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

Petrogenesis of the early Permian Hongliujing granite complex in the Chinese Eastern Tianshan orogen: Evidence for crustal growth in the Central Tianshan microcontinent - He, Zhen Yu; Klemd, Reiner; Lu, Tian Yu; Yan, Li Li; Xiang, Hua (Geological Society of America Bulletin, 2024)
The generation and modification of silicic magma systems are essential processes in resolving the differentiation of continental crust. This understanding motivated the geochronological and geochemical study of the early Permian Hongliujing granite complex, consisting of quartz monzonite, granite, and leucogranite in the Central Tianshan microcontinent of the southern Central Asian Orogenic Belt. Laser ablation–inductively coupled plasma–mass spectrometry (LA-ICP-MS) zircon U-Pb dating of the Hongliujing complex rock units revealed almost identical ages (279 ± 2 Ma to 270 ± 2 Ma). The high-silica leucogranite and granite are characterized by positive Rb and negative Eu anomalies and Ba, Sr, P, and Ti depletions. The zircon trace elements are characterized by relatively low Ti and Th/U and high Yb/Gd. In contrast, the quartz monzonite and its mafic microgranular enclaves display minor negative Ba, Sr, P, Ti, and Eu anomalies, while the zircon trace elements are characterized by relatively high Ti and Th/U and low Yb/Gd. The complex has similar zircon Hf and whole-rock Nd isotopic compositions, with Hf and Nd model ages younger than 1.4 Ga, suggesting that their magmas were derived from an isotopically depleted mantle, with some contributions from crustal melts. The leucogranites further showed relatively large variations of εHf(t) and lower εNd(t) values, implying that their magma was affected by higher amounts of crustal contamination. We suggest that crystal-melt segregation was the major mechanism responsible for the evolution of the magmatic system, and that the early Permian magmatism represents a crust-forming episode triggered by slab rollback of the subducting South Tianshan oceanic plate beneath the eastern Central Tianshan microcontinent. Thus, our study reveals that microcontinents with Precambrian crustal basement were major sites of juvenile continental growth during the accretionary evolution of the Central Asian Orogenic Belt.
CRIS-Team Scopus Importer:2024-08-16

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 Anna; 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

Polyphase growth history of peritectic garnet from a granite: Trace-element zonation, Lu-Hf ages and their significance for the duration of granite-forming processes - Jung, S.; Pfänder, J. A.; Mezger, K.; Hellebrand, E.; Brandt, Sönke (Lithos, 2022)
Determining the ages and duration of high-grade metamorphic episodes during orogenesis and concomitant melt extraction events is pivotal in reconstructing and quantifying the chemical and petrological evolution of the Earth's continental crust over time. Major and trace elements combined with multichronometric garnet data from the Pan-African Damara belt of Namibia place absolute time constraints on high-grade regional metamorphism and melting in the lower crust that led to the production of widespread granites emplaced in the upper crust. Some of these granites contain inherited peritectic garnet with inferred igneous rims that record their genesis and evolution from formation by partially melting in the deep crust to the emplacement of their host rock at shallower levels. Particular characteristics of these garnets are textural and chemical disequilibrium features such as resorption, local development of partly euhedral crystal faces and occurrence of quartz-feldspar stringers in the rim of the garnet and trace element abundances with sharp concentration gradients. These features document a previous melting event followed by garnet crystallization in an ascending melt. With the exception of the outermost rim, which records late-stage diffusional features, the garnet crystals have constant Mg and Mn concentrations. In contrast, Ca shows pronounced chemical zoning. Trace elements (HREE, LREE, Zr, Sr, Y) are depleted in the core and enriched in the rim region indicating disequilibrium conditions during garnet growth. A pseudosection calculated with the garnet rim composition and the composition of the host granite yields P-T conditions of 0.62 GPa and 760 °C for the formation of the rim. This result is consistent with a P-T estimate of 0.68 GPa and 760 °C derived from the conventional garnet-biotite thermobarometer. Regional metamorphic conditions were above the cordierite-andalusite stability field with estimated conditions of 550-600 °C and 0.4–0.5 GPa. This P-T regime indicates that the garnet originally crystallized at deep crustal levels. Diffusion modelling suggests that the observed concentration gradient of Sm in garnet is consistent with a maximum duration of ca. 0.5–1.5 Ma for the inferred melting interval during peak metamorphism in the lower crust. High-precision multi-point Lu-Hf garnet-whole rock data yield dates of 522.0 ± 1.0 and 522.3 ± 0.9 Ma for two samples. Because of presumed short intervals between melting in the lower crust and intrusion of the granite, these dates are interpreted as the age of the melting event during high-grade metamorphism and are temporally indistinguishable from the crystallization interval. Thus, dehydration melting in the deeper crust during peak metamorphism produced peritectic garnet that was incorporated into the granitic melt followed by subsequent new growth of igneous garnet around peritectic cores during intrusion. Previously obtained Sm-Nd garnet whole rock ages are 20–25 Ma younger and likely represent cooling ages. This study shows that granites enriched in mafic components such as garnet and biotite may intrude as mixtures of melt and the peritectic assemblage produced by incongruent melting involving dehydration-melting of biotite in the lower crust. Melting episodes represent short-lived processes relative to the absolute duration of orogenic cycles.
CRIS-Team Scopus Importer:2022-04-15
Keywords: Damara orogen; Lu-Hf garnet dating; Peritectic garnet; Pseudosection modelling; Trace element garnet

Pore‑fluid‑dependent controls of matrix and bulk thermal conductivity of mineralogically heterogeneous sandstones - Kämmlein, Marion; Stollhofen, Harald (Geothermal Energy, 2019)
For a variety of geothermal engineering applications, the only indirectly determinable matrix thermal conductivity (λm) is frequently used to convert the measured bulk rock thermal conductivity (λb) of air-saturated sandstones to water-saturated conditions. However, the necessary assumption that the absolute value of λm remains constant irrespective of the pore fluid present turns out to be not valid in practice and the explicit control factors on λm have not been demonstrated yet for different pore fluids. A pore fluid-controlled change in the λm value also questions the transferability of empirical proxy models for the estimation of water-saturated λb when they were calibrated on air-saturated samples. This study applies a multiple regression analysis to quantitative mineralogical composition data and porosity (Φ) to identify the controls of the λm for different types of pore fluids (water- vs. air-saturation). In addition, the differences in the calculated λm values resulting from different calculation methods or input data (theoretical geometric mean model or mineralogical composition data) are examined. We further test the suitability of different sandstone properties as potential proxies for the estimation of the λb, with respect to the pore fluid type. Differences in the absolute value of λm of sandstones from different measurement conditions (air- or water-saturated) are most probably related to the formation of authigenic kaolinite in the pore space, originating from the alteration of alkali feldspar. In addition, the thermal properties of the rock matrix are mainly controlled by the volume fractions of the high thermally conductive mineral fractions quartz and dolomite. Empirical models that have solely Φ or P-wave velocity (vp) as variables are not suitable for the prediction of water-saturated λb of sandstones. Instead, quantitative mineralogical data of high thermally conductive mineral phases such as quartz and dolomite have to be included. The easily measureable vp is proposed as a promising proxy for both pore fluid types tested: combined with the total quartz volume/porosity ratio for air-saturated sandstones, and combined with the quartz plus dolomite volume fractions for water-saturated sandstones.<br
Keywords: Matrix thermal conductivity; Bulk thermal conductivity; Pore fluid; Sandstone; Mineralogical composition; Anisotropy

Porenüberdruck im Bayerischen Molassebecken - Drews, Michael; Bauer, Wolfgang; Stollhofen, Harald (Erdoel Erdgas Kohle/EKEP, 2018)

Porenüberdruck im Bayerischen Molassebecken - Drews, Michael; Bauer, Wolfgang; Stollhofen, Harald (DGMK Tagungsbericht 2018-April, 2018)

Pore structure of hardened cement paste containing colloidal polymers with varied glass transition temperature and surface charges - Zhang, Chaoyang; Kong, Xiangming; Lu, Zichen; Jansen, Daniel; Pakusch, Joachim; Wang, Shengxian (Cement & Concrete Composites, 2019)
Influences of four polymer latexes with varied glass-transition-temperature (Tg) and colloidal surface properties on pore structure of hardened cement pastes (hcps) were investigated by means of mercury intrusion porosimetry (MIP), nitrogen adsorption measurement (NAM) and SEM. MIP measurement indicates that polymer addition leads to increase of total pore volume and threshold pore size, whereas NAM shows that pore volume in the range of 2–100 nm decreases with addition of polymers, implying a sealing effect. The conflicting results between MIP and NAM originate from destruction and movement of the polymer phase by high pressure mercury intrusion during MIP measurement. SEM reveals that low-Tg polymers form continuous film while high-Tg polymers remain particle form in hcps. The film-forming polymers provide stronger sealing effect than the non-film-forming polymers. Moreover, the non-adsorbing polymers exhibit stronger sealing effect than the adsorbing polymers due to their preferential locations in aqueous phase of fresh cement paste.
CRIS-Team Scopus Importer:2019-10-08
Keywords: Hardened cement paste (hcp); Polymer latex; Pore structure; Sealing effect

Porphyry and epithermal deposits in Greece: An overview, new discoveries, and mineralogical constraints on their genesis - Voudouris, P.; Mavrogonatos, C.; Spry, P. G.; Baker, T.; Melfos, V.; Klemd, Reiner; Haase, Karsten; Repstock, A.; Djiba, A.; Bismayer, U.; Tarantola, A.; Scheffer, C.; et al. (Ore Geology Reviews, 2019)
Greece hosts a variety of magmatic-hydrothermal ore deposits/prospects with porphyry- and epithermal styles playing a major role in its total gold endowment. These deposit types are mainly clustered in two areas, the Rhodope- and Attico-Cycladic massifs, and formed from about 33 Ma to the Pleistocene, as a result of back-arc extension in the Aegean Sea, metamorphic core complex formation, and contemporaneous post-subduction and arc magmatism. In the Serbo-Macedonian massif, porphyry Cu-Au deposits include Skouries, Fisoka, Tsikara, Vathi and Gerakario. Causative intrusives are Oligocene to Miocene granodiorites to monzonites. Gold and PGE mineralization is associated with potassic alteration of the intrusives. In the eastern Rhodope massif and the NE Aegean islands, porphyry prospects occur at Pagoni Rachi, Konos Hill, Myli, Melitena (west Thrace), Fakos, Sardes, and Kaspakas (Limnos island) and Stypsi (Lesvos island). Mineralization is associated with Oligocene to Miocene subvolcanics of calc-alkaline to shoshonitic affinity. Feature of these prospects, which they share in common with several porphyry Au-only systems, is their shallow depth of emplacement, the presence of potassic/sodic-calcic and/or phyllic alteration, a strong epithermal overprint, their low Cu content, an extreme Re-enrichment, the multistage introduction of Au, the presence of banded quartz veinlets, and the local presence of tourmaline. New discoveries of porphyry-style mineralization at King Arthur, St. Philippos and Aisymi, increases the gold potential in west Thrace. High-intermediate sulfidation epithermal Au-Ag polymetallic deposits/prospects overprint and/or occur laterally from porphyry-style mineralization, where they are spatially associated with lithocaps of advanced argillic alteration. High-intermediate sulfidation Au-Ag epithermal mineralization at Perama Hill, Mavrokoryfi and Pefka in west Thrace, and at Pterounda, Mesotopos and Megala Therma on Lesvos island is controlled by steeply-dipping extensional faults within volcanic rocks, without any obvious genetic relationship to spatially-related porphyry-style mineralization. Polymetallic epithermal deposits and prospects contain critical and energy critical metals (e.g., Te, Se, Bi, Sb, In, Ge and Ga), which may be considered as by-products. In the Attico-Cycladic area, porphyry Mo-W mineralization occurs as sheeted quartz veins and stockworks cutting a potassic- to sericitic-altered Miocene granodiorite stock in the Lavrion district. Bonanza grade Au- and/or Ag-rich veins with epithermal affinities crosscut metamorphic rocks at Lavrion, and on Syros, Tinos, Antiparos and Anafi islands. Milos island is characterized by shallow submarine volcanic-hosted IS-HS epithermal Au-Ag-Te and base metal deposits. Antimony-As-Ag-Au deposits/prospects on Chios, Samos and Kos islands in the eastern Aegean Sea, indicate the potential for Carlin-style mineralization in Greece. Several factors played a role to the metal endowment of the Aegean porphyry-epithermal systems: magma fertility in the source regions, depth of emplacement of causative intrusives, relative contribution of mantle versus crustal material, redox state of subduction-related magmas, and physico-chemical fluid conditions at the site of ore deposition.
CRIS-Team Scopus Importer:2019-05-09
Keywords: Alteration; Epithermal; Greece; Ore mineralogy; Porphyry

Positive sport-biosphere interactions? − Cross-country skiing delays spring phenology of meadow vegetation - Steinbauer, Manuel; Kreyling, Jürgen; Stöhr, Caroline; Audorff, Volker (Basic and Applied Ecology, 2018)
Space requirements by winter sports and accelerating global warming are usually perceived as stressors for mountain meadow plant communities. Cross-country ski track preparation (i.e. grooming), however, might retard effects of climate change and, being limited in space requirements, might increase abiotic heterogeneity. The effect of cross-country ski tracks on meadow vegetation was quantified along a representative ski track that had been operated for 30 years in the Fichtelgebirge, a low mountain range in central Europe. Paired sampling was implemented to assess the effect of skiing operations on snow and soil properties, plant phenology, biomass production and species composition. Additionally, boosted regression tree analyses were used to quantify the relative importance of the cross-country ski track compared to other environmental conditions. The cross-country ski track strongly increased snow density, enhanced soil frost, and retarded snowmelt, thereby delaying flower phenology (by 2.1 days) and the early development stages of plant species on the track. However, biomass, species richness and species composition were unaffected by skiing operations except for one species (Leontodon autumnalis) showing exclusive occurrence on the track while four others showed reduced relative occurrence on the track. While snow and soil properties were influenced by cross-country ski track preparation, natural environmental variability was more influential for species composition and biomass production than the ski track. We therefore conclude that the ski track – without artificial snow – did not negatively affect species composition. By delaying flower phenology, effects of the ski track even counteracted global warming to some degree. Due to their small spatial extent in the landscape, these ski tracks may add to environmental heterogeneity and thus support sustaining diverse species compositions during environmental changes.

Possible links between groundwater geochemistry and chronic kidney disease of unknown etiology (CKDu): an investigation from the Ginnoruwa region in Sri Lanka - Balasooriya, Shyamalie; Munasinghe, Harshaka; Herath, A. T.; Diyabalanage, Saranga; Ileperuma, O. A.; Manthrithilake, Herath; Daniel, Christoph; Amann, Kerstin Ute; Zwiener, Christian; Barth, Johannes; Chandrajith, Rohana (Exposure and Health, 2019)
Since at least two decades, Chronic Kidney Disease of Uncertain Etiology (CKDu) has become an increasingly discussed health issue in Sri Lanka and as well as in other tropical regions. Areas that are particularly affected with the disease are mostly located in the dry zone of Sri Lanka. The disease is more prominent among communities that consume groundwater as their main source of drinking water. Hydrogeochemical investigations were carried out in the Ginnoruwa area, a known hotspot of CKDu. It revealed possible links between drinking water chemistry and the spreading of the disease. This work compares hydrogeochemical data of drinking water sources of wells whose consumers are affected by CKDu and other nearby wells whose consumers were not affected by the disease. A total of 63 groundwater samples were collected from selected wells. About one-third of these samples (i.e., 19) were collected from wells used by CKDu patients. Significantly higher values of pH, total hardness, electrical conductivity, Ca2+, Mg2+, F−, Cl−, PO4 3−, and SO4 2− were found in wells that were used by CKDu patients. Mean contents of Na+, Ca2+, and Mg2+ in CKDu affected wells were 33.8 mg/L, 30.1 mg/L, and 14.9 mg/L, respectively, compared to 23.1 mg/L, 26.7 mg/L, and 9.65 mg/L in non-CKDu wells. Differences in major ion geochemistry in groundwaters are possibly governed by variable time periods of water storage in fractured hard rock aquifers in this region. Hydrogeochemical parameters were statistically compared by a Mann–Whitney U test and indicated significant differences in total dissolved solids (TDS) (p = 0.016), SO4 2− (p = 0.005), PO4 3− (p = 0.030), F− (p = 0.048), Na+ (p = 0.008), and Mg2+(p = 0.008) between non-CKDu and CKDu wells at p = 0.050 level. Other suspected solutes such as nephrotoxic trace elements including As, Cd, and Pb were similar in both types of wells. They were also lower than the accepted guideline limits of the World Health Organization (WHO). Results of this study suggest that fluoride in drinking water in combination with water hardness may be one of the responsible factors for kidney damage and progression of the disease. This may be particularly the case when elevated amounts of Mg2+ are present in hard groundwater.
CRIS-Team Scopus Importer:2019-12-31
Keywords: Fluoride; Girandurukotte; Kidney damage; Magnesium; Mann–Whitney U test; Water hardness

Possible oceanic circulation patterns, surface water currents and upwelling zones in the Early Palaeozoic - Servais, Thomas; Danelian, Taniel; Harper, David A.T.; Munnecke, Axel (GFF, 2014)
As global reconstructions for the Early Palaeozoic (Cambrian, Ordovician and Silurian periods) are now becoming more reliable, ancient atmospheric and oceanic circulation patterns may now be modelled with increasing confidence. Here we examine previous studies on Early Palaeozoic palaeoceanography. It is assumed that past circulation patterns were governed by the same factors that govern them today. We here introduce some hypothetical base maps that predict the possible locations of ancient surface water currents, the position of oceanic gyres and possible ancient upwelling zones. © 2014 © 2014 Taylor & Franci
Keywords: Early Palaeozoic; palaeoceanography; palaeogeography; upwelling zones

Post-collisional shortening in the late Pan-African Hamisana high strain zone, SE Egypt: Field and magnetic fabric evidence - de Wall, Helga; et al. (Precambrian Research, 2001)
Keywords: Arabian-Nubian shield; Hamisana zone; Late-orogenic compression; Magnetic susceptibility

Post-Columbian environmental history of Lago Petén Itzá, Guatemala - Pérez, Liseth; Bugja, Rita; Massaferro, Julieta; Steeb, Philip; van Geldern, Robert; Frenzel, Peter; Brenner, Mark; Scharf, Burkhard; Schwalb, Antje (Revista Mexicana De Ciencias Geologicas, 2010)
Keywords: Chironomids; Eutrophication; Freshwater ostracodes; Geochemistry; Guatemala; Lago Petén Itzá; Lake level

Post-depositional alteration of stable isotope signals by preferential degradation of algae-derived organic matter in reservoir sediments - Liu, Xiaoqing; Wendt-Potthoff, Katrin; Barth, Johannes; Friese, Kurt (Biogeochemistry, 2022)
Post-depositional degradation of organic matter (OM) in freshwater sediments is crucial for driving the biogeochemical dynamics and influencing the carbon burial. This process also often causes diagenetic alteration on paleoenvironmental proxies. Yet, mechanisms behind degradation of sedimentary OM and depth-related variations in stable isotope ratios can so far only be explained in part. Degradation of sedimentary OM in two drinking water reservoirs with contrasting eutrophic and mesotrophic states and different catchment land use (agriculture versus forestry) was studied. A 4-step procedure was used to chemically separate sedimentary OM in terms of biochemical composition. Here we presented depth profiles of biochemical composition of sedimentary OM that helped to quantify preferential degradation of aquatic proteins and carbohydrates and the following removal of aquatic lipids. Sediment in the eutrophic reservoir, which reflected a larger contribution of algal-derived OM than the mesotrophic reservoir with a forest dominated catchment, was therefore subject to more intensive degradation of sedimentary OM along with delta C-13 and delta N-15 alterations. In addition, changes in the relative proportions of biochemical components in sedimentary OM had more pronounced impact on delta N-15 values relative to delta C-13. Our findings suggest that the lability of algae-derived OM leads to uncertainties for the estimation of carbon burial in water bodies and obscures paleo-limnological information derived from isotopic proxies. Post-depositional modifications are more pronounced in eutrophic freshwaters that accumulated more readily degradable OM of algal origin in their sediments. Recognition of these modifications will help constrain carbon burial rates of productive lakes and reservoirs and assess the role of reservoirs in carbon cycling.
CRIS-Team WoS Importer:2022-05-27

Post-depositional REE mobility in a Paleoarchean banded iron formation revealed by La-Ce geochronology: A cautionary tale for signals of ancient oxygenation - Bonnand, P.; Lalonde, S. V.; Boyet, M.; Heubeck, C.; Homann, M.; Nonnotte, P.; Foster, I.; Konhauser, K. O.; Köhler, Inga (Earth and Planetary Science Letters, 2020)
Precambrian banded iron formations (BIF) are chemical sedimentary deposits whose trace element signatures have been widely used to interrogate the chemical composition and redox state of ancient seawater. Here we investigated trace element signatures in BIF of the 3.22 Ga Moodies Group, Barberton Greenstone Belt (South Africa), which are interbedded with near-shore siliciclastic sedimentary rocks and represent one of the oldest known shallow-water occurrences of BIF. Unusual rare earth element (REE) signatures, notably with pronounced negative Ce anomalies in shale-normalized spectra, have been previously reported for chemical sediments of the Moodies Group, which we confirm here through an expanded dataset for Moodies BIF spanning three different localities. We find negative Ce anomalies as low as 0.2 Ce/Ce⁎ that are associated with unusual enrichment of LREE relative to HREE in the sample set. While total REE abundances and certain REE features appear strongly related to the concentration of detrital indicators (e.g., Zr), and are likely primary, other features, notably LREE enrichment, cannot be explained as a primary feature of the sediment. This is better explained by later addition of REE from a LREE-enriched but Ce-depleted fluid that generated the significant negative Ce anomalies observed in surface samples of Moodies Group BIF. This REE addition event influenced both Sm-Nd and La-Ce isotope systematics, the latter yielding an isochron of 60 ± 32 Ma, thus constraining the timing of emplacement of the negative Ce anomalies to the past 100 Ma, possibly upon surface exposure of the Barberton Greenstone Belt to wetter conditions during the Cenozoic. Our findings constitute a cautionary tale in that even the most immobile elemental redox proxies may be more sensitive to post-depositional modification than previously thought, and demonstrate the clear advantage offered by paleoredox proxies coupled to radiometric geochronometers to enable the direct dating of ancient signals of Earth surface oxygenation.
CRIS-Team Scopus Importer:2020-07-31
Keywords: Ce anomalies; La-Ce geochronology; rare earth element mobility; trace element signatures

Post-glacial microbialite formation in coral reefs of the Pacific, Atlantic, and Indian Oceans - Heindel, Katrin; Birgel, Daniel; Brunner, Benjamin; Thiel, Volker; Westphal, Hildegard; Gischler, Eberhard; Ziegenbalg, Simone; Cabioch, Guy; Sjövall, Peter; Peckmann, Jörn (Chemical Geology, 2012)
Keywords: Coral reef; EPS-mineralization; Fertilization; Microbial mat; Sulfate-reducing bacteria; Volcanic hinterland

Post-Variscan structurally-controlled hydrothermal Zn-Fe-Pb sulfide and F-Ba mineralization in deep-seated Paleozoic units of the North German Basin: A review - Nadoll, Patrick; Sosnicka, Marta; Kraemer, Dennis; Duschl, Florian (Ore Geology Reviews, 2019)
Hydrothermal Zn-Pb-Fe sulfide and F-Ba mineralization occur as open space fillings, veins, and fracture coatings in various parts of the North German Basin in Paleozoic sedimentary rocks and volcanic units at depths of up to four kilometers. We present a petrographic and geochemical (fluid inclusion, mineral and formation water geochemistry) inventory of the mineralized zones and review the basin architecture, evolution, and stratigraphy in order to decipher the timing, extent, fluid pathways, and fluid-rock interactions associated with the ore formation. A particular focus lies on the sediment-hosted Zn-Fe-Pb sulfides in the western part of the North German Basin, the Lower Saxony Basin. Samples from hydrothermal veins from the Pre-Permian basement are also being investigated and compared to the North German Basin-style mineralization to uncover possible genetic links between them. The sediment-hosted sulfide mineralization in the Lower Saxony Basin in the Permian Stassfurt Carbonate unit (Ca2) shares many characteristics that are typical for carbonate-hosted base metal sulfide deposits such as MVT deposits. Petrographic observations, fluid inclusion and isotope data provide evidence that Zn-Fe-Pb sulfides were deposited by highly saline metal-rich basinal brines at temperatures of similar to 160 degrees C. Carbon and oxygen isotope data point toward fluid mixing augmented by structurally-controlled fluid migration during the late Cretaceous basin inversion as the primary ore precipitation mechanism with no magmatic component. In the Altmark-Brandenburg Basin, steeply-dipping F-Ba (calcite, anhydrite, quartz) veinlets in Permo-Carboniferous sandstones and volcanic units are evidence for enhanced post-Variscan structurally-controlled fluid flow. Sulfides are, apart from rare occurrences of chalcopyrite, absent. This is interpreted to reflect the paleogeographic position of the Altmark-Brandenburg Basin (deeper paleogeographic basin position without carbonate aquifers), the lack of reductants, and the predominance of nitrogen-rich fluids as documented by fluid inclusions. Measurements on formation waters from the NGB show geochemical similarities to fluid inclusions in ore and gangue minerals and could represent a potential future exploration tool for hydrothermal ore deposits. This has the potential to aid future research and exploration of deeply covered sediment-hosted deposits and to meet future mineral resources demands.
CRIS-Team WoS Importer:2019-04-09
Keywords: Fluorite; Hydrothermal; Permian; Zn-Fe-Pb sulfides; MVT; North German Basin

Postvariszische Krustenstapelung am Westrand der Boehmischen Masse; Geologische Interpretation des 9,1 km tiefen KTB-Krustenprofils - de Wall, Helga; et al. (Geowissenschaften, 1995)
UnivIS-Import:2015-03-05:Pub.1995.nat.dgeo.IGM.c3tekt.postva

Postvulkanische Rotliegend-Schwemmfächersysteme am Hunsrück-Südrand, Saar-Nahe-Becken, SW-Deutschland. - Stollhofen, Harald (Jahresberichte und Mitteilungen des Oberrheinischen Geologischen Vereins, 2007)
UnivIS-Import:2015-03-09:Pub.2007.nat.dgeo.IGM.LG.postvu

Potenziale und Herausforderungen der oberflächennahsten Geothermie - Müller, Johannes (Der Geothermie Kongress 2019, 2019)
Die oberflächennahe Geothermie als solches stellt einen wichtigen Baustein für eine treibhausgasfreie Wärme- und Kälteversorgung für Neu- und Bestandsgebäude dar. Durch Verwendung von oberflächennahen Geothermiesystemen kann thermische Energie aus dem Erdreich entzogen werden. Mit Hilfe einer Wärmepumpe können die saisonal beeinflussten Temperaturen des Erdreichs auf die benötigten gebäudeseitigen Verbrauchertemperaturen angehoben werden. Dies ist abhängig von der Gebäudehülle und dem Nutzerverhalten. Der Einsatz oberflächennahe Geothermie reicht von dezentral operierenden Einfamilienhäuser, über Mehrfamilienhäuser bis hin zu Quartierlösung. Die oberflächennahe Geothermie bietet die Möglichkeit Synergien verschiedener erneuerbarer Energiekonzepte sinnvoll miteinander zu verbinden. Sei es durch innovative MRS-Steuerung, sich auf natürliche Weise regenerierende Speicherlösungen oder die Vorteile eines energetisch verlustarmen kalten Nahwärmenetzes. All diese Potenziale werden innerhalb des Workshops vorgestellt und beleuchtet. Daneben wird auch auf die Herausforderungen eines individuellen Wärme- und Kältemarkts eingegangen. Das Nutzerverhalten innerhalb eines Wohnquartiers ist stark von den persönlichen Lebensgewohnheiten seiner Bewohner abhängig. Die Herausforderung besteht darin, die Versorgung und damit die Energieübertragung von der geothermischen Quelle zum Endverbraucher (und umgekehrt) durch Monitoring besser zu verstehen und durch innovative Technologien (z. B. deep learning, KI) zu optimieren. Die Herausforderungen der oberflächennahen Geothermiesysteme bestehen vor allem darin, dass die Dimensionierung der Anlagen von mehreren Parametern abhängt. Der wichtigste Parameter ist die thermische Leitfähigkeit, die von mehreren anderen physikalischen Eigenschaften des Bodens abhängt. Dies sind neben der Lagerungsdichte, die mit der Tiefe zunimmt, vor allem die Bodenfeuchte sowie die Korngrößenverteilung des Substrats. Hydrogeologische Bedingungen sind für die Gesamtbetrachtung einer Anlage essenziell, um die Regenerationspotenziale einer Anlage besser einschätzen zu können.
Keywords: oberflächennahe Geothermie; treibhausgasfreie Wärme- und Kälteversorgung

PPFG prediction in complex tectonic settings: The North Alpine thrust front and foreland basin, SE Germany - Drews, Michael; Stollhofen, Harald (2nd EAGE Workshop on Pore Pressure Prediction, 2019)
Estimation of pore and fracture pressures in complex tectonic settings, such as fold-and-thrust belts and their adjacent foreland basins, is usually challenging and often requires local calibration. The Cenozoic North Alpine Thrust Front and Foreland Basin in SE Germany provide an interesting and challenging example for such a complex system, comprising overpressured sections in the thrust belt, the overthrusted foreland sediments below the main detachment and the undeformed foreland basin. Based on the synthesis of recent research in the study area and new analyses of additional well data from the thrust front, pore and fracture pressure models will be presented for the different parts of the North Alpine Thrust Front and Foreland Basin in SE Germany. The results demonstrate, that understanding of the geological history, stress regime variations and overpressure generation are key to estimate pore and fracture pressures in complex tectonic settings, such as the North Alpine Thrust Front and Foreland Basin in SE Germany.
CRIS-Team Scopus Importer:2019-06-21

Practical guidelines for Bayesian phylogenetic inference using Markov Chain Monte Carlo (MCMC) - Barido-Sottani, Joëlle; Schwery, Orlando; Warnock, Rachel; Zhang, Chi; Wright, April Marie (Open Research Europe, 2023)
Phylogenetic estimation is, and has always been, a complex endeavor. Estimating a phylogenetic tree involves evaluating many possible solutions and possible evolutionary histories that could explain a set of observed data, typically by using a model of evolution. Modern statistical methods involve not just the estimation of a tree, but also solutions to more complex models involving fossil record information and other data sources. Markov Chain Monte Carlo (MCMC) is a leading method for approximating the posterior distribution of parameters in a mathematical model. It is deployed in all Bayesian phylogenetic tree estimation software. While many researchers use MCMC in phylogenetic analyses, interpreting results and diagnosing problems with MCMC remain vexing issues to many biologists. In this manuscript, we will offer an overview of how MCMC is used in Bayesian phylogenetic inference, with a particular emphasis on complex hierarchical models, such as the fossilized birth-death (FBD) model. We will discuss strategies to diagnose common MCMC problems and troubleshoot difficult analyses, in particular convergence issues. We will show how the study design, the choice of models and priors, but also technical features of the inference tools themselves can all be adjusted to obtain the best results. Finally, we will also discuss the unique challenges created by the incorporation of fossil information in phylogenetic inference, and present tips to address them.
CRIS-Team Scopus Importer:2024-12-16
Keywords: Bayesian phylogenetic inference; BEAST2; fossilized birth-death; MCMC; MrBayes; phylogenetic inference software; total-evidence; troubleshooting

Preboreal onset of Norwegian cold-water coral growth beyond the Arctic Circle revealed by radiocarbon and U-series dating and neodymium isotopes - López Correa, Matthias; Montagna, Paolo; Joseph, Nina; Rüggeberg, Andres; Fietzke, Jan; Flögel, Sascha; Dorschel, Boris; Goldstein, Steve; Wheeler, Andrew; Freiwald, André (Quaternary Science Reviews, 2012)
Cold-water coral mounds of Lophelia pertusa are widespread across the Scandinavian shelf, which was completely ice-covered during the Last Glacial Maximum between 22 to 18ka BP. Rapid deglacial meltdown of the Fennoscandian inland ice and the retreat of its ice-streams freed most of the shelf of ice by 15ka BP. However, cold-water coral growth commenced only after the Pleistocene-Holocene transition at 11.65ka BP, when modern-like climatic patterns and oceanographic conditions were established. A tight climatic coupling has been constrained with U-series ages. Coupled 14C ages provide local reservoir ages from various gravity cores in a fjord-setting in Stjernsund at 70°N and on the open shelf in Trænadjupet at 66°N. Reinvestigation of earlier 14C coral chronologies suggests that coral ecosystems widely established themselves across the entire 3000km long Scandinavian shelf prior to 10ka BP. The earliest occurrence of Madrepora oculata at 2.4ka BP suggests a late Holocene colonization of the Norwegian shelf, which is linked to a prominent mound growth hiatus in Trænadjupet (64°N). Mound growth rates near the northern biogeographic boundary of L.pertusa with up to 614cmka -1 during certain growth periods are much higher than the previously reported fastest rates of 220cmka -1 from the Irish margin. Contemporaneous rapid fjordbasin sedimentation is slower with 63cmka -1. Matrix 14C ages overlap with coral 14C ages from the same horizon. This indicates rapid framework construction and efficient trapping of background sediment. Hiatuses are frequent in on-mound sediments and only short periods of coral growth are recorded. Coupled Δ 14C and ε Nd values indicate a persistent Holocene inflow of the North Atlantic Current in Stjernsund, but also deglacial meltwater mixing during the early Holocene prior to 9.5ka BP. Reservoir ages are overall close to the surface marine reservoir age, but ΔR is highly localized. © 2011 Elsevier Ltd.
UnivIS-Import:2015-03-09:Pub.2012.nat.dgeo.IGM.LP.prebor

Precambrian gold mineralization at Djamgyr in the Kyrgyz Tien Shan: Tectonic and metallogenic implications - Konopelko, Dmitry; Klemd, Reiner; Petrov, S.V.; Apayarov, F.; Nazaraliev, B.; Vokueva, O.; Scherstén, A.; Sergeev, S. (Ore Geology Reviews, 2017)
The Djamgyr gold deposit is located within the Neoproterozoic basement of the Middle Tien Shan terrane immediately west of the Talas-Fergana fault. The deposit comprises a system of auriferous quartz veins cross-cutting the Beshtor plagiogranite. The veins are surrounded by hydrothermal alteration aureoles and are oriented parallel to the Talas-Fergana fault. The Beshtor granite sampled in the vicinity of the deposit yielded a Neoproterozoic (Tonian) U-Pb zircon age of 815 ± 6 Ma, which is the first single grain zircon age of the Middle Tien Shan basement west of the Talas-Fergana fault. Ar-Ar dating of two muscovite fractions from the alteration aureoles of the auriferous quartz veins yielded ages of 804 ± 3 and 805 ± 3 Ma suggesting that the mineralization in the Djamgyr deposit occurred during the Neoproterozoic ca. 10 m.y. after emplacement of the Beshtor granite. The structural pattern of the auriferous quartz veins and the new geochronological data, combined with the results of previous structural studies, may tentatively constrain the age of pre-existing major fault possibly marking an inherited terrane boundary in the northern part of the present-day Talas-Fergana strike-slip fault. The discovery of Precambrian gold mineralization in the Middle Tien Shan suggests re-evaluation of the metallogenic potential of its Precambrian basement that occupies significant areas west and east of the Talas-Fergana fault.
Keywords: Tien Shan (Tian Shan); Talas-Fergana fault; Djamgyr (Jamgyr) Au deposit; Neoproterozoic

Preceramic polymer derived cellular ceramics - Zeschky, Jürgen; Götz-Neunhoeffer, Friedlinde; Neubauer, Jürgen; Lo, S.H. Jason; Kummer, Bernhard; Scheffler, Michael; Greil, Peter (Composites Science and Technology, 2003)
Ceramic foams were prepared by a self-blowing process of a poly(silsesquioxane) melt at 270 °C. The cell size, the interconnectivity density and the shape of the foam cells were adjusted by a thermal pre-curing procedure of the polymer at 200 °C. Inorganic fillers were used to modify processing behaviour and properties of the pyrolysed ceramic foam. After pyrolysis in inert atmosphere at 1200 °C ceramic composite foams with a total porosity up to 87% were obtained. The open cell ceramic foams had a mean cell diameter of 1.2 mm and a mean strut thickness of 0.2 mm. Interpenetrating phase composites (IPCs) were fabricated by infiltrating the open cellular ceramic preform with Mg alloy melt at 680 °C and a pressure of 86 MPa. The mechanical properties were found to depend on the reactions between the metal and the ceramic forming MgO, Mg2Si and Al12Mg17 as the major reaction products. The IPCs showed a significantly higher creep resistance at 135 °C, compression strength and elastic modulus compared to the unreinforced magnesium alloys. © 2003 Elsevier Ltd. All rights reserved.
UnivIS-Import:2015-03-09:Pub.2003.nat.dgeo.IGM.LM.precer
Keywords: Ceramic foam

Predictability and controlling factors of overpressure in the North Alpine Foreland Basin, SE Germany: an interdisciplinary post-drill analysis of the Geretsried GEN-1 deep geothermal well - Drews, Michael C.; Hofstetter, Peter; Zosseder, Kai; Shipilin, Vladimir; Stollhofen, Harald (Geothermal Energy, 2020)
The North Alpine Foreland Basin in SE Germany is Germany's most active deep geothermal province. However, in its southern and eastern part the basin is considerably overpressured, which is a significant challenge for drilling deep geothermal wells. In this study, we combine drilling data and velocity-based pore pressure analyses with 3D basin modeling to assess the predictability and controlling factors of overpressure in the sub-regional context (area of 80 km x 50 km) around the Geretsried GEN-1 well, a deep geothermal exploration well in the southern part of the North Alpine Foreland Basin in SE Germany. Drilling data and velocity-based pore pressure analyses indicate overpressure maxima in the Lower Oligocene (Rupelian and Schoeneck Formation) and up to mild overpressure in the Upper Oligocene (Chattian) and Upper Cretaceous, except for the hydrostatically pressured northwestern part of the study area. 3D basin modeling calibrated to four hydrocarbon wells surrounding the Geretsried GEN-1 well demonstrates the dominating role of disequilibrium compaction and low permeability units related to overpressure generation in the North Alpine Foreland Basin. However, secondary overpressure generation mechanisms are likely contributing. Also, the impact of Upper Cretaceous shales, which are eroded in the northwestern part of the study area, on overpressure maintenance is investigated. The calibrated basin model is tested against the drilling history and velocity (VSP) data-based pore pressure estimate of the Geretsried GEN-1 well and reveals that pore pressure prediction is generally possible using 3D basin modeling in the North Alpine Foreland Basin, but should be improved with more detailed analysis of lateral drainage systems and facies variations in the future. The results of the study are of relevance to future well planning and drilling as well as to geomechanical modeling of subsurface stresses and deep geothermal production in the North Alpine Foreland Basin.
CRIS-Team WoS Importer:2020-07-31

Predicting extinction from fossil trajectories of geographical ranges in benthic marine molluscs - Tietje, Melanie; Kießling, Wolfgang (Journal of Biogeography, 2013)
Aim: The geographical ranges of marine taxa wax and wane in a nearly symmetrical fashion over their durations. We use this pattern as well as the age distribution of genera to predict the time of extinction of extant genera of benthic marine molluscs. Location: A global occurrence database (Paleobiology Database) of fossil marine molluscs from the Mesozoic and Cenozoic eras was used for this study. Methods: For the geographical range method, we determined the average trajectories of geographical range size for extinct genera of bivalves and gastropods. The maxima of these trajectories were used as landmarks for predicting the time of extinction for extant genera. Prediction was done by cross-multiplication, using the time elapsed until the maximum was reached and the position of the landmark. For the duration-frequency method, we calculated the time of extinction based on probabilities derived from the frequency distribution of stratigraphic ranges (durations) of all extinct genera. The accuracy and precision of predictions were tested with extinct genera and then applied to extant genera. Results: On average, bivalve and gastropod extinct genera reached their maximum geographical range size at 62% and 50% of their total duration. The accuracy of predictions ranged from -3.1 to 11.0 million years (Myr) for both groups, and the precision ranged from 13.6 to 19.5 Myr. Only a small subset of extant genera was suitable for prediction with the geographical range method, mainly because the geographical ranges of most extant genera are still rising on geological time-scales. The second method provided a similar prediction quality, but showed a substantial decrease in quality when predicting long-duration (> 100 Myr) genera. Main conclusions: The mean probability for an accurate prediction using the geographical range approach is 57% with a precision of ± 15 Myr. Prediction is possible only for genera whose peak geographical range has already elapsed (17% of extant bivalves, 16% of extant gastropods). The duration-frequency approach does not have this prerequisite and is therefore applicable to many more genera, but prediction quality declines with duration. The two methods therefore complement each other and can supplement the various efforts used to estimate extinction risk. © 2012 Blackwell Publishing Ltd.
UnivIS-Import:2015-03-09:Pub.2013.nat.dgeo.IGM.LP.predic
Keywords: Cenozoic; Extinction; Geographical range; Marine biogeography; Marine molluscs; Mesozoic; Prediction

Predicting δ13CDIC dynamics in CCS: A scheme based on a review of inorganic carbon chemistry under elevated pressures and temperatures - Becker, Veith; Myrttinen, Anssi; Blum, Philipp; van Geldern, Robert; Barth, Johannes (International Journal of Greenhouse Gas Control, 2011)

PREDICTION OF FAULT ROCK PERMEABILITY WITH DEEP LEARNING: TRAINING DATA FROM TRANSFER SAMPLES OF FAULT CORES - Schmatz, J.; Klaver, J.; Wellmann, E.; Jiang, M.; Kraus, W.; Freitag, Simon; Hoffmann, A.; Deckert, H. (83rd EAGE Conference and Exhibition 2022, 2022)
While the influence of clay smear on the sealing properties of fault zones in siliciclastic rocks can be predicted by validated concepts such as the SGR or CSP reliable models for predicting the structural and hydraulic properties of faults in layered limestone-marl sequences do not yet exist. The main goal of our study is to analyse the development of fault sealing as a result of marl smearing in interaction with mechanical mixing as well as fracturing and cementation processes in dependence of mechanically alternating bedding and fault geometry. Oriented transfer samples of fault cores from different normal fault systems destabilised by the fault process with adjacent damage zone were successfully extracted from outcrops with Jurassic limestone in a quarry Northern Bavaria, Germany. Microanalytical tools and multiscale (m-nm) analyses workflows were developed to provide ground truth for the training of machine learning algorithms for the efficient interpretation of 2D microstructural image data. The systematic macroscopic and microstructural examination of the transfer specimens has shown that the fault zones are built up by recurrent building blocks, whose variation and expression are strongly influenced by the presence and nature of interbedded marly layers.
CRIS-Team Scopus Importer:2022-12-09

Prediction of ion selectivity by quantum chemical calculations X: A recent (personal) review - Puchta, Ralph; Begel, Svetlana; van Eldik, Rudi (Computational Chemistry, 2019)
In this review we present a simple and robust method to investigate the ion selectivity of cryptands based on quantum chemical methods. Based on easily understandable model equations and fundamental structural consideration one can rationalize or predict the observed selectivity and the underlying structural conditions. Additionally, we can learn unhampered from neighboring effects the changes in the cryptand to host the ions most effectively. The performance of this concept is demonstrated on several well known cryptands from different supramolecular groups like Lehn and others.
CRIS-Team Scopus Importer:2019-08-23
Keywords: DFT; Main group ions; Selective ion complexation; 2-Cryptands

Prehistoric and recent mass movements of the World Cultural Heritage Site Hallstatt, Austria - Moser, Michael; et al. (Environmental Geology, 2005)
Keywords: Landslide; Northern Calcareous Alps; Hallstatt; Hazard; Austria; Archaeological site; Earth flow; Cultural Heritage

Prehistoric and recent mass movements of the World Cultural Heritage Site Hallstatt, Austria - Rohn, Joachim; et al. (Environmental Geology, 2005)
Hallstatt Village, located in the Austrian Alps, is designated by the United Nations Educational, Scientific and Cultural Organization as part of the World Cultural Heritage Site "Hallstatt-Dachstein". This region is recognized for its salt deposits that have been exploited since the Neolithic period. In former times, these salt deposits were very rare and precious. Due to unfortunate bedding conditions, mass movements have been frequent in the past and continue to affect the site today. These active and inactive mass movements were mapped geotechnically to a scale of 1:5,000 and the mineralogical and mechanical properties of the main instable soft rocks were investigated. Rock spreads, rock slides, rock falls, rock topples, earth flows and earth and debris slides are the primary types of mass movements recorded. They are most frequently observed in areas affected by mining, though they may also occur in areas where no anthropogenic influence is recognized. Evidence exists in the archaeological record that indicates prehistoric mining activities were also seriously affected by the impact of mass movements. © Springer-Verlag 2005.
UnivIS-Import:2015-04-14:Pub.2005.nat.dgeo.IGM.profes_3.prehis
Keywords: Archaeological site; Austria; Cultural Heritage; Earth flow; Hallstatt; Hazard; Landslide; Northern Calcareous Alps

Preliminary Estimation of Paleoproductivity via TOC and Habitat Types: Which Method Is More Reliable? —A Case Study on the Ordovician–Silurian Transitional Black Shales of the Upper Yangtze Platform, South China - Wenbo, Su; Yongbiao, Wang; Cramer, Bradley D.; Munnecke, Axel; Zhiming, Li; Lipu, Fu (Journal of China University of Geosciences, 2008)
New total organic carbon (TOC) data from the two Ordovician-Silurian transitional graptolite-bearing black shale intervals, the Wufeng Formation and the Longmaxi Formation in Central Guizhou and West Hubei, respectively, as well as previously reported TOC data from the same intervals in other places on the Yangtze platform of South China, have been used to produce an initial estimate of the primary paleoproductivity via a conventional inverse method (i.e., R). The values of the R are estimated to be 32 (43-21) gC/(m·a) (Wufeng Formation) and 21 (27-16) gC/(m·a) (Longmaxi Formation). Also, simultaneously, the habitat types (i.e., HT; cf., BA: benthic assemblage) and their temporal and spatial changes have been documented from the same succession, and an initial estimate of the primary paleoproductivity has been produced using a forward method (i.e., R). Being bounded mainly by the peritidal to inner-shelf environment shelly-facies or mixed-facies successions with BA1 to BA3 faunas both at the top and the base, which indicates the habitat types from HT II to HT III, the biohabitat type of the two graptolite-bearing black shale intervals can be limited to HT III to HT IV, corresponding to the inner shelf to the outer shelf, with depths from roughly 60 m to 200-300 m. Based on the current data from the South China Sea and the southern part of the East China Sea, values of R should be about 100 to 400 gC/(m·a). The difference in the results via the two methods suggests that paleoproductivity estimates from the geological strata need to be made cautiously, with particular attention paid to the paleogeographic setting, oxic-anoxic conditions, as also the preservation factor of organic carbon. © 2008 China University of Geosciences.
Keywords: primary productivity; black shale; TOC; habitat type (HT); Ordovician; Silurian transition; South China

Preliminary magnetic susceptibility characteristics of the Bharati promontory (Grovness Peninsula), Larsemann Hills, Prydz Bay region, East Antarctica - Pandit, Manoj K.; de Wall, Helga (Journal of the Geological Society of India, 2014)
Keywords: Bharati promontory; East Antarctica; Gneisses; Larsemann Hills; Magnetic susceptibility

Preliminary magnetic susceptibility results on the Neoproterozoic Mt.Abu granite, NW-Indian craton: correlation between magnetic fabric and deformation - de Wall, Helga; Pandit, M. K. (Geotectonic Research, 2007)
UnivIS-Import:2015-03-09:Pub.2007.nat.dgeo.IGM.c3tekt.lowfie

Pre-mass extinction decline of latest Permian ammonoids - Kießling, Wolfgang; Schobben, Martin; Ghaderi, Abbas; Hairapetian, Vachik; Leda, Lucyna; Korn, Dieter (Geology, 2018)
The devastating end-Permian mass extinction is widely considered to have been caused by large-scale and rapid greenhouse gas release by Siberian magmatism. Although the proximate extinction mechanisms are disputed, there is widespread agreement that a major extinction pulse occurred immediately below the biostratigraphically defined Permian-Triassic boundary. Our statistical analyses of stratigraphic confidence intervals do not comply with a single end-Permian extinction pulse of ammonoids in Iran. High turnover rates and extinction pulses are observed over the last 700 k.y. of the Permian period in two widely separated sections representative of a larger area. Analyses of body sizes and morphological complexity support a gradual decline over the same interval. Similar pre-mass extinction declines and disturbances of the carbon cycle have sometimes been reported from other regions, suggesting a widespread, but often overlooked, environmental deterioration at a global scale, well before the traditional main extinction pulse.

Present and future challenges of urban systems affected by seawater and its intrusion: the case of Venice, Italy - Di Sipio, Eloisa; Zezza, Fulvio (Hydrogeology Journal, 2011)
Keywords: Coastal aquifers; Salinization; Sea salt damage; Non destructive techniques; Italy

Pressure-temperature evolution during two granulite-facies metamorphic events (2.62 and 2.02 Ga) in rocks from the Central Zone of the Limpopo Belt, South Africa - Brandt, Sönke; Klemd, Reiner; Li, Qiuli; Kröner, Alfred; Brandl, Guenther; Fischer, Andreas; Bobek, Patrick; Zhou, Tian (Precambrian Research, 2018)
The Central Zone of the Limpopo Belt in southern Africa is a classical example of a polymetamorphic terrane that experienced three metamorphic events at 3.22 Ga (M1), 2.66–2.61 Ga (M2) and 2.02 (M3). However, the geodynamic significance of these events is controversial as their P-T evolution was poorly constrained. We present new petrological and geochronological data for the M2 and M3 events. The Neoarchean M2 event is well-preserved in samples from a newly discovered enclave of supracrustal and magmatic rocks in the 2.612 Ga Bulai pluton that shielded the enclave against a Paleoproterozoic M3 overprint, which is dominant in rocks exposed outside the pluton. P-T pseudosection modelling for migmatitic Grt-Crd metapelites from the enclave and the rock sequence outside the pluton indicates an opposite metamorphic evolution, a counterclockwise P-T path for M2 but a clockwise path for M3. Spinel-quartz assemblages in the enclave metapelites record early heating to UHT conditions (ca. 930 °C, 5.5 kbar) at intermediate crustal levels. The peak-pressure M2-assemblage garnet-cordierite-sillimanite-K-feldspar-plagioclase-quartz ± rutile formed at ca. 860 °C and 7.5 kbar during a moderate pressure increase. Cordierite coronas around garnet record subsequent decompression. We interpret the counterclockwise P-T evolution during M2 to result from convergence of the Zimbabwe and Kaapvaal Cratons, which has led to subduction of oceanic lithosphere beneath the Zimbabwe Craton. Subsequent slab retreat has caused asthenosphere upwelling, thereby inducing delamination of the lithospheric mantle. Intrusion of hot asthenospheric material beneath the crust induced early UHT metamorphism at mid-crustal levels. The subsequent moderate pressure increase was related to the ensuing collision of the cratons. Post-peak decompression records incorporation of the enclave into the Bulai pluton melt and uplift in the ascending granitoid melt. The peak M3-assemblage garnet-cordierite-sillimanite-K-feldspar-rutile-plagioclase-quartz formed in metapelites occurring outside the pluton during near-UHT conditions (ca. 880 °C, 7.5 kbar). Cordierite coronas around garnet record subsequent decompression. New growth of garnet and sillimanite at the expense of cordierite documents late near-isobaric cooling to <700 °C. The resulting clockwise P-T path for M3 granulite-facies metamorphism is interpreted to record an intracontinental Paleoproterozoic transpressional orogeny within the consolidated Kaapvaal-Zimbabwe Craton, which was induced by far-field tectonic processe
Keywords: Limpopo Belt; Pseudosection; P-T path; Granulite; Neoarchean; Delamination

Pressure-temperature evolution of blueschist facies rocks from Sifnos, Greece, and implications for the exhumation of high-pressure rocks in the Central Aegean - Schmädicke, Esther; et al. (Journal of Metamorphic Geology, 2003)
Keywords: Exhumation; Cyclades; Pseudosection; High-pressure metamorphism; Sifnos

Prevailing anoxia in the Kungurian (Permian) of South China: Possible response to divergent climate trends between the tropics and Gondwana - Liu, Chao; Jarochowska, Emilia; Du, Yuansheng; Munnecke, Axel; Dai, Xianduo (Gondwana Research, 2017)
Keywords: Early–Middle Permian; Icehouse–greenhouse climate transition; Ocean stagnation; Primary productivity

Primary versus diagenetic isotope signals in Pseudorthoceras sp. from the Buckhorn Asphalt Quarry (mid-Pennsylvanian, Oklahoma) - a detailed study of cameral deposits - Seuß, Barbara; Titschack, Jürgen; Nützel, Alexander (Annual Meeting of the Paläontologische Gesellschaft, 2010)
Oxygen and carbon stable isotope studies of well-preserved fossils present an important data source for palaeoclimatic studies. Commonly, the older the fossils, the less good they are preserved. The Buckhorn Asphalt Quarry Lagerstätte from the mid-Pennsylvanian of Oklahoma is one of the few Palaeozoic examples, where original (metastable) shell material, such as aragonite and high magnesium calcite (HMC) is found, due to their early post-mortal hydrocarbon impregnation. The Buckhorn Asphalt Quarry is characterised by fossiliferous sediments soaked with hydrocarbons, which commonly prevented diagenesis. This study presents microstructural, mineralogical and stable isotope data from Pseudorthoceras sp. (two chambers with their cameral deposits). Therefore data from thin section analysis, scanning electron microscope (SEM) combined with an energy disperse x-ray (EDX), and x-ray diffraction (XRD) with a general area detection diffraction system (GADDS) analysis were combined. XRD-GADDS is a relatively new method to investigate the shells mineralogy and allows the non-destructive, site-specific identification of mineral phases. Altogether seven microstructures were differed in the sections drilled for isotope dating. These could be divided into two primary mineralogies, aragonite and HMC. We don’t have any knowledge of cameral deposits with a HMC mineralogy or found any evidence of this in literature. The only partially unaltered preserved microstructure is the nacre of the septum. All other microstructures exhibit a partial or complete alteration to low magnesium calcite (LMC), or in case of the primary HMC to LMC and dolomite. According to the isotope signature the diagenesis took place most likely in the meteoric environment. The partial diagenesis results in isotope values, which plot along a linear trend between the two end-members. This linear trend could easily be misinterpreted as kinetic vital effect, if no sorrow phase control was performed. The isotopic signal of the primary nacre of the septum suggest a normal marine environment for these nektonic molluscs, with tropical temperatures of 14°C to 15°C (δ18Oseawater 1.5 ‰, a typical value for modern tropical marginal seas

Primitive andesites from the Taupo Volcanic Zone formed by magma mixing - Beier, Christoph; Haase, Karsten; Brandl, Philipp; Krumm, Stefan (Contributions To Mineralogy and Petrology, 2017)
Andesites with Mg# >45 erupted at subduction zones form either by partial melting of metasomatized mantle or by mixing and assimilation processes during melt ascent. Primitive whole rock basaltic andesites from the Pukeonake vent in the Tongariro Volcanic Centre in New Zealand’s Taupo Volcanic Zone contain olivine, clino- and orthopyroxene, and plagioclase xeno- and antecrysts in a partly glassy matrix. Glass pools interstitial between minerals and glass inclusions in clinopyroxene, orthopyroxene and plagioclase as well as matrix glasses are rhyolitic to dacitic indicating that the melts were more evolved than their andesitic bulk host rock analyses indicate. Olivine xenocrysts have high Fo contents up to 94%, δO of +5.1‰, and contain Cr-spinel inclusions, all of which imply an origin in equilibrium with primitive mantle-derived melts. Mineral zoning in olivine, clinopyroxene and plagioclase suggest that fractional crystallization occurred. Elevated O isotope ratios in clinopyroxene and glass indicate that the lavas assimilated sedimentary rocks during stagnation in the crust. Thus, the Pukeonake andesites formed by a combination of fractional crystallization, assimilation of crustal rocks, and mixing of dacite liquid with mantle-derived minerals in a complex crustal magma system. The disequilibrium textures and O isotope compositions of the minerals indicate mixing processes on timescales of less than a year prior to eruption. Similar processes may occur in other subduction zones and require careful study of the lavas to determine the origin of andesite magmas in arc volcanoes situated on continental crust.
Keywords: Crustal magmatic processes; Magma mixing; Primitive andesites; Subduction zones; Taupo Volcanic Zone

Processes of Groundwater Contamination in Coastal Aquifers in Sri Lanka: A Geochemical and Isotope-Based Approach - Ratnayake, Movini Sathma; Senarathne, Sachintha Lakshan; Diyabalanage, Saranga; Bandara, Chaminda; Wickramarathne, Sudeera; Chandrajith, Rohana (Water, 2025)
Over the last decade, concern has increased about the deterioration of groundwater quality in coastal aquifers due to salinization processes resulting from uncontrolled abstraction and the impacts of global climate change. This study investigated the groundwater geochemistry of a narrow sandy peninsula bounded by the ocean and brackish water lagoons in northern Sri Lanka. The population of the region has grown rapidly over the last decade with increasing agricultural activities, and therefore, the use of groundwater has increased. To investigate the effects of seawater intrusion and anthropogenic activities, selected water quality parameters and water isotopes (δ2H and δ18O) were measured in 51 groundwater samples. The results showed that selected shallow groundwater wells are vulnerable to contamination from anthropogenic processes and seawater intrusion, mainly indicated by Cl/Br ratios. Iron-rich groundwater (0.11 to 4.2 mg/L) could represent another problem in the studied groundwater. According to Water Quality Index calculations, 41% of shallow wells contained poor and unsuitable water for domestic and irrigation purposes. Most of the groundwater in the region was saturated with Ca and Mg containing mineral phases such as calcite, dolomite, magnesite and gypsum. Water isotopes (δ2H and δ18O) showed that about 50% of the groundwater samples were scattered near the local meteoric water line. This indicates sufficient rainwater infiltration. However, some samples exhibit elevated isotope values due to seawater admixture and secondary evaporation under semi-arid conditions. This study showed the utility of Cl/Br ratios as indicators for distinguishing anthropogenic sources of Cl contributions to groundwater in shallow, permeable aquifer systems.
CRIS-Team Scopus Importer:2025-06-20
Keywords: Cl/Br ratios; Fe-rich groundwater; reductive dissolution; seawater intrusion; septic tanks

Productivitiy and bottom water redox conditions on both sides of the Eovariscan Belt: constraints from trace element geochemistry. - Joachimski, Michael; et al. (Developments in Palaeontology and Stratigraphy, 2005)
UnivIS-Import:2015-03-09:Pub.2005.nat.dgeo.IGM.LG.produc

Productivity controlled cold-water coral growth periods during the last glacial off Mauritania - Frank, Norbert; Wienberg, Claudia; Hebbeln, Dierk; López Correa, Matthias; Douville, Eric; Freiwald, André; Eisele, Markus (Marine Geology, 2011)
Cold-water corals are widely distributed along the Atlantic continental margin with varying growth patterns in relation to their specific environment. Here, we investigate the long-term development of cold-water corals that once thrived on a low-latitude (17°40'N) cold-water coral mound in the Banda Mound Province off Mauritania during the last glacial-interglacial cycle. U/Th dates obtained from 20 specimens of the cold-water coral Lophelia pertusa, revealed three distinct periods of coral growth during the last glacial at 65 to 57. kyr. BP, 45 to 32. kyr. BP and 14. kyr. BP, thus comprising the cool periods of Marine Isotopic Stages (MIS) 2-4. These coral growth periods occur during periods of increased productivity in the region, emphasizing that productivity seems to be the major steering factor for coral growth off Mauritania, which is one of the major upwelling regions in the world. This pattern differs from the well studied coral mounds off Ireland, where the current regime predominantly influences the prosperity of the cold-water corals. Moreover, coral growth off Ireland takes place during rather warm interglacial and interstadial periods, whereas off Mauritania coral growth is restricted to glacial and stadial periods. However, the on-mound sedimentation patterns off Mauritania largely resemble the observations reported from the Irish mounds. The bulk of the preserved sediments derives from periods of coral growth, whereas during periods without corals hardly any net sedimentation or mound growth took place. © 2011 Elsevier B.V.
UnivIS-Import:2015-03-09:Pub.2011.nat.dgeo.IGM.LP.produc
Keywords: Banda Mound Province; Carbonate mounds; Cold-water corals; Lophelia; NW-Africa; Primary productivity

Progetto ITER: il miglioramento dell'efficienza termica degli scambiatori di calore orizzontale - Di Sipio, Eloisa; Bertermann, David (Convegno finale Progetto GEOTERM - GEOSCAMBIO IN TERRITORIO ALPINO, 2016)

Progressive changes in crystallographic textures of biominerals generate functionally graded ceramics - Wallis, David; Harris, Joseph; Böhm, Corinna; Wang, Di; Zavattieri, Pablo; Feldner, Patrick; Merle, Benoit; Pipich, Vitaliy; Hurle, Katrin; Leupold, Simon; Hansen, Lars N.; Marin, Frederic; et al. (Materials Advances, 2021)
Biomineralizing organisms are widely praised for their ability to generate structural materials with exceptional crystallographic control. While earlier studies highlighted near-to single-crystalline biominerals, complex polycrystalline features are more widespread yet challenging to account for. Here, we propose that biominerals whose crystal texture varies with depth are functionally graded materials. Using the exemplary case of the nacro-prismatic pearl oyster Pinctada margaritifera, we demonstrate systematic textural changes in a biogenic ceramic. This bivalve employs three synergistic mechanisms to generate a texture gradient across its outer calcitic shell layer. This prismatic layer transitions from an initially weakly-textured to a strongly-textured material. Such changes in texture cause a variation in Young's modulus normal to the shell, owing to the anisotropic mechanical properties of the composing crystallites. Based on finite-element simulations and indentation experiments on the bivalve shell, we conclude that such graded bioceramics yield intrinsic toughening properties similar to those found in compositionally-graded synthetic materials. Notwithstanding, the gradation concept of Pinctada margaritifera is unparalleled among synthetic materials as it rests solely upon elastic anisotropy, making oyster shells potential blueprints for future bioinspired functional materials and damage-resistant ceramics.
CRIS-Team WoS Importer:2022-01-14

Progressive Changes in Magma Transport at the Active Serreta Ridge, Azores - Romer, René; Beier, Christoph; Haase, Karsten; Kluegel, A.; Hamelin, C. (Geochemistry Geophysics Geosystems, 2019)
Volcanism in the Eastern Azores Plateau occurs at large central volcanoes and along subaerial and submarine fissure zones, resulting from a mantle melting anomaly combined with transtensional stresses. Volcanic structures are aligned WNW-ESE and NW-SE, reflecting two tectonic stress fields that control the direction of lateral melt transport. Terceira Island is influenced by both stress fields, dividing the island into an eastern and western part. Several submarine volcanic ridges with variable orientations are located west of Santa Bárbara, the youngest central volcano on Terceira. Major, trace element and Sr-Nd-Pb-Hf isotope compositions from submarine lavas and glasses, in part associated with the 1998–2001 Serreta Ridge eruption, vary between different lava suites, suggesting a formation from different mantle sources. Submarine lavas are more primitive than those from Santa Bárbara volcano, indicating that they are not laterally connected with the shallow magma reservoir located in 2- to 5-km depth beneath the central volcano. Mineral thermobarometric data suggest that the older Serreta magmas were laterally transported at depths >5 km from Santa Bárbara predominantly in WNW direction. We propose that lithospheric extension controls magma transport from the central volcano to Serreta Ridge. The youngest Serreta lavas differ from Santa Bárbara and other submarine ridges in having less radiogenic Pb and higher Hf isotope ratios representing a new magma pulse ascending from the mantle. We conclude that lateral magma transport and the morphology of volcanic ridges are controlled by tectonic stresses in the lithosphere, whereas vertical melt transport is initiated by processes in the mantle.
CRIS-Team Scopus Importer:2019-12-10
Keywords: Azores; evolution; magmatic; melt transport; ocean island; tectonic

Proliferation and demise of deep-sea corals in the Mediterranean during the Younger Dryas - McCulloch, Malcolm; Taviani, Marco; Montagna, Paolo; López Correa, Matthias; Remia, Alessandro; Mortimer, Graham (Earth and Planetary Science Letters, 2010)
Uranium-series and radiocarbon ages are reported for deep-sea corals Madrepora oculata, Desmophyllum dianthus, Lophelia pertusa and Caryophyllia smithii from the Mediterranean Sea. U-series dating indicates that deep-sea corals have persisted in the Mediterranean for over 480,000years, especially during cool interstadial periods. The most prolific period of growth however appears to have occurred within the Younger Dryas (YD) period from 12,900 to 11,700years BP followed by a short ( 330years) phase of post-YD coral growth from 11,230 to 10,900years BP. This indicates that deep-sea corals were prolific in the Mediterranean not only during the return to the more glacial-like conditions of the YD, but also following the rapid deglaciation and transition to warmer conditions that followed the end of the YD. Surprisingly, there is a paucity Last Glacial Maximum (LGM) coral ages, implying they were largely absent during this period when cold-water conditions were more prevalent. Radiocarbon ages show that the intermediate depth waters of the Mediterranean generally had increment14C compositions similar to surface waters, indicating that these waters were extremely well ventilated. The only exception is a narrow period in the YD (12,500±100years BP) when several samples of Lophelia pertusa from the Ionian Sea had increment14C values falling significantly below the marine curve. Using a refined approach, isolation ages (τisol) of 300years to 500years are estimated for these intermediate (800-1000m) depth waters relative to surface marine waters, indicating a reduction or absence of deep-water formation in the Ionian and adjacent Adriatic Seas during the YD. Contrary to previous findings, we find no evidence for widespread intrusion of low increment14C Atlantic waters into the Mediterranean. Prolific growth of deep-sea corals in the Mediterranean ended abruptly at 10,900years BP, with many of the coral-bearing mounds on the continental slopes being draped in a thin veneer of mud. Their demise is attributed to a number of factors, including the direct loss of habitat due to high sedimentation that accompanied glacial meltwater pulses, together with rising temperatures that would have finally pervaded the deeper water of the Mediterranean following the onset of Holocene warming. © 2010 Elsevier B.V.
UnivIS-Import:2015-03-09:Pub.2010.nat.dgeo.IGM.LP.prolif
Keywords: Deep-sea corals; Demise; Environment; Prolific; U-series dating; Younger Dryas

Promoting origination - Kießling, Wolfgang (Nature Geoscience, 2010)
UnivIS-Import:2015-03-09:Pub.2010.nat.dgeo.IGM.LP.promot

Proterozoic evolution of the North Atlantic - Arctic Caledonides: Insight from detrital zircon analysis of metasedimentary rocks from the Pearya Terrane, Canadian High Arctic. - Malone, Shawn J.; Mcclelland, William C.; von Gosen, Werner; Piepjohn, Karsten (Journal of Geology, 2014)
The Pearya Terrane, recognized as the only exotic terrane along the Canadian Arctic margin, includes a Neoproterozoic–early Paleozoic basinal or passive-margin metasedimentary sequence that is structurally juxtaposed with arc-related Paleozoic rocks and a metamorphic basement complex containing early Neoproterozoic orthogneiss. The Neoproterozoic siliciclastic sequence is similar to other clastic sections formed at the breakup of Rodinia, but its paleogeographic origin and crustal affinity are uncertain. Detrital zircon age spectra from seven samples reveal three groups: Group A, with numerous peaks at c. 1100–1800 Ma and the youngest population at c. 1020 Ma; Group B, defined by a dominant c. 970 Ma age peak; and Group C, with dominant peaks from c. 970–1800 Ma and a small population of c. 635–710 Ma grains. Spectra from Group A resemble data from the latest Mesoproterozoic units in Svalbard, East Greenland, and the Scandinavian Caledonides, with the ubiquitous Mesoproterozoic ages observed in all these regions compatible with derivation from the Grenville-Sveconorwegian Orogen of Laurentia and Baltica. The dominance of 930–970 Ma ages in Group B reflects input from magmatic rocks of this age in Pearya and Sval-bard, while the 635–710 Ma ages observed in Group C overlap with magmatic ages observed in the Arctic Alaska–Chukotka Terrane and units in the Taimyr-Timanide region. The Neoproterozoic siliciclastic strata of the Pearya Terrane originated distal to northeastern Laurentia, in a position similar to that of the constituent terranes of Svalbard and the Eleonore Bay Supergroup of East Greenland, and they record deposition along a Neoproterozoic convergent margin active during the prolonged breakup of Rodinia.
UnivIS-Import:2015-10-26:Pub.2014.nat.dgeo.IGM.LG.proter

Provenace, distributiion and trade of the local building materials in the Sarno River Plain (Campania) from the 6th Century BC to AD 79. - Kastenmeier, Pia; Ballasone, Pina; Boni, Maria; Di Maio, Ernesto; Joachimski, Michael (ASMOSIA X. Proceedings of the 10th International Conference, 2014)
UnivIS-Import:2015-07-08:Pub.2014.nat.dgeo.IGM.LG.proven

Provenance of Palaeozoic sediments during subduction of Palaeotethys: detrital zircon ages and the analysis of olistoliths from Chios Island, Greece. - Meinhold, Guido; Lehnert, Oliver; Reischmann, Thomas; Kostopoulos, Dimitrios; Matukov, Dmitry; Sergeev, Sergej (Palaeogeography, Palaeoclimatology, Palaeoecology, 2008)
UnivIS-Import:2015-03-09:Pub.2008.nat.dgeo.IGM.LG.proven

Provenance of Tertiary volcanoclastic sediment in NW Thrace (Bulgaria): Evidence from detrital amphibole and pyroxene geochemistry - Caracciolo, Luca; et al. (Sedimentary Geology, 2016)
Detrital heavy mineral and bulk rock geochemistry and a review of sandstone petrographic data have been used to investigate the post-collisional effusive magmatism that followed the closure of the Vardar Ocean and the generation of volcanic sediments in a complex and compositionally variable volcanic region. Available petrographic data gives evidence of contributions from three key source areas corresponding to the three main tectonic units: the structurally lower Gneiss-Migmatite Complex (Byala Reka-Kechros and Kesebir-Kardamos domes) and the upper Variegated (Kimi) Complex, both fringed by the low-to-medium-grade Mesozoic rocks of the Circum-Rhodope Belt. Besides the deposition of siliciclastic material, volcanic contributions from both, intermediate and acid products represent an important source of sediment in the area. Despite dominant intermediate to acid volcanic products, volcanic lithic fragments in sandstones (microlithic, lathwork and brown vitric textures) indicate main inputs from intermediate and basic-intermediate products generating questions on the interpretation of volcanic detritus in reconstruction of provenance. Detrital amphibole and pyroxene chemistry is used to characterise the supply of volcanic material as well as the dispersal mechanisms and understand the role played by each of the volcanic centers present in the area in the infill of the north-western Thrace basin. Amphibole chemistry reveals high compositional heterogeneity according to both compositional variability of the numerous volcanic centres active at the time of deposition and presence of metamorphic amphibole. Al-4 and Al-T apfu values indicate that most of the amphiboles from the NERZ are not of volcanic origin and their presence can only be attributed to the numerous amphibolite facies metamorphic rocks abundantly documented in the area. Detrital amphibole compositions from the ZKVS indicate major contributions from the Iran Tepe and Zvedzel volcanoes. Analysed detrital clinopyroxenes from the NERZ are mostly diopside-augite, with no hedenbergite or Fe-augite detected. The Al-4/Al-6 ratio is comparable with compositions of volcanic pyroxenes from the Momchilgrad-Arda (ZKVS) region and products from the pre-caldera phase of the Borovitza. (C) 2016 Elsevier B.V. All rights reserved.
Keywords: Single grain geochemistry; Provenance analysis; Thrace Basin; Rhodope; Volcaniclastic sedimentation; Eastem Mediterranean basin

Pseudotachylyte in muscovite-bearing quartzite: Coseismic friction-induced melting and plastic deformation of quartz - Bestmann, Michel; Pennacchioni, Giorgio; Frank, Gerhard; Göken, Mathias; de Wall, Helga (Journal of Structural Geology, 2011)
Thin (0.5–2 mm thick) pseudotachylyte veins occur within muscovite-bearing ( 10% volume), amphibolite-facies quartzites of the Schneeberg Normal Fault Zone (Austroalpine, Southern Tyrol, Italy). Pseudotachylytes are associated with precursor localized plastic microshear zones (50–150 extgreekmm thick) developed sub-parallel to the host-rock foliation and with conjugate sets oriented at a high angle to the foliation. Such microshear zones are characterized by recrystallization to ultrafine-grained (1–2 extgreekmm grain size) mosaic aggregates of quartz showing a transition from a host-controlled to a random crystallographic preferred orientation towards the shear zone interior. Subsequent coseismic slip mainly exploited these microshear zones. Microstructural analysis provides evidence of extensive friction-induced melting of the muscovite-bearing quartzite, producing a bimodal melt composition. First, the host-rock muscovite was completely melted and subsequently crystallized, mainly as K-feldspar. Then, about 60% volume of the ultrafine-grained quartz underwent melting and crystallized as spherulitic rims (mostly consisting of quartz ± Ti ± Fe) around melt-corroded quartz clasts. The two melts show immiscibility structures in the major injection veins exploiting microshear zones at high angles to the quartzite foliation. In contrast, they were mechanically mixed during flow along the main fault veins.
WW1::896

Putative ichnogenus Paralanicichnites Ghare and Badve 1981 from the Palaeogene of the Kachchh Basin (India) is a coral - Kulkarni, Kantimati G.; Sikilkar, Namra (Annales Societatis Geologorum Poloniae, 2020)
Structures, reported as the trace fossil, Paralanicichnites conflueris, were described from the Palaeogene rocks of the Kachchh (Kutch) District, Gujarat State, India, by Ghare and Badve as a new ichnogenus and ichnospecies. Restudy of the type specimens revealed that the form described as a burrow in fact is a scleractinian coral, as evidenced by its phaceloid morphology, septate calcareous exoskeleton, and twelve primary septa. It appears that there is also confusion regarding the exact geological formation, from which the specimens under consideration were taken by the original authors, as well as the age assigned by them.
CRIS-Team WoS Importer:2020-09-11

Putting the F into FBD analysis: tree constraints or morphological data? - Barido-Sottani, Joëlle; Pohle, Alexander; De Baets, Kenneth; Murdock, Duncan; Warnock, Rachel (Palaeontology, 2023)
The fossilized birth–death (FBD) process provides an ideal model for inferring phylogenies from both extant and fossil taxa. Using this approach, fossils are directly integrated into the tree, leading to a statistically coherent prior on divergence times. Since fossils are typically not associated with molecular sequences, additional information is required to place fossils in the tree. We use simulations to evaluate two different approaches to handling fossil placement in FBD analyses: using topological constraints, where the user specifies monophyletic clades based on established taxonomy, or using total-evidence analyses, which use a morphological data matrix in addition to the molecular alignment. We also explore how rate variation in fossil recovery or diversification rates impacts these approaches. We find that the extant topology is well recovered under all methods of fossil placement. Divergence times are similarly well recovered across all methods, with the exception of constraints which contain errors. We see similar patterns in datasets which include rate variation, however, relative errors in extant divergence times increase when more variation is included in the dataset, for all approaches using topological constraints, and particularly for constraints with errors. Finally, we show that trees recovered under the FBD model are more accurate than those estimated using non-time calibrated inference. Overall, we show that both fossil placement approaches are reliable even when including uncertainty. Our results underscore the importance of core taxonomic research, including morphological data collection and species descriptions, irrespective of the approach to handling phylogenetic uncertainty using the FBD process.
CRIS-Team Scopus Importer:2023-11-24
Keywords: fossilized birth–death; morphological data; phylogenetic inference; taxonomy; topological constraints; total-evidence

Pyrite chemistry: A new window into Au-Te ore-forming processes in alkaline epithermal districts, Cripple Creek, Colorado - Keith, Manuel; Smith, Daniel J.; Doyle, Keiran; Holwell, David A.; Jenkin, Gawen R.T.; Barry, Tiffany L.; Becker, Joseph; Rampe, Jason (Geochimica Et Cosmochimica Acta, 2020)
Tellurium has a wide variety of applications, most importantly in the solar energy industry and is eco-toxicologically significant; however, the magmatic-hydrothermal processes causing the pronounced Te enrichment together with Au in some epithermal districts are still poorly constrained. Hydrothermal and alkaline magmatic activity in post-subduction environments are suggested to be a critical component in the evolution of this Te-rich sub-class of low-sulfidation epithermal deposits. Cripple Creek represents an example for a world-class low-sulfidation epithermal Au-Te anomaly in the continental crust. This area represents a natural laboratory to investigate the processes of ore-formation and Au-Te enrichment in alkaline igneous rock-hosted epithermal systems. Here, we present the first micro-analytical approach that combines petrographic observations with in situ LA-ICP-MS analyses and trace element mapping to define the key ore-forming processes of Au and Te in the Cripple Creek epithermal complex. Two main styles of mineralization can be distinguished: (1) low-grade Au disseminated pyrite-rich ores in the permeable brecciated host rocks and (2) high-grade quartz-fluorite veins rich in calaverite (AuTe2), coloradoite (HgTe), petzite (Ag3AuTe2), altaite (PbTe) and native Au. Pyrite trace element mapping revealed distinct variations and decoupling of elements (Au-Te) and element pairs (Au-As vs. Co-Ni) within and between different sites in the epithermal district. This is reflected by the concentric/growth zoning of these elements in pyrite that were interpreted to be caused by fluid boiling associated with the deposition of the low-grade disseminated host rock ores at temperatures between 220 and 350 °C leading to the precipitation of Au, As, Co and Ni from the liquid phase and the preferential partitioning of Te into the vapor phase. The subsequent condensation of the Te-rich vapors in metal-bearing meteoric waters led to the Te precipitation being decoupled from Au in the low-grade ores. The high-grade Au-Te mineralization was likely initiated by the influx of magmatically derived oxidized fluids. Subsequently, fluid temperatures dropped due to mixing with meteoric waters resulting in fluid boiling under low pressure conditions at shallower crustal levels (<1000 m) compared to the low-grade ores. Elevated fO2 minimized the loss of Te to the vapor phase and the strong boiling conditions at lower fluid temperatures (105–200 °C) caused the contemporaneous precipitation of Au and Te in the high-grade veins.
CRIS-Team Scopus Importer:2020-02-25
Keywords: Epithermal Au-Te deposits; Fluid boiling; LA-ICP-MS analysis; Telluride mineralogy; Trace elements in pyrite

Pyrite trace element proxies for magmatic volatile influx in submarine subduction-related hydrothermal systems - Falkenberg, Jan; Keith, Manuel; Haase, Karsten; Klemd, Reiner; Kutzschbach, Martin; Grosche, Anna; Scicchitano, Maria Rosa; Strauss, Harald; Kim, Jonguk (Geochimica Et Cosmochimica Acta, 2024)
Seafloor massive sulfides are modern analogues to ancient volcanogenic massive sulfide deposits, which are particularly enriched in volatile and precious metals (e.g., Te, Au, Ag, Cu, Bi, Se) in subduction-related settings. However, the sources of metals are still poorly constrained, and it remains elusive, whether magmatic volatile influx controls their distribution in submarine hydrothermal systems on the plate tectonic-scale. Here, we demonstrate, for the first time, that Te, As, and Sb contents as well as related Te/As and Te/Sb ratios vary systematically with the δ34S composition of pyrite and native S, as reported by high-resolution coupled SIMS δ34S and trace element LA-ICP-MS micro-analysis. The better correlation of element ratios (Te/As, Te/Sb) opposed to trace element contents (e.g., Te) with δ34S in pyrite demonstrates that element ratios provide a more robust record of magmatic volatile influx than their absolute contents. On this basis, we define a quantitative threshold of high Te/As (>0.004) and Te/Sb (>0.6) ratios in pyrite that are indicative of magmatic volatile influx to submarine subduction-related hydrothermal systems. Two-component fluid mixing simulations further revealed that <5 % of magmatic volatile influx drastically changes the Te/As (and Te/Sb) ratio of the modelled fluid, but only slightly changes its δ34S composition. This suggests that Te/As and Te/Sb ratios are more sensitive to a magmatic volatile influx into seawater-dominated hydrothermal systems than δ34S signatures if the magmatic volatile influx was low. Beyond this, our results demonstrate that magma-derived fluid mixing with seawater only has a negligible effect on the magmatic volatile record of Te/As and Te/Sb, while the S isotope system is prone for seawater overprinting leading to commonly ambiguous source signatures. Thus, Te/As and Te/Sb systematics in pyrite provide a robust proxy to evaluate the contribution of magmatic volatiles to submarine hydrothermal systems from the grain- to plate tectonic-scale.
CRIS-Team Scopus Importer:2024-04-26
Keywords: Black smokers; coupled SIMS δ; In-situ sulfide chemistry; Magmatic fluids; Magmatic volatile phase; Pyrite; Submarine hydrothermal systems

Pyrophosphate ions inhibit calcium phosphate cement reaction and enable storage of premixed pastes with a controlled activation by orthophosphate addition - Weichhold, Jan; Götz-Neunhoeffer, Friedlinde; Hurle, Katrin; Gbureck, Uwe (Ceramics International, 2022)
The standard preparation routine of a calcium phosphate cement includes mixing a solid and a liquid component (reactive cement powder and mixing liquid) in an open bowl at the operating theatre. This poses the risk of preparation-related deviations of the resulting properties when the cements are mixed by different persons. Hence, facilitating this mixing procedure is highly desirable. It can be achieved by application of premixed cement pastes: The mixing liquid and a stable suspension of the cement powder are assembled and mixed in a special syringe, minimizing the impact of these preparation-related effects. In this study, a suspension of reactive α-tricalcium phosphate powder in water was stabilized by sodium pyrophosphate decahydrate (PP). Controlled activation of these premixed pastes was then accomplished by adding a concentrated Na2HPO4/NaH2PO4 (Na2/Na) solution. Systematic assessment of the activation mechanism, including the effect of the PP concentration and the amount of Na2/Na added, was performed by isothermal calorimetry, quantitative in-situ X-ray diffraction, rheological characterization and automated Gillmore needle measurements at 37 °C. Premixed pastes with addition of at least 0.05 wt% PP were successfully stabilized for up to 2 weeks at 25 °C, and even 4 weeks at 4 °C. This pre-storage had no significant impact on the setting performance of the pastes. Increasing the PP concentration at constant Na2/Na amount systematically retarded the setting reaction, while an elevated quantity of Na2/Na addition at constant PP concentration resulted in an acceleration. Based on these results, a composition stabilized with 0.05 wt% PP and activated with 20.8 vol% Na2/Na related to the amount of liquid in the premixed pastes appears ideal with respect to the desired setting performance.
CRIS-Team Scopus Importer:2022-04-22
Keywords: Apatite (D); Biomedical applications (E); Premixed cement pastes; X-ray methods (B)

Quantification of a mixture of synthetic Alite and Belite by the Rietveld method - Neubauer, Jürgen; Sieber, Roland (Materials Science Forum, 1996)
Alite and beute are the main components in ordinary portland cement. The quantification by X-ray diffraction methods is very difficult due to the wide range of overlapping reflections. The presented investigations deal with the quantification by fullprofile refinement. To get good structure data of alite and belite both were synthesized in a laboratory furnace at 1400°C. Their chemical composition was the same as that of alite and belite of technically produced cement clinker (modified composition proposed by Taylor 1990 [1]). X-ray investigation of alite shows best fits to the monoclinic superstructure published by Nishi & Takeuchi (1985) [2]. Belite could be described by the structure data of Jost et al. (1977) [3]. Both structures were refined by the Rietveld PC software of Wiles and Young modified by Howard. Afterwards synthetic alite and belite were mixed in different ratios and quantified by the same software. Three different mixtures show a smaller deviation from the input than 1 wt.%.
UnivIS-Import:2015-03-05:Pub.1996.nat.dgeo.IGM.LM.quanti_9
Keywords: Portland Cement; Quantification; Rietveld Method; Synthetic Mixture

Quantification of groundwater infiltration into urban sewer systems using stable isotopes - Penckwitt, Jan; van Geldern, Robert; Hagspiel, Burkard; Packebusch, Birgit; Mahr, Alexander; Burkhardt, Klaus; Barth, Johannes (Grundwasser, 2016)

Quantification of groundwater-seawater interaction in a coastal sandy aquifer system: A study from Panama, Sri Lanka - Chandrajith, Rohana; Chaturangani, Dinusha; Abeykoon, Sumith; Barth, Johannes; van Geldern, Robert; Edirisinghe, E. A. N. V.; Dissanayake, C. B. (Environmental Earth Sciences, 2014)

Quantification of long-term wastewater fluxes at the surface water/groundwater-interface: An integrative model perspective using stable isotopes and acesulfame - Engelhardt, I.; Barth, Johannes; Bol, Roland; Schulz, M.; Ternes, T. A.; Schueth, C.; van Geldern, Robert (Science of the Total Environment, 2014)

Quantification of sediment transport by rockfall and rockslide processes on a proglacial rock slope (Kaunertal, Austria) - Vehling, Lucas; Baewert, H.; Glira, P.; Moser, Michael; Rohn, Joachim; Morche, David (Geomorphology, 2017)
Rockfalls and rockslides are significant geomorphic processes on high alpine proglacial rock slopes. In this study, we quantitatively evaluate sediment transport on a recently deglaciated rock slope that is directly connected to the shrinking Gepatschferner glacier, by multi-temporal terrestrial and airborne LiDAR observations. According to the LiDAR measurements, sediment transport by gravitational mass movements on this single proglacial rock slope (0.2 km2) yielded 159 GJ/a geomorphic work. The most significant part (141 GJ/a) was released by rockfall while 18 GJ/a were performed by the sliding activity of a 1,250,000 m3 large unstable rock mass. The results indicate that slope development and talus formation in proglacial environments may be a rapid process despite of being caused by continuous rockfall activity over several millennia. © 2016 Elsevier B.V.
Keywords: glacier; landslide; lidar; proglacial environment; rockfall; sediment transport; Austria; Kaunertal; Tyrol

Quantification of small magnitude rockfall processes at a proglacial high mountain site, Gepatsch glacier (Tyrol, Austria) - Vehling, Lucas; Moser, Michael; Rohn, Joachim (Zeitschrift für Geomorphologie, 2016)
Keywords: Proglacial geosystem; Rockfall collectors; Rockfall intensity

Quantification of wall surface heterogeneity and its influence on species diversity at medieval castles - implications for the environmentally friendly preservation of cultural heritage - Steinbauer, Manuel; Gohlke, Andreas; Mahler, Christine; Schmiedinger, Andreas; Beierkuhnlein, Carl (Journal of Cultural Heritage, 2013)
Historic buildings are important for cultural history and provide a variety of habitats for animals and plants. Especially structural heterogeneity of wall surfaces is perceived to support biological diversity. Nevertheless, in traditional approaches goals of biodiversity preservation and monument restoration are perceived to interfere and to be mutually exclusive. As a consequence, priority is often given to constructional restoration accepting the loss of local populations and biodiversity. At walls of medieval castles, including an experimental restoration project where conventional and less intensive restoration techniques were applied, we relate species composition and richness to wall properties. Especially wall surface structure is quantified using a novel approach. The study focuses on lichens, mosses and vascular plants. Boosted regression tree analyses and non-metric multidimensional scaling techniques are applied to detect the influence of abiotic site conditions on biodiversity. We find species richness to be promoted by wall surface heterogeneity. However, species composition is more affected by restoration approaches than species richness. Lichen composition varies considerably while vascular plants and mosses are less affected by wall properties. We suggest strategies that are combining both societal targets, the preservation of historic monuments and of species diversity. Careful restoration is capable of supporting both, the maintenance of cultural heritage and of rare and unique anthropogenic habitats. Wall surface heterogeneity needs to be witnessed for both aspects as it affects both species composition as well as the effectiveness of cleaning methods.
Keywords: Biodegradation; Biodeterioration; Historic buildings; Monuments; Nature conservation; Wall vegetation

Quantifizierung von Mischungen aus synthetischem Alit und Belit mit Hilfe der Rietveld Methode - Neubauer, Jürgen; Sieber, Roland; Kuzel, Hans Jürgen (European Journal of Mineralogy, 1995)
UnivIS-Import:2015-03-05:Pub.1995.nat.dgeo.IGM.LM.quanti

Quantifying the Effects of Changing Deposition Rates and Hiatii on the Stratigraphic Distribution of Fossils - Hohmann, Niklas (2018)
Keywords: Stratigraphy; Paleontology; Statistics; Stratigraphic Paleobiology; Data Processing; Measure Theory; Information Theory

Quantitative Analyse des CO_2_-Gehaltes im Heißmehl der PZ-Klinkerproduktion - Götz-Neunhoeffer, Friedlinde; Neubauer, Jürgen; Muck, Michael; Hans-Willhelm, Meyer (14. Internationale Baustofftagung IBAUSIL, 2000)
UnivIS-Import:2015-04-16:Pub.2000.nat.dgeo.IGM.LM.quanti_80

Quantitative analysis of crystal-interface frequencies in granitoids: Implications for modelling of parent-rock texture and its influence on the properties of plutoniclastic sands - Weltje, Gert Jan; Paredis, Bram; Caracciolo, Luca; Heins, William (Sedimentary Geology, 2018)
Generation of sediments from crystalline rocks is the result of a complex and incompletely understood suite of processes. The time evolution of the rock-fragment assemblage in sands derived from granitoids is determined by the relative strengths of crystal interfaces and their abundances in the parent rock. In this study we highlight the role of crystal-interface frequencies in granitoids. Strong evidence for non-random texture with significant implications for predicted interface frequencies have been reported in previous studies. We analysed available interface-frequency data from granitoids using methods of compositional data analysis, and connected our results to existing texture classifications. On average, granitoids display a high degree of ordering with significant depletion of isomineralic interfaces relative to expectations based on random texture. Analysis of 210 normalized interface frequency distributions from nine different granitoids reveals a consistent pattern of variation among interface frequencies, which suggests a single underlying petrogenetic process related to the combined effects of nucleation and textural equilibration ("coarsening").In view of the large scatter of relative interface frequencies within and among granitoids, we propose to model their distribution empirically for the purpose of calibrating sediment-generation studies. Multivariate normal distributions of centred log-ratio transformed relative frequencies are capable of capturing ∼95% of the observed variability with a limited number of dimensions. As a rule of thumb, the number of dimensions needed to approximate interface-frequency counts can be taken equal to the number of mineral classes, which is (much) smaller than the number of interface classes. Mathematical analysis shows that the joint variability of rock texture and composition may be factorized into three statistically independent measures: modal composition, crystal-size probability density functions, and normalized interface frequencies. The potential independence of these measures permits objective identification of petrogenetically significant correlations among them, which will be indicated by statistically significant cross-covariances. At this stage, inferences from microscopic texture analysis cannot be extrapolated to the scale of entire drainage basins in which sediments are generated, because insufficient data are available on the large-scale spatial heterogeneity of texture and composition of granitoid parent rocks<br

Quantitative analysis of crystalline and amorphous phases in glass-ceramic composites like LTCC by the rietveld method - Kemethmüller, Stefan; Roosen, Andreas; Götz-Neunhoeffer, Friedlinde; Neubauer, Jürgen (Journal of the American Ceramic Society, 2006)
Glass-ceramic composites like low-temperature cofired ceramics are densified at temperatures below 900°C via liquid-phase sintering. For high-frequency applications, materials with low dielectric losses are needed. At these frequencies glass exhibits higher dielectric losses than a crystalline phase; therefore, the glass amount is reduced after densification by crystallization. To perform a quantitative X-ray analysis of such glass-ceramic composites, a method based on Rietveld refinement was developed. For optimum results, the X-ray diffraction patterns were fitted using the software TOPAS 2.1 from Bruker AXS. With this method, it is possible to determine quantitatively the amount of crystalline phases and also the amount of the remaining amorphous phase. © 2006 The American Ceramic Society.
UnivIS-Import:2015-03-09:Pub.2006.nat.dgeo.IGM.LM.quanti

Quantitative analysis of CSH in hydrating alite pastes by in-situ XRD - Bergold, Sebastian; Götz-Neunhoeffer, Friedlinde; Neubauer, Jürgen (Cement and Concrete Research, 2013)
In this study about the early hydration of monoclinic alite, a method is presented that allows to follow the formation of the Calcium-Silicate-Hydrates directly and quantitatively over time. The combination of the PONKCS method [20] and the G-factor method [6] allowed the refinement and calibration of a C-S-H phase model which can be used for direct quantification of C-S-H in cementitious pastes. The comparison between the heat flow measured by calorimetry and the heat flow calculated from the phase development of C-S-H revealed that C-S-H formation starts later than is indicated by the measured heat flow. It is therefore assumed that the silicate reaction proceeds the following way: A not XRD-detectable C-S-H phase is precipitated which then evolves into a long-range ordered, XRD-detectable C-S-H. This C-S-H acts as a nucleation site for further long-range ordered C-S-H and leads to the acceleration of alite dissolution and direct formation of C-S-H. © 2013 Elsevier Ltd.
UnivIS-Import:2015-03-09:Pub.2013.nat.dgeo.IGM.LM.quanti
Keywords: Ca; Calcium-silicate-hydrates (C-S-H); Calorimetry (A); Hydration (A); X-ray diffraction (B)

Quantitative analysis of suture lines in Carboniferous ammonoids - Wegerer, Michael; de Baets, Kenneth; Korn, Dieter (FOSSIL RECORD, 2018)
Two morphometric methods are applied and compared for the analysis of suture lines in Early Carboniferous ammonoids of the superfamilies Pericycloidea, Girtyoceratoidea and Goniatitoidea. We analysed (1) classic metric data (proportions of the width and depths or heights of lobes and saddles) using multivariate statistic methods and (2) outline data of the external lobe and the ventrolateral saddle of the same ammonoid taxa using the elliptic Fourier analysis. Both methods lead to similar results and simultaneously demonstrate ontogenetic and phylogenetic trends of these ammonoids. Our results are consistent with three previously suggested evolutionary patterns: (1) a general decrease of the amplitude of lobes and saddles, (2) a proportional widening of the external lobe and (3) a heightening of the median saddl

QUANTITATIVE ANALYSIS OF THE STRENGTH GENERATING C-S-H-PHASE IN CONCRETE BY IR-SPECTROSCOPY - Schmidt-Döhl, Frank Michael; Schulenberg, David; Tralow, Franziska; Neubauer, Jürgen; Wolf, Julian; Ectors, Dominique (Acta Polytechnica CTU Proceedings, 2022)
The C-S-H-phase is the most important strength generating phase in concrete and other cementitious materials. The analysis of C-S-H is therefore an important instrument of innovations in the field of concrete and its durability and sustainability. The quantification and insights in C-S-H are hindered by the predominantly amorphous structure of C-S-H. Only the time consuming and expensive solid state nuclear magnetic resonance spectroscopy (NMR) gives a chance to get results, but is restricted to model substances. A new technique, based on the cheap and widespread infrared-spectroscopy (IR) was developed. The quantitative analysis is based on the silicon content in the different structural units of C-S-H and a calibration with natural and synthetic materials with known silicon content in these units. The technique allows to investigate specimens from real structures. Specimens with quartz or limestone aggregate can be analyzed directly. In other cases the aggregates must be separated, for example with heavy liquid separation. Tests with different mortars showed a good correspondence of measured and expected values of C-S-H concentration.
CRIS-Team Scopus Importer:2022-09-02
Keywords: Calcium-Silicate-Hydrate (C-S-H); quantitative analysis; spectroscopy

Quantitative biochronology of Devonian ammonoids from Morocco and proposals for a refined unitary association method - Monnet, Claude; Klug, Christian; Goudemand, Nicolas; de Baets, Kenneth; Bucher, Hugo (Lethaia, 2011)
Based on a rich dataset, the biostratigraphy of the late Emsian and the Eifelian (Early-Middle Devonian) ammonoids from the Moroccan Tafilalt is re-evaluated. We processed this dataset (comprising 53 species from 15 sections) with the unitary association method (UAM), by means of the UA-graph freeware. This led to the construction of a sequence of 17 UAs (maximal sets of actually or virtually coexisting taxa), which are grouped into 10 laterally reproducible association zones. This biostratigraphical subdivision of this interval is in some parts finer than the classically used empirical stratigraphical scheme and than a previous graphic correlation analysis. It enabled us to measure regional ammonoid diversity of this interval in detail. The UAM is a powerful biochronological method, which benefits from complementary tools to analyse conflicting intertaxon stratigraphical relationships inherent to complex biostratigraphical datasets. In cases of under-constrained superpositional relationships between the taxa, the UAM can yield results, which are not parsimonious in terms of reconstructed virtual coexistences. We suggest several additions to complement the algorithmic steps of the method. The most important is the exhaustive or heuristic reconstruction of possible solutions resolving the observed biostratigraphical contradictions (conflicting inter-taxon superpositional relationships and cycles between maximal cliques) and the selection among the solutions of the most-parsimonious one(s) in terms of reconstructed virtual coexistences. Multiple equivalent results may then be processed with standard consensus techniques. Finally, the robustness of the results can be tested by bootstrapping methods to provide confidence estimates on the ranges and associations of studied taxa.
Keywords: Ammonites; Anti-Atlas; biostratigraphy; correlation; zonation; diversity

Quantitative determination of anhydrite III from dehydrated gypsum by XRD - Seufert, Sebastian; Hesse, Christoph; Götz-Neunhoeffer, Friedlinde; Neubauer, Jürgen (Cement and Concrete Research, 2009)
Technical OPC contains mixed sulfate carriers in varying amounts. Gypsum and anhydrite are added to the clinker during the milling process where the gypsum dehydrates partially to bassanite and anhydrite. Due to different hydration kinetics of these phases, it is crucial to be able to characterize the composition of sulfate in a cement system to reach an optimal and reproducible cement hydration. In the current paper different calcium sulfate compositions are investigated by XRD methods in order to identify phase content. Special focus is put on the discrimination of the hemihydrate (bassanite) and anhydrite III as well as on transformation processes of anhydrite III through ambient humidity. © 2009 Elsevier Ltd. All rights reserved.
UnivIS-Import:2015-03-09:Pub.2009.nat.dgeo.IGM.LM.quanti
Keywords: Calcium sulfate; Hydration; Portland cement; X-ray diffraction characterization

Quantitative determination of the decarbonation degree in hot meal of OPC Production by XRD - Muck, Michael; Götz-Neunhoeffer, Friedlinde; Neubauer, Jürgen; Hans-Willhelm, Meyer (1999)
UnivIS-Import:2015-03-05:Pub.1999.nat.dgeo.IGM.LM.quanti_7

Quantitative Fracture Set Characterization. - Drews, Michael; Deckert, Hagen; et al. (Geotectonic Research 96/01 – Special Issue TSK 13 Abstracts, 2010)

Quantitative in-situ X-ray diffraction analysis of early hydration of Portland cement at defined temperatures - Götz-Neunhoeffer, Friedlinde; Neubauer, Jürgen; Hesse, Christoph; Gäberlein, Peter; Bräu, Michael (Powder Diffraction, 2009)
Investigation into the early hydration of Portland cement was performed by in situ X-ray diffraction (XRD). Technical white cement was used for the XRD analysis on a D5000 diffractometer (Siemens). All diffraction patterns of the in situ measurement which were recorded up to 22 h of hydration at defined temperatures were analyzed by Rietveld refinement. The resulting phase composition was transformed with respect to free water and C-S-H leading to the total composition of the cement paste. The hydration reactions can be observed by dissolution of clinker phases as well as by the formation of the hydrate phases ettringite and portlandite. With increasing temperatures the reactions proceed faster. The formation of ettringite is directly influenced by the rate of dissolution of anhydrite and tricalcium aluminate (C3 A). The beginning of the main period of hydration is marked by the start of portlandite formation. The experiments point out that a quantitative phase analysis of the cement hydration is feasible with standard laboratory diffractometers. © 2009 International Centre for Diffraction Data.
UnivIS-Import:2015-03-09:Pub.2009.nat.dgeo.IGM.LM.quanti_9
Keywords: Cement; Hydration; In situ XRD; Rietveld analysis

Quantitative Relationship between Low-Field AMS and Phyllosilicate Fabric: A Review - de Wall, Helga; et al. (Physics and Chemistry of the Earth, 1997)
UnivIS-Import:2015-03-05:Pub.1997.nat.dgeo.IGM.c3tekt.quanti

Quantitative Röntgenbeugungsanalyse an Portlandzementklinkern mit Hilfe der Rietveld Methode - Neubauer, Jürgen; Sieber, Roland (European Journal of Mineralogy, 1996)
UnivIS-Import:2015-03-05:Pub.1996.nat.dgeo.IGM.LM.quanti

Quantitative Röntgenbeugungsanalyse zur Prozessoptimierung bei der Portlandzementproduktion - Neubauer, Jürgen (European Journal of Mineralogy, 2000)
UnivIS-Import:2015-03-09:Pub.2000.nat.dgeo.IGM.LM.quanti_0

Quantitative röntgenographische Bestimmung des Entsäuerungsgrades im Portlandzement-Heißmehl - Muck, Michael; Götz-Neunhoeffer, Friedlinde; Neubauer, Jürgen; Hans-Willhelm, Meyer (2000)
UnivIS-Import:2015-03-09:Pub.2000.nat.dgeo.IGM.LM.quanti

Quantitative röntgenographische Phasenanalyse an Portlandzementklinkern - Grundlagen und Anwendung - Neubauer, Jürgen (1999)
UnivIS-Import:2016-07-26:Pub.1999.nat.dgeo.IGM.LM.quanti_20

Quartz pseudomorphs after coesite in eclogites from the Saxonian Erzgebirge - Schmädicke, Esther (European Journal of Mineralogy, 1991)

Quartz texture and the chemical composition fingerprint of ore-forming fluid evolution at the Bilihe porphyry Au deposit, NE China - Hong, Jingxin; Zhai, Degao; Keith, Manuel (American Mineralogist, 2024)
Quartz is widely distributed in various magmatic-hydrothermal systems and shows variable textures and trace element contents in multiple generations, enabling quartz to serve as a robust tracer for monitoring hydrothermal fluid evolution. This study demonstrates that integrated high-resolution SEM-CL textures and trace element data of quartz can be used to constrain physicochemical fluid conditions and trace the genesis of quartz in porphyry ore-forming systems. The Bilihe deposit is a gold-only porphyry deposit located in the Central Asian orogenic belt, NE China. Four quartz generations were distinguished following a temporal sequence from early-stage dendritic quartz, unidirectional solidification textured quartz (UST quartz), gray banded vein quartz (BQ), to late-stage white calcite vein quartz (CQ), with the Au precipitation being mostly related to dendritic quartz, UST quartz, and BQ. The well-preserved dendritic quartz with sector-zoned CL intensities and euhedral oscillatory growth zones crystallized rapidly during the late magmatic stage. The relatively low Al contents of dendritic quartz were interpreted to be related to contemporaneous feldspar or mica crystallization, while the high-Ti contents indicate high-crystallization temperatures ( 750 °C). The comb-layered UST quartz displays heterogeneous, patchy luminescence with weak zoning, hosts coeval melt and fluid inclusions, and retains the chemical characteristics of magmatic dendritic quartz. High-Ti and low-Al contents of UST quartz suggest a formation at relatively high temperatures ( 700 °C) and high-pH conditions. Three sub-types can be defined for hydrothermal BQ (BQ1, BQ2, and BQ3) based on contrasting CL features and trace element contents. The Al contents increase from BQ1 to BQ2 followed by a drop in BQ3, corresponding to an initial decrease and subsequent increase in fluid acidity. Temperature estimates of BQ decrease from BQ1 (635 °C) to BQ3 (575 °C), which may, however, be disturbed by high growth rates and/or high-TiO2 activities. The CQ typically displays a CL-bright core and CL-dark rim with oscillating CL intensities and is characterized by the lowest Ti and highest Al, Li, and Sb contents compared to the other quartz types, which suggests a deposition from more acidic and lower temperature fluids ( 250 °C). Trace element patterns indicate that a coupled Si4+ ↔ (Al3+) + (K+) element exchange vector is applicable to dendritic quartz, UST quartz, and BQ. By contrast, charge-compensated cation substitution of Si4+ ↔ (Al3+, Sb3+) + (Li+, Rb+) is favored for CQ. The comparison with compiled trace element data of quartz from other porphyry Au, Cu, and Mo deposits worldwide suggests that Ti, Al, Li, K, and Ge concentrations, as well as Al/Ti and Ge/Ti ratios, have the potential to discriminate the metal fertility of porphyry mineralization.
CRIS-Team Scopus Importer:2024-07-26
Keywords: Bilihe; fluid evolution; porphyry Au deposit; quartz; SEM-CL texture; trace elements

Radiogenic heat production of Variscan granites from the Western Bohemian Massif, Germany - Scharfenberg, Lars; Regelous, Anette; de Wall, Helga (Journal of Geosciences, 2019)
Much of the Mid-European basement has been consolidated during the Variscan Orogeny and includes large volumes of granitic intrusions. Gamma radiation spectroscopic measurements in three study areas along the western margin of the Bohemian Massif give a record of radiogenic element concentrations in the Variscan granites. Most intrusions of the Fichtelgebirge (except for the Tin Granite) and intrusive complexes in the Bavarian Forest show Th/U ratios exceeding unity, most likely related to abundance of monazite. In contrast, some of the Oberpfalz granites located near the Saxothuringian-Moldanubian boundary (FlossenbUrg, Steinwald and Friedenfels types) are characterized by higher uranium concentrations and thus Th/U < 1. The low Th/U ratios here are in agreement with a possible U mobilisation along the Saxothuringian-Moldanubian contact zone observed in previous studies. Heat production rates of granites in the three study areas vary between 3.9 and 8.9 mu W/m(3), with a mean of 4.9 mu W/m(3). This classifies the intrusions as moderate- to high-heat-producing granites. Considering the huge volume of granitic bodies in the Variscan crust of the Bohemian Massif, the contribution of in situ radiogenic heat production had to have a major impact and should be considered in further thermal modeling.
CRIS-Team WoS Importer:2020-02-28

Radiolarian biodiversity dynamics through the Triassic and Jurassic: implications for proximate causes of the end-Triassic mass extinction - Kocsis, Ádám; Kießling, Wolfgang; Palfy, Jozsef (Paleobiology, 2014)
Within a 60-Myr interval in the Late Triassic to Early Jurassic, a major mass extinction took place at the end of Triassic, and several biotic and environmental events of lesser magnitude have been recognized. Climate warming, ocean acidification, and a biocalcification crisis figure prominently in scenarios for the end-Triassic event and have been also suggested for the early Toarcian. Radiolarians, as the most abundant silica-secreting marine microfossils of the time, provide a control group against marine calcareous taxa in testing selectivity and responses to changing environmental parameters. We analyzed the origination and extinction rates of radiolarians, using data from the Paleobiology Database and employing sampling standardization, the recently developed gap-filler equations and an improved stratigraphic resolution at the substage level. The major end-Triassic event is well-supported by a late Rhaetian peak in extinction rates. Because calcifying and siliceous organisms appear similarly affected, we consider global warming a more likely proximate trigger of the extinctions than ocean acidification. The previously reported smaller events of radiolarian turnover fail to register above background levels in our analyses. The apparent early Norian extinction peak is not significant compared to the long-term trajectory, and is probably a sampling artifact. The Toarcian Oceanic Anoxic Event, previously also thought to have caused a significant radiolarian turnover, did not significantly affect the group. Radiolarian diversity history appears unique and complexly forced, as its trajectory parallels major calcareous fossil groups at some events and deviates at other

Radiolarian biodiversity dynamics through the Triassic and Jurassic: implications for proximate causes of the end-Triassic mass extinction - Kocsis, Adam T.; Kießling, Wolfgang; Palfy, Jozsef (Paleobiology, 2014)
UnivIS-Import:2015-03-09:Pub.2014.nat.dgeo.IGM.LP.radiol

Radiolarian diversity patterns in the latest Jurassic-earliest Cretaceous - Kießling, Wolfgang (Palaeogeography, Palaeoclimatology, Palaeoecology, 2002)
The global diversity patterns of latest Jurassic-earliest Cretaceous (Tithonian-Berriasian) radiolarian faunas were analyzed based on samples from the European Alps, Oman, Philippines and Antarctica and an extensive literature survey. Several measures of diversity were applied to faunas from tropical (Oman, Mexico, Pacific), subtropical (Alps, California, Philippines, Japan), and subpolar (Antarctic Peninsula, New Zealand, Northern Russia) localities. Original diversity patterns are obscured by taxonomic, sedimentological, and preservational biases. Qualitative and quantitative corrections of these biases indicated a significant diversity gradient from tropical-subtropical to subpolar latitudes, but no significant difference between tropical and subtropical assemblages. The latitudinal diversity gradient was apparently asymmetrical, being steeper in the Northern Hemisphere than in the Southern Hemisphere. In the Southern Hemisphere the diversity gradient was similar to the one observed in modern radiolarian sedimentary assemblages. Considering the more equable climate of the Tithonian-Berriasian, it appears unlikely that temperature was the only control of the observed diversity patterns. The results substantiate the notion of latitudinal diversity gradients as a time-invariant feature of the Earth, possibly driven by gradients in biome size. © 2002 Elsevier Science B.V. All rights reserved.
UnivIS-Import:2015-03-09:Pub.2002.nat.dgeo.IGM.LP.radiol
Keywords: Biodiversity; Cretaceous; Jurassic; Paleogeography; Radiolarians