Ian G.; Boyle, John F.; Stollhofen, Harald; Deocampo, Daniel M.; Deino, Alan; McHenry, Lindsay J.; Toth, Nicholas; Schick, Kathy; Njau, Jackson K. (Palaeogeography, Palaeoclimatology, Palaeoecology, 2020)
The analysis of geochemical palaeoclimate and palaeosalinity proxy elements Ti, Mg, and Al, derived from X-ray fluorescence (XRF) scans of Olduvai Beds I and II from Olduvai Gorge Coring Project (OGCP) borehole Cores 2A and 3A, provides a record of cyclic variation between 1.3 Ma and 2.0 Ma. The boreholes were drilled into the depocentre of the Olduvai Basin between Fifth and FLK Faults, where Palaeolake Olduvai was most persistent and deepest. During most of Bed I the lake was particularly deep and probably meromictic, preserving high TOC contents and commonly preserving fine lamination due to lack of bioturbation. Accretion rates were also high during Bed I, when rates of basinal subsidence were maximal due to crustal stretching, associated with basaltic volcanism, towards the end of bimodal Ngorongoro volcanism. Basaltic magma effusive activity is manifested as tuffs, scoriaceous layers and the Bed I Basalt complex lava flows. A magnesium anomaly is recorded in the claystone geochemistry at this time and deposition of dolomite and limestone beds are restricted to this syn-volcanic phase of basin history. During Bed I deposition, accretion rates (0.23 mm/yr) were high enough to permit recognition of cycles with an average periodicity of 22.3 kyr corresponding to the Earth's precession. Only the high values during the Mg anomaly are adequate for the application of the palaeosalinity proxy element ratio Mg/Al. But Ti counts provide a cyclic record in both Bed I and Bed II. During Bed II deposition, the accretion rate was much slower (0.058 mm/yr) and cyclicity averaged 40.4 kyr, corresponding to Earth's orbital obliquity. The Bed II interval corresponds to MIS Stages 40 to 64. Coincidence of precessional and obliquity minima at 1.8 Ma explains the superdrought that affected the basin at the time of emplacement of Tuff IF, when the lake was dried out. The aridity of the sequence containing Tuff IA is also associated with a precessional minimum. The cyclic record suggests that three Bed I Basalt flows were extruded at 1.94 Ma during a time span lasting between 6 kyr and 15 kyr.
CRIS-Team Scopus Importer:2020-03-31
Keywords: Basaltic magmatism; Obliquity; Olduvai Basin; Orbital forcing; Precession; XRF scanning

Palaeovegetation changes recorded in Palaeolake Olduvai OGCP Core 2A (2.09–2.12 Ma) Naibor Soit Formation Olduvai Gorge, Tanzania - Rodríguez-Cintas, A.; Albert, R. M.; Bamford, M. K.; Stanistreet, I. G.; Stollhofen, Harald; Stone, J. R.; Rivera-Rondón, C.; Pronzato, R.; Njau, J. K.; Schick, K.; Toth, N. (Palaeogeography, Palaeoclimatology, Palaeoecology, 2020)
For five decades Olduvai Gorge has been a key site to reconstruct and understand the relationship between environmental and landscape conditions and use of affordances by early African hominin populations. Following the first Olduvai Gorge Coring project (OGCP) during 2014, a multiproxy microbiological analysis, which includes phytoliths, pollen, diatoms, sponge spicules and chrysophyte cysts, was undertaken on samples collected from various borehole cores. The aim of the study is to better understand palaeoenvironmental and palaeovegetation conditions and changes through time and their relationship to hominin presence and evolution. This study details the first palaeobotanical and palaeoenvironmental study of Borehole 2A at Olduvai Gorge. It represents the as yet oldest known sedimentary sequence in the Olduvai Basin for a portion of the pre-Bed I Naibor Soit Formation; this is a unit that is not accessible in any natural exposures in Olduvai Gorge, and has only recently been encountered by drilling. Here we present the results from a particularly phytolith-prone portion between 2.09 Ma and 2.12 Ma. Phytolith results indicate a savannah environment dominated by grasses, where Poaceae were a key component and where the C3 Pooideae grasses were mostly dominant, alternating with C4 grasses. Oscillations between grass subfamilies, C3 Pooideae, C4 Chloridoideae, and C4 Panicoideae to lesser degrees, indicate five substantial climatic shifts, varying between more humid and arid conditions. Associated with phytoliths, freshwater indicators such as diatoms, sponge spicules and chrysophyte cysts were also identified, suggesting the presence of wetlands in the lake catchment area. Pollen is extremely rare in the sediments but when present, comprises fungal spores and Poaceae pollen, thus supporting the wetland and grassland reconstructions, respectively. These results offer for the first time, a whole picture of the palaeovegetation and associated palaeoenvironments for this pre-Bed I period. Together with previous results from other areas and chronological periods, they improve our understanding of the evolution and adaptation of early hominins and their close relationship to the surrounding landscape.
CRIS-Team Scopus Importer:2020-08-28
Keywords: East Africa; Diatoms; Sponge spicules; Pleistocene; Phytoliths; Palaeoenvironmental reconstruction

Palaeozoic calcareous plankton: Evidence from the Silurian of Gotland - Munnecke, Axel; Servais, Thomas (Lethaia, 2008)
In order to investigate whether or not equivalents to modern calcareous plankton existed in Palaeozoic times, extremely well-preserved successions have to be investigated. The Silurian strata on Gotland (Sweden) are exceptionally well preserved because they have not experienced deep burial conditions and tectonic stress, due to their position on the stable Baltic Shield. Scanning electron microscope investigations of polished, slightly etched rock surfaces revealed the presence of a variety of calcareous micro- and nannofossils. Among these organisms, many can be termed 'calcispheres' (60-100 μm in diameter), whereas others due to their size range (nannofossils) are informally termed herein as 'nannospheres' (10-25 μm in diameter). The systematic attribution of these fossils is unknown (incertae sedis). Mesozoic calcispheres are usually attributed to calcareous cysts of dinoflagellates following comparisons of ultrastructure with modern species. The abundance of different calcispheres in the Silurian sediments of Gotland and the observation that many of the calcareous microfossils occur in distinctly different facies as well as their spherical shape indicate that they probably belong to calcareous micro- and nannoplankton. We therefore conclude that calcareous plankton most probably existed already during the Palaeozoic, but can only be observed under conditions of exceptional preservation. © 2008 The Authors, Journal compilation © 2008 The Lethaia Foundation.
Keywords: Calcareous plankton; Palaeozoic; Silurian; Gotland; Nannofossils; Baltic Shield

Palaeozoic evolution of animal mouthparts - Klug, Christian; Frey, Linda; Pohle, Alexander; de Baets, Kenneth; Korn, Dieter (Bulletin of Geosciences, 2017)
During the Palaeozoic, a diversification in modes of life occurred that included a wide range of predators. Major macroecological events include the Cambrian Explosion (including the Agronomic Substrate Revolution and the here introduced ’Ediacaran-Cambrian Mouthpart Armament’), the Great Ordovician Biodiversification Event, the Palaeozoic Plankton Revolution, the Siluro-Devonian Jaw Armament (newly introduced herein) and the Devonian Nekton Revolution. Here, we discuss the evolutionary advancement in oral equipment, i.e. the Palaeozoic evolution of mouthparts and jaws in a macroecological context. It appears that particularly the latest Neoproterozoic to Cambrian and the Silurian to Devonian were phases when important innovations in the evolution of oral structures occurred.
Keywords: Gnathostomata; Cephalopoda; evolution; convergence; diversity; nekton; jaws

Palaeozoic Reefs and Bioaccumulations: Climatic and Evolutionary Controls - Álvaro, José-Javier; Aretz, Markus; Boulvain, Frédéric; Munnecke, Axel; Vachard, Daniel; Vennin, Emmanuelle (2007)
The difficulty of studying reefs and shell accumulations rests primarily on its multidisciplinary position crossing numerous disciplines, such as biostratigraphy, geochemistry, palaeobiology, palaeoecology, petrology, sedimentology and taphonomy. The facies characterization of these bioclastic-bearing strata is, like many other biosedimentary structures, a process that requires the acquisition and integration of a wide and multiscale diversity of observations, which include field (global geometries), sample (fabrics) and thin-section (textures) scales. When we organized an international meeting focused on 'Climatic and Evolutionary Controls on Palaeozoic Reefs and Bioaccumulations' (7-9 September 2005, Paris, France), it was our intention to provide a forum for discussing the evolution of reefs, shell accumulations and their transitional deposits. We invited specialists on a wide range of taxonomic groups, siliciclasticmixed carbonate platforms and Palaeozoic ages to introduce a number of topics that are the focus of current research in the world of Palaeozoic benthic communities. The result of their contributions is presented in this Special Publication, which shows the complexity of intrareef synecological relationships and the diversity of concepts used to characterize both reefs and bioaccumulations. The editors offer, in the introductory paper (, lvaro et al.), a discussion about concepts and definitions related to reefs and bioaccumulations. The transition between the concepts of reef and shell accumulation is gradual, as illustrated by some Palaeozoic examples, where reworked coquinas were episodically stabilized by encrusting communities and/or early diagenetic cements, in some cases forming the sole for future frame-building fabrics. Three Cambrian works are focused on shell-rich phosphorites from the Montagne Noire, France (Clausen & ,iAvaro), and microbial and archaeocyathanmicrobial reef complexes from Sardinia, Italy (Gandin et al.) and the High Atlas, Morocco (Alvaro & Clausen), the latter directly controlled by volcanogenic turbidity. The increase in biodiversity recorded in Ordovician bioaccumulations is illustrated by the characterization of a distinct echinoderm assemblage rich in ophiuroids and stylophorans (Hunter et al.). Kershaw et al. show that some Silurian reefs from Gotland and the UK have sharp boundaries, with the surrounding sediments terminating abruptly against the reef edge, and the sharp margins made up of automicrites; the sharp reef edges indicate coherence of the micritic fabric, interpreted as a lithified wall against which bedded limestones were deposited. Hubmann & Suttner provide a review of Alpine Late Silurian-Late Devonian reefs and pavements, spanning a wide range of different autochthonous carbonates (e.g. brachiopod pavements, algal reefs, stromatoporoidcoral patch reefs) as well as allochthonous accumulations (e.g. serpulid accumulations). Two related papers offer an updated synthesis of the establishment of a carbonate platform (Mabille & Boulvain) and the sea-level-controlled evolution of Devonian mounds and atolls in the Dinant Synclinorium from Belgium (Boulvain). Examples for the youngest reefs of the Middle Palaeozoic reef community of stromatoporoids and corals are described from the latest Frasnian of Belgium (Poty & Chevalier). The struggle to establish a successful reef assemblage in the aftermath of the Kellwasser events and the importance of microbial communities in Famennian and Carboniferous reefs is described from Belgium (Aretz & Chevalier). The influence of palaeobathymetry and local synsedimentary tectonics in the establishment of carbonate factories is discussed in two papers focused on the development of Carboniferous chaetetid 'reefs' (Almaz n-Vazquez et al.) and neighbouring crinoidal thickets (Buitr6n-S nchez et aL) in Sonora, Mexico, whereas the documentation of sea-floor instability related to the evolution of the Permian foreland basin recorded in the southern Urals is characterized by Vennin. The input of cool waters within tropical PermoCarboniferous seas is analysed in Oman by Weidlich, and opens a large field of future discussions. Th6ry et al. provide new insights into the latest Permian reefs and bioaccumulations from eastern Europe and the Caucasus. And, finally, Zapalski et al. offer an estimation of palaeoenvironmental changes based on the distribution of late Middle Devonian tabulae in tabulate corals from northern France. One of the messages of this collection of papers is the wide diversity of sedimentary geometries and facies displayed by reefs, shell accumulations and transitional composite deposits. Readers will find that the papers in this Special Publication cover specific nomenclatural problems, evidenced by the widespread terminology used to describe skeletal assemblages. Rather than attempt a complete revision of terms, we have touched on some of the major issues at this stage of development in the field: the major climatic, environmental and evolutionary factors that controlled the Palaeozoic development of shell accumulations and reefs. We hope that this volume attracts the attention of everyone interested in the fascinating diversity of Palaeozoic reefs and shell accumulation. It will be useful to senior undergraduate and postgraduate students of Earth Sciences and engineering. We also hope that it may prove useful to professionals who explore and economically exploit Palaeozoic skeletal-rich strata. The editors would like to thank all contributors and referees for their rapid and stimulating collaboration. Thanks also for their suggestions, discussions, editorial work and constructive review
Keywords: Palaeozoic; Reefs; Bioaccumulations; Climate; Evolutionary Controls

Palaeozoic stromatoporoid diagenesis: a synthesis - Kershaw, Stephen; Munnecke, Axel; Jarochowska, Emilia; Young, Graham (Facies, 2021)
Palaeozoic stromatoporoids, throughout their 100-million + year history (Middle Ordovician to Late Devonian and rare Carboniferous), are better preserved than originally aragonite molluscs, but less well-preserved than low magnesium-calcite brachiopods, bryozoans, trilobites and corals. However, the original mineralogy of stromatoporoids remains unresolved, and details of their diagenesis are patchy. This study of approximately 2000 stromatoporoids and the literature recognises three diagenetic stages, applicable throughout their geological history. Timing of processes may vary in and between stages; some components are not always present. Stage 1, on or just below sediment surface, comprises the following: micrite filling of upper gallery space after death, then filling of any remaining space by non-ferroan then ferroan calcite in decreasing oxygen of pore-waters; partial lithification of associated sediment from which stromatoporoids may be exhumed and redeposited, evidence of general early lithification of middle Palaeozoic shallow-marine carbonates; microdolomite formation, with the Mg interpreted to have been derived from original high-Mg calcite (HMC) mineralogy (likely overlaps Stage 2). Stage 2, short distance below sediment surface, comprising the following: fabric-retentive recrystallisation (FRR) of stromatoporoid skeletons forming fabric-retentive irregular calcite (FRIC), mostly orientated normal to growth layers, best seen in cross-polarised light. FRIC stops at stromatoporoid margins in contact with sediment and bioclasts. FRIC geometry varies, indicating some taxonomic control. Evidence that FRIC formed early in diagenetic history includes syntaxial continuation of FRIC into some sub-stromatoporoid cavities (Type 1 cement), although others were pre-occupied by early cement fills (Type 2 cement) formed before FRR, preventing syntaxial continuation of FRIC into cavities. Likely contemporaneous with FRIC formation, stromatoporoids in argillaceous micrites drew carbonate from adjacent sediment during reorganisation of argillaceous micrite into limestone–marl rhythms that are also early diagenetic. Stage 3, largely shallow burial, comprises the following: dissolution and silicification, but these may have occurred earlier in stromatoporoid diagenetic histories (more data required); burial pressure dissolution forming stylolites.
CRIS-Team Scopus Importer:2021-06-11
Keywords: Hypercalcified sponges; Stromatoporoids; Tabulates; Taphonomy

Palaeozoic stromatoporoids and chaetetids analysed using Electron Backscatter Diffraction (EBSD); implications for original mineralogy and microstructure - Balthasar, Uwe; Kershaw, Stephen; Da Silva, Anne-Christine; Seuß, Barbara; Cusack, Maggie; Eichenseer, Kilian; Chung, Peter (Facies, 2021)

Palaxius salataensis Brönnimann, Cros and Zaninetti, 1972, the oldest crustacean microcoprolite from the early Carboniferous of Guangxi, South China - Senowbari-Daryan, Baba; El Rab, Amro Gad; Heindel, Katrin; Gischler, Eberhard; Peckmann, Joern (Palaeontologische Zeitschrift, 2017)
Palaxius salataensis Brönnimann, Cros and Zaninetti, 1972, is described from early Carboniferous stromatolite mounds of a fore-reef slope setting from Laibin, Guangxi, South China. This is the oldest occurrence of internally structured crustacean coprolites. The geographic distribution and stratigraphic range of the ichnospecies as well as paleoecological implications of this new record of P. salataensis are discussed.
UnivIS-Import:2017-12-18:Pub.2017.nat.dgeo.IGM.LP.palaxi
Keywords: Carboniferous; Guangxi; Microcoprolite; Palaxius; South China

Paleobiogeography, high-resolution stratigraphy, and the future of Paleozoic biostratigraphy: Fine-scale diachroneity of the Wenlock (Silurian) conodont Kockelella walliseri - Cramer, Bradley D.; Kleffner, Mark A.; Brett, Carlton E.; Mclaughlin, Patrick I.; Jeppsson, Lennart; Munnecke, Axel; Samtleben, Christian (Palaeogeography, Palaeoclimatology, Palaeoecology, 2010)
The Wenlock Epoch of the Silurian Period has become one of the chronostratigraphically best-constrained intervals of the Paleozoic. The integration of multiple chronostratigraphic tools, such as conodont and graptolite biostratigraphy, sequence stratigraphy, and δC chemostratigraphy, has greatly improved global chronostratigraphic correlation and portions of the Wenlock can now be correlated with precision better than ±100kyr. Additionally, such detailed and integrated chronostratigraphy provides an opportunity to evaluate the fidelity of individual chronostratigraphic tools. Here, we use conodont biostratigraphy, sequence stratigraphy and carbon isotope (δC) chemostratigraphy to demonstrate that the conodont Kockelella walliseri, an important guide fossil for middle and upper Sheinwoodian strata (lower stage of the Wenlock Series), first appears at least one full stratigraphic sequence lower in Laurentia than in Baltica. Rather than serving as a demonstration of the unreliability of conodont biostratigraphy, this example serves to demonstrate the promise of high-resolution Paleozoic stratigraphy. The temporal difference between the two first occurrences was likely less than 1million years, and although it is conceptually understood that speciation and colonization must have been non-instantaneous events, Paleozoic paleobiogeographic variability on such short timescales (tens to hundreds of kyr) traditionally has been ignored or considered to be of little practical importance. The expansion of high-resolution Paleozoic stratigraphy in the future will require robust biostratigraphic zonations that embrace the integration of multiple chronostratigraphic tools as well as the paleobiogeographic variability in ranges that they will inevitably demonstrate. In addition, a better understanding of the paleobiogeographic migration histories of marine organisms will provide a unique tool for future Paleozoic paleoceanography and paleobiology research. © 2010 Elsevier B.
Keywords: Carbon isotope; Chronostratigraphy; Conodont zonation; Ireviken Event; Paleobiogeography; Sequence stratigraphy; Silurian; Wenlock

Paleobiogeography of Lower-Middle Devonian Conulariids from southwest Gondwana - Rodrigues Ribeiro, Victor; Dowding, Elizabeth; Nascimento Sousa, Felipe; Augusto Carbonaro, Fábio; Pirani Ghilardi, Renato (Journal of South American Earth Sciences, 2023)
The bioregionalization of the Devonian fauna in southwest Gondwana has been extensively studied, focusing on the occurrences of brachiopods and trilobites, however, little attention has been given to Conulariids. The main goal of this paper is to propose a bioregionalization for the Conulariids (Conularia albertensis, C. quichua, C. sp., Paraconularia africana, P. ulrichana, and Reticulaconularia baini) from the Lower-Middle Devonian in southwest Gondwana. After a clustering analysis and diversity tests we have identified two distinct bioregions for Conulariids: the Amazon and southwest Gondwana, in the Amazon region the diversity is low, and can be attributed to scarcity of palaeontological data on the area. On the other hand, in the southwest Gondwana bioregion, diversity ranges from moderate to relatively high, which helps define a second-order bioregion, the Andeo-South Africa and Interior Gondwana. The first includes areas where diversity has higher values bordering southwest Gondwana (Bolivian Chaco-Peru, Zorritas-NOA-South Bolivia, South Africa and Malvinas areas). Further, in the Interior Gondwana bioregion are the Parnaíba (Parnaíba Basin), Alto Garças (north and northwest of Paraná Basin), Paraná (south of Paraná Basin, Uruguay and Paraguay) areas, where the diversity is slightly lower when compared to the Andeo-South Africa bioregion.
CRIS-Team Scopus Importer:2023-09-29
Keywords: Bioregion; Clustering; Diversity; Paleontology; South America

Paleoclimate perturbations before the early Sheinwoodian Glaciation: A trigger for extinctions during the Ireviken Event. - Lehnert, Oliver; Maennik, Peep; Joachimski, Michael; Calner, Mikael; Fryda, Jiri (Palaeogeography, Palaeoclimatology, Palaeoecology, 2010)
UnivIS-Import:2015-03-09:Pub.2010.nat.dgeo.IGM.LG.paleoc

Paleoclimatic significance of Phanerozoic reefs - Kießling, Wolfgang (Geology, 2001)
UnivIS-Import:2015-03-09:Pub.2001.nat.dgeo.IGM.LP.paleoc

Paleoenvironmental significance of the monospecific biostromes in the Campanian-Maastrichtian Duwi Formation (Eastern Desert, Egypt) - Abdelhady, Ahmed Awad; Seuß, Barbara; Fürsich, Franz; Ali, Ahmed; Abdel-Racheem, Khalaf H.M.; Mohamed, Ramadan S.A. (Sedimentary Geology, 2020)

Paleoenvironment of the lower–middle cambrian evaporite series in the tarim basin and its impact on the organic matter enrichment of shallow water source rocks - Wei, Mingyang; Bao, Zhidong; Munnecke, Axel; Liu, Wei; Harrison, G. William M.; Zhang, Hua; Zhang, Demin; Li, Zongfeng; Xu, Xiting; Lu, Kai; Shen, Zheng (Minerals, 2021)
Just as in deep-water sedimentary environments, productive source rocks can be developed in an evaporitic platform, where claystones are interbedded with evaporites and carbonates. However, the impact of the paleoenvironment on the organic matter enrichment of shallow water source rocks in an evaporite series has not been well explored. In this study, two wells in the central uplift of the Tarim Basin were systematically sampled and analyzed for a basic geochemical study, including major elements, trace elements, and total organic carbon (TOC), to understand the relationship between TOC and the paleoenvironmental parameters, such as paleosalinity, redox, paleoclimate, paleo-seawater depth, and paleoproductivity. The results show that the Lower–Middle Cambrian mainly developed in a fluctuating salinity, weak anoxic to anoxic, continuous dry and hot, and proper shallow water environment. The interfingering section of evaporites, carbonates, and claystones of the Awatag Fm. have higher paleoproductivity and higher enrichment of organic matter. Paleosalinity, redox, paleoclimate, paleo-seawater depth, and paleoproductivity jointly control the organic matter enrichment of shallow water source rocks in the evaporite series. The degree of enrichment of organic matter in shallow water source rocks first increases and then decreases with the increase in paleosalinity. All the samples with high content of organic matter come from the shallower environment of the Awatag Fm.
CRIS-Team Scopus Importer:2021-07-02
Keywords: Evaporite series; Lower–Middle Cambrian; Paleoenvironment; Shallow water source rock; Tarim Basin

Paleogene initiation of the Western Branch of the East African Rift: The uplift history of the Rwenzori Mountains, Western Uganda - Jess, Scott; Köhn, Daniel; Fox, Matthew; Enkelmann, Eva; Sachau, Till; Aanyu, Kevin (Earth and Planetary Science Letters, 2020)
The two branches of the East African Rift System (EARS) are believed to have initiated diachronously. However, a growing body of work continues to suggest the onset of rifting in the Western Branch occurred in the Paleogene, coeval to the Eastern Branch. Due to a lack of pre-Miocene stratigraphy, attempts to resolve the geological history of the Western Branch must study the uplift and erosional histories of the modern rift topography. In this study, the rock uplift history of the Rwenzori Mountains, Western Uganda, is resolved to better our understanding of the tectonic history of the Western Branch of the EAR. Through the application of low-temperature thermochronology, χ-mapping and the modelling of river profiles, we show that rock uplift of the Rwenzori dates back to the Oligocene, with thermal history models suggesting uplift induced exhumation may date back as far as the Eocene. This provides tangible evidence that extension began in the region in the Paleogene, coeval with the Eastern Branch, and not the late Neogene. These results have broad implications for the tectonic evolution of the entire East African Rift System and suggest our current understanding of the region's rift history remains incomplete.
CRIS-Team Scopus Importer:2020-10-09
Keywords: East African Rift; rifting; river profile; thermochronology; uplift; Western Branch

Paleogene sedimentation and Eurekan deformation in the Stenkul Fiord area of southeastern Ellesmere Island (Canadian Arctic): Evidence for a polyphase history - von Gosen, Werner; Reinhardt, L.; Piepjohn, K.; Schmitz, M. D. (Circum-Arctic Structural Events: Tectonic Evolution of the Arctic Margins and Trans-Arctic Links with Adjacent Orogens, 2019)
Field studies and interpretative mapping of the area southeast of Stenkul Fiord (Ellesmere Island) revealed that the Margaret Formation clastic deposits consist of at least four sedimentary units (Units 1-4) separated by unconformities. Several centimeter-thick volcanic ash layers, identified within coal layers and preserved as crandallite group minerals (Ca-bearing goyazite), suggest an intense volcanic ash fall activity. Based on new U-Pb zircon dating (ID-TIMS) of three ash samples from one layer, this activity took place at 53.7 Ma in the early Eocene, i.e., within the period of the Eocene Thermal Maximum 2 hyperthermal. This age further suggests that the lowermost Unit 1 can be assigned to the late Paleocene-earliest Eocene, Unit 2 to the early Eocene, whereas Units 3 and 4 might be early to middle Eocene in age.
CRIS-Team WoS Importer:2019-11-15

Paleogeographic differences in temperature, water depth and conodont biofacies during the Late Devonian - Girard, Catherine; Cornée, Jean Jacques; Joachimski, Michael; Charruault, Anne Lise; Dufour, Anne Béatrice; Renaud, Sabrina (Palaeogeography, Palaeoclimatology, Palaeoecology, 2020)
Keywords: Oxygen isotopes; Palmatolepis; Famennian; Montagne Noire; Saxo-Thuringia; Sedimentary facies

Paleontological Museum of the University of Zürich: Exhibition Guide - de Baets, Kenneth; Brinkmann, Winand (Universität Zürich, 2012)

Paleoproterozoic (2.01 Ga) high-pressure granulite facies metamorphism and isothermal decompression of garnet-orthopyroxene-cordierite-orthoamphibole gneisses from the Central Zone of the Limpopo Belt in eastern Botswana - Brandt, Sönke; Klemd, Reiner; Ramos, Joshua; Drueppel, Kirsten; Xie, Hanqiang (Lithos, 2023)
The Central Zone (CZ) of the Limpopo Belt in southern Africa is a complex high-grade metamorphic zone that experienced a, in part, poorly understood poly-metamorphic history. To address this, we present petrological and SHRIMP U-Pb zircon age data for samples of a garnet-and orthopyroxene-bearing cordierite-orthoamphibole (Grt-Opx-Crd-Oam) paragneiss and a charnockite from the Baines Drift and the Phikwe Complexes, respectively. The two complexes are the north-western segments of the CZ in which the metamorphic history is poorly con-strained. High-pressure (HP) granulite facies metamorphism and a clockwise P-T evolution for the feldspar-free Grt-Opx-Crd-Oam gneiss of the Baines Drift Complex are constrained by the application of pseudosection modelling, Grt-Opx thermometry, and quartz in-garnet (QinG) elastic barometry. Our results show that the peak-metamorphic garnet-orthopyroxene-rutile-ilmenite-quartz assemblage formed at HP granulite facies conditions of >900 degrees C and 14 kbar, followed by significant decompression at granulite facies conditions, as recorded by conspicuous orthopyroxene-cordierite coronas around garnet. The widespread formation of orthoamphibole documents subsequent near-isobaric cooling into the amphibolite facies. Based on the formation of metamorphic zircon in the Grt-Opx-Crd-Oam gneiss we precisely determined an age of 2014 +/- 8 Ma for HP granulite facies metamorphism in the Baines Drift Complex. Rare detrital zircons document a possible deposition of the sedi-mentary protolith later than ca. 2.55 Ga, as part of a poorly documented Paleoproterozoic sediment sequence of the Central Zone. The clockwise P-T path and the age of HP granulite facies metamorphism in the Baines Drift Complex as constrained here, are consistent with constraints from 2.02 Ga metamorphism in the Beit Bridge Complex, the major segment of the CZ. The HP metamorphism is interpreted to reflect intracontinental Paleo-proterozoic transpressional orogeny within the consolidated Kaapvaal-Zimbabwe Craton. The association of lower-crustal HP granulite facies rocks of the Baines Drift Complex next to mid-crustal upper-amphibolite facies rocks of the Phikwe Complex may reflect progress of nappe tectonics during the Paleoproterozoic orogeny. SHRIMP U-Pb zircon data indicate that the granite protolith of the charnockite from the Phikwe Complex intruded at 2586 +/- 27 Ma, broadly synchronously with major granitoid emplacement in the Beit Bridge Com-plex. The similar P-T evolution of ca. 2.02 Ga metamorphism and comparable voluminous granite emplacement at ca. 2.6 Ga indicate a common evolution of the Baines Drift, the Phikwe and the Beit Bridge Complexes in the CZ of the Limpopo Belt.
CRIS-Team WoS Importer:2023-03-03

PaleoReef - a database on Phanerozoic reefs - Kießling, Wolfgang; et al. (SEPM Special Publication, 2002)
UnivIS-Import:2015-03-09:Pub.2002.nat.dgeo.IGM.LP.paleor_86

Paleoreef Maps: Evaluation of a comprehensive database of Phanerozoic reefs - Kießling, Wolfgang; et al. (Aapg Bulletin, 1999)
To get a better understanding of controls on reef development through time, we created a comprehensive database on Phanerozoic reefs. The database currently comprises 2470 reefs and contains information about geographic position/paleo-position, age, reef type, dimensions, environmental setting, paleontological and petrographical features, and reservoir quality of each buildup. Reef data were analyzed in two qualitatively different ways. The first type of analysis was by visualization of paleogeographic reef distribution maps. Five examples (Late Devonian, Early Permian, Late Triassic, Late Jurassic, middle Miocene) are presented to show the potential of paleoreef maps for paleogeographic and paleoclimatological reconstructions. The second type of analysis was a numerical processing of coded reef characteristics to realize major trends in reef evolution and properties of reef carbonates. The analysis of paleolatitudinal reef distributions through time shows pronounced asymmetries in some time slices, probably related to climatic asymmetries rather than controlled by plate tectonic evolution alone. The dominance of particular reef builders through time suggests that there are seven cycles of Phanerozoic reef development. First curves for the Phanerozoic distribution of bio-erosion in reefs, bathymetric setting, and debris potential of reefs are presented. The observed pattern in the temporal and spatial distribution of reefs with reservoir quality may assist in hydrocarbon exploration. Statistical tests on the dependencies of reefal reservoir quality suggest that large size, high debris potential, low paleolatitude, high amount of marine aragonite cement, and a platform/shelf edge setting favor reservoir quality. Reefal reservoirs are significantly enhanced in times of high evaporite sedimentation, elevated burial of organic carbon, low oceanic crust production, low atmospheric CO2 content, and cool paleoclimate, as well as when they are present in aragonite oceans.
UnivIS-Import:2015-03-05:Pub.1999.nat.dgeo.IGM.LP.paleor

Paleosol at the Archean-Proterozoic contact in NW India revisited: Evidence for oxidizing conditions during paleo-weathering? - Pandit, Manoj K.; de Wall, Helga; Chauhan, Narendra K. (Journal of Earth System Science, 2008)
Keywords: Aravalli craton; Archean-proterozoic contact; NW India; Oxidation; Paleosol

Paleosol occurrences along the Archean-Proterozoic contact in the Aravalli craton, NW India - de Wall, Helga; Pandit, Manoj K.; Chauhan, Narendra K. (Precambrian Research, 2012)
Keywords: Aravalli craton; Archean; NW India; Paleosol; Proterozoic contact

Paleotectonics of a complex Miocene half graben formed above a detachment fault: The Diligencia basin, Orocopia Mountains, southern California - Caracciolo, Luca; et al. (Lithosphere, 2014)
These palinspastic restorations result in a coherent set of SW-NE-trending normal faults, basins (including Diligenica basin) and antiformal structures consistent with NW-SE-directed crustal extension from 24 to 18 Ma, likely resulting from the unstable configuration of the Mendocino triple junction.

Paleotemperature record of the Middle Devonian Kačák Episode - Suttner, Thomas J; Kido, Erika; Joachimski, Michael; Vodrážková, Stanislava; Pondrelli, Monica; Corradini, Carlo; Corriga, Maria; Simonetto, Luca; Kubajko, Michal (Scientific Reports, 2021)
The Middle Devonian Epoch, 393–383 million years ago, is known for a peak in diversity and highest latitudinal distribution of coral and stromatoporoid reefs. About 388 million years ago, during the late Eifelian and earliest Givetian, climax conditions were interrupted by the polyphased Kačák Episode, a short-lived period of marine dys-/anoxia associated with climate warming that lasted less than 500 kyr. Reconstruction of the seawater temperature contributes to a better understanding of the climate conditions marine biota were exposed to during the event interval. To date, conodont apatite-based paleotemperatures across the Eifelian–Givetian boundary interval have been published from Belarus, France, Germany and North America (10–36° S paleolatitude). Here we provide new δ18Oapatite data from the Carnic Alps (Austria, Italy) and the Prague Synform (Czech Republic). For better approximation of the paleotemperature record across the Kačák Episode, a latitude-dependent correction for Middle Devonian seawater δ18O is applied. Because δ18Oapatite data from shallow marine sections are influenced by regional salinity variations, calculated mean sea surface temperatures (SST) are restricted to more open marine settings (22–34° S paleolatitude). Water temperatures reach 34 °C in the Prague Synform and 33 °C in the Carnic Alps and suggest that SSTs of the southern hemisphere low latitudes were 6 °C higher than previously assumed for this time interval.

Paleotethys seawater temperature rise and an intensified hydrological cycle following the end-Permian mass extinction. - Schobben, Martin; Joachimski, Michael; Korn, Dieter; Leda, Lucyna; Korte, Christoph (Gondwana Research, 2014)
UnivIS-Import:2015-03-09:Pub.2014.nat.dgeo.IGM.LG.paleot

Paleozoic cold seep carbonates from Europe and North Africa - an integrated isotopic and geochemical approach. - Buggisch, Werner; Krumm, Stefan (Facies, 2005)
UnivIS-Import:2015-03-09:Pub.2005.nat.dgeo.IGM.LG.paleoz

Paleozoic ophiolitic mélanges from the South Tianshan Orogen, NW China: Geological, geochemical and geochronological implications for the geodynamic setting. - Jiang, Tuo; Gao, Jun; Klemd, Reiner; Qian, Qing; Zhang, Xi; Xiong, Xianming; Wang, Xinshui; Tan, Zhou; Chen, Bangxue (Tectonophysics, 2014)
Two ophiolitic mélange belts, the South Central Tianshan Ophiolite Belt (SCTOB) and the South Tianshan Ophiolite Belt (STOB), extend almost parallel to the Chinese South Tianshan Orogen - the southernmost part of the Central Asian Orogenic Belt (CAOB). The SCTOB occurs interlayered in the South Central Tianshan Suture Zone, the STOB as exotic blocks in Palaeozoic sedimentary strata. However, their tectonic settings and ages, which are crucial for understanding the formation of the CAOB, are still controversially discussed. In order to better understand these geological problems, geological, geochemical and geochronological investigations were conducted on the Guluogou (SCTOB) as well as on the Serikeyayilake and Aertengkesi ophiolitic mélanges (STOB). The ophiolitic suites are composed of basalts, gabbros and mantle peridotites. Laser ablation ICP-MS (LA-ICP-MS) U-Pb zircon ages of 334. ±. 5. Ma and 332. ±. 7. Ma were obtained for the Guluogou gabbros, while SHRIMP U-Pb zircon ages of 423. ±. 10. Ma and 423. ±. 4. Ma were determined for the Serikeyayilake and Aertengkesi gabbros. The mineral composition of the mantle peridotites and the geochemical characteristics of the basalts suggest a mid-ocean ridge (MOR) type affinity for the Guluogou ophiolite and a SSZ type affinity for the Serikeyayilake and Aertengkesi ophiolites. The present data, combined with previously published results, indicate that the STOB may have been derived from a forearc rifting setting that existed during the early Silurian to the early Carboniferous (ca. 439-356. Ma), whereas the SCTOB may represent fragments of a normal wide ocean that lasted to the early Carboniferous (ca. 332. Ma). © 2013 Elsevier B.V.
UnivIS-Import:2015-03-09:Pub.2014.nat.dgeo.IGM.c3geoc.paleoz
Keywords: Geochemistry; Geochronology; Ophiolitic mélange; Palaeozoic tectonic evolution; South Tianshan Orogen

Paleozoic origins of cheilostome bryozoans and their parental care inferred by a new genome-skimmed phylogeny - Orr, Russell J.S.; Martino, Emanuela Di; Ramsfjell, Mali H.; Gordon, Dennis P.; Berning, Björn; Chowdhury, Ismael; Craig, Sean; Cumming, Robyn L.; Figuerola, Blanca; Florence, Wayne; Harmelin, Jean Georges; Hirose, Masato; et al. (Science Advances, 2022)
Phylogenetic relationships and the timing of evolutionary events are essential for understanding evolution on longer time scales. Cheilostome bryozoans are a group of ubiquitous, species-rich, marine colonial organisms with an excellent fossil record but lack phylogenetic relationships inferred from molecular data. We present genome-skimmed data for 395 cheilostomes and combine these with 315 published sequences to infer relationships and the timing of key events among c. 500 cheilostome species. We find that named cheilostome genera and species are phylogenetically coherent, rendering fossil or contemporary specimens readily delimited using only skeletal morphology. Our phylogeny shows that parental care in the form of brooding evolved several times independently but was never lost in cheilostomes. Our fossil calibration, robust to varied assumptions, indicates that the cheilostome lineage and parental care therein could have Paleozoic origins, much older than the first known fossil record of cheilostomes in the Late Jurassic.
CRIS-Team Scopus Importer:2022-04-15

Paleozoic plate kinematics during the Pannotia – Pangea supercontinent cycle - Kroner, Uwe; Stephan, Tobias; Romer, Rolf L.; Roscher, Marco (Geological Society Special Publication, 2020)
Three supercontinents have been suggested to have existed in the last 1 Gyr. The supercontinent status of Pangea and Rodinia is undisputed. In contrast, there is an ongoing controversy whether Pannotia existed at all. Here we test the hypothesis of a Pannotian supercontinent. Using first order tectonic constraints we reconstruct the Paleozoic kinematics of major continents relative to the East European Craton. Back-rotation from Pangea results in a supercontinent constellation in the early Paleozoic corroborating the existence of Pannotia. The presented model explains first order constraints for both the breakup of Pannotia and the subsequent assembly of Pangea. The breakup of Pannotia comprises (i) the early Paleozoic opening of Iapetus II and in turn the Rheic Ocean concomitant with the subduction of the Neo-Proterozoic Iapetus I Ocean, and (ii) the coeval opening of the Paleo-Arctic Ocean, that separated Siberia from the North American Craton. The subsequent convergence of the North American Craton, Avalonia, Gondwana, and Siberia with the East European Craton resulted in Paleozoic collisional orogenies at different plate boundary zones. The existence of Rodinia, Pannotia, and Pangea as pari passu supercontinents implicates two complete supercontinent cycles from Rodinia to Pannotia and from Pannotia to Pangea in the Neoproterozoic and the Paleozoic, respectively.<br

Paleozoic Subduction-Accretion in the Southern Central Asian Orogenic Belt: Insights From the Wuwamen Accretionary Complex of the Chinese South Tianshan - Wang, Xin Shui; Klemd, Reiner; Li, Ji Lei; Gao, Jun; Jiang, Tuo; Zong, Ke Qing; Xue, Sheng Chao (Tectonics, 2022)
Accretionary complexes are a major component of the Central Asian Orogenic Belt (CAOB) and are important for understanding its architecture and evolution. The Wuwamen accretionary complex in the Chinese South Tianshan contains a tectonic mélange that witnessed the dynamic evolution from early accretion to final collision of the western CAOB with the Tarim Craton. We present geochronological and geochemical studies on the exotic blocks and metasedimentary matrix of the tectonic mélange in order to refine the subduction-accretion processes in the CAOB. Geochemical and age data reveal that the exotic blocks are of diverse origins, including arc-related granite and arc basalt-like garnet amphibolite from the upper plate, and MORB-like amphibolite from the subducting slab. The blocks underwent subduction-related high-temperature metamorphism between ca. 397 and 340 Ma. Detrital zircons in the metasedimentary matrix are dominated by Paleozoic ages corresponding to the continuous arc magmatism in the Yili-Central Tianshan Block. This finding is consistent with the accretion of the Wuwamen complex on the southern margin of the Yili-Central Tianshan Block above the northward subducting South Tianshan Ocean. A ca. 307 Ma post-accretion granite dyke intruded the Wuwamen complex, thereby providing a minimum age limit for its terminal accretion. In conjunction with subduction-related magmatism, metamorphism, and sedimentation, the accretion of the Wuwamen accretionary complex was active during the early Ordovician to the late Carboniferous. Our new results reiterate that long-lasting accretionary processes in the South Tianshan Ocean and the terminal collision due to its closure exert a major control on the architecture of the southwestern CAOB.
CRIS-Team Scopus Importer:2022-03-04
Keywords: accretionary complex; Central Asian Orogenic Belt; metamorphism; subduction; Tianshan; zircon U–Pb

Pan-African eclogite facies metamorphism of ultramafic rocks in the Shackleton Range, Antarctica - Schmädicke, Esther; et al. (Journal of Metamorphic Geology, 2009)
Keywords: Antarctica; Pan-African orogeny; Eclogite facies; Sm-Nd age dating; Shackleton Range

Pan-African overprint on Eburnian granitoids at the northern boundary of the West African Craton, Zenaga Inlier, central Anti-Atlas, Morocco - de Wall, Helga; et al. (Journal of African Earth Sciences, 2001)

Pan-European planning tool for sustainable energy systems – ThermoMap project - Bertermann, David; Jocic, Nikola; Müller, Johannes (Book of Abstracts / 8th International Urban Geographies of Post-communist States Conference, 2019)

Parallel evolution controlled by adaptation and covariation in ammonoid cephalopods - Monnet, Claude; de Baets, Kenneth; Klug, Christian (BMC Evolutionary Biology, 2011)
Conclusions: The morphological evolution of these two Devonian ammonoid lineages follows a near parallel evolutionary path for some important shell characters during several million years and through their phylogeny. Evolution of some traits (involution, umbilical lid) appears to be mainly driven by adaptation to improve the hydrodynamic properties of the shell, whereas other characters (sutural complexity) evolved due to covariation with features that play a central role in the morphogenesis of mollusc shells. This example provides evidence that parallel evolution can be driven simultaneously by different factors such as covariation (constructional constraints) and adaptation (natural selection).

Parasites of Ammonoids - de Baets, Kenneth; Keupp, Helmut; Klug, Christian (Ammonoid Paleobiology: From anatomy to Ecology, 2015)

Past and future decline of tropical pelagic biodiversity - Yasuhara, Moriaki; Wei, Chih Lin; Kucera, Michal; Costello, Mark J.; Tittensor, Derek P.; Kießling, Wolfgang; Bonebrake, Timothy C.; Tabor, Clay R.; Feng, Ran; Baselga, Andrés; Kretschmer, Kerstin; Kusumoto, Buntarou; et al. (Proceedings of the National Academy of Sciences of the United States of America, 2020)
A major research question concerning global pelagic biodiversity remains unanswered: when did the apparent tropical biodiversity depression (i.e., bimodality of latitudinal diversity gradient [LDG]) begin? The bimodal LDG may be a consequence of recent ocean warming or of deep-time evolutionary speciation and extinction processes. Using rich fossil datasets of planktonic foraminifers, we show here that a unimodal (or only weakly bimodal) diversity gradient, with a plateau in the tropics, occurred during the last ice age and has since then developed into a bimodal gradient through species distribution shifts driven by postglacial ocean warming. The bimodal LDG likely emerged before the Anthropocene and industrialization, and perhaps ∼15,000 y ago, indicating a strong environmental control of tropical diversity even before the start of anthropogenic warming. However, our model projections suggest that future anthropogenic warming further diminishes tropical pelagic diversity to a level not seen in millions of years.
CRIS-Team Scopus Importer:2020-06-16
Keywords: Climate change; Last Glacial Maximum; Latitudinal diversity gradients; Planktonic foraminifera; Temperature

Patterns and drivers of phytodiversity in steppe grasslands of Central Podolia (Ukraine) - Kuzemko, Anna A.; Steinbauer, Manuel; Becker, Thomas; Didukh, Yakiv P.; Dolnik, Christian; Jeschke, Michael; Naqinezhad, Alireza; Ugurlu, Emin; Vassilev, Kiril; Dengler, Juergen (Biodiversity and Conservation, 2016)
We asked: (i) Which environmental factors determine the level of α-diversity at several scales and β-diversity in steppic grasslands? (ii) How do the effects of environmental factors on α- and β-diversity vary between the different taxonomic groups (vascular plants, bryophytes, lichens)? We sampled nested-plot series ranging from 0.0001 to 100 m2 and additional 10-m2 plots, covering different vegetation types and management regimes in steppes and semi-natural dry grasslands of Central Podolia (Ukraine). We recorded all terricolous taxa and used topographic, soil, land-use and climatic variables as predictors. Richness-environment relationships at different scales and across taxonomic groups were assessed with multimodel inference. We also fitted power-law species-area relationships, using the exponent (z value) as a measure of β-diversity. In general, the richness values in the study region were intermediate compared to those known from similar grasslands throughout the Palaearctic, but for 1 cm2 we found seven species of vascular plants, a new world record. Heat index was the most important factor for vascular plants and bryophytes (negative relation), while lichen diversity depended mainly on stone and rock cover (positive). The explanatory power of climate-related variables increased with increasing grain size, while anthropogenic burning was the most important factor for richness patterns at the finest grain sizes (positive effect). The z values showed more variation at the finest grain sizes, but no significant differences in their mean between scales. The results highlight the importance of integrating scale into ecological analyses and nature conservation assessments in order to understand and manage biological diversity in steppe ecosystems.
Keywords: Biodiversity; Bryophyte; Lichen; Scale dependence; Species richness; Species-area relationship

Patterns and processes of ancient reef crises - Kießling, Wolfgang (The Paleontological Society Papers, 2011)
UnivIS-Import:2015-03-09:Pub.2011.nat.dgeo.IGM.LP.patter

Patterns of island treeline elevation - a global perspective - Irl, Severin D. H.; Anthelme, Fabien; Harter, David E. V.; Jentsch, Anke; Lotter, Elisabeth; Steinbauer, Manuel; Beierkuhnlein, Carl (Ecography, 2016)
Treeline research has strongly focused on mountain systems on the mainland. However, island treelines offer the opportunity to contribute to the global framework on treeline elevation due to their island-specific attributes such as isolation, small area, low species richness and relative youth. We hypothesize that, similar to the mainland, latitude-driven temperature variation is the most important determinant of island treeline elevation on a global scale. To test this hypothesis, we compared mainland with island treeline elevations. Then we focused 1) on the global effects of latitude, 2) on the regional effects of island type (continental vs oceanic islands) and 3) the local effects of several specific island characteristics (age, area, maximum island elevation, isolation and plant species richness). We collected a global dataset of islands (n = 86) by applying a stratified design using GoogleEarth and the Global Island Database. For each island we extracted data on latitude and local characteristics. Treeline elevation decreased from the mainland through continental to oceanic islands. Island treeline elevation followed a hump-shaped latitudinal distribution, which is fundamentally different from the mainland double-hump. Higher maximum island elevation generated higher treeline elevation and was found the best single predictor of island treeline elevation, even better than latitude. Lower island treeline elevation may be the result of a low mass elevation effect (MEE) influencing island climates and an increasingly impoverished species pool but also trade wind inversion-associated aridity. The maximum island elevation effect possibly results from an increasing mass elevation effect (MEE) with increasing island elevation but also range shifts during climatic fluctuations and the summit syndrome (i.e. high wind speeds and poor soils in peak regions). Investigating islands in treeline research has enabled disentangling the global effect of latitude from regional and local effects and, at least for islands, a comprehensive quantification of the MEE.

Patterns of Phanerozoic carbonate platform sedimentation - Kießling, Wolfgang; et al. (Lethaia, 2003)
Carbonate platforms changed substantially in spatial extent, geometry, composition and palaeogeographical distribution through the Phanerozoic. Although reef construction and carbonate platform development are intimately linked today, this was not the case for most of the Phanerozoic. Carbonate production by non-enzymatic precipitation and non-reefal organisms is mostly responsible for this decoupling. Non-reefal carbonate production was especially prolific during times of depressed reef growth, balancing losses in reef carbonate production. Palaeogeographical distribution and spatial extent of Phanerozoic carbonate platforms exhibit trends related to continental drift, evolutionary patterns within carbonate platform biotas, climatic change and, possibly, variations in ocean chemistry. Continental drift moved large Palaeozoic tropical shelf areas into higher latitudes, thereby reducing the potential size of tropical platforms. However, the combined global size of carbonate platforms shows no significant decline through the Phanerozoic, suggesting that availability of tropical shelf areas was not a major control of platform area. This is explained by the limited platform coverage of low-latitude shelves (42% maximum) and occasional high-latitude excursions of platform carbonates. We speculate that reduced tropical shelf area in the icehouse tropics forced the migration of the many carbonate-secreting organisms into higher latitudes and, where terrigenous input was sufficiently low, extensive carbonate platform could develop.
UnivIS-Import:2015-03-09:Pub.2003.nat.dgeo.IGM.LP.patter
Keywords: Carbonate platforms; Palaeoclimate; Palaeogeography; Phanerozoic; Reefs

Patterns of Phanerozoic reef crises - Flügel, Erik; Kießling, Wolfgang (Phanerozoic reef patterns, 2002)
UnivIS-Import:2015-04-20:Pub.2002.nat.dgeo.IGM.LP.patter

Pelagic palaeoecology: the importance of recent constraints on ammonoid palaeobiology and life history - Ritterbush, Kathleen A.; Hoffmann, René; de Baets, Kenneth; Lukeneder, Alexander (Journal of Zoology, 2014)
A review of fossil evidence supports a pelagic mode of life (in the water column) of ammonoids, but they may have spent their life close to the seabottom (demersal), planktonically, or nektonically depending upon the ontogenetic stage and taxon. There are good indications for a planktonic mode of life of ammonoid hatchlings, but a broad range of reproductive strategies might have existed (egg-laying, fecundity). Isotope and biogeographical studies indicate that some forms migrated or swam for considerable distances, whereas others may have been primarily transported by oceanic currents during early and/or late ontogeny. Diverse ammonoid habitats are also supported by evidence from predator-prey relationships derived from characteristic injuries and exceptional fossil finds, which indicate chiefly predatory or scavenging lifestyles. Sublethal injuries preserved in some ammonoid shells, as well as rare stomach and coprolite contents, provide evidence of predation by other cephalopods, arthropods and various jawed vertebrates. Various lines of evidence suggest that different groups of ammonoids had quite different ecologies, but shell shape alone can only give upper constraints on ammonoid capabilities, a matter that needs to be considered when interpreting their diversity and evolutionary history.
Keywords: predator-prey relationships; habitat; anatomy; reproductive strategy; isotope analysis; palaeoecology

Pendant bioconstructions cemented by microbial carbonate in submerged marine caves (Holocene, SE Sicily) - Adriano, Guido; Heindel, Katrin; Birgel, Daniel; Antonietta, Rosso; Mastandrea, Adelaide; Sanfilippo, R.; Russo, Franco; Peckmann, Jörn (Palaeogeography, Palaeoclimatology, Palaeoecology, 2013)
Keywords: Autochthonous micrite; Biostalactites; Serpulids; Sicily; Submerged caves; Sulfate-reducing bacteria

Pennsylvanian Bryozoans of Exceptional Preservation from the Buckhorn Asphalt Quarry, Oklahoma - Seuß, Barbara; Taylor, Paul; Ernst, Andrej; Nützel, Alexander (GSA Annual Meeting, 2016)
The Pennsylvanian (Desmoinesian–Virgilian) Buckhorn Asphalt Quarry (Boggy Formation, Deese Group) in Oklahoma, USA is well known for its exceptional preservation of a diverse marine invertebrate fauna. This includes preservation of original shell material, microscopic characters on shells, or color patterns. Preservation is exceptionally because of early impregnation with hydrocarbons that soaked sediments and fossils. Results from the latest study and the first focusing exclusively on the Buckhorn bryozoans are presented. Nine genera and species are recognized, two of them are new (Stenophragmidium buckhornensis and Streblotrypa (S.) heltzelae) and two genera (Shishoviclema, Shulgapora) are identified in North American strata for the first time. Some skeletal characteristics that are usually lost during diagenesis are uniquely preserved or seen for the first time in Paleozoic bryozoans. These include small to large (5-50 µm in diameter) node-like surface expressions of styles that most likely strengthened the skeleton or were for attachment of the soft tissue rather than defense. ‘Nanoperforations’ observed in S. (S.) heltzelae, S. buckhornensis and Rhombocladia delicatula are tiny holes with a diameter of only 0.5 µm countersunk (bevelled) into the laminated skeletal walls. Such structures are unknown from other bryozoans (recent and fossil) and their genesis – produced by small-sized symbionts (bacteria?), by microendoliths or by the bryozoans themselves? – is unclear. The most likely hypothesis is that they are due to symbionts that lived embedded in the growing walls of the bryozoan zooids. In fractured branches of S. (S.) heltzelae, closely spaced ‘granule’ bands (diameter of granules approximately 6 µm) on the walls of the autozooids were found. Again, such structures have not been observed elsewhere and their origin and function are enigmatic. Mural spines (of varied size and morphology depending on the genus) are reported from R. delicata and Stenoporella sp. Spinose hemiphragms, with spines of 3-30 µm in length, are new features of unknown function found in some trepostomes. Finally, a transverse fibrous fabric found in the fenestrate Septopora blanda is reminiscent of a fabric common in post-Paleozoic cyclostome bryozoans but hitherto not reported in palaeostomates from the Paleozoi

Pennsylvanian in North Central Texas, USA - The Finis Shale - Seuß, Barbara; Mapes, Royal H. (IGCP 596 Climate Change and Biodiversity Patterns in the Mid-Palaeozoic, 2016)

Pennsylvanian of Southern Oklahoma (Upper Carboniferous, USA) - The Buckhorn Asphalt Quarry - Seuß, Barbara (IGCP 596 Climate Change and Biodiversity Patterns in the Mid-Palaeozoic, 2016)
UnivIS-Import:2015-03-09:Pub.2012.nat.dgeo.IGM.LP.oxygen
Keywords: Cameral deposits; Diagenetic end-members; Oxygen isotopes; Pennsylvanian; Stable carbon isotopes; XRD-GADDS

Performance of machine-learning approaches in identifying ammonoid species based on conch properties - de Baets, Kenneth (2021)
There are less and less experts on taxonomy of particular groups particularly among early career paleontologists and (paleo)biologists – this also includes ammonoid cephalopods. Techniques cannot replace this taxonomic expertise (Engel et al. 2021) but machine learning approaches can make taxonomy more efficient, reproducible as well as passing it over more sustainable. Initially ammonoid taxonomy was a black box with small differences sometimes sufficient to erect different species as well as really idiosyncratic groupings of superficially similar specimens (see De Baets et al. 2015 for a review). In the meantime, scientists have embraced more quantitative assessments of conch shape and morphology more generally (see Klug et al. 2015 for a more recent review). The approaches still rely on important but time-intensive collection work and seeing through daisy chains of more or less accessible papers and monographs without really knowing how these approaches perform (other than expert opinion). In addition, younger scientists are usually trained by more experienced scientists, but this practice is becoming more and more difficult which makes it difficult to resolve the taxonomic gap. This relates to the fact that less and less experienced researchers with this kind of expertise get employed as well as graduate students or postdocs choosing different research or job avenues after their initial training effectively leading to a leaky pipeline and taxonomic impediment. Robust taxonomy and stratigraphy is the basis for all other studies we do as paleontologists/paleobiologists so Foxon (2021) represents the first step to use supervised and unsupervised machine-learning approaches and test their efficiency on ammonoid conch properties. This pilot study demonstrates that machine learning approaches can be reasonably accurate (60-70%) in identifying ammonoid species (Foxon, 2021) – at least similar to that in other mollusk taxa (e.g., Klinkenbuß et al. 2020) - and might also be interesting to assist in cases where more traditional methods are not feasible. Novel approaches might even allow to further approve the accuracy as has been demonstrated for other research objects like pollen (Romero et al. 2020). Further applying of machine learning approaches on larger datasets and additional morphological features (e.g., suture line) are now necessary in order to test and improve the robustness of these approaches for ammonoids as well as test their performance more broadly within paleontology.<br

Permian age of orogenic thickening and crustal melting in the Garm Block, South Tien Shan, Tajikistan - Konopelko, Dmitry; Klemd, Reiner; Mamadjanov, Y.; Hegner, E.; Knorsch, Manuel; Fidaev, D.; Kern, Matti; Sergeev, S. (Journal of Asian Earth Sciences, 2015)
In this paper we present new data for the metamorphic Garm Block (150 × 40 km) that was traditionally shown on regional maps as fragment of a Precambrian basement. The Garm Block comprises migmatized gneisses and schists for some of which peak metamorphic conditions (600–660 °C at 7–9 kbar) characteristic for medium P/T series metamorphic belts were determined. U–Pb ages of overgrown rims of zircon grains and newly grown magmatic zircon grains from four migmatitic samples indicate that melting occurred during peak metamorphic conditions between 299 and 290 Ma. Thus the Garm Block is the first Early Permian regional metamorphic terrane established in the southern part of the Central Asian Orogenic Belt. A crosscutting granite intrusion yields a concordia age of 290 Ma identical to the age of metamorphism and similar to ages of post-collisional intrusions elsewhere in the Tien Shan. Detrital zircon grains from the Garm samples yield an age spectrum with major peaks at 700–550 Ma and 1150–700 Ma, and smaller ones at ca. 2.7–2.4 Ga and 3.5–3.3 Ga. The youngest grains define an Ediacarian maximum depositional age of the sedimentary protoliths. The presence of Grenvillian ages of 1150–800 Ma, which are characteristic for the Tarim Craton, and the lack of ca. 1.6–1.2 Ga ages, characteristic for the Northern Tien Shan, suggest an origin of the Precambrian zircon grains from southern continental blocks similar to the Tarim Craton. Six granitoid samples yield negative εNd values of −10.6 to −3.7 consistent with the reworking of crustal material with 1.8–1.1 Ga average crustal residence times and the formation of the South Tien Shan belt on a continental basement with Paleoproterozoic or older crust. The Garm Block formed as a consequence of lithospheric thickening during the Late Carboniferous collision of two continental blocks that created the South Tien Shan fold belt. Lateral crustal melt flow coupled with extension may have resulted in exhumation of the Permian metamorphic rocks.<br
Keywords: Tajikistan; South Tien Shan (Tianshan); Garm Block; Permian metamorphism; Zircon ages; Nd isotopes

Permian (Artinskian to Wuchapingian) conodont biostratigraphy in the Tieqiao section, Laibin area, South China - Sun, Yadong; Liu, X. T.; Yan, J. X.; Li, B.; Chen, B.; Bond, D. P G; Wignall, P. B.; Wang, X.; Lai, X. L.; Joachimski, Michael (Palaeogeography, Palaeoclimatology, Palaeoecology, 2017)
Permian strata from the Tieqiao section (Jiangnan Basin, South China) contain several distinctive conodont assemblages. Early Permian (Cisuralian) assemblages are dominated by the genera Sweetognathus, Pseudosweetognathus and Hindeodus with rare Neostreptognathodus and Gullodus. Gondolellids are absent until the end of the Kungurian stage—in contrast to many parts of the world where gondolellids and Neostreptognathodus are the dominant Kungurian conodonts. A conodont changeover is seen at Tieqiao and coincided with a rise of sea level in the late Kungurian to the early Roadian: the previously dominant sweetognathids were replaced by mesogondolellids. The Middle and Late Permian (Guadalupian and Lopingian Series) witnessed dominance of gondolellids (Jinogondolella and Clarkina), the common presence of Hindeodus and decimation of Sweetognathus. Twenty main and seven subordinate conodont zones are recognised at Tieqiao, spanning the lower Artinskian to the middle Wuchiapingian Stage. The main (first appearance datum) zones are, in ascending order by stage: the Sweetognathus (Sw.) whitei, Sw. toriyamai, and Sw. asymmetrica n. sp. Zones for the Artinskian; the Neostreptognathodus prayi, Sw. guizhouensis, Sw. iranicus, Sw. adjunctus, Sw. subsymmeticus and Sw. hanzhongensis Zones for the Kungurian; the Jinogondolella (J.) nankingensis Zone for the Roadian; the J. aserrata Zone for the Wordian; the J. postserrata, J. shannoni, J. altudaensis, J. prexuanhanensis, J. xuanhanensis, J. granti and Clarkina (C.) hongshuiensis Zones for the Capitanian and the C. postbitteri Zone and C. transcaucasica Zone for the base and middle of the Wuchiapingian. The subordinate (interval) zones are the Pseudosweetognathus (Ps.) costatus, Ps. monocornus, Hindeodus (H.) gulloides, Pseudohindeodus ramovsi, Gullodus (G.) sicilianus, G. duani and H. excavates Zones. In addition, three new species, Gullodus tieqiaoensis n. sp., Pseudohindeodus elliptica n. sp. and Sweetognathus asymmetrica n. sp. are described. Age assignments for less common species (e.g., G. duani, H. catalanoi and Pseudosweetognathus monocornus etc.) are reassessed based on a rich conodont collection.
Keywords: Biostratigraphy; Cisuralian; Conodont; Guadalupian; Kungurian; South China

Permian - McCann, Tom; Kiersnowski, Hubert; Krainer, Karl; Vozárová, Anna; Peryt, Tadeuz; Oplustil, Stanislav; Stollhofen, Harald; Schneider, Jörg W.; Wetzel, Andreas; Boulvain, Frédéric; Dusar, Michiel; Török, Ákos; et al. (The Geology of Central Europe, Vol. 1: Precambrian and Palaeozoic., 2008)
UnivIS-Import:2015-04-20:Pub.2008.nat.dgeo.IGM.LG.permia_7

Permo-Carboniferous carbon isotope stratigraphy of sections from China (Yangtze platform), USA (Kansas) and Russia (Moscow Basin and Urals). - Buggisch, Werner; Wang, Xiang-Dong; Alekseev, Alexander S.; Joachimski, Michael (Palaeogeography, Palaeoclimatology, Palaeoecology, 2011)
UnivIS-Import:2015-03-09:Pub.2011.nat.dgeo.IGM.LG.permoc

Persistent ecological shifts in marine molluscan assemblages across the end-Cretaceous mass extinction - Kießling, Wolfgang; Aberhan, Martin; Kiessling, Wolfgang (Proceedings of the National Academy of Sciences of the United States of America, 2015)
Contemporary biodiversity loss and population declines threaten to push the biosphere toward a tipping point with irreversible effects on ecosystem composition and function. As a potential example of a global-scale regime shift in the geological past, we assessed ecological changes across the end-Cretaceous mass extinction based on molluscan assemblages at four well-studied sites. By contrasting preextinction and postextinction rank abundance and numerical abundance in 19 molluscan modes of life-each defined as a unique combination of mobility level, feeding mode, and position relative to the substrate-we find distinct shifts in ecospace utilization, which significantly exceed predictions from null models. The magnitude of change in functional traits relative to normal temporal fluctuations at far-flung sites indicates that molluscan assemblages shifted to differently structured systems and faunal response was global. The strengths of temporal ecological shifts, however, are mostly within the range of preextinction site-to-site variability, demonstrating that local ecological turnover was similar to geographic variation over a broad latitudinal range. In conjunction with varied site-specific temporal patterns of individual modes of life, these spatial and temporal heterogeneities argue against a concerted phase shift of molluscan assemblages from one well-defined regime to another. At a broader ecological level, by contrast, congruent tendencies emerge and suggest deterministic processes. These patterns comprise the well-known increase of deposit-feeding mollusks in postextinction assemblages and increases in predators and predator-resistant modes of life, i.e., those characterized by elevated mobility and infaunal life habits.
UnivIS-Import:2015-07-08:Pub.2015.nat.dgeo.IGM.LP.persis
Keywords: Ecospace; End-Cretaceous mass extinction; Functional groups; Mollusks; Regime shift

Perturbations in the carbon cycle during the carnian humid episode: Carbonate carbon isotope records from southwestern China and Northern Oman - Sun, Yadong; Richoz, S.; Krystyn, L.; Zhang, Z. T.; Joachimski, Michael (Journal of the Geological Society, 2019)

Petrogenesis of anorthosites throughout Earth history - Sotiriou, Paul; Polat, Ali (Precambrian Research, 2023)
Petrologists are still trying to solve the ‘anorthosite problem’, which was first identified by N.L. Bowen in 1917 and revolves around the uncertainty surrounding the petrogenesis, tectonic setting, emplacement, and parental magma compositions of anorthosites. Anorthosites are volumetrically minor to significant, occur worldwide and have implications for upper mantle depletion, oceanic and continental crust growth and evolution, the longevity of plate tectonic processes on Earth, and magma chamber processes. Anorthosites have formed throughout Earth history from 3950 Ma to the Present. Anorthosites are far more common than previously thought as there are at least 2,126 known preserved anorthosite occurrences worldwide. Anorthosites are closely associated with gabbros and leucogabbros and spatially associated with pillow-bearing mafic volcanic rocks in ophiolites and layered intrusions, except for Proterozoic anorthosites that are closely associated with intermediate to felsic intrusives. Archean anorthosites often contain near-spherical calcic plagioclase (An70-100) megacrysts up to 45 cm in diameter and magmatic amphibole, Proterozoic anorthosites have elongate (≤1 m) andesine (An30-50) megacrysts, and Phanerozoic anorthosites contain calcic plagioclase (An70-100). The plagioclase anorthite contents of anorthosites vary throughout Earth history, troughing in the Proterozoic. This corroborates the whole-rock geochemistry of anorthosites, which also varies throughout Earth history and indicates that crustal contamination played a significant role in the petrogenesis of Proterozoic anorthosites. Relatively high mantle heat flow and partial melting and the thermal blanketing of Proterozoic supercontinents led to the generation of large anorthosite massifs. Archean, Proterozoic and Phanerozoic anorthosites crystallised from tholeiitic or high-Al tholeiitic parental magmas that were derived from depleted mantle sources and significantly assimilated continental crust in the Proterozoic. Archean anorthosites crystallised from hydrous Ca- and Al-rich tholeiitic parental magmas derived by partial melting of hydrated sub-arc depleted mantle sources. Anorthosites have predominantly formed in subduction-related settings throughout Earth history, indicating that plate tectonic processes have operated since the beginning of the Eoarchean. The proportion of subduction-related anorthosites significantly declined in the Proterozoic following supercontinent amalgamation. Calcic megacrystic anorthosites and massif-type anorthosites are largely restricted to the Archean and Proterozoic, respectively, yet they occur throughout Earth history. The petrogenesis of anorthosites reflects the secular evolution of the Earth.
CRIS-Team Scopus Importer:2022-12-23
Keywords: Anorthosites; Archean; Earth history; Phanerozoic; Proterozoic; Secular evolution

Petrogenesis of boninitic lavas from the Troodos Ophiolite, and comparison with Izu–Bonin–Mariana fore-arc crust - Wölki, Dominic; Regelous, Marcel; Haase, Karsten; Romer, René; Beier, Christoph (Earth and Planetary Science Letters, 2018)
Supra-subduction zone (SSZ) ophiolites such as the Troodos Ophiolite of Cyprus are thought to have formed at spreading centres close to subduction zones. Similarities in the geochemistry between lavas from SSZ ophiolites and fore-arc lavas from active subduction zones, and the presence of boninites in both, haveled to the suggestion that SSZ ophiolites represent fragments of fore-arc crust and mantle, formed during subduction initiation. Here we present major and trace element and Sr, Nd and Pb isotope data for fresh volcanic glasses from a section through the lava pile on the southern margin of the Troodos Ophiolite, and compare these to lavas from the Izu–Bonin–Mariana fore-arc. In Troodos, boninites and tholeiitic basalts are interbedded and were derived from a highly depleted mantle source that was later enriched by both fluids and melts derived largely from subducted sediment, before melting beneath the spreading axis. Troodos boninites differ from Izu–Bonin–Mariana boninites by their greater source depletion, enrichment in Nb by small degree melts, and lack of Zr enrichment relative to Sm. Together with the lack of fore-arc basalts in Troodos, our data imply that the Troodos Ophiolite was formed in a fore-arc location at a back-arc spreading centre that propagated into arc crust. The Troodos Ophiolite was thus not formed during subduction initiation and thus may not be used as analogue for the formation of fore-arc basalts.<br

Petrogenesis of tertiary hornblende-bearing lavas in the rhön, germany - Mayer, Bernhard; Jung, Stefan; Romer, Rolf; Stracke, Andreas; Haase, Karsten; Garbe-Schönberg, Dieter (Journal of Petrology, 2013)
Hornblende-bearing basanites and alkali basalts from the Rhön area of Germany (part of the Central European Volcanic Province; CEVP) have high TiO (3-4 wt %), moderately high Mg# (mostly >0.50), variable Cr (400-30 ppm) and Ni (160-20 ppm) abundances, and are enriched in incompatible trace elements and rare earth elements (REE). In primitive mantle-normalized multielement diagrams they show a strong depletion in Ba, Rb, and K relative to trace elements of similar incompatibility. Some alkali basalts and more differentiated rocks have lower Mg# and lower abundances of Ni and Cr, and have undergone fractionation of olivine, clinopyroxene, Fe-Ti oxides and amphibole. The trace element constraints (e.g. low Nb/U and Ce/Pb and the Nd-Sr-Pb isotope compositions of some basalts) indicate that assimilation of lower crustal material has modified the composition of the primary mantle-derived magmas. Most of the basanites and alkali basalts approach the Sr-Nd-Pb isotope compositions inferred for the EAR (European Asthenospheric Reservoir) component. Variations in REE abundances and correlations between REE ratios suggest partial melting of amphibole-bearing spinel peridotite containing a significant portion of non-peridotitic material (i.e. pyroxenite). The presence of residual amphibole, indicated by depletion of Kand Rb relative to Ba and Nb, requires melting close to the asthenosphere- lithosphere boundary or within the lithospheric mantle, most probably of a veined mantle source. Temperature and pressure estimates indicate a depth of melting for the most primitive lavas at 80 km at temperatures of 1290°C. Based on Sr-Nd isotope and trace element constraints it is proposed that asthenospheric melts similar in composition to EAR melts observed elsewhere in the CEVP froze at the asthenosphere-lithosphere thermal boundary as veins in the lithospheric mantle. These veins were remelted after only short storage times by ascending asthenospheric melts, imposing the prominent amphibole signature upon the basalts. The fairly radiogenic Pb isotope signatures are expected to originate from melting of enriched, low melting temperature components incorporated in the depleted upper (asthenospheric) mantle and therefore do not require upwelling of deep-seated mantle sources for the Rhön or many other continental alkaline lavas with similar Pb isotope signatures. © The Author 2013. Published by Oxford University Press All rights reserved.
Keywords: Hornblende phenocryst; Intraplate-alkaline continental basalts; Lithosphere-asthenosphere boundary; Mantle metasomatism

Petrography and shock-related remagnetization of pyrrhotite in drill cores from the Bosumtwi Impact Crater Drilling Project, Ghana - de Wall, Helga; et al. (Meteoritics & Planetary Science, 2007)
Rock magnetic and magnetic mineralogy data are presented from the International Continental Scientific Drilling Program (ICDP) drill cores LB-07A and LB-08A of the Bosumtwi impact structure in order to understand the magnetic behavior of impact and target lithologies and their impact-related remagnetization mechanism. Basic data for the interpretation of the magnetic anomaly patterns and the magnetic borehole measurements as well as for new magnetic modeling are provided. Magnetic susceptibility (150-500 × 10-6 SI) and natural remanent magnetization (10-3-10-1 A/m) are generally weak, but locally higher values up to 10.6 × 10-3 SI and 43 A/m occur. Sixty-three percent of the investigated rock specimens show Q values above 1 indicating that remanence clearly dominates over induced magnetization, which is a typical feature of impact structures. Ferrimagnetic pyrrhotite is the main magnetite phase, which occurs besides minor magnetite and a magnetic phase with a Curie temperature between 330 and 350 °C, interpreted as anomalous pyrrhotite. Coercive forces are between 20 and 40 mT. Brecciation and fracturing of pyrrhotite is a common feature confirming its pre-impact origin. Grain sizes of pyrrhotite show a large variation but the numerous stress-induced nanostructures observable by transmission electron microscopy (TEM) are assumed to behave as single-domain grains. We suggest that the drilled rocks lost their pre-shock remanence memory during the shock event and acquired a new, stable remanence during shock-induced grain size reduction. The observed brittle microstructures indicate temperatures not higher than 250 °C, which is below the Curie temperature of ferrimagnetic pyrrhotite (310 °C). © The Meteoritical Society, 2007. Printed in USA.
UnivIS-Import:2015-03-09:Pub.2007.nat.dgeo.IGM.c3tekt.petrog

PETROLOGICAL, GEOCHEMICAL, AND STATISTICAL ANALYSIS OF EOCENE-OLIGOCENE SANDSTONES OF THE WESTERN THRACE BASIN, GREECE AND BULGARIA - Caracciolo, Luca; et al. (Journal of Sedimentary Research, 2012)
The Rhodopian Orogen developed since the Late Cretaceous early Eocene during accretionary processes following the closure of the Vardar ocean basin, a branch of Neotethys. Through a multidisciplinary approach, including sandstone petrology and geochemistry of the clastic and volcanoclastic sediments, we reconstruct the unroofing history of the Rhodopian orogen and characterize the formation and the evolution of the western portions of the Thrace basin, in Greece and Bulgaria, between the late Eocene and Oligocene. Detrital modes of 127 sandstone samples provide evidence of three distinctive petrofacies: quartzolithic, quartzofeldspathic, and volcanoclastic. The petrographic composition gives evidence of contributions from three key source areas corresponding to the three main tectonic units: the Circum-Rhodope Belt, the Variegated Complex (ultramafic complex), and the Gneiss-Migmatite Complex. The three petrofacies reflect multiple provenance from different tectonic settings as they evolve from quartzolithic to quartzofeldspathic to volcanoclastic, corresponding to collisional orogen, crustal block uplift, and volcanic arc settings, respectively. Geochemical data on major elements and trace elements are used to discuss the efficacy of tectonic-setting discrimination diagrams and compare them to the Dickinson model as well as to distinguish and characterize (i) petrographically homogeneous gneiss-supplied subbasins and (ii) volcanic contributions to sandstone composition. Multivariate statistical techniques are used to unravel the complex web of factors controlling sediment composition. Biplot analysis highlights the influence of two independent processes: (1) mixing between carbonate and silicate phases, and (2) evolution from mafic to felsic source rocks. The latter indicates progressively increasing supply rates from deeper crustal levels. The compositional evolution of the sandstone suites of Thrace basin in NE Greece and SE Bulgaria is strictly related to various geodynamic stages of the Rhodope region. Provenance analysis of Thrace sandstones provide an example of the changing nature of orogenic belt sand associate basins through time, and may contribute to the general understanding of similar geodynamic settings.

Petrology and geochemistry of basalts from the northern Kolbeinsey Ridge, North Atlantic: Implications for magmatic processes and mantle heterogeneity beneath a slow-spreading segment. - Haase, Karsten; Devey, Colin; Wieneke, Martin (Contributions To Mineralogy and Petrology, 2003)
UnivIS-Import:2015-03-09:Pub.2003.nat.dgeo.IGM.legeo.petrol

Petrology and geochemistry of the Tertiary Suez rift volcanism, Sinai, Egypt - Shallaly, N. A.; Beier, Christoph; Haase, Karsten; Hammed, M. S. (Journal of Volcanology and Geothermal Research, 2013)
The Tertiary basaltic rocks of Southwestern Sinai, situated along the Wadi Nukhul-Wadi Matullah-Wadi El Tayiba join, were selected to study the Gulf of Suez rift related-lavas and their geochemical and petrological relation with the rifting process. Whole rock samples were studied petrographically and analysed for major and trace elements. The samples from dykes, sills and flows from multiple magmatic events display a large variety in texture and in modal mineral compositions. They range from olivine dolerites and olivine-bearing basalts to vitrophyric, texturally heterogeneous basalts and crystal lithic tuffs. The transitional tholeiitic basalts display low compatible element concentrations and an enrichment of the whole spectrum of the incompatible elements. Major, trace and Rare Earth Element data suggest that the melts formed by 5% melting of mantle peridotite at the spinel-garnet transition zone (80-90. km depth), in the presence of 2-4% residual garnet. During the melt ascent, the fractionating phases were olivine, clinopyroxene and, to a lesser extent, plagioclase. Thermobarometric calculations indicate the presence of two crystallization levels beneath the Gulf of Suez rift: a shallower stage at 15-20. km and a deeper stage at depths of 25-30. km. The mantle source consists of streaks and blobs of enriched mantle, preserved in the geochemical signatures of these rocks. The enriched mantle sources melted preferentially compared to the surrounding ambient mantle and thus led to a preferential enrichment of the sources of the Gulf of Suez rift. © 2013 Elsevier B.V.
Keywords: Basalt; Egypt; Geochemistry; Gulf of Suez rift; Petrology; Thermobarometry

Petrology and geochronology of a suite of meta-supracrustal rocks from Madukkarai, Tamil Nadu: Implications for the Ediacaran-Cambrian orogenesis of the Granulite Terrane of South India - Roy Choudhury, Sirina; Dey, Anindita; Brandt, Sönke; Sanyal, Sanjoy; Sengupta, Pulak (Lithos, 2021)
The Granulite Terrane of South India (GTSI) has two major components. An orthogneiss dominated northern block of Archaean/early Palaeoproterozoic age and an Ediacaran-Cambrian, high to ultra-high temperature meta-supracrustal dominated southern block (the Madurai Block, MB). It is commonly perceived that the two blocks of GTSI came into juxtaposition along the Palghat-Cauvery Shear/Suture Zone (PCSZ) during a continent-continent collision. However, the timing and the nature of the contact relations between the two major components remains controversial. In this work, detail petrological and geochronological study of two metapelites along with a meta-psammite (only for geochronological study), from the Madukkarai Supracrustal Unit (MSU) within the PCSZ, are presented. The studied metapelites show two distinct assemblages: A. Garnet + biotite + sillimanite (both idioblasts and pseudomorphs after kyanite) + K-feldspar + plagioclase + quartz + ilmenite (rutile, zircon and monazite as accessory phases). B. Mineralogy is similar to A but contains cordierite and minor spinel, but no zircon. Both the metapelites develop a gneissic fabric that is defined by centimetre thick laterally discontinuous garnet-bearing leucosomes. ‘Frozen in’ reaction textures, phase equilibria modelling and mineralogical thermobarometry yielded “peak” temperature and pressure of metamorphism in the range of 730–790 °C, 5.5–7 kbar (considering sillimanite and ilmenite to be stable). Subsequently, the rocks followed a decompressive retrograde P-T path recorded till 630 °C and 4 kbar. The geometry of the construed retrograde P-T path is similar to that commonly found in rocks of a continent-continent collision zone. LA-ICP-MS U[sbnd]Pb zircon dating and U-Th-total Pb monazite dating constrain the major high-grade metamorphism and deformation during 550–520 Ma with vestiges of 600 Ma old tectonothermal/ thermal event. The geological history of the MSU shares many characteristics with the Ediacaran-Cambrian meta-supracrustal rocks lying on both sides of the PCSZ, in terms of lithological association, timing of protolith formation, deformation and metamorphism. The variation in intensity of metamorphism in the meta-supracrustal rocks of the GTSI could be linked to differential upliftment of the GTSI during the neotectonic activities, followed by erosion. Integrating all the geological, geochronological and geophysical information, it has been argued that the GTSI behaved as a coherent continental block that was involved in continent-continent collision during the formation of the Ediacaran-Cambrian supercontinent Gondwanaland. The findings of this study do not corroborate the view that PCSZ is an Ediacaran-Cambrian terrane boundary.
CRIS-Team Scopus Importer:2021-08-06
Keywords: Gondwanaland supercontinent; Granulite Terrane of South India; Palghat Cauvery Shear Zone; Phase equilibria modelling; Th–U–total Pb monazite dating; U-Pb zircon dating

Petrophysical characterization, BIB-SEM imaging, and permeability models of tight carbonates from the Upper Jurassic (Malm ss), SE Germany - Freitag, Simon; Klaver, Jop; Malai, Iulian S. S.; Klitzsch, Norbert; Urai, Janos L. L.; Stollhofen, Harald; Bauer, Wolfgang; Schmatz, Joyce (Geothermal Energy, 2022)
Tight carbonate rocks are important hydrocarbon and potential geothermal reservoirs, for example, in CO2-Enhanced Geothermal Systems. We report a study of outcrop samples of tectonically undeformed tight carbonates from the upper Jurassic "Malm (sic) " formation in Southern Germany near the town of Simmelsdorf (38 km NE of Nuremberg) to understand bulk petrophysical properties in relation to microstructure and to compare models for permeability prediction in these samples. We applied Archimedes isopropanol immersion, Helium pycnometry, mercury injection, gamma density core logging, and gas permeability measurements, combined with microstructural investigations and liquid metal injection (LMI-BIB-SEM). In addition, ultrasonic velocity was measured to allow geomechanical comparison of stratigraphically equivalent rocks in the South German Molasse Basin (SGMB). Results show only small variations, showing that the formation is rather homogeneous with bulk porosities below 5% and argon permeabilities around 1.4E-17 m(2). The presence of stylolites in some of the samples has neither a significant effect on porosity nor permeability. Pores are of submicron size with pore throats around 10 nm and connected as shown by Mercury injection and Liquid Metal injection. Samples have high dynamic Young's Modulus of 73 +/- 5 GPa as expected for lithified and diagenetically overmature limestones. Moreover, no trends in properties were observable toward the faults at meter scale, suggesting that faulting was post-diagenetic and that the matrix permeabilities were too low for intensive post-diagenetic fluid-rock interaction. Petrophysical properties are very close to those measured in the SGMB, illustrating the widespread homogeneity of these rocks and justifying the quarry as a reasonable reservoir analog. Permeability prediction models, such as the percolation theory-based Katz-Thompson Model, Poiseuille-based models, like the Winland, the Dastidar, the capillary tube, and the Kozeny-Carman Models, as well as several empirical models, namely, the Bohnsack, the Saki, and the GPPT Models, were applied. It is shown that the capillary tube Model and the Saki Model are best suited for permeability predictions from BIB-SEM and mercury injection capillary pressure results, respectively, providing a method to estimate permeability in the subsurface from drill cuttings. Matrix permeability is primarily controlled by the pore (throat) diameters rather than by the effective porosity.
CRIS-Team WoS Importer:2023-01-06

Petrostratigraphic analysis of a Late Miocene mixed siliciclastic-carbonate depositional system (Calabria, Southern Italy): Implications for Mediterranean paleogeography - Caracciolo, Luca; et al. (Sedimentary Geology, 2013)
Keywords: Late Miocene; Mixed siliciclastic-carbonate sediments; Petrostratigraphy; Shallow water environments

Petrostratigraphic evolution of the Thrace Basin (Bulgaria, Greece, Turkey) within the context of Eocene-Oligocene post-collisional evolution of the Vardar-Izmir-Ankara suture zone - Caracciolo, Luca; et al. (Geodinamica Acta, 2013)
Eocene-Oligocene paleogeographic/paleotectonic reconstructions of the Rhodopian - northern Aegean - western Black Sea region largely ignore the Thrace Basin, a large sedimentary basin up to 9 km thick that has been long interpreted as a forearc basin developed in a context of northward subduction. Recent structural, stratigraphic, petrologic, and sedimentologic data challenge this notion and may instead be interpreted within a context of upper-plate extension during the complex transition between the collisional tectonic regime related to the closure of Vardar-Izmir-Ankara oceanic realm and the extensional regime characterizing the Oligocene-Neogene evolution of the Aegean and peri-Aegean regions. The detritus filling the Thrace Basin was derived from two main sediment source areas: (i) the mostly metamorphic terrains of the Rhodopes to the west and (ii) the Vardar-Izmir-Ankara and Biga (intra-Pontide?) subduction-accretion prisms to the southwest. During most of the Eocene-Oligocene, the entire basin was characterized by a complex physiography, as shown by commercial seismic lines in the subsurface and abrupt lateral facies change at the surface. Such physiography was controlled by a series of basement highs trending from WNW-ESE (in the eastern and northern portions of the basin) to WSW-ENE (in the western and southern portions of the basin) which influenced sediment dispersal and the areal distribution of paleoenvironments.
Keywords: post-orogenic collapse; upper plate extension; sandstone detrital modes

Phanerozoic marine biodiversity: a fresh look at data, methods, patterns and processes. Global biodiversity, extinction intervals and biogeographic perturbations through time - Aberhan, Martin; Kießling, Wolfgang (Global Biodiversity, Extinction Intervals and Biogeographic Perturbations Through Time, 2012)
UnivIS-Import:2015-04-20:Pub.2012.nat.dgeo.IGM.LP.phaner

Phanerozoic parasitism and marine metazoan diversity: dilution versus amplification - de Baets, Kenneth; Huntley, John Warren; Scarponi, Daniele; Klompmaker, Adiël A.; Skawina, Aleksandra (Philosophical Transactions of the Royal Society B-Biological Sciences, 2021)
Growing evidence suggests that biodiversity mediates parasite prevalence. We have compiled the first global database on occurrences and prevalence of marine parasitism throughout the Phanerozoic and assess the relationship with biodiversity to test if there is support for amplification or dilution of parasitism at the macroevolutionary scale. Median prevalence values by era are 5% for the Paleozoic, 4% for the Mesozoic, and a significant increase to 10% for the Cenozoic. We calculated period-level shareholder quorum sub-sampled (SQS) estimates of mean sampled diversity, three-timer (3T) origination rates, and 3T extinction rates for the most abundant host clades in the Paleobiology Database to compare to both occurrences of parasitism and the more informative parasite prevalence values. Generalized linear models (GLMs) of parasite occurrences and SQS diversity measures support both the amplification (all taxa pooled, crinoids and blastoids, and molluscs) and dilution hypotheses (arthropods, cnidarians, and bivalves). GLMs of prevalence and SQS diversity measures support the amplification hypothesis (all taxa pooled and molluscs). Though likely scale-dependent, parasitism has increased through the Phanerozoic and clear patterns primarily support the amplification of parasitism with biodiversity in the history of life. This article is part of the theme issue ‘Infectious disease macroecology: parasite diversity and dynamics across the globe’.
Keywords: paleopathology; Phanerozoic; paleoparasitolog; marine disease; Metazoa; biodiversity

Phanerozoic Reef Patterns - Kießling, Wolfgang; Flügel, Erik; Golonka, Jan (Society for Sedimentary Geology (SEPM), 2002)
UnivIS-Import:2015-05-08:Pub.2002.nat.dgeo.IGM.LP.frompa
Keywords: Reefs; Geology

Phanerozoic reef trends based on the Paleoreefs database - Kießling, Wolfgang (The History and Sedimentology of Ancient Reef Systems, 2001)
UnivIS-Import:2015-04-20:Pub.2001.nat.dgeo.IGM.LP.phaner

Phanerozoic time scale and definition of time slices - Golonka, Jan; Kießling, Wolfgang (Phanerozoic Reef Patterns, 2002)
UnivIS-Import:2015-04-20:Pub.2002.nat.dgeo.IGM.LP.phaner

Phanerozoic trends in skeletal mineralogy driven by mass extinctions - Kießling, Wolfgang; et al. (Nature Geoscience, 2008)
Marine calcifying organisms that produce sediments and build reefs generally have skeletons and shells that are composed of either aragonite or calcite. Long-term changes in the estimated Mg/Ca ratios of sea water tend to correspond to changes in the prevailing mineralogy of these creatures. High Mg/Ca ratios are expected to favour the spread of aragonitic organisms, whereas calcitic taxa are thought to benefit from low Mg/Ca ratios. Here we test these patterns throughout the Phanerozoic eon and assess the relative impacts of changing ocean chemistry and mass extinctions on the evolutionary success of calcifying organisms. We find that mass extinctions are more important in regulating long-term patterns of skeletal mineralogy than the Mg/Ca ratios of the global oceans. Furthermore, selective recovery from mass extinctions is usually more important than selective extinction, in driving the Phanerozoic pattern of skeletal mineralogy. But even in the recovery phase there is no clear connection between changes in the dominance of aragonite or calcite and the Mg/Ca ratio of the oceans, thus providing further evidence for the complexity of biotic recoveries. © 2008 Macmillan Publishers Limited.
UnivIS-Import:2015-03-09:Pub.2008.nat.dgeo.IGM.LP.phaner

Phanerozoic trends in the global diversity of marine invertebrates - Alroy, John; Aberhan, Martin; Fürsich, Franz; Bottjer, David; Foote, Michael; Harries, Peter; Hendy, Austin; Holland, Steven; Ivany, Linda; Kießling, Wolfgang (Science, 2008)
It has previously been thought that there was a steep Cretaceous and Cenozoic radiation of marine invertebrates. This pattern can be replicated with a new data set of fossil occurrences representing 3.5 million specimens, but only when older analytical protocols are used. Moreover, analyses that employ sampling standardization and more robust counting methods show a modest rise in diversity with no clear trend after the mid-Cretaceous. Globally, locally, and at both high and low latitudes, diversity was less than twice as high in the Neogene as in the mid-Paleozoic. The ratio of global to local richness has changed little, and a latitudinal diversity gradient was present in the early Paleozoic.
UnivIS-Import:2015-04-14:Pub.2008.nat.dgeo.IGM.LP.phaner_3

Phanerozoic trends in the global geographic disparity of marine biotas - Kießling, Wolfgang; et al. (Paleobiology, 2009)
Previous analyses of the history of Phanerozoic marine biodiversity suggested that the post-Paleozoic increase observed at the family level and below was caused, in part, by an increase in global provinciality associated with the breakup of Pangea. Efforts to characterize the Phanerozoic history of provinciality, however, have been compromised by interval-to-interval variations in the methods and standards used by researchers to calibrate the number of provinces. With the development of comprehensive, occurrence-based data repositories such as the Paleobiology Database (PaleoDB), it is now possible to analyze directly the degree of global compositional disparity as a function of geographic distance (geo-disparity) and changes thereof throughout the history of marine animal life. Here, we present a protocol for assessing the Phanerozoic history of geo-disparity, and we apply it to stratigraphic bins arrayed throughout the Phanerozoic for which data were accessed from the PaleoDB. Our analyses provide no indication of a secular Phanerozoic increase in geo-disparity. Furthermore, fundamental characteristics of geo-disparity may have changed from era to era in concert with changes to marine venues, although these patterns will require further scrutiny in future investigations. © 2009 The Paleontological Society. All rights reserved.
UnivIS-Import:2015-03-09:Pub.2009.nat.dgeo.IGM.LP.phaner

Phase and porosity changes in a calcium aluminate cement and alumina system under hydrothermal conditions - Köhler, Andreas; Rößler, C.; Neubauer, Jürgen; Götz-Neunhoeffer, Friedlinde (Ceramics International, 2023)
When refractory castables are dried, hydrothermal conditions may result inside the bodies if the H2O cannot escape from the material. Under such high-pressure conditions, problems such as explosive spalling can arise. As different curing temperatures during the hydration of calcium aluminate cement (CAC)-bound castables lead to the formation of different hydrate phases, different microstructures can develop in the hardened material. This study presents the changes in porosity and in the mineralogical composition of a refractory castable model system under hydrothermal conditions depending on the curing temperature (5, 23 and 40 °C). Quantitative X-ray diffraction (QXRD) measurements show that different hydrate phases are formed during curing, while C3AH6 and boehmite are formed in the same quantities after hydrothermal treatment in an autoclave at ∼11 bar/180 °C. Although the mineralogical composition after autoclaving is not different, the three samples differ in their microstructure. Mercury intrusion porosimetry measurements reveal that although the total porosity after autoclaving is the same, the 40 °C samples have a higher proportion of large pores. SEM images also show that the appearance of C3AH6 in the 40 °C autoclaved samples varies, which originates from the starting phase composition and microstructure after curing.
CRIS-Team Scopus Importer:2022-10-21
Keywords: Calcium aluminate (D); Porosity (B); Refractories (E); X-ray methods (B)

Phase changes during the drying of calcium aluminate cement bond castables – the influence of curing and drying conditions - Köhler, Andreas; Neubauer, Jürgen; Götz-Neunhoeffer, Friedlinde (Cement, 2022)
This study presents the influence of different curing temperatures and the availability of unbound H2O on the phase changes during the drying process of a simplified calcium aluminate cement bond castable. A mixture of CAC and alumina was hydrated for 48 h at 5, 23 and 40 °C, which represents different working conditions during casting. After the curing process, these samples were heated up to 180 °C, and in some of them, the remaining unbound H2O had been removed by vacuum drying beforehand. The quantitative phase composition was determined by QXRD. Thermogravimetric analysis and gravimetric measurements were also used to characterize the differently cured samples. While the mineral phases in the samples cured at 40 °C were barely affected by the heating process in the investigated temperature range, the initial conditions before the drying of the samples cured at 5 and 23 °C strongly affected the final phase composition.
Keywords: Curing; Drying; Hydration; Temperature; X-ray diffraction; Calcium aluminate cement; Refractory cement

Phase characterization of lithium silicate biomedical glass-ceramics produced by two-stage crystallization - Hurle, Katrin; Belli, Renan; Götz-Neunhoeffer, Friedlinde; Lohbauer, Ulrich (Journal of Non-Crystalline Solids, 2019)
A commercially available lithium (di)silicate glass-ceramic used for dental prostheses was characterized with respect to its quantitative phase composition and crystallinity. For analysis of quantitative phase content, X-ray diffraction (XRD) was used combined with the G-factor method, an external standard technique. Samples of the material were analyzed in the pre-crystallized state and after final crystallization heat-treatment in order to characterize the changes occurring during the final crystallization stage. The bulk chemical composition of the commercial blocks, matching the composition of the precursor glass, was determined by a combination of X-ray Fluorescence (XRF) and Inductively Coupled Plasma - Optical Emission Spectroscopy (ICP-OES) analysis.
CRIS-Team WoS Importer:2019-04-04

Phase Composition of Phosphate Containing OPC Clinker - Götz-Neunhoeffer, Friedlinde; Neubauer, Jürgen (1998)
UnivIS-Import:2015-03-05:Pub.1998.nat.dgeo.IGM.LM.phasec

Phase Equilibria and Crystal Chemistry in the System CaO-Al_2_O_3_-Y_2_O_3_ - Richter, Andreas; Göbbels, Matthias (Journal of Phase Equilibria and Diffusion, 2010)
The phase relations in the system CaO-Al2O3-Y2O3 at 1400 and 1500 °C have been determined. The phase relations presented are in agreement with the calculated phase diagram by Udalov et al. (Russ. J. Inorg. Chem., 1979, 24(10), p 1549-1553). In addition ternary solid solution series of the binary compounds YAM (Y4Al2O9), YAP (YAlO3), and YAG (Y3Al5O12) could be described.
UnivIS-Import:2015-03-09:Pub.2010.nat.dgeo.IGM.LM.phasee
Keywords: crystal; chemistryphase; equilibria; Y-gehlenite; YAG; YAM; YAP

Phasenanalyse und Spurenelementgehalte von Riffsanden der Seychellen - Bausch, Walter; Krumm, Stefan; Munnecke, Axel (Erlanger Beiträge zur Petrographischen Mineralogie, 2012)
Riffsande der Seychellen-Inseln setzen sich im Mittel aus knapp 60 % Aragonit und knapp 30 % Mg-Calcit zusammen. Quarz und zwei andere Calcit-Varietäten stellen den Rest. Häufigstes Spurenelement ist Magnesium mit 1,6 %, gefolgt von Strontium mit 4550 ppm (Mittelwerte; bei erheblicher Streubreite). Extrapoliert auf reine Komponenten, finden sich 6-7 % Mg im Mg-Calcit, sowie 7160 ppm Sr im Aragonit. Eine Gleichung der negativen Korrelation Sr/Mg kann festgelegt werden. Die Riffsande variieren auch in den Korngrößen. Grobe Sande enthalten relativ mehr Mg-Calcit, feine Sande relativ mehr Aragonit. Konsequenterweise variieren auch die Spurenelementgehalte sinngemäß: feine Sande führen relativ mehr Sr, grobe Sande relativ mehr Mg.
Keywords: Calcit; Riffsande; Seychellen; Aragonit; Mg-Calcit; Strontium; Sr; Spurenelemente

Phasenbeziehungen im System SrO-BaO-Nb2O5 photorefraktiver Materialien - Nikasch, Christian; Göbbels, Matthias (Berichte der DMG, 2003)
UnivIS-Import:2015-04-16:Pub.2003.nat.dgeo.IGM.LM.phasen

Phase relations and lattice parameters in the system SrO-BaO-Nb2O5 focussing on SBN (SrxBa1-xNb2O6) - Göbbels, Matthias; et al. (Journal of Crystal Growth, 2004)
In this paper we report the phase relations of the tetragonal tungsten bronze type strontium barium niobate (SrxBa1−xNb2O6) solid solution in the temperature range from 1200°C to 1450°C. The x-value depends on the synthesis temperature and reaches from 0.19 ⩽ x ⩽ 0.62 at 1200°C up to 0.18 ⩽ x ⩽ 0.84 at 1440°C. In addition lattice parameters of the stable phases at 1300°C depending on their chemical compositions are given. Samples with different SrO:BaO:Nb2O5 ratios were sintered in vertical tube furnaces at suitable temperatures in air. The chemical composition of the quenched equilibrated phase associations were determined by EPMA. Lattice parameters of the resulting crystalline phases were derived from refinement of d-values from XRD patterns. The phase field of SBN is strongly temperature dependent. The Ba-rich end-member of the solid solution contains 80 mol% Ba and 20 mol% Sr independently of the synthesis temperature. On the other hand the maximum Sr-content of the solid solution increases with temperature from 62 mol% Sr at 1200°C up to 84 mol% Sr at 1450°C. Also the Nb-content varies with temperature especially at synthesis temperatures below 1400°C. In particular at 1300°C the solid solution field of SBN extents to higher Nb-contents on the Ba-rich side leading to a Sr-free end-member of the solid solution. For this Ba-rich side of the solid solution series a substitutional formula Ba4Sr1−yNbyNb10O30+1.5y (0 ⩽ y ⩽ 1) can be given. A new compound (Sr, Ba)5Nb8O25 in the SrO–BaO–Nb2O5 system has been found, exhibiting also a solid solution range. Chemical compositions of some previously described phases could be determined in more detail. The lattice parameters of the tetragonal tungsten bronze cell (A12A24C4M12M28O30) depend on the chemical composition of the solid solution. In the Sr-rich region and at low Nb-contents the a-parameter shifts strongly while on the Ba-rich side and at high Nb-contents the variation is lower. The c-parameter increases with the Ba-conten
UnivIS-Import:2015-03-09:Pub.2004.nat.dgeo.IGM.LM.phaser
Keywords: A1. Phase diagrams; A1. Solid solution; B1. Niobates; B2. Photo-refractive materials

Phase relations in peridotitic and pyroxenitic rocks in the model systems CMASH and NCMASH - Schmädicke, Esther (Journal of Petrology, 2000)
Alpine-type peridotites and associated pyroxenites are found as lenses in the continental crust in many different orogens. The reconstruction of the pressure-temperature (P-T) evolution of these rocks is, however, difficult or even impossible. With geothermobarometry, usually one point on the overall P-T path can be obtained. To use the different mineral assemblages observed in ultramafic rocks as P-T indicators, quantitative P-T phase diagrams are required. This study presents new calculated phase diagrams for peridotitic and pyroxenitic rocks in the model systems CaO-MgO-Al2O3-SiO2-H2O (CMASH) and Na2O-CaO-MgO-Al2O3-SiO2-H2O (NCMASH), which include the respective solid solutions as continuous exchange vectors. These phase diagrams represent applicable petrogenetic grids for peridotite and pyroxenite. On the basis of these general petrogenetic grids, phase diagrams for particular peridotite and pyroxenite bulk compositions are constructed. In an example of pyroxenite from the Shackleton Range, Antarctica, the different observed mineral assemblages are reflected by the phase diagrams. For these rocks, a high-pressure metamorphic stage around 18 kbar and an anticlockwise P-T evolution, not recognized previously, can be inferred.
UnivIS-Import:2017-03-24:Pub.2000.nat.dgeo.IGM.profes_1.phaser_26
Keywords: Antarctic; High-pressure metamorphism; Peridotite; Phase diagrams; Pyroxenite

Phase relations in the greenschist-blueschist-amphibolite-eclogite facies in the system Na2O-CaO-FeO-MgO-Al2O3-SiO2-H 2O (NCFMASH), with application to metamorphic rocks from Samos, Greece - Schmädicke, Esther; et al. (Contributions To Mineralogy and Petrology, 1998)

Phase relations of calcic amphibole- orthoamphibole-chlorite-talc assemblages, with applications to ultramafic rocks from the KTB pilot hole, Bavaria - Schmädicke, Esther; et al. (International Journal of Earth Sciences, 1997)
Lenses of ultramafic rocks intercalated within a metagabbro-amphibolite sequence were encountered in the KTB pilot hole. A pervasive metamorphic overprint formed the dominating assemblage calcic amphibole-orthoamphibole- chlorite-talc. In this study the phase relations of ultramafic rocks are investigated in order to (a) constrain the stability field of this assemblage in general, and (b) define the equilibrium pressure-temperature (P-T) conditions of this assemblage in the ultramafic rocks from the KTB borehole. For that purpose, phase equilibria were calculated in the model systems CaO-MgO-Al 2O3-SiO2-H2O (CMASH) and CaO-MgO-FeO-Al2O3-SiO2-H2O (CMFASH). Thereby, the continuous compositional change of solid solutions with pressure and temperature was modeled, including the Tschermak's substitution and the MgFe-1 exchange. Based on these results, petrogenetic grids were constructed, revealing that calcic amphibole-orthoamphibole-chlorite-talc assemblages cover a stability field of < 650-770°C/1 → 14 kbar (CMASH) and < 550-650°C/1 → 14 kbar (CMFASH), respectively. This explains the widespread occurrence of the considered assemblage. Based on the bulk rock composition of the KTB samples, a special P-T diagram was constructed, limiting the stability field of the calcic amphibole-orthoamphibole-chlorite- talc assemblage. At 580°C the stability field extends from 6 to 14 kbar pressure, and shrinks to 10-11 kbar at 630°C. Conventional estimates using the mineral compositions of the KTB samples yield a temperature around 630°C, at which the calculated stability field of calcic amphibole-orthoamphibole-chlorite-talc extends from 10 to 11 kbar. © Springer-Verlag 1997.
UnivIS-Import:2017-03-24:Pub.1997.nat.dgeo.IGM.profes_1.phaser
Keywords: Bohemian massif; Geothermobarometry; KTB; Metamorphic rocks; Phase petrology; Ultramafic rocks; Variscides; Zone of Erbendorf-Vohenstrauss

Phase separation and fluid mixing revealed by trace element signatures in pyrite from porphyry systems - Keith, Manuel; Haase, Karsten; Chivas, Allan R.; Klemd, Reiner (Geochimica Et Cosmochimica Acta, 2022)
Porphyry deposits host various trace elements in economic amounts, but the hydrothermal processes causing their fractionation and enrichment are still not fully understood, but vital to target the most prospective mineralisation. We present the first micro-analytical study on the trace element composition of pyrite from the Koloula Cu-Au porphyry in the young and thin (<25 km) Solomon Islands arc. A statistical evaluation of the trace element data of pyrite indicates that mineral inclusions obscure the chemical signature of the mineralisation processes. The filtered pyrite data, from which the inclusions were excluded, correlate with variations in temperature and salinity, as defined by fluid inclusions from several alteration zones. Trace element ratios in pyrite show systematic variations with fluid temperature and salinity (Co/Ni, Se/Te), phase separation (Co/Ni, Co/As) and mixing of magmatic fluids and meteoric waters (Se/Ge). The mineralisation in the potassic alteration zone was controlled by the formation of a hypersaline liquid (Co/As > 1, Co/Ni > 50) from a magma-derived fluid (Se/Ge 100) at lithostatic pressure conditions and temperatures of up to 700 °C (Se/Te > 50). This was followed by a transition to hydrostatic pressure conditions due to open-fracture continuity towards the paleo-surface, marking the onset of boiling in the chlorite-sericite to sericitic alteration zone (Co/As < 1), where minor proportions of meteoric water were involved (Se/Ge < 100). The shallowest part of the mineralisation is controlled by lower temperature (<300 °C, Se/Te < 50) vapour-rich fluids (Co/As < 1) that condensed into meteoric waters in an epithermal transition zone (Co/Ni < 50, Se/Ge < 100). Trace element systematics in pyrite from progressive alteration zones therefore preserve the time-space evolution of porphyry (-epithermal) systems in young and thin oceanic island arcs.
CRIS-Team Scopus Importer:2022-07-01
Keywords: Fluid inclusions; Porphyry alteration; Porphyry systems in oceanic island arcs; Solomon Islands; western Pacific porphyry deposits; Sulfide chemistry; laser ablation ICP-MS

Phase solubility changes during hydration of monocalciumaluminate and calcite-the influence of alkali accumulation - Manninger, Tanja; Jansen, Daniel; Neubauer, Jürgen; Götz-Neunhoeffer, Friedlinde (Materials, 2020)
The reaction of CA (monocalcium aluminate) with calcite was closely monitored with regard to phase development, pore water ion content and heat flow. Calcite acts as filler and reactant, finally leading to thermodynamically stable products after hydration at ambient conditions. For better understanding the mechanism taking place, a CA-cement and a commercial calcite mix were compared to a pure CA and pure calcite mix. Both reaction paths were compared. Thermodynamic modeling with PhreeqC gave insight about factors that can influence the course of the hydration reaction. Alkali ions in pore solution of the CA-cement relocate solubility curves of hydration products. Taking into account as many of the alkaline ions as possible, resulted in the closest representation of the measured phase content, confirming thermodynamic modeling. The high dynamics that develop during reaction could only be addressed if a concentration of alkalis in the pore solution at later points in time was respected, thus leading to a shift of solubility curves over time. This was not observed with the pure CA in absence of alkalis.
CRIS-Team Scopus Importer:2020-04-14
Keywords: CA; Calcite; Hydration kinetics; Modelling; Pore water

Phase-specific bioactivity and altered Ostwald ripening pathways of calcium carbonate polymorphs in simulated body fluid - Myszka, Barbara; Schüßler, Martina; Hurle, Katrin; Demmert, Benedikt; Detsch, Rainer; Boccaccini, Aldo R.; Wolf, Stephan (RSC Advances, 2019)
Calcium carbonate is an abundant biomineral, and already archeological records demonstrate its bioactivity and applicability for osseo-integrative implants. Its solubility, which is generally higher than those of calcium phosphates, depends on its polymorph turning calcium carbonate into a promising biomaterial with tunable bioresorption rate. However, the phase-dependent bioactivity of calcium carbonate, i.e., its osteoconductivity, is still insufficiently characterized. In this study, we address this issue by monitoring the behavior of the four most important calcium carbonate phases, i.e., calcite, aragonite, vaterite, and amorphous calcium carbonate, in simulated body fluid solution at 37 °C. Our results demonstrate that the thermodynamically stable calcite phase is essentially inert. In contrast, the metastable phases aragonite and vaterite are bioactive, thus promoting the formation of calcium phosphate. Amorphous calcium carbonate (ACC) shows prominent bioactivity accompanied by pronounced redissolution processes. Mg-stabilized ACC was additionally tested since its increased stability eases formulation and handling in future applications. It is highly bioactive and, moreover, the additional release of Mg promotes cell viability. Overall, our results demonstrate that bioactivity of calcium carbonate is phase-dependent, allowing tailored response and bioactivity of future calcareous biomaterials. Our results also reveal that phosphate ions strongly interfere with Ostwald-Lussac step ripening of calcium carbonate, kinetically stabilizing metastable polymorphs such as vaterite and aragonite; this is a distinctive feature of the calcium carbonate mineral system which clearly has to be considered in future applications of calcium carbonate as a bioceramic.
CRIS-Team Scopus Importer:2019-07-09

Phosphorus Cycle and Primary Productivity Changes in the Tethys Ocean During the Permian-Triassic Transition: Starving Marine Ecosystems - Müller, Johann; Sun, Yadong; Yang, Fen; Fantasia, Alicia; Joachimski, Michael (Frontiers in Earth Science, 2022)
The ultimate cause(s) of the end-Permian mass extinction (∼252 Ma ago) has been disputed. A complex interplay of various effects, rather than a single, universal killing mechanism, were most likely involved. Climate warming as consequence of greenhouse gas emissions by contemporaneous Siberian Traps volcanism is widely accepted as an initial trigger. Synergetic effects of global warming include increasing stratification of the oceans, inefficient water column mixing, and eventually low marine primary productivity culminating in a series of consequences for higher trophic levels. To explore this scenario in the context of the end-Permian mass extinction, we investigated sedimentary total organic carbon, phosphorus speciation as well as nickel concentrations in two low-latitude Tethyan carbonate sections spanning the Permian-Triassic transition. Total organic carbon, reactive phosphorus and nickel concentrations all decrease in the latest Permian and are low during the Early Triassic, pointing to a decline in primary productivity within the Tethyan realm. We suggest that the productivity collapse started in the upper C. yini conodont Zone, approximately 30 ka prior to the main marine extinction interval. Reduced primary productivity would have resulted in food shortage and thus may serve as explanation for pre-mass extinction perturbations among marine heterotrophic organisms.<br

Phosphorus cycling during the Hirnantian glaciation - Müller, Johann; Joachimski, Michael; Lehnert, Oliver; Männik, Peep; Sun, Yadong (Palaeogeography, Palaeoclimatology, Palaeoecology, 2024)
Unlike other mass extinctions of the Phanerozoic, the Late Ordovician mass extinction took place during an icehouse interval, accompanied by the glaciation of Gondwana. Ice sheets reached their maximum during the Hirnantian and global sea-level dropped substantially. Consequently, the shallow tropical shelf environments of Laurentia and Baltica became subaerially exposed or remaining submerged shelves were characterized by very shallow water-depths. Redox proxies suggest that most shallow shelf settings were well oxygenated to that time, while the global extent of anoxic environments increased, implying that deoxygenation was confined to the open ocean. We speculate that the burial rate of the nutrient phosphorus (P) on shelves was minimal during the Hirnantian glacial maximum (HGM) due to bypass of the shelves in respect to the incoming riverine dissolved load. Hence, a large excess of bioavailable P entering the open ocean would have stimulated phytoplankton production which lowered oxygen concentrations by aerobic respiration. In order to test this hypothesis, we determined reactive P (Preact) contents in two low-latitude carbonate successions (Anticosti Island and Estonia) spanning the HGM. Moreover, we measured total organic carbon (C) concentrations and calculated C/P ratios to evaluate the burial efficiency of P. Samples from both sites are characterized by overall low Preact contents. We observe a decreasing trend in Preact towards the HGM, reaching a minimum during the initial transgression thereafter. C/P ratios suggest efficient P-burial throughout the study interval and, hence, Preact contents are assumed to be a direct measure of primary productivity, P-availability, and P-burial. Using the Preact concentrations, we modeled shelf P-burial fluxes with estimates for global shelf area and sedimentation rates. The model suggests that shelf P-burial fluxes around the HGM were approximately halved due to a reduced shelf area and minimum Preact contents. With the assumption of a constant P-input to the ocean, the proposed scenario serves as a plausible explanation for the observed redox gradient
Keywords: Phosphorus cycle; Hirnantian; Glaciation; Primary productivity; Sea level; Anoxia

PHREASIM: a computer-aided expert system to characterize horizontal fluid flow in and around wells PHREASIM – Ein Expertensystem zur Simulation von Fließverhältnissen in Grundwassermessstellen und deren unmittelbarem Nahfeld - Drews, Michael; et al. (Grundwasser, 2015)
Keywords: Groundwater flow; In-hole flow; Navier-Stokes-Brinkman; PHREASIM; Well flow simulation

Physical and environmental drivers of Paleozoic tetrapod dispersal across Pangaea - Brocklehurst, Neil; Dunne, Emma; Cashmore, Daniel; Frӧbisch, Jӧrg (Nature Communications, 2018)
The Carboniferous and Permian were crucial intervals in the establishment of terrestrial ecosystems, which occurred alongside substantial environmental and climate changes throughout the globe, as well as the final assembly of the supercontinent of Pangaea. The influence of these changes on tetrapod biogeography is highly contentious, with some authors suggesting a cosmopolitan fauna resulting from a lack of barriers, and some identifying provincialism. Here we carry out a detailed historical biogeographic analysis of late Paleozoic tetrapods to study the patterns of dispersal and vicariance. A likelihood-based approach to infer ancestral areas is combined with stochastic mapping to assess rates of vicariance and dispersal. Both the late Carboniferous and the end-Guadalupian are characterised by a decrease in dispersal and a vicariance peak in amniotes and amphibians. The first of these shifts is attributed to orogenic activity, the second to increasing climate heterogeneity.<br

Physicochemical constraints on indium-, tin-, germanium-, gallium-, gold-, and tellurium-bearing mineralizations in the Pefka and St Philippos polymetallic vein- and breccia-type deposits, Greece - Voudouris, Panagiotis; Repstock, Alexander; Spry, Paul G.; Frenzel, Max; Mavrogonatos, Constantinos; Keith, Manuel; Tarantola, Alexandre; Melfos, Vasilios; Tombros, Stylianos; Zhai, Degao; Cook, Nigel J.; Ciobanu, Cristiana L.; et al. (Ore Geology Reviews, 2021)
The Pefka Cu-Au-Te-In-Se and nearby St Philippos Pb-Zn-Bi-Sn-Ge-Ga-In vein- and breccia-type deposits in western Thrace, Greece, display strong similarities, but also differences in terms of mineralization style, ore mineralogy, and chemistry, and host rock compositions. The Pefka mineralization consists of two crosscutting vein systems with high sulfidation (HS)- and intermediate-sulfidation (IS) assemblages hosted by andesitic lavas and is unusually enriched in In (up to 700 ppm), Te (>1000 ppm), Se (>100 ppm), and Cu (>1 wt%). The main In-carriers are roquesite (CuInS2) and In-bearing tennantite-(Cu) which contains up to 6.5 wt% In, substituting into the C site. Roquesite is associated with enargite and arsenosulvanite/colusite, as part of the HS assemblage at Pefka. Selenium-bearing galena and a large suite of tellurides including calaverite, sylvanite, petzite, kostovite, empressite, tellurantimony, and coloradoite, in addition to native tellurium, account for the marked tellurium and selenium enrichment in the ores from Pefka. Tellurides and native gold were introduced together at Pefka and accompany the precipitation of Te-bearing minerals of the tetrahedrite group, such as “stibiogoldfieldite” and “arsenogoldfieldite”, and Cu-excess varieties of tetrahedrite and tennantite. However, the bulk of telluride deposition is associated with normal, fully substituted tetrahedrite-tennantite varieties. The St Philippos deposit is associated with a brecciated fault zone hosted by Eocene sandstones and Oligocene quartz-feldspar porphyry dikes. It is enriched in a large suite of incompatible elements, including Bi (>2000 ppm), Sn (>100 ppm), U (up to 200 ppm), Pb (>1 wt%), Zn (>1 wt%), Mo (up to 62 ppm), Ge (>100 ppm), Ga (up to 466 ppm) and In (up to 222 ppm), contrasting with the element suite defining the nearby Pefka deposit. The main carrier of In, Ga, and Ge is sphalerite (and wurtzite) with In-rich zones in sphalerite containing up to 6.1. wt% In. Germanium and Ga in sphalerite reach concentrations of up to 0.27 and 0.32 wt%, respectively. Sphalerite from the St Philippos deposit is extremely Fe-poor (<0.04 wt%), and is associated with an unusual suite of Sn-bearing sulfosalts (kësterite-stannite, Mn-bearing kësterite, unnamed Cu2MnSnS4), and enargite, marking an early HS event. Kësterite also hosts indium (up to 0.6 wt% In). Mn-bearing varieties of tennantite host inclusions of minor tellurides (e.g., hessite, altaite, and tsumoite) and formed later in the paragenetic sequence under transitional HS-IS and IS conditions. Both deposits are characterized by early high-temperature (>300 °C) and HS fluid conditions, followed by IS assemblages as temperatures waned. Rhyolitic oxidized magmas are considered to be the sources of metals in the St Philippos deposit; however, their anomalous W, Sn, U, and Bi contents suggest a contamination by crustal rocks. The Cu-Au-Te signature of the Pefka deposit is compatible with a genetic relationship to less fractionated andesitic magmas, although a possible contribution of In from rhyolitic magmas could explain the high In contents of the ore. However, other factors, as for example different metal-deposition mechanisms resulting in metal zonation around causative porphyry centers at depth, may also account for the observed metal endowment in these two deposits. The Sn-Te-In-(Ge-Ga) element association at Pefka and St Philippos is unusual in that it has been previously reported from only a few other places in the world (e.g., Capillitas deposit, Argentina, and the Kawazu deposit, Japan). We conclude based on this exotic mineralization-style that the northeastern part of Greece represents an area of great potential for the exploitation of critical metals and metalloids.

Physikalisch-chemische Mineralogie kompakt - Göbbels, Matthias; Goetze, Jens; Lieber, Werner (Springer Spektrum, 2020)
Dieses Buch stellt das Grundwissen der Mineralogie knapp und verständlich dar. Als Studierende der Mineralogie, Geowissenschaften, Werkstoff-/ Materialwissenschaften und benachbarter Fachrichtungen, werden Ihnen die essentiellen physikalisch-chemischen Grundlagen in diesem Lehrbuch übersichtlich vorgestellt. Als Absolventen dient Ihnen diese kurze Zusammenstellung hervorragend zum Nachschlagen der wichtigsten Fakten. Es werden vier große Kernbereiche behandelt: Die Kristallographie, von den Grundlagen der Symmetrie bis hin zum Realkristall, vom Feinbau der Kristalle über die Bravais Gitter, röntgenographische Grundlagen bis zum Realbau der Kristalle. Die Kristallchemie, mit den grundlegenden Prinzipien, chemischen Variationen und ausgewählten Begrifflichkeiten. Die Mineralphysik, mit einem Überblick der physikalischen Eigenschaften von Kristallen. Und die Phasenlehre mit geometrischer Betrachtung und Interpretation von unären, binären und ternären Systemen allgemeiner Ar
Keywords: in Stichworten; Kristallographie; Kristallografie; Mineralpyhsik; Phasenlehre; geometrisch; Bravais Gitter; röntgenographische; Realkristall; Verzwillingungen; Materialwissenschaften

Phytoplankton dynamics across the Ordovician/Silurian boundary at low palaeolatitudes: correlations with carbon isotopic and glacial events. - Delabroye, Aurelien; Munnecke, Axel; Vecoli, Marco; Copper, Paul; Tribovillard, Nicolas; Joachimski, Michael; Desrochers, Andre; Servais, Thomas; Munnecke, Axel (Palaeogeography, Palaeoclimatology, Palaeoecology, 2011)
The Late Ordovician culminated in a major glacial period that has been related to one of the strongest mass extinctions recorded during the Phanerozoic. During this interval, Anticosti Island (Québec, eastern Canada) was located at low to intermediate palaeolatitudes (15-30° S) on the eastern margin of Laurentia. It displays a relatively complete section across the Ordovician-Silurian (O/S) boundary. Upper Ordovician to Lower Silurian strata of Anticosti studied here comprise the Vauréal (Katian), Ellis Bay (Hirnantian) and Becscie (latest Hirnantian-Rhuddanian) formations. Phytoplankton dynamics inferred from the acritarch content of these strata are locally compared with new geochemical environmental proxies (δ13C), with recent palynological data from Baltica and also with phytoplankton dynamics as described from near-polar, high latitude localities of the Gondwana region. Two positive excursions of the carbon isotope record have been identified in the lower and upper Ellis Bay Formation.Overall, phytoplankton trends are as follows: (1) as with chitinozoans, conodonts, brachiopods and corals, acritarchs from Anticosti display a major turn-over during the early Hirnantian (uppermost Vauréal Formation-lower Ellis Bay Formation), with the appearance of taxa that exhibit Silurian affinities (e.g., Tylotopalla sp., Ammonidium sp., Oppilatala sp., Evittia sp., Dilatisphaera spp.). High polymorphism for some common taxa is observed in the interval corresponding to the first δ13C positive excursion. Using sequence stratigraphy, this period may be related to a first glacially driven sea-level drawdown corresponding to terrestrial ice-sheet growth on Gondwana, such as recorded in Morocco. (2) Subsequently, during the late Hirnantian of Anticosti (uppermost Ellis Bay Formation), phytoplanktic communities suffered a crisis, exemplified by the disappearance of several typical, large Late Ordovician taxa (i.e., Orthosphaeridium spp., Peteinosphaeridium spp., large Baltisphaeridum spp., Sacculidium sp.). The lower Becscie strata, corresponding to the time of deglaciation at the O/S boundary interval, only contain a low diversity assemblage dominated by large acritarchs of the genus Hoegklintia and other morphologically related forms, and a few tolerant and long-ranging taxa (e.g., Evittia remota, Micrhystridium spp., leiospheres). Despite a possible taphonomic bias in the uppermost Ellis Bay Formation, the major crisis in the late Hirnantian coincides with the second δ13C excursion and a second, stronger glacially-driven sea-level fall corresponding to the time of the maximum extend of the ice sheets on Gondwana. (3) Such phytoplankton events have also been detected in Gondwanan ice-center area, but with "typical Ordovician taxa crises" occurring apparently later when plotted against positive carbon isotope excursions, as also observed in Baltica. This time-lag may be linked to a basin configuration of the studied areas, where environmental stress consequently differed or linked to the presence of omission surfaces coupled with preservation bias of acritarch assemblages in the uppermost Ordovician strata of Anticosti. In addition to their biostratigraphic and palaeobiogeographic utility, acritarchs turn out to be more specific in highlighting palaeoenvironmental conditions. © 2011 Elsevier B.
UnivIS-Import:2015-03-09:Pub.2011.nat.dgeo.IGM.LG.phytop
Keywords: Baltica; Carbon isotopes; Gondwana; Laurentia; Ordovician-Silurian boundary; Phytoplankton

Pläner: a traditional building stone in Saxo-Bohemian Cretaceous and Münsterland Cretaceous Basin - Lehr, Ralf (Environmental Earth Sciences, 2022)
Sandy-marly siltstones, sandy-silty marlstones, silicified marlstones and marly silicites are the characteristic cyclically deposited sediments in large areas of the Bohemian–Saxonian and Münsterland Cretaceous Basins. In the German-speaking area, these typical sedimentary rocks are called Pläner. In the Czech Republic they are called opuka, in Poland/Lithuania opoka and in France/Wallonia gaize. They can be easily quarried as managable dimensional stones, which can be formatted with little effort and were therefore the preferred material for use as a masonry stone. In the Middle Ages, Pläner was therefore the dominant stone used for exterior architecture. Harder Pläner was used as floor slabs and for paving. In Prague, a local Pläner is exposed with beds reaching a thickness of 1.3 m. This local variety is called the Golden Pläner/zlatá opuka, where it was also used for high-quality sculptural work. The Golden Pläner is therefore a stone with a wide variety of uses. Prague also owes its title as the "Golden City" to this rock. The Golden Pläner is well studied. Its mineral composition, important petrophysical characteristics and weathering behavior have been published in several geoscientific papers. Publications dealing with the other Pläner stones of the Czech Republic, those in Saxony or exposed in the Münsterland are still lacking. The aim of this paper is to illustrate the similarities and differences of the Pläner stones used as a building material from the Cretaceous basins considered here. Four different types of Pläners can be classified based on their primary facies and early diagenetic characteristics, but also the limestones that are called Pläners, which occur within the Pläner sequences and the residuals of these Pläners are considered. The high proportion of very fine-grained constituents requires the combination of several analytical and observational methods such as optical microscopy, microanalysis, powder X-ray diffraction and textural analysis of pore space by mercury porosimetry. To be able to classify the weathering resistance, and thus the possibility of using Pläners as a natural stone, the structural parameters of compressive strength, porosity, water absorption, freeze–thaw resistance and hygric dilatation were also determined.
CRIS-Team Scopus Importer:2022-04-15
Keywords: Münsterland Cretaceous Basin; Opuka; Pläner; Saxo-Bohemian Cretaceous Basin; Silicite

Plant invasion and speciation along elevational gradients on the oceanic island La Palma, Canary Islands - Steinbauer, Manuel; Irl, Severin D. H.; Maria Gonzalez-Mancebo, Juana; Breiner, Frank T.; Hernandez-Hernandez, Raquel; Hopfenmueller, Sebastian; Kidane, Yohannes; Jentsch, Anke; Beierkuhnlein, Carl (Ecology and Evolution, 2017)
Ecosystems that provide environmental opportunities but are poor in species and functional richness generally support speciation as well as invasion processes. These processes are expected not to be equally effective along elevational gradients due to specific ecological, spatial, and anthropogenic filters, thus controlling the dispersal and establishment of species. Here, we investigate speciation and invasion processes along elevational gradients. We assess the vascular plant species richness as well as the number and percentage of endemic species and non-native species systematically along three elevational gradients covering large parts of the climatic range of La Palma, Canary Islands. Species richness was negatively correlated with elevation, while the percentage of Canary endemic species showed a positive relationship. However, the percentage of Canary–Madeira endemics did not show a relationship with elevation. Non-native species richness (indicating invasion) peaked at 500 m elevation and showed a consistent decline until about 1,200 m elevation. Above that limit, no non-native species were present in the studied elevational gradients. Ecological, anthropogenic, and spatial filters control richness, diversification, and invasion with elevation. With increase in elevation, richness decreases due to species–area relationships. Ecological limitations of native ruderal species related to anthropogenic pressure are in line with the absence of non-native species from high elevations indicating directional ecological filtering. Increase in ecological isolation with elevation drives diversification and thus increased percentages of Canary endemics. The best preserved eastern transect, including mature laurel forests, is an exception. The high percentage of Canary–Madeira endemics indicates the cloud forest's environmental uniqueness—and thus ecological isolation—beyond the Macaronesian islands.
Keywords: alien species; altitudinal gradient; colonization; diversification; diversity; endemism; exotic; high-elevation ecosystems; island biogeography

Plant responses to climatic extremes: Within-species variation equals among-species variation - Malyshev, Andrey V.; Khan, Mohammed A. S. Arfin; Beierkuhnlein, Carl; Steinbauer, Manuel; Henry, Hugh A. L.; Jentsch, Anke; Dengler, Juergen; Willner, Evelin; Kreyling, Juergen (Global Change Biology, 2016)
Within-species and among-species differences in growth responses to a changing climate have been well documented, yet the relative magnitude of within-species vs. among-species variation has remained largely unexplored. This missing comparison impedes our ability to make general predictions of biodiversity change and to project future species distributions using models. We present a direct comparison of among- versus within-species variation in response to three of the main stresses anticipated with climate change: drought, warming, and frost. Two earlier experiments had experimentally induced (i) summer drought and (ii) spring frost for four common European grass species and their ecotypes from across Europe. To supplement existing data, a third experiment was carried out, to compare variation among species from different functional groups to within-species variation. Here, we simulated (iii) winter warming plus frost for four grasses, two nonleguminous, and two leguminous forbs, in addition to eleven European ecotypes of the widespread grass Arrhenatherum elatius. For each experiment, we measured: (i) C/N ratio and biomass, (ii) chlorophyll content and biomass, and (iii) plant greenness, root 15N uptake, and live and dead tissue mass. Using coefficients of variation (CVs) for each experiment and response parameter, a total of 156 within- vs. among-species comparisons were conducted, comparing within-species variation in each of four species with among-species variation for each seed origin (five countries). Of the six significant differences, within-species CVs were higher than among-species CVs in four cases. Partitioning of variance within each treatment in two of the three experiments showed that within-species variability (ecotypes) could explain an additional 9% of response variation after accounting for the among-species variation. Our observation that within-species variation was generally as high as among-species variation emphasizes the importance of including both within- and among-species variability in ecological theory (e.g., the insurance hypothesis) and for practical applications (e.g., biodiversity conservation).
Keywords: Disturbance; Extreme climatic events; Genetic diversity; Inter-specific variation; Intraspecific variation; Niche models; Provenance

Plasticity and seasonality of the vertical migration behaviour of Antarctic krill using acoustic data from fishing vessels - Bahlburg, Dominik; Hüppe, Lukas; Böhrer, Thomas; Thorpe, Sally E.; Murphy, Eugene J.; Berger, Uta; Meyer, Bettina (Royal Society Open Science, 2023)
Understanding the vertical migration behaviour of Antarctic krill is important for understanding spatial distribution, ecophysiology, trophic interactions and carbon fluxes of this Southern Ocean key species. In this study, we analysed an eight-month continuous dataset recorded with an ES80 echosounder on board a commercial krill fishing vessel in the southwest Atlantic sector of the Southern Ocean. Our analysis supports the existing hypothesis that krill swarms migrate into deeper waters during winter but also reveals a high degree of variability in vertical migration behaviour within seasons, even at small spatial scales. During summer, we found that behaviour associated with prolonged surface presence primarily occurred at low surface chlorophyll a concentrations whereas multiple ascent-descent cycles per day occurred when surface chlorophyll a concentrations were elevated. The high plasticity, with some krill swarms behaving differently in the same location at the same time, suggests that krill behaviour is not a purely environmentally driven process. Differences in life stage, physiology and type of predator are likely other important drivers. Finally, our study demonstrates new ways of using data from krill fishing vessels, and with the routine collection of additional information in potential future projects, they have great potential to significantly advance our understanding of krill ecology.
CRIS-Team Scopus Importer:2023-10-27
Keywords: Antarctic krill; seasonal vertical migration; vertical migration behaviour

Plastikmüllbelastung im Nordpolarmeer - Analyse der Mikroplastikkontamination arktischer Bohrmuscheln - Teichert, Sebastian; Löder, Martin; Pyko, Ines; Schulbert, Christian; Wisshak, Max; Laforsch, Christian (GIT Labor-Fachzeitschrift, 2022)

Platinum-group element concentrations in base-metal sulphides from the Platreef, Mogalakwena Platinum Mine, Bushveld Complex, South Africa - Klemd, Reiner; Junge, Malte; Oberthür, Thomas; Herderich, Tobias; Schouwstra, R. P.; Roberts, Jaques (South African Journal of Geology, 2016)
Base-metal sulphides (BMS) are important host minerals for platinum-group elements (PGE) in orthomagmatic Ni-Cu-PGE deposits. The PGE distribution and concentration in the BMS provide important genetic, exploration and mineral processing information. Therefore, detailed mineralogical work and an in situ laser ablation inductively-coupled plasma mass spectrometry (LA-ICP-MS) analysis of trace elements were conducted on the BMS of mineralised samples from the Overysel and Sandsloot localities of the Mogalakwena Platinum Mine. These localities access the Platreef of the northern Bushveld Complex. Platinum-group element enrichment trends in the BMS are similar in the Overysel and Sandsloot samples, although the overall PGE concentrations in the Overysel BMS are lower than those in the Sandsloot BMS. A general decoupling of the PGE from the BMS due to fluid activity, as advocated by other authors for the Sandsloot reef lithologies, was not observed in the samples studied. A major portion of the PGE mineralisation is associated with BMS as is indicated by the ‘moderate’ (Overysel r = +0.62) to ‘very good’ (Sandsloot r = +0.79) PPGE-S bulk-rock correlation, whereas an excellent PPGE-Ni correlation (especially at Overysel) indicates that pentlandite is a major PGE- carrier. These results are corroborated by the trace element contents of the BMS and by mass balance calculations. For instance, the LA-ICP-MS BMS study revealed average concentrations of 65 to 165 ppm Pd and 0.17 to 13 ppm Rh at Overysel, and 156 to 412 ppm Pd and 18 to 57 ppm Rh at Sandsloot in pentlandite of both the mineralized pyroxenites. In contrast, chalcopyrite and pyrrhotite are almost devoid of PGE. Platinum and the IPGE (Ir, Os, Ru) are very low in the BMS and, therefore, are thought to be hosted in discrete PGM grains. This conclusion is supported by the mass balance calculations for Pt and by the actual presence of PGM grains in both sample suites. The presence of discrete PGM grains explains the calculated gap between the whole-rock PPGE concentrations and the PPGE concentration in the mineral phases as revealed by the mass balance calculations. The PPGE concentrations in the BMS and the complementary mass balance calculations are in general agreement with those of the Merensky Reef and the UG-2, in both of which large proportions of the whole-rock Pd and Rh are hosted by pentlandite, whereas Pt and the IPGE mainly occur in discrete PGM rather than being hosted by BMS. However, comparison of our results with those of the Merensky Reef and the UG-2 indicates that the average maximum Pd and Rh concentrations in pentlandite are distinctly lower in the Platree
Keywords: Africa; base metals; Bushveld Complex; copper ores; geochemical methods; ICP mass spectra; igneous rocks; Malmani Subgroup; mass spectra; metal ores; metals; mineral exploration; nickel ores; platinum group; platinum ores; plutonic rocks; pyroxenite; South Africa; Southern Africa; spectra; sulfides; ultramafics; whole rock; Sandsloot Mine; Mogalakwena Mine; Platreef Mine

Platinum-group element distribution in base-metal sulfides of the Merensky Reef from the eastern and western Bushveld Complex, South Africa. - Osbahr, Inga; Klemd, Reiner; Oberthuer, Thomas; Brätz, Helene; Schouwstra, Robert (Mineralium Deposita, 2013)
Base-metal sulfides in magmatic Ni-Cu-PGE deposits are important carriers of platinum-group elements (PGE). The distribution and concentrations of PGE in pentlandite, pyrrhotite, chalcopyrite, and pyrite were determined in samples from the mineralized portion of four Merensky Reef intersections from the eastern and western Bushveld Complex. Electron microprobe analysis was used for major elements, and in situ laser ablation inductively-coupled plasma mass spectrometry (LA-ICP-MS) for trace elements (PGE, Ag, and Au). Whole rock trace element analyses were performed on representative samples to obtain mineralogical balances. In Merensky Reef samples from the western Bushveld, both Pt and Pd are mainly concentrated in the upper chromitite stringer and its immediate vicinity. Samples from the eastern Bushveld reveal more complex distribution patterns. In situ LA-ICP-MS analyses of PGE in sulfides reveal that pentlandite carries distinctly elevated PGE contents, whereas pyrrhotite and chalcopyrite only contain very low PGE concentrations. Pentlandite is the principal host of Pd and Rh in the ores. Palladium and Rh concentrations in pentlandite reach up to 700 and 130 ppm, respectively, in the samples from the eastern Bushveld, and up to 1,750 ppm Pd and up to 1,000 ppm Rh in samples from the western Bushveld. Only traces of Pt are present in the base-metal sulfides (BMS). Pyrrhotite contains significant though generally low amounts of Ru, Os, and Ir, but hardly any Pd or Rh. Chalcopyrite contains most of the Ag but carries only extremely low PGE concentrations. Mass balance calculations performed on the Merensky Reef samples reveal that in general, pentlandite in the feldspathic pyroxenite and the pegmatoidal feldspathic pyroxenite hosts up to 100 % of the Pd and Rh and smaller amounts (10-40 %) of the Os, Ir, and Ru. Chalcopyrite and pyrrhotite usually contain less than 10 % of the whole rock PGE. The remaining PGE concentrations, and especially most of the Pt (up to 100 %), are present in the form of discrete platinum-group minerals such as cooperite/braggite, sperrylite, moncheite, and isoferroplatinum. Distribution patterns of whole rock Cu, Ni, and S versus whole rock Pd and Pt show commonly distinct offsets. The general sequence of "offset patterns" of PGE and BMS maxima, in the order from bottom to top, is Pd in pentlandite → Pd in whole rock → (Cu, Ni, and S). The relationship is not that straightforward in general; some of the reef sequences studied only partially show similar trends or are more complex. In general, however, the highest Pd concentrations in pentlandite appear to be related to the earliest, volumetrically rather small sulfide liquids at the base of the Merensky Reef sequence. A possible explanation for the offset patterns may be Rayleigh fractionation. © 2012 Springer-Verlag.
UnivIS-Import:2015-03-09:Pub.2013.nat.dgeo.IGM.c3geoc.platin
Keywords: Base-metal sulfides; Bushveld Complex; LA-ICP-MS; Merensky Reef; Platinum-group elements; South Africa; Trace element distribution patterns

Platinum-group element distribution in base-metal sulfides of the UG2 chromitite, Bushveld Complex, South Africaa reconnaissance study - Osbahr, Inga; Oberthuer, Thomas; Klemd, Reiner; Josties, Anja (Mineralium Deposita, 2014)
Two drill cores of the UG2 chromitite from the eastern and western Bushveld Complex were studied by whole-rock analysis, ore microscopy, SEM/Mineral Liberation Analysis (MLA), and laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) analysis. The top and base of the UG2 main seam have the highest bulk-rock Pd and Pt concentrations. Sulfides mostly occur as aggregates of pentlandite, chalcopyrite, and rare pyrrhotite and pyrite or as individual grains associated mostly with chromite grains. In situ LA-ICP-MS analyses reveal that pentlandite carries distinctly elevated platinum-group element (PGE) contents. In contrast, pyrrhotite and chalcopyrite contain very low PGE concentrations. Pentlandite shows average maximum values of 350-1,000 ppm Pd, 200 ppm Rh, 130-175 ppm Ru, 20 ppm Os, and 150 ppm Ir, and is the principal host of Pd and Rh in the studied ores of the UG2. Mass balance calculations were conducted for samples representing the UG2 main seam of the drill core DT46, eastern Bushveld. Pentlandite consistently hosts elevated contents of the whole-rock Pd (up to 55 %) and Rh (up to 46 %), and erratic contents of Os (up to 50 %), Ir (2 to 17 %), and Ru (1-39 %). Platinum-group mineral (PGM) investigations support these mass balance results; most of the PGM are Pt-dominant such as braggite/cooperite and Pt-Fe alloys or laurite (carrying elevated concentrations of Os and Ir). Palladium and Rh-bearing PGM are rare. Both PGE concentrations and their distribution in base-metal sulfides (BMS) in the UG2 largely resemble that of the Merensky Reef, as most of the Pd and Rh are incorporated in pentlandite, whereas pyrrhotite, chalcopyrite, and pyrite are almost devoid of PGE. © 2014 Springer-Verlag Berlin Heidelberg.
UnivIS-Import:2015-03-09:Pub.2014.nat.dgeo.IGM.c3geoc.platin
Keywords: Bushveld Complex; LA-ICP-MS; MLA; Platinum-group elements (PGE); South Africa; UG2

Pleistocene paleo-groundwater as a pristine fresh water resource in southern Germany - Evidence from stable and radiogenic isotopes - van Geldern, Robert; Baier, Alfons; Subert, Hannah Lisa; Kowol, Sigrid; Balk, Laura; Barth, Johannes (Science of the Total Environment, 2014)

Pleistocene to Recent rejuvenation of the Hebron Fault, south-western Namibia. - White, Stephen; Stollhofen, Harald; Stanistreet, Ian G.; Lorenz, Volker (Palaeoseismology: Historical and prehistorical records of earthquake ground effects for seismic hazard assessment, 2009)
The Hebron Fault in SW Namibia is associated with a ,1 m to 9.6 m high scarp displacing Proterozoic basement and Middle to Late Pliocene crystalline conglomerates. The young age of strata exposed in the fault scarp together with evidence for displacement of aeolian dunes, post-dating the Middle Stone Age, suggests that latest fault displacements occurred during the Late Pleistocene to recent. Recorded historical seismic events show that the fault zone is still active. Latest movements of the fault are recorded by: down-to-the-SW offset of calcretecemented conglomerate; fluvially modified, asymmetric hanging wall, graben-like structures; at least two left-stepping jogs in the fault trace and structural data from basement rocks in which late-stage crush zones overprint earlier cataclasite. These features provide consistent evidence that the present scarp formed predominantly by normal dip-slip displacement on a NW-striking, steeply SW-dipping master fault with only a minor dextral strike-slip component. Strongly veined cataclastic fault rocks adjacent to the scarp in basement most probably originated at depths of 4–10 km. The conclusion is therefore that recent fault activity has reactivated a preexisting, much older fault. Aerial photographic lineaments and similar fault scarps identifiedNWand SE of the present study area are interpreted as extensions of the same fault structure. Hence the total length of the Hebron Fault is at least 300 km subparallel to the Atlantic margin of southern Africa. Our observations confirm that the Hebron Fault is a neotectonic feature of regional significance that may relate to late Cenozoic and particularly Quaternary neotectonic activity in NE Namibia and NW Botswana.
UnivIS-Import:2015-04-20:Pub.2009.nat.dgeo.IGM.LG.pleist_1

Pleistocene to Recent scleractinian deep-water corals and coral facies in the Eastern Mediterranean - Taviani, Marco; Vertino, Agostina; López Correa, Matthias; Savini, Alessandra; De Mol, Ben; Remia, Alessandro; Montagna, Paolo; Angeletti, Lorenzo; Zibrowius, Helmut; Alves, Tiago; Salomidi, Maria; Ritt, Bénédicte; et al. (Facies, 2011)
Recent investigations of the Eastern Mediterranean Sea carried out during the GECO cruise with RV Urania provided a substantial number of new cold-water coral (CWC) records, including branching and solitary scleractinian species. These new sites are located along steep escarpments and on topographic highs along the margins of Crete, Karpathos, and Rhodes. The majority of the corals represent fossil occurrences, predominantly Late Pleistocene assemblages. Our research documents that the Eastern Mediterranean Basin has been colonized by CWC at favorable times during the Last Glacial, in particular during the Younger Dryas. Schizocyathus fissilis is reported for the first time for the Mediterranean, while the finding of Ceratotrochus magnaghii represents the first record for the Eastern Mediterranean. Various coral facies occur on the southerly island slopes of Crete, Karpathos, and Rhodes, including hardgrounds and loose skeletal sediments. Hardgrounds occur on steep topographies between ca. 500 and 1,700 m, and can conveniently be subdivided as (1) Neopycnodonte-Desmophyllum framestone, (2) Desmophyllum-Caryophyllia framestone, (3) Madrepora-Lophelia rudstone, (4) Pelagic mudstone and wackestone, and (5) Siliciclastic-carbonate conglomerate and breccia. Unconsolidated skeletal sediments containing corals mainly occur on gentler topographic situations between ca. 140 and 600 m and can be subdivided as: (A) Lophelia-Madrepora rubble, (B) Dendrophyllia rubble, (C) Stenocyathus rubble, (D) Caryophyllia calveri rubble, and (E) fine-grained sediment with octocoral axes. Many of these facies types are also present in the western part of the Mediterranean and have fossil representatives from the Pleistocene to the Recent. Radiocarbon dating (AMS- 14C) reveals Younger Dryas ages between 12.4 and 12.0 ka cal BP for Lophelia pertusa and Madrepora oculata. Desmophyllum dianthus occurs during the Last Glacial Maximum (21.8 ka cal BP) and the Younger Dryas (11.7 ka cal BP), as well as during the Late Holocene and subrecent times (4.4-0.6 ka cal BP). Caryophyllia sarsiae occurs during the Late Glacial (15.5 ka cal BP), while Caryophyllia calveri occurs during the Early Preboreal (10.8 ka cal BP). The ages for the framework-constructing corals L. pertusa and M. oculata are coherent with their temporal predominance during the Younger Dryas in other parts of the Mediterranean. © 2010 Springer-Verlag.
UnivIS-Import:2015-03-09:Pub.2011.nat.dgeo.IGM.LP.pleist
Keywords: Cold-water corals; Eastern Mediterranean; Facies; Holocene; Late Pleistocene

Pliocene-Pleistocene climate change, sea-level and uplift history recorded by the Horingbaai fan-delta, NW Namibia. - Stollhofen, Harald; Stanistreet, Ian G.; Von Hagke, Christoph; Nguno, Anna (Sedimentary Geology, 2014)
Its location on a tectonically relatively stable passive margin and its degree of interaction with the sea make the Horingbaai fan-delta, NW Namibia, an exceptional record of coastal activity, providing insights into the response of ephemeral fluvial systems to changes in climate, sea level and continent-scale uplift. The fan comprises upper, middle and lower segments. The upper fan and middle fan are dominated by a braided river system; only in the upper fan are fluvial sediments interleaved with hyperconcentrated flow deposits. Plio-Pleistocene sea level highstands have left marine terraces on the fan surface which enable correlation with the offshore marine record and provide timelines to constrain fan growth. The bulk of fan-delta progradation took place at . 2.7-2.4. Ma, between the formation of a widespread erosional surface incising the middle Pliocene Karpfenkliff and Kamberg Formations, but prior to the emplacement of the warm-water fauna-bearing late Pliocene "Oyster Terrace" ( . 2.4-2.2. Ma), an equivalent of the +. 30 mP (marine terrace package) in coastal southwestern Africa. Major fan progradation is contemporaneous with widespread regional uplift ( . 12. ±. 5. m/Ma) and climate change in southwestern Africa, the latter associated with intensification of northern hemisphere glaciations. Younger fan growth phases are weaker and constrained by <. 10. m asl marine terrace bodies that yield mostly cold-water fauna, corresponding to the onset of strong glacial/interglacial climatic fluctuations superimposed on a general aridification trend and the introduction of colder sea-surface temperatures after 2.2. Ma. © 2014 Elsevier B.V.
UnivIS-Import:2015-03-09:Pub.2014.nat.dgeo.IGM.LG.plioce
Keywords: Alluvial fan; Climate change; Marine terraces; Namibia; Sea level; Uplift

Plio-Pleistocene syn-sedimentary fault compartments underpin lake margin paleoenvironmental mosaic, Olduvai Gorge, Tanzania - Stollhofen, Harald; Stanistreet, Ian G. (Journal of Human Evolution, 2012)
Normal faults displacing Upper Bed I and Lower Bed II strata of the Plio-Pleistocene Lake Olduvai were studied on the basis of facies and thickness changes as well as diversion of transport directions across them in order to establish criteria for their synsedimentary activity. Decompacted differential thicknesses across faults were then used to calculate average fault slip rates of 0.05e0.47 mm/yr for the Tuff IE/IF interval (Upper Bed I) and 0.01e0.13 mm/yr for the Tuff IF/IIA section (Lower Bed II). Considering fault recurrence intervals of w1000 years, fault scarp heights potentially achieved average values of 0.05 e0.47 m and a maximum value of 5.4 m during Upper Bed I, which dropped to average values of 0.01 e0.13 m and a localized maximum of 0.72 m during Lower Bed II deposition. Synsedimentary faults were of importance to the form and paleoecology of landscapes utilized by early hominins, most traceably and provably Homo habilis as illustrated by the recurrent density and compositional pattern of Oldowan stone artifact assemblage variation across them. Two potential relationship factors are: (1) fault scarp topographies controlled sediment distribution, surface, and subsurface hydrology, and thus vegetation, so that a resulting mosaic of microenvironments and paleoecologies provided a variety of opportunities for omnivorous hominins; and (2) they ensured that the most voluminous and violent pyroclastic flows from the Mt. Olmoti volcano were dammed and conduited away from the Olduvai Basin depocenter, when otherwise a single or set of ignimbrite flows might have filled and devastated the topography that contained the central lake body. In addition, hydraulically active faults may have conduited groundwater, supporting freshwater springs and wetlands and favoring growth of trees.
UnivIS-Import:2015-03-09:Pub.2012.nat.dgeo.IGM.LG.pliopl

Plume-ridge interaction revisited: Evidence for melt mixing from He, Ne and Ar isotope and abundance systematics - Stroncik, Nicole; Niedermann, Samuel; Haase, Karsten (Earth and Planetary Science Letters, 2008)
Submarine volcanic glass He, Ne and Ar data from the Pacific-Antarctic-Rise at its intersection with the Foundation Seamount Chain have been obtained to further elucidate one of the main outstanding problems in plume-ridge interaction studies: the physical state in which mantle flow and mixing occur in those settings. Mixing of plume mantle and mid-ocean ridge basalt source material may either be in the form of two solids, of solid-melt or of two melt phases only. The positive correlation of 4He/ 40Ar * with 206Pb/ 204Pb as well as the negative correlation of 4He/ 40Ar * with 40Ar * and 4He concentrations, combined with a lack of correlation between 4He/ 40Ar * and ridge depth or MgO concentration, indicate that the enriched mantle plume material has been extensively degassed prior to mixing with the mid-ocean ridge source material. Degassing of the plume source and mid-ocean ridge source material prior to mixing is also suggested by the He versus Pb isotope systematics. However, the occurrence of degassing processes requires the existence of melts, implying that mixing between the plume and the mid-ocean ridge material occurs in the physical form of melts. © 2008 Elsevier B.V. All rights reserved.
UnivIS-Import:2015-03-09:Pub.2008.nat.dgeo.IGM.legeo.plumer
Keywords: degassing; mixing processes; noble gases; partial melting; plume-ridge interaction

Plumes and their role in whole mantle convection and recycling - Beier, Christoph; Rushmer, Tracy; Turner, Simon; Widom, Elizabeth; Franca, Zilda (GSA Today, 2008)
The Azores plume provides evidence for Archaean subduction and long term storage in the mantle. It has low buoyancy flux, large variation in radiogenic and stable isotopes in erupted products, and contains evidence for recycling of materials subducted beneath an arc. The mantle plumes' importance and impact to the geodynamic evolution and behavior of Earth's mantle have urged geochemists, experimentalists, modelers, and seismologists to conduct a conference. The meeting will be held at the Aldeia da Fonte Hotel in Pico, Azores. It will include three days of presentations and two days of field observations.

Polar coralline algal CaCO3-production rates correspond to intensity and duration of the solar radiation - Teichert, Sebastian; Freiwald, André (Biogeosciences, 2014)
In this study we present a comparative quantification of CaCO3 production rates by rhodolith-forming coralline red algal communities situated in high polar latitudes and assess which environmental parameters control these production rates. The present rhodoliths act as ecosystem engineers, and their carbonate skeletons provide an important ecological niche to a variety of benthic organisms. The settings are distributed along the coasts of the Svalbard archipelago, being Floskjeret (78°18' N) in Isfjorden, Krossfjorden (79°08' N) at the eastern coast of Haakon VII Land, Mosselbukta (79°53' N) at the eastern coast of Mosselhalvøya, and Nordkappbukta (80°31' N) at the northern coast of Nordaustlandet. All sites feature Arctic climate and strong seasonality. The algal CaCO3 production rates were calculated from fuchsine-stained, presumably annual growth increments exhibited by the rhodoliths and range from 100.9 g (CaCO3) m−2 yr−1 at Nordkappbukta to 200.3 g (CaCO3) m−2 yr−1 at Floskjeret. The rates correlate to various environmental parameters with geographical latitude being the most significant (negative correlation, R2 = 0.95, p = 0.0070), followed by the duration of the polar night (negative correlation, R2 = 0.93, p = 0.0220), the duration of the sea ice cover (negative correlation, R2 = 0.87, p = 0.0657), and the annual mean temperature (positive correlation, R2 = 0.48, p = 0.0301). This points out sufficient light incidence to be the main control of the growth of the examined coralline red algal rhodolith communities, while temperature is less important. Thus, the ongoing global change with its rising temperatures will most likely result in impaired conditions for the algae, because the concomitant increased global runoff will decrease water transparency and hence light incidence at the four offshore sites. Regarding the aforementioned role of the rhodoliths as ecosystem engineers, the impact on the associated organisms will presumably also be negative.
UnivIS-Import:2015-03-09:Pub.2014.nat.dgeo.IGM.LP.polarc
Keywords: carbonate factories; coralline red algae; Lithothamnion glaciale; polar night; photosynthesis; rhodoliths; sea ice; solar radiation; Svalbard

Polar coralline red algae as potential environmental recorder. - Teichert, Sebastian; Freiwald, André (2nd International Sclerochronology Conference, 2010)
UnivIS-Import:2015-04-16:Pub.2010.nat.dgeo.IGM.LP.polarc_6

Poly-cyclic Metamorphic Evolution of Eclogite: Evidence for Multistage Burial–Exhumation Cycling in a Subduction Channel - Li, Jilei; Klemd, Reiner; Gao, Jun; John, Timm (Journal of Petrology, 2016)
(Ultra-)high-pressure [(U)HP] eclogites provide direct evidence for metamorphic processes at mantle depths in subduction zones. Textural evidence and pressure–temperature ( P – T ) path reconstruction allow a unique opportunity to constrain the geodynamic processes along the plate interface. To better understand the dynamics of subduction channels, we present a detailed petrographical, petrological and pseudosection modeling study of a metamorphically complex HP eclogite sample from a tectonic block of the Akeyazi (U)HP metamorphic terrane in the Chinese Tianshan. Mineral chemical variations and textural discontinuities show that all the major phases of the rock (garnet, epidote, clinopyroxene and amphibole) display multiple growth zones compatible with a poly-cyclic evolution including two burial–exhumation cycles. The precise P – T path derived from thermodynamic modeling based on effective bulk compositions suggests that the eclogite underwent complex burial–exhumation cycles with two P – Tloops indicated by the occurrence of polyphase garnet and mutually replaced and regrown amphibole. It is suggested that the eclogite sample, which represents a relic of tectonically detached oceanic crust, underwent two burial–exhumation cycles during convective flow in a subduction channel. This natural occurrence is consistent with numerical simulation studies showing that pressure cycling is to be expected for deeply subducted oceanic crust in a subduction channel. The modeled exhumation process for the eclogite sample corresponds to a previously suggested subduction channel exhumation model for the Akeyazi (U)HP rocks.<br
Keywords: subduction channel; Chinese Tianshan; eclogite; poly-cyclic metamorphism; polyphase mineral growth; pseudosection; P–T path