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Sample records for early triassic mass

  1. Early Triassic alternative ecological states driven by anoxia, hyperthermals, and erosional pulses following the end-Permian mass extinction

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    Pietsch, C.; Petsios, E.; Bottjer, D. J.

    2015-12-01

    The end-Permian mass extinction, 252 million years ago, was the most devastating loss of biodiversity in Earth's history. Massive volcanic eruptions of the Siberian Traps and the concurrent burning of coal, carbonate, and evaporite deposits emplaced greenhouse and toxic gasses. Hyperthermal events of the surface ocean, up to 40°C, led to reduced gradient-driven ocean circulation which yielded extensive equatorial oxygen minimum zones. Today, anthropogenic greenhouse gas production is outpacing carbon input modeled for the end-Permian mass extinction, which suggests that modern ecosystems may yet experience a severe biotic crisis. The Early Triassic records the 5 million year aftermath of the end-Permian mass extinction and is often perceived as an interval of delayed recovery. We combined a new, high resolution carbon isotope record, sedimentological analysis, and paleoecological collections from the Italian Werfen Formation to fully integrate paleoenvironmental change with the benthic ecological response. We find that the marine ecosystem experienced additional community restructuring events due to subsequent hyperthermal events and pulses of erosion. The benthic microfauna and macrofauna both contributed to disaster communities that initially rebounded in the earliest Triassic. 'Disaster fauna' including microbialites, microconchids, foraminifera, and "flat clams" took advantage of anoxic conditions in the first ~500,000 years, dominating the benthic fauna. Later, in the re-oxygenated water column, opportunistic disaster groups were supplanted by a more diverse, mollusc-dominated benthic fauna and a complex ichnofauna. An extreme temperature run-up beginning in the Late Dienerian led to an additional hyperthermal event in the Late-Smithian which co-occurred with increased humidity and terrestrial run-off. Massive siliciclastic deposits replaced carbonate deposition which corresponds to the infaunalization of the benthic fauna. The disaster taxa dominated

  2. Redox chemistry changes in the Panthalassic Ocean linked to the end-Permian mass extinction and delayed Early Triassic biotic recovery.

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    Zhang, Guijie; Zhang, Xiaolin; Hu, Dongping; Li, Dandan; Algeo, Thomas J; Farquhar, James; Henderson, Charles M; Qin, Liping; Shen, Megan; Shen, Danielle; Schoepfer, Shane D; Chen, Kefan; Shen, Yanan

    2017-02-21

    The end-Permian mass extinction represents the most severe biotic crisis for the last 540 million years, and the marine ecosystem recovery from this extinction was protracted, spanning the entirety of the Early Triassic and possibly longer. Numerous studies from the low-latitude Paleotethys and high-latitude Boreal oceans have examined the possible link between ocean chemistry changes and the end-Permian mass extinction. However, redox chemistry changes in the Panthalassic Ocean, comprising ∼85-90% of the global ocean area, remain under debate. Here, we report multiple S-isotopic data of pyrite from Upper Permian-Lower Triassic deep-sea sediments of the Panthalassic Ocean, now present in outcrops of western Canada and Japan. We find a sulfur isotope signal of negative Δ(33)S with either positive δ(34)S or negative δ(34)S that implies mixing of sulfide sulfur with different δ(34)S before, during, and after the end-Permian mass extinction. The precise coincidence of the negative Δ(33)S anomaly with the extinction horizon in western Canada suggests that shoaling of H2S-rich waters may have driven the end-Permian mass extinction. Our data also imply episodic euxinia and oscillations between sulfidic and oxic conditions during the earliest Triassic, providing evidence of a causal link between incursion of sulfidic waters and the delayed recovery of the marine ecosystem.

  3. PALAEOECOLOGICAL CHANGES AFTER THE END-PERMIAN MASS EXTINCTION: EARLY TRIASSIC OSTRACODS FROM NORTHWESTERN GUANGXI PROVINCE,SOUTH CHINA

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    SYLVIE CRASQUIN-SOLEAU

    2006-03-01

    Full Text Available Early Triassic (Griesbachian to Spathian ostracod faunas are here first discovered and described form the Guangxi Province, South China. Thirty-seven species belonging to fourteen genera are recognized. Seven species are new: Bairdia fengshanensis n.sp., Bairdia wailiensis n.sp., Liuzhinia guangxiensis n.sp., Ptychobairdia luciaae n.sp., Ptychobairdia aldaae n.sp., Paracypris jinyaensis n.sp. and Paracypris gaetanii n.sp. The Griesbachian assemblage from the basal microbial limestone is well diversified and does not suggest any abnormal palaeoenvironmental conditions in terms of salinity, temperature or oxygen content. Particularly, the ostracods are typical of well oxygenated water and do not reflect any anoxia. Dienerian and Smithian ostracods are evidenced for the first time and the assemblages suggest less favourable palaeoenviromental conditions. Diversity and abundance of ostracod assemblages recovered from the Spathian on. The main taxonomic turnover among ostracod assemblages occurred seemingly between the Griesbachian and the Spathian.

  4. Paleosol formation during the Early Triassic Biotic Crisis in Norway

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    Knies, Jochen; Müller, Axel; Zwingmann, Horst; Fredin, Ola; Brönner, Marco; Viola, Giulio

    2016-04-01

    Fractured and kaolinite weathered basement rocks have been discovered in various wells off the Norwegian coast and inferences on timing, source to sink relationships, and environmental implications have been widely discussed. The reason for the kaolitinization has often been related to intensive chemical weathering during late Triassic to early Jurassic times. Chronological control has primarily been inferred from the overlying late Jurassic/early Cretaceous marine transgression and poorly constrained K-Ar datings from weathered basement onshore as well as climate conditions favourable for kaolinite formation. In this study, we present evidence that the deeply weathered basement off the mid-Norwegian coast represent a complete paleosol profile. Quartz geochemical fingerprinting indicate that transgressional marine inorganic sediments of late Jurassic age are derived from the paleosols. Whole-rock XRD analysis suggests characteristic mineral alteration zones topped with a kaolinite-Fe-oxyhyroxide zones composed of >80% kaolinite. Potassium feldspar is practically absent in the uppermost kaolinitic zones. Mass-balance changes show significant depletion-enrichment trends. Applying potassium/argon (K/Ar) geochronology on authigenic illite clay that grew in-situ at the time of paleosol formation reveals a early Triassic age (~250 Ma). The age corroborates with the Early Triassic biotic crisis and suggest a causal relationship between intense chemical weathering, high atmospheric CO2 concentration, extreme ocean warming, increased riverine flux of nutrients and widespread anoxia/euxinia on adjacent epicontinental seas.

  5. Early Triassic marine biotic recovery: the predators' perspective.

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    Scheyer, Torsten M; Romano, Carlo; Jenks, Jim; Bucher, Hugo

    2014-01-01

    Examining the geological past of our planet allows us to study periods of severe climatic and biological crises and recoveries, biotic and abiotic ecosystem fluctuations, and faunal and floral turnovers through time. Furthermore, the recovery dynamics of large predators provide a key for evaluation of the pattern and tempo of ecosystem recovery because predators are interpreted to react most sensitively to environmental turbulences. The end-Permian mass extinction was the most severe crisis experienced by life on Earth, and the common paradigm persists that the biotic recovery from the extinction event was unusually slow and occurred in a step-wise manner, lasting up to eight to nine million years well into the early Middle Triassic (Anisian) in the oceans, and even longer in the terrestrial realm. Here we survey the global distribution and size spectra of Early Triassic and Anisian marine predatory vertebrates (fishes, amphibians and reptiles) to elucidate the height of trophic pyramids in the aftermath of the end-Permian event. The survey of body size was done by compiling maximum standard lengths for the bony fishes and some cartilaginous fishes, and total size (estimates) for the tetrapods. The distribution and size spectra of the latter are difficult to assess because of preservation artifacts and are thus mostly discussed qualitatively. The data nevertheless demonstrate that no significant size increase of predators is observable from the Early Triassic to the Anisian, as would be expected from the prolonged and stepwise trophic recovery model. The data further indicate that marine ecosystems characterized by multiple trophic levels existed from the earliest Early Triassic onwards. However, a major change in the taxonomic composition of predatory guilds occurred less than two million years after the end-Permian extinction event, in which a transition from fish/amphibian to fish/reptile-dominated higher trophic levels within ecosystems became apparent.

  6. Early Triassic marine biotic recovery: the predators' perspective.

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    Torsten M Scheyer

    Full Text Available Examining the geological past of our planet allows us to study periods of severe climatic and biological crises and recoveries, biotic and abiotic ecosystem fluctuations, and faunal and floral turnovers through time. Furthermore, the recovery dynamics of large predators provide a key for evaluation of the pattern and tempo of ecosystem recovery because predators are interpreted to react most sensitively to environmental turbulences. The end-Permian mass extinction was the most severe crisis experienced by life on Earth, and the common paradigm persists that the biotic recovery from the extinction event was unusually slow and occurred in a step-wise manner, lasting up to eight to nine million years well into the early Middle Triassic (Anisian in the oceans, and even longer in the terrestrial realm. Here we survey the global distribution and size spectra of Early Triassic and Anisian marine predatory vertebrates (fishes, amphibians and reptiles to elucidate the height of trophic pyramids in the aftermath of the end-Permian event. The survey of body size was done by compiling maximum standard lengths for the bony fishes and some cartilaginous fishes, and total size (estimates for the tetrapods. The distribution and size spectra of the latter are difficult to assess because of preservation artifacts and are thus mostly discussed qualitatively. The data nevertheless demonstrate that no significant size increase of predators is observable from the Early Triassic to the Anisian, as would be expected from the prolonged and stepwise trophic recovery model. The data further indicate that marine ecosystems characterized by multiple trophic levels existed from the earliest Early Triassic onwards. However, a major change in the taxonomic composition of predatory guilds occurred less than two million years after the end-Permian extinction event, in which a transition from fish/amphibian to fish/reptile-dominated higher trophic levels within ecosystems became

  7. Trophic network models explain instability of Early Triassic terrestrial communities.

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    Roopnarine, Peter D; Angielczyk, Kenneth D; Wang, Steve C; Hertog, Rachel

    2007-09-07

    Studies of the end-Permian mass extinction have emphasized potential abiotic causes and their direct biotic effects. Less attention has been devoted to secondary extinctions resulting from ecological crises and the effect of community structure on such extinctions. Here we use a trophic network model that combines topological and dynamic approaches to simulate disruptions of primary productivity in palaeocommunities. We apply the model to Permian and Triassic communities of the Karoo Basin, South Africa, and show that while Permian communities bear no evidence of being especially susceptible to extinction, Early Triassic communities appear to have been inherently less stable. Much of the instability results from the faster post-extinction diversification of amphibian guilds relative to amniotes. The resulting communities differed fundamentally in structure from their Permian predecessors. Additionally, our results imply that changing community structures over time may explain long-term trends like declining rates of Phanerozoic background extinction.

  8. Early archosauromorph remains from the Permo-Triassic Buena Vista Formation of north-eastern Uruguay

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    Martín D. Ezcurra

    2015-02-01

    Full Text Available The Permo-Triassic archosauromorph record is crucial to understand the impact of the Permo-Triassic mass extinction on the early evolution of the group and its subsequent dominance in Mesozoic terrestrial ecosystems. However, the Permo-Triassic archosauromorph record is still very poor in most continents and hampers the identification of global macroevolutionary patterns. Here we describe cranial and postcranial bones from the Permo-Triassic Buena Vista Formation of northeastern Uruguay that contribute to increase the meagre early archosauromorph record from South America. A basioccipital fused to both partial exoccipitals and three cervical vertebrae are assigned to Archosauromorpha based on apomorphies or a unique combination of characters. The archosauromorph remains of the Buena Vista Formation probably represent a multi-taxonomic assemblage composed of non-archosauriform archosauromorphs and a ‘proterosuchid-grade’ animal. This assemblage does not contribute in the discussion of a Late Permian or Early Triassic age for the Buena Vista Formation, but reinforces the broad palaeobiogeographic distribution of ‘proterosuchid grade’ diapsids in Permo-Triassic beds worldwide.

  9. Early archosauromorph remains from the Permo-Triassic Buena Vista Formation of north-eastern Uruguay.

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    Ezcurra, Martín D; Velozo, Pablo; Meneghel, Melitta; Piñeiro, Graciela

    2015-01-01

    The Permo-Triassic archosauromorph record is crucial to understand the impact of the Permo-Triassic mass extinction on the early evolution of the group and its subsequent dominance in Mesozoic terrestrial ecosystems. However, the Permo-Triassic archosauromorph record is still very poor in most continents and hampers the identification of global macroevolutionary patterns. Here we describe cranial and postcranial bones from the Permo-Triassic Buena Vista Formation of northeastern Uruguay that contribute to increase the meagre early archosauromorph record from South America. A basioccipital fused to both partial exoccipitals and three cervical vertebrae are assigned to Archosauromorpha based on apomorphies or a unique combination of characters. The archosauromorph remains of the Buena Vista Formation probably represent a multi-taxonomic assemblage composed of non-archosauriform archosauromorphs and a 'proterosuchid-grade' animal. This assemblage does not contribute in the discussion of a Late Permian or Early Triassic age for the Buena Vista Formation, but reinforces the broad palaeobiogeographic distribution of 'proterosuchid grade' diapsids in Permo-Triassic beds worldwide.

  10. High sedimentation rates in the Early Triassic after latest Permian mass extinction: Carbonate production is main factor in non-Arctic regions

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    Horacek, Micha; Brandner, Rainer

    2016-04-01

    A substantial change in sedimentation rates towards higher values has been documented from the Late Permian to the Lower Triassic. Although it is assumed and also has been shown that the deposition of siliciclastic material increased in the Lower Triassic due to stronger erosion because of loss of land cover and increased chemical and physical weathering with extreme climate warming, the main sediment production occurred by marine carbonate production. Still, carbonate production might have been significantly influenced by weathering and erosion in the hinterland, as the transport of dust by storms into the ocean water probably was a main nutrient source for microbial carbonate producers, because "normal" nutrient supply by ocean circulation, i. e. upwelling was strongly reduced due to the elevated temperatures resulting in water-column stratification . Sediment accumulation was also clearly influenced by the paleo-geographic and latitudinal position, with lower carbonate production and sedimentation rates in moderate latitudes. The existence of a "boundary clay" and microbial carbonate mounds and layers in the immediate aftermath of the latest Permian mass extinction points towards a development from a short-timed acid ocean water - resulting in a carbonate production gap and the deposition of the boundary clay towards the deposition of the microbial mounds and layers due to the microbial production of micro-environments with higher alkalinity allowing the production of carbonate. After the return of the ocean water to normal alkalinity planktic production of carbonate resulted in a very high sedimentation rate, especially taking into account the absence of carbonate producing eukaryotic algae and animals.

  11. New Early Jurassic Tetrapod Assemblages Constrain Triassic-Jurassic Tetrapod Extinction Event

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    Olsen, P. E.; Shubin, N. H.; Anders, M. H.

    1987-08-01

    The discovery of the first definitively correlated earliest Jurassic (200 million years before present) tetrapod assemblage (Fundy basin, Newark Supergroup, Nova Scotia) allows reevaluation of the duration of the Triassic-Jurassic tetrapod extinction event. Present are tritheledont and mammal-like reptiles, prosauropod, theropod, and ornithischian dinosaurs, protosuchian and sphenosuchian crocodylomorphs, sphenodontids, and hybodont, semionotid, and palaeonisciform fishes. All of the families are known from Late Triassic and Jurassic strata from elsewhere; however, pollen and spore, radiometric, and geochemical correlation indicate an early Hettangian age for these assemblages. Because all ``typical Triassic'' forms are absent from these assemblages, most Triassic-Jurassic tetrapod extinctions occurred before this time and without the introduction of new families. As was previously suggested by studies of marine invertebrates, this pattern is consistent with a global extinction event at the Triassic-Jurassic boundary. The Manicouagan impact structure of Quebec provides dates broadly compatible with the Triassic-Jurassic boundary and, following the impact theory of mass extinctions, may be implicated in the cause.

  12. Reccurent Early Triassic marine anoxia, impacts of volcanics?

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    Grasby, Stephen; Beauchamp, Benoit; Sanei, Hamed

    2014-05-01

    NW Pangea records a complex history of recurrent development of anoxia through the Permo-Triassic Biotic Crises. The Early Triassic record from the Smithian strato-type in the Sverdrup Basin, as well as for the more open ocean setting of Svalbard, have organic carbon isotope records that closely correspond to major fluctuations in the inorganic carbon records from the Tethys, demonstrating truly global perturbations of the carbon cycle occurred during this time. Geochemical proxies for anoxia are strongly correlated with carbon isotopes, whereby negative shifts in ?13Corg are associated with shifts to more anoxic to euxinic conditions, and positive shifts are related to return to more oxic conditions. Rather than a delayed or prolonged recovery, the Early Triassic is characterized better by a series of aborted biotic recoveries related to shifts back to ocean anoxia, potentially driven by recurrent volcanism.

  13. Atmospheric Carbon Injection Linked to End-Triassic Mass Extinction

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    Ruhl, M.; Bonis, N.R.; Reichart, G.J.; Sinninghe Damsté, J.S.; Kürschner, W.M.

    2011-01-01

    The end-Triassic mass extinction (similar to 201.4 million years ago), marked by terrestrial ecosystem turnover and up to similar to 50% loss in marine biodiversity, has been attributed to intensified volcanic activity during the break-up of Pangaea. Here, we present compound-specific carbon-isotope

  14. A new chronology for the end-Triassic mass extinction

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    Deenen, M. H. L.; Ruhl, M.; Bonis, N. R.; Krijgsman, W.; Kuerschner, W. M.; Reitsma, M.; van Bergen, M. J.

    2010-03-01

    The transition from the Triassic to Jurassic Period, initiating the 'Age of the dinosaurs', approximately 200 Ma, is marked by a profound mass extinction with more than 50% genus loss in both marine and continental realms. This event closely coincides with a period of extensive volcanism in the Central Atlantic Magmatic Province (CAMP) associated with the initial break-up of Pangaea but a causal relationship is still debated. The Triassic-Jurassic (T-J) boundary is recently proposed in the marine record at the first occurrence datum of Jurassic ammonites, post-dating the extinction interval that concurs with two distinct perturbations in the carbon isotope record. The continental record shows a major palynological turnover together with a prominent change in tetrapod taxa, but a direct link to the marine events is still equivocal. Here we develop an accurate chronostratigraphic framework for the T-J boundary interval and establish detailed trans-Atlantic and marine-continental correlations by integrating astrochronology, paleomagnetism, basalt geochemistry and geobiology. We show that the oldest CAMP basalts are diachronous by 20 kyr across the Atlantic Ocean, and that these two volcanic pulses coincide with the end-Triassic extinction interval in the marine realm. Our results support the hypotheses of Phanerozoic mass extinctions resulting from emplacement of Large Igneous Provinces (LIPs) and provide crucial time constraints for numerical modelling of Triassic-Jurassic climate change and global carbon-cycle perturbations.

  15. The Permian-Triassic boundary & mass extinction in China

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    Ian Metcalfe; Lance Black; Qu Xun; Mao Xiaodong; Robert S. Nicoll; Roland Mundil; Clinton Foster; Jonathan Glen; John Lyons; Wang Xiaofeng; Wang Cheng-yuan; Paul R. Renne

    2001-01-01

    @@ The first appearance of Hindeodus parvus (Kozur & Pjatakova) at the Permian-Triassic (P-T) GSSP level (base of Bed 27c) at Meishan is here confirmed. Hindeodus changxingensis Wang occurs from Beds 26 to 29 at Meishan and appears to be restricted to the narrow boundary interval immediately above the main mass extinction level in Bed 25. It is suggested that this species is therefore a valuable P-T boundary interval index taxon.

  16. Unexpected Early Triassic marine ecosystem and the rise of the Modern evolutionary fauna.

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    Brayard, Arnaud; Krumenacker, L J; Botting, Joseph P; Jenks, James F; Bylund, Kevin G; Fara, Emmanuel; Vennin, Emmanuelle; Olivier, Nicolas; Goudemand, Nicolas; Saucède, Thomas; Charbonnier, Sylvain; Romano, Carlo; Doguzhaeva, Larisa; Thuy, Ben; Hautmann, Michael; Stephen, Daniel A; Thomazo, Christophe; Escarguel, Gilles

    2017-02-01

    In the wake of the end-Permian mass extinction, the Early Triassic (~251.9 to 247 million years ago) is portrayed as an environmentally unstable interval characterized by several biotic crises and heavily depauperate marine benthic ecosystems. We describe a new fossil assemblage-the Paris Biota-from the earliest Spathian (middle Olenekian, ~250.6 million years ago) of the Bear Lake area, southeastern Idaho, USA. This highly diversified assemblage documents a remarkably complex marine ecosystem including at least seven phyla and 20 distinct metazoan orders, along with algae. Most unexpectedly, it combines early Paleozoic and middle Mesozoic taxa previously unknown from the Triassic strata, among which are primitive Cambrian-Ordovician leptomitid sponges (a 200-million year Lazarus taxon) and gladius-bearing coleoid cephalopods, a poorly documented group before the Jurassic (~50 million years after the Early Triassic). Additionally, the crinoid and ophiuroid specimens show derived anatomical characters that were thought to have evolved much later. Unlike previous works that suggested a sluggish postcrisis recovery and a low diversity for the Early Triassic benthic organisms, the unexpected composition of this exceptional assemblage points toward an early and rapid post-Permian diversification for these clades. Overall, it illustrates a phylogenetically diverse, functionally complex, and trophically multileveled marine ecosystem, from primary producers up to top predators and potential scavengers. Hence, the Paris Biota highlights the key evolutionary position of Early Triassic fossil ecosystems in the transition from the Paleozoic to the Modern marine evolutionary fauna at the dawn of the Mesozoic era.

  17. Unexpected Early Triassic marine ecosystem and the rise of the Modern evolutionary fauna

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    Brayard, Arnaud; Krumenacker, L. J.; Botting, Joseph P.; Jenks, James F.; Bylund, Kevin G.; Fara, Emmanuel; Vennin, Emmanuelle; Olivier, Nicolas; Goudemand, Nicolas; Saucède, Thomas; Charbonnier, Sylvain; Romano, Carlo; Doguzhaeva, Larisa; Thuy, Ben; Hautmann, Michael; Stephen, Daniel A.; Thomazo, Christophe; Escarguel, Gilles

    2017-01-01

    In the wake of the end-Permian mass extinction, the Early Triassic (~251.9 to 247 million years ago) is portrayed as an environmentally unstable interval characterized by several biotic crises and heavily depauperate marine benthic ecosystems. We describe a new fossil assemblage—the Paris Biota—from the earliest Spathian (middle Olenekian, ~250.6 million years ago) of the Bear Lake area, southeastern Idaho, USA. This highly diversified assemblage documents a remarkably complex marine ecosystem including at least seven phyla and 20 distinct metazoan orders, along with algae. Most unexpectedly, it combines early Paleozoic and middle Mesozoic taxa previously unknown from the Triassic strata, among which are primitive Cambrian-Ordovician leptomitid sponges (a 200–million year Lazarus taxon) and gladius-bearing coleoid cephalopods, a poorly documented group before the Jurassic (~50 million years after the Early Triassic). Additionally, the crinoid and ophiuroid specimens show derived anatomical characters that were thought to have evolved much later. Unlike previous works that suggested a sluggish postcrisis recovery and a low diversity for the Early Triassic benthic organisms, the unexpected composition of this exceptional assemblage points toward an early and rapid post-Permian diversification for these clades. Overall, it illustrates a phylogenetically diverse, functionally complex, and trophically multileveled marine ecosystem, from primary producers up to top predators and potential scavengers. Hence, the Paris Biota highlights the key evolutionary position of Early Triassic fossil ecosystems in the transition from the Paleozoic to the Modern marine evolutionary fauna at the dawn of the Mesozoic era. PMID:28246643

  18. Triassic-Jurassic Mass Extinction: Evidence for Bolide Impact?

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    Perry, R.; Becker, L.; Haggart, J.; Poreda, R.

    2003-04-01

    The Triassic-Jurassic (TJ) mass extinction event is one of the most severe in geologic history and is one of the five largest in the Phanerozoic with as many as 80% of the species lost. It is also one of the most poorly understood. Only a few geologic sections have been identified for the TJ extinction and most of those are not well preserved. Previously, the paucity of suitable stratigraphic sections has prevented corroborative geochemical studies. Recently a well-preserved stratigraphic section spanning the Triassic-Jurassic boundary (˜200 mya) was identified at Kennecott Point, Queen Charlotte, Islands, British Columbia. Initial studies have shown that the Kennecott Point sequence is one of the best preserved and contains one of the most complete radiolarian microfossil turnovers known. Analyses of stable isotopes have shown that a 13C perturbation exits within the sequence and suggests a decline in organic productivity (Ward et al., 2001). Preliminary results of laser desorption mass spectrometry (LDMS) of selected Queen Charlotte samples suggest that fullerenes (C60 to C200) may be present in the Kennecott Point stratigraphic sequence. Previous studies have shown that fullerenes are present in the mass extinction boundary of the Permian-Triassic (˜251 mya) as well as the well-known "dinosaur" extinction event of the Cretaceous-Tertiary (˜65 mya). Therefore, three of the big five extinction events appear to have associated fullerenes. The possible presence of fullerenes along with the productivity collapse (rapid environmental change) suggests that a cometary or asteroidal impact may have occurred. Although no known impact crater exists, we hope to present chemical evidence that an impact or multiple impacts may have been responsible for the TJ mass extinction.

  19. Triassic tectonics of the Ailaoshan Belt (SW China): Early Triassic collision between the South China and Indochina Blocks, and Middle Triassic intracontinental shearing

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    Faure, Michel; Lin, Wei; Chu, Yang; Lepvrier, Claude

    2016-06-01

    In SE Yunnan, the Ailaoshan Belt has been extensively studied for the ductile shearing coeval with the left-lateral Cenozoic activity of the Red River fault. However, the Late Triassic unconformity of the continental red beds upon metamorphic and ductilely deformed rocks demonstrates that the Ailaoshan Belt was already built up by Early Mesozoic tectonics. From West to East, the belt is subdivided into Western, Central, Eastern Ailaoshan, and Jinping zones. The Western Ailaoshan and Central Ailaoshan zones correspond to a Carboniferous-Permian magmatic arc, and an ophiolitic mélange, respectively. The Eastern Ailaoshan, and the Jinping zones consist of deformed Proterozoic basement and Paleozoic to Early Triassic sedimentary cover series both belonging to the South China Block. This litho-tectonic zonation indicates that the Ailaoshan Belt developed through a SW-directed subduction followed by the collision between Indochina and South China blocks. Crustal thickening triggered per-aluminous magmatism dated at ca 247-240 Ma. Field and microscope-scale top-to-the-NE ductile shearing observed only in the pre-Late Triassic formations, but never in Late Triassic or younger formations, complies with this geodynamic polarity. Furthermore, the late collisional two-mica granitoids and felsic per-aluminous volcanites record a ductile deformation that argues for a continuing crustal shearing deformation after the Early Triassic collision up to the Middle Triassic. Therefore, a two-stage tectonic evolution accounts well for the documented structural and magmatic features. The Triassic architecture of the Ailaoshan Belt, and its geodynamic evolution, correlate well to the South and North with the North Vietnam orogens and the Jinshajiang Belt, respectively.

  20. Early Triassic conodonts of Jiarong, Nanpanjiang Basin, southern Guizhou Province, South China

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    Chen, Yanlong; Jiang, Haishui; Lai, Xulong; Yan, Chunbo; Richoz, Sylvain; Liu, Xiaodan; Wang, Lina

    2015-06-01

    Jiarong (Huishui County, Guizhou Province, South China) is a key locality for the study of the Early Triassic recovery after the end-Permian mass extinction. The size reduction of conodonts at the Smithian/Spathian transition was first documented in Jiarong, and it is also a locality that contributes to the documentation of the Early Triassic paleo-seawater temperatures. In the Jiarong sections, thirteen conodont zones were identified for the Early Triassic; in ascending order, they are Hindeodus parvus Zone, Hindeodus sosioensis Zone, Clarkina krystyni Zone, Neoclarkina discreta Zone, Neospathodus cristagalli-Eurygnathodus costatus assemblage zone, Novispathodus waageni eowaageni Zone, Novispathodus waageni waageni Zone, Discretella discreta Zone, Pachycladina-Parachirognathus assemblage zone, Novispathodus pingdingshanensis Zone, Icriospathodus collinsoni Zone, Triassospathodus homeri Zone, Triassospathodus triangularis Zone. These conodont zones in the Jiarong sections improve the global correlation of Early Triassic sections and also provide better regional age constraints in an area that is important for studies of recovery from the extinction. Based on the first appearance of Nv. waageni eowaageni, the Induan/Olenekian boundary is recognized at 3.6 m above the base of the Jiarong III Section. The dominance of blade-shaped (segminate) conodonts was replaced by gondola-shaped (segminiplanate) conodonts twice; the first time was in the late Griesbachian, and the second time was in the early Spathian. The dominance of segminiplanate conodonts probably indicates that the deeper seawater environment became more oxygenated during the late Griesbachian and early Spathian for short time intervals, as it is believed that the Griesbachian segminiplanate conodonts favored deeper oxygenated water habitats. A new genus, Spathogondolella gen. nov., and a new species, Spathogondolella jiarongensis sp. nov., have been recognized.

  1. Patterns of Reef Ecosystem Recovery Indicate That Adverse Early Triassic Ocean Conditions Extended into Middle Triassic Time

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    Kelley, B. M.; Yu, M.; Lehrmann, D. J.; Jost, A. B.; Lau, K. V.; Li, X.; Schaal, E. K.; Payne, J.

    2013-12-01

    The pattern of reef ecosystem recovery from the end-Permian extinction is poorly constrained due to the limited stratigraphic, spatial, and geographic range of reef buildups in Early Triassic and Anisian (early Middle Triassic) strata. In this study, we combined field studies and petrographic analysis to examine the pattern of reef evolution in latest Permian to Late Triassic carbonate platforms in the Nanpanjiang Basin of South China, an area of extensive shallow-water carbonate deposition in the tropical eastern Tethys. We find that early Mesozoic reef recovery in the eastern Tethys was a five-step process: (1) in the immediate aftermath of extinction, calcimicrobial biostromes (P/T boundary microbialites) developed in shallow-water platform settings; (2) in late Induan time, biohermal stromatolites developed in platform interior settings; (3) in latest Spathian time, large-scale Tubiphytes, microbial, and cement reefs lacking skeletal metazoans initiated on the margins and steep upper slopes of carbonate platforms, signaling the return of reefs to platform-margin settings; (4) in the Aegean or Bithynian (early Anisian), diminutive (mm-scale) calcareous sponges and calcareous algae appeared in the Tubiphytes reef, marking the reappearance of skeletal metazoans and calcareous algae to reefs in the eastern Tethys; and (5) in the late Anisian, the appearance of scleractinian corals coincided with increased abundance, size, and diversity of metazoan and algal reef builders. Early Mesozoic reefs of the eastern Tethys were dominated by microbes, Tubiphytes, and early-marine cements until the late Anisian, several million years into the Middle Triassic. The appearance of small metazoan buildups in Early Triassic strata in other parts of the world indicates that potential reef-building organisms were present much earlier. The limited stratigraphic range of those buildups, however, reinforces the interpretation that episodic environmental disturbances such as euxinia

  2. Amelioration of marine environments at the Smithian-Spathian boundary, Early Triassic

    Science.gov (United States)

    Zhang, L.; Zhao, L.; Chen, Z.-Q.; Algeo, T. J.; Li, Y.; Cao, L.

    2015-03-01

    The protracted recovery of marine ecosystems following the Permian-Triassic mass extinction may have been caused, in part, by episodic environmental and climatic crises during the Early Triassic, among which the Smithian-Spathian boundary (SSB) event is conspicuous. Here, we investigate the SSB event in the Shitouzhai section, Guizhou Province, South China, using a combination of carbonate carbon (δ13Ccarb) and carbonate-associated sulfate sulfur isotopes (δ34SCAS), rare earth elements, and elemental paleoredox and paleoproductivity proxies. The SSB at Shitouzhai is characterized by a +4‰ shift in δ13Ccarb and a -10 to -15‰ shift in δ34SCAS, recording negative covariation that diverges from the positive δ13Ccarb-δ34SCAS covariation that characterizes most of the Early Triassic. This pattern is inferred to reflect an increase in organic carbon burial (e.g., due to elevated marine productivity) concurrently with the oxidation of isotopically light H2S, as the result of enhanced vertical advection of nutrient- and sulfide-rich deep waters to the ocean-surface layer. Enhanced upwelling was likely a response to climatic cooling and the reinvigoration of global-ocean overturning circulation at the SSB. Coeval decreases in chemical weathering intensity and detrital sediment flux at Shitouzhai are also consistent with climatic cooling. A decline in marine biodiversity was probably associated with the late Smithian thermal maximum (LSTM) rather than with the SSB per se. The SSB thus marked the termination of the extreme hothouse conditions of the Griesbachian-Smithian substages of the Early Triassic and is significant as a record of accompanying climatic, environmental, and biotic changes. The ultimate cause of the SSB event is uncertain but may have been related to a reduction in intrusive magmatic activity in the Siberian Traps large igneous province.

  3. Synchrotron Reveals Early Triassic Odd Couple: Injured Amphibian and Aestivating Therapsid Share Burrow.

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    Vincent Fernandez

    Full Text Available Fossorialism is a beneficial adaptation for brooding, predator avoidance and protection from extreme climate. The abundance of fossilised burrow casts from the Early Triassic of southern Africa is viewed as a behavioural response by many tetrapods to the harsh conditions following the Permo-Triassic mass-extinction event. However, scarcity of vertebrate remains associated with these burrows leaves many ecological questions unanswered. Synchrotron scanning of a lithified burrow cast from the Early Triassic of the Karoo unveiled a unique mixed-species association: an injured temnospondyl amphibian (Broomistega that sheltered in a burrow occupied by an aestivating therapsid (Thrinaxodon. The discovery of this rare rhinesuchid represents the first occurrence in the fossil record of a temnospondyl in a burrow. The amphibian skeleton shows signs of a crushing trauma with partially healed fractures on several consecutive ribs. The presence of a relatively large intruder in what is interpreted to be a Thrinaxodon burrow implies that the therapsid tolerated the amphibian's presence. Among possible explanations for such unlikely cohabitation, Thrinaxodon aestivation is most plausible, an interpretation supported by the numerous Thrinaxodon specimens fossilised in curled-up postures. Recent advances in synchrotron imaging have enabled visualization of the contents of burrow casts, thus providing a novel tool to elucidate not only anatomy but also ecology and biology of ancient tetrapods.

  4. Ocean acidification and the Permo-Triassic mass extinction.

    Science.gov (United States)

    Clarkson, M O; Kasemann, S A; Wood, R A; Lenton, T M; Daines, S J; Richoz, S; Ohnemueller, F; Meixner, A; Poulton, S W; Tipper, E T

    2015-04-10

    Ocean acidification triggered by Siberian Trap volcanism was a possible kill mechanism for the Permo-Triassic Boundary mass extinction, but direct evidence for an acidification event is lacking. We present a high-resolution seawater pH record across this interval, using boron isotope data combined with a quantitative modeling approach. In the latest Permian, increased ocean alkalinity primed the Earth system with a low level of atmospheric CO2 and a high ocean buffering capacity. The first phase of extinction was coincident with a slow injection of carbon into the atmosphere, and ocean pH remained stable. During the second extinction pulse, however, a rapid and large injection of carbon caused an abrupt acidification event that drove the preferential loss of heavily calcified marine biota.

  5. Ocean acidification and the Permo-Triassic mass extinction

    Science.gov (United States)

    Clarkson, M. O.; Kasemann, S. A.; Wood, R. A.; Lenton, T. M.; Daines, S. J.; Richoz, S.; Ohnemueller, F.; Meixner, A.; Poulton, S. W.; Tipper, E. T.

    2015-04-01

    Ocean acidification triggered by Siberian Trap volcanism was a possible kill mechanism for the Permo-Triassic Boundary mass extinction, but direct evidence for an acidification event is lacking. We present a high-resolution seawater pH record across this interval, using boron isotope data combined with a quantitative modeling approach. In the latest Permian, increased ocean alkalinity primed the Earth system with a low level of atmospheric CO2 and a high ocean buffering capacity. The first phase of extinction was coincident with a slow injection of carbon into the atmosphere, and ocean pH remained stable. During the second extinction pulse, however, a rapid and large injection of carbon caused an abrupt acidification event that drove the preferential loss of heavily calcified marine biota.

  6. The Permian-Triassic boundary & mass extinction in China

    Science.gov (United States)

    Metcalfe, I.; Nicoll, R.S.; Mundil, R.; Foster, C.; Glen, J.; Lyons, J.; Xiaofeng, W.; Cheng-Yuan, W.; Renne, P.R.; Black, L.; Xun, Q.; Xiaodong, M.

    2001-01-01

    The first appearance of Hindeodus parvus (Kozur & Pjatakova) at the Permian-Triassic (P-T) GSSP level (base of Bed 27c) at Meishan is here confirmed. Hindeodus changxingensis Wang occurs from Beds 26 to 29 at Meishan and appears to be restricted to the narrow boundary interval immediately above the main mass extinction level in Bed 25. It is suggested that this species is therefore a valuable P-T boundary interval index taxon. Our collections from the Shangsi section confirm that the first occurrence of Hindeodus parvus in that section is about 5 in above the highest level from which a typical Permian fauna is recovered. This may suggest that that some section may be missing at Meishan. The age of the currently defined Permian-Triassic Boundary is estimated by our own studies and a reassessment of previous worker's data at c. 253 Ma, slightly older than our IDTIMS 206Pb/238U age of 252.5 ??0.3 Ma for Bed 28, just 8 cm above the GSSP boundary (Mundil et al., 2001). The age of the main mass extinction, at the base of Bed 25 at Meishan, is estimated at slightly older than 254 Ma based on an age of >254 Ma for the Bed 25 ash. Regardless of the absolute age of the boundary, it is evident that the claimed <165,000 y short duration for the negative carbon isotope excursion at the P-T boundary (Bowring et al., 1998) cannot be confirmed. Purportedly extraterrestrial fullerenes at the boundary (Hecker et al., 2001) have equivocal significance due to their chronostratigraphic non-uniqueness and their occurrence in a volcanic ash.

  7. The Triassic dicynodont Kombuisia (Synapsida, Anomodontia) from Antarctica, a refuge from the terrestrial Permian-Triassic mass extinction.

    Science.gov (United States)

    Fröbisch, Jörg; Angielczyk, Kenneth D; Sidor, Christian A

    2010-02-01

    Fossils from the central Transantarctic Mountains in Antarctica are referred to a new species of the Triassic genus Kombuisia, one of four dicynodont lineages known to survive the end-Permian mass extinction. The specimens show a unique combination of characters only present in this genus, but the new species can be distinguished from the type species of the genus, Kombuisia frerensis, by the presence of a reduced but slit-like pineal foramen and the lack of contact between the postorbitals. Although incomplete, the Antarctic specimens are significant because Kombuisia was previously known only from the South African Karoo Basin and the new specimens extend the taxon's biogeographic range to a wider portion of southern Pangaea. In addition, the new finds extend the known stratigraphic range of Kombuisia from the Middle Triassic subzone B of the Cynognathus Assemblage Zone into rocks that are equivalent in age to the Lower Triassic Lystrosaurus Assemblage Zone, shortening the proposed ghost lineage of this taxon. Most importantly, the occurrence of Kombuisia and Lystrosaurus mccaigi in the Lower Triassic of Antarctica suggests that this area served as a refuge from some of the effects of the end-Permian extinction. The composition of the lower Fremouw Formation fauna implies a community structure similar to that of the ecologically anomalous Lystrosaurus Assemblage Zone of South Africa, providing additional evidence for widespread ecological disturbance in the extinction's aftermath.

  8. Amelioration of marine environments at the Smithian–Spathian boundary, Early Triassic

    Directory of Open Access Journals (Sweden)

    L. Zhang

    2014-11-01

    Full Text Available Life on Earth underwent a protracted recovery following the Permian–Triassic mass extinction. The slowness of the recovery process may have been caused, in part, by episodic environmental and climatic crises during the Early Triassic, among which the Smithian–Spathian boundary (SSB event is conspicuous. Here, we investigate the SSB event in the Shitouzhai section, South China, using a combination of carbonate carbon (δ13Ccarb and carbonate-associated sulfate sulfur isotopes (δ34SCAS, rare earth elements, and elemental palaeoredox and palaeoproductivity proxies. Unlike the positive δ13Ccarb-δ34SCAS covariation that characterizes most of the Early Triassic, the SSB at Shitouzhai exhibits negative covariation between δ13Ccarb (+4‰ and δ34SCAS (−14‰. This relationship may reflect an increase in organic carbon burial (e.g., due to elevated marine productivity concurrently with oxidation of isotopically light H2S, a pattern that we attribute to enhanced vertical advection of nutrient- and sulfide-rich deepwaters to the ocean-surface layer. Enhanced upwelling was a likely response to the well-documented climatic cooling event at the SSB that terminated the extreme hothouse conditions of the Griesbachian–Smithian, a cooling that we infer to have transiently invigorated the global-ocean overturning circulation. Evidence at Shitouzhai for concurrent decreases in chemical weathering intensity and detrital sediment influx are also consistent with climatic cooling. A penecontemporaneous decline in marine biodiversity was probably associated with the late Smithian thermal maximum rather than the SSB event itself, and the affected marine faunas did not recover immediately in response to climatic and environmental amelioration at the SSB but, rather, underwent a stepwise recovery during the early to middle Spathian. The ultimate cause of the SSB event is uncertain but may have been related to reduced intrusive magmatic activity in the Siberian

  9. Astronomical tuning of the end-Permian extinction and the Early Triassic Epoch of South China and Germany

    Science.gov (United States)

    Li, Mingsong; Ogg, James; Zhang, Yang; Huang, Chunju; Hinnov, Linda; Chen, Zhong-Qiang; Zou, Zhuoyan

    2016-05-01

    The timing of the end-Permian mass extinction and subsequent prolonged recovery during the Early Triassic Epoch can be established from astronomically controlled climate cycles recorded in continuous marine sedimentary sections. Astronomical-cycle tuning of spectral gamma-ray logs from biostratigraphically-constrained cyclic stratigraphy through marine sections at Meishan, Chaohu, Daxiakou and Guandao in South China yields an integrated time scale for the Early Triassic, which is consistent with scaling of magnetostratigraphy from climatic cycles in continental deposits of the Germanic Basin. The main marine mass extinction interval at Meishan is constrained to less than 40% of a 100-kyr (kilo-year) cycle (i.e., Permian extinction. The durations of the Griesbachian, Dienerian, Smithian and Spathian substages, including the uncertainty in placement of widely used conodont biostratigraphic datums for their boundaries, are 1.4 ± 0.1, 0.6 ± 0.1, 1.7 ± 0.1 and 1.4 ± 0.1 myr, implying a total span for the Early Triassic of 5.1 ± 0.1 myr. Therefore, relative to an assigned 251.902 ± 0.024 Ma for the Permian-Triassic boundary from the Meishan GSSP, the ages for these substage boundaries are 250.5 ± 0.1 Ma for base Dienerian, 249.9 ± 0.1 Ma for base Smithian (base of Olenekian stage), 248.2 ± 0.1 Ma for base Spathian, and 246.8 ± 0.1 Ma for the base of the Anisian Stage. This astronomical-calibrated timescale provides rates for the recurrent carbon isotope excursions and for trends in sedimentation accumulation through the Early Triassic of studied sections in South China.

  10. The Luoping biota: exceptional preservation, and new evidence on the Triassic recovery from end-Permian mass extinction.

    Science.gov (United States)

    Hu, Shi-xue; Zhang, Qi-yue; Chen, Zhong-Qiang; Zhou, Chang-yong; Lü, Tao; Xie, Tao; Wen, Wen; Huang, Jin-yuan; Benton, Michael J

    2011-08-07

    The timing and nature of biotic recovery from the devastating end-Permian mass extinction (252 Ma) are much debated. New studies in South China suggest that complex marine ecosystems did not become re-established until the middle-late Anisian (Middle Triassic), much later than had been proposed by some. The recently discovered exceptionally preserved Luoping biota from the Anisian Stage of the Middle Triassic, Yunnan Province and southwest China shows this final stage of community assembly on the continental shelf. The fossil assemblage is a mixture of marine animals, including abundant lightly sclerotized arthropods, associated with fishes, marine reptiles, bivalves, gastropods, belemnoids, ammonoids, echinoderms, brachiopods, conodonts and foraminifers, as well as plants and rare arthropods from nearby land. In some ways, the Luoping biota rebuilt the framework of the pre-extinction latest Permian marine ecosystem, but it differed too in profound ways. New trophic levels were introduced, most notably among top predators in the form of the diverse marine reptiles that had no evident analogues in the Late Permian. The Luoping biota is one of the most diverse Triassic marine fossil Lagerstätten in the world, providing a new and early window on recovery and radiation of Triassic marine ecosystems some 10 Myr after the end-Permian mass extinction.

  11. The sail-backed reptile Ctenosauriscus from the latest Early Triassic of Germany and the timing and biogeography of the early archosaur radiation.

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    Richard J Butler

    Full Text Available BACKGROUND: Archosaurs (birds, crocodilians and their extinct relatives including dinosaurs dominated Mesozoic continental ecosystems from the Late Triassic onwards, and still form a major component of modern ecosystems (>10,000 species. The earliest diverse archosaur faunal assemblages are known from the Middle Triassic (c. 244 Ma, implying that the archosaur radiation began in the Early Triassic (252.3-247.2 Ma. Understanding of this radiation is currently limited by the poor early fossil record of the group in terms of skeletal remains. METHODOLOGY/PRINCIPAL FINDINGS: We redescribe the anatomy and stratigraphic position of the type specimen of Ctenosauriscus koeneni (Huene, a sail-backed reptile from the Early Triassic (late Olenekian Solling Formation of northern Germany that potentially represents the oldest known archosaur. We critically discuss previous biomechanical work on the 'sail' of Ctenosauriscus, which is formed by a series of elongated neural spines. In addition, we describe Ctenosauriscus-like postcranial material from the earliest Middle Triassic (early Anisian Röt Formation of Waldhaus, southwestern Germany. Finally, we review the spatial and temporal distribution of the earliest archosaur fossils and their implications for understanding the dynamics of the archosaur radiation. CONCLUSIONS/SIGNIFICANCE: Comprehensive numerical phylogenetic analyses demonstrate that both Ctenosauriscus and the Waldhaus taxon are members of a monophyletic grouping of poposauroid archosaurs, Ctenosauriscidae, characterised by greatly elongated neural spines in the posterior cervical to anterior caudal vertebrae. The earliest archosaurs, including Ctenosauriscus, appear in the body fossil record just prior to the Olenekian/Anisian boundary (c. 248 Ma, less than 5 million years after the Permian-Triassic mass extinction. These earliest archosaur assemblages are dominated by ctenosauriscids, which were broadly distributed across northern Pangea and

  12. A new species of Garjainia Ochev, 1958 (Diapsida: Archosauriformes: Erythrosuchidae from the Early Triassic of South Africa.

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    David J Gower

    Full Text Available A new species of the erythrosuchid archosauriform reptile Garjainia Ochev, 1958 is described on the basis of disarticulated but abundant and well-preserved cranial and postcranial material from the late Early Triassic (late Olenekian Subzone A of the Cynognathus Assemblage Zone of the Burgersdorp Formation (Beaufort Group of the Karoo Basin of South Africa. The new species, G. madiba, differs from its unique congener, G. prima from the late Olenekian of European Russia, most notably in having large bony bosses on the lateral surfaces of the jugals and postorbitals. The new species also has more teeth and a proportionately longer postacetabular process of the ilium than G. prima. Analysis of G. madiba bone histology reveals thick compact cortices comprised of highly vascularized, rapidly forming fibro-lamellar bone tissue, similar to Erythrosuchus africanus from Subzone B of the Cynognathus Assemblage Zone. The most notable differences between the two taxa are the predominance of a radiating vascular network and presence of annuli in the limb bones of G. madiba. These features indicate rapid growth rates, consistent with data for many other Triassic archosauriforms, but also a high degree of developmental plasticity as growth remained flexible. The diagnoses of Garjainia and of Erythrosuchidae are addressed and revised. Garjainia madiba is the geologically oldest erythrosuchid known from the Southern Hemisphere, and demonstrates that erythrosuchids achieved a cosmopolitan biogeographical distribution by the end of the Early Triassic, within five million years of the end-Permian mass extinction event. It provides new insights into the diversity of the Subzone A vertebrate assemblage, which partially fills a major gap between classic 'faunal' assemblages from the older Lystrosaurus Assemblage Zone (earliest Triassic and the younger Subzone B of the Cynognathus Assemblage Zone (early Middle Triassic.

  13. On the origin and early diagenesis of early Triassic carbonate mud (Dolomites, Italy)

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    Preto, Nereo; Westphal, Hildegard; Birgel, Daniel; Carampin, Raul; Dal Corso, Jacopo; Gattolin, Giovanni; Montinaro, Alice; Peckmann, Jörn

    2015-04-01

    The earliest Triassic (early Induan) deposits of the Italian Southern Alps are shallow water oolites, and lime-mudstone formed in an open shelf (mid to outer carbonate ramp) sedimentary environment, deposited after the end-Permian extinction that killed all carbonate producers. The origin of these lime-mudstones is thus enigmatic. We used a multidisciplinary petrographic and geochemical approach to identify the origin and early diagenesis of early Triassic lime-mudstones of the Dolomites (Northern Italy). This fine carbonate is made of pitted crystals of microsparite, ~ 25 μm in diameter, exhibiting zonation both in fluorescence and cathodoluminescence. Field and standard petrographic observations exclude an origin from fragmentation or abrasion of carbonate grains. Strontium content, measured in-situ with electron microprobe, has a bimodal distribution with values locally as high as > 4000 ppm. Lipid biomarker analysis revealed molecular fossils of bacteria (terminally-branched alkanes, hopanes, and scarce methylhopanes) along with compounds of low source specificity (n-alkanes), whereas biomarkers of algae (steranes) were not detected. This suggests that, differently from modern Caribbean shelfs, this fine carbonate did not originate from the disgregation of green algae. A Pristane to Phytane ratio < 1 also suggests deposition under anoxic conditions, in agreement with the known status of "superanoxia" of earliest Triassic oceans. Overall, our observations suggest an aragonitic mineralogy of the carbonate mud, followed by calcite replacement and cementation in the marine burial early diagenetic environment. Our data strongly suggest that the early Triassic carbonate mud of the Dolomites was precipitated in the water column, similarly to the modern whitings of the Bahamas, and then settled on a shelf bottom below wave base. Our study shows that these lime-mudstones contain aragonite replaced by calcite and calcite cement, in variable proportions. The δ13C of

  14. Severest crisis overlooked-Worst disruption of terrestrial environments postdates the Permian-Triassic mass extinction.

    Science.gov (United States)

    Hochuli, Peter A; Sanson-Barrera, Anna; Schneebeli-Hermann, Elke; Bucher, Hugo

    2016-06-24

    Generally Early Triassic floras are believed to be depauperate, suffering from protracted recovery following the Permian-Triassic extinction event. Here we present palynological data of an expanded East Greenland section documenting recovered floras in the basal Triassic (Griesbachian) and a subsequent fundamental floral turnover, postdating the Permian-Triassic boundary extinction by about 500 kyrs. This event is marked by a swap in dominating floral elements, changing from gymnosperm pollen-dominated associations in the Griesbachian to lycopsid spore-dominated assemblages in the Dienerian. This turnover coincides with an extreme δ(13)Corg negative shift revealing a severe environmental crisis, probably induced by volcanic outbursts of the Siberian Traps, accompanied by a climatic turnover, changing from cool and dry in the Griesbachian to hot and humid in the Dienerian. Estimates of sedimentation rates suggest that this environmental alteration took place within some 1000 years. Similar, coeval changes documented on the North Indian Margin (Pakistan) and the Bowen Basin (Australia) indicate the global extent of this crisis. Our results evidence the first profound disruption of the recovery of terrestrial environments about 500kyrs after the Permian-Triassic extinction event. It was followed by another crisis, about 1myrs later thus, the Early Triassic can be characterised as a time of successive environmental crises.

  15. Severest crisis overlooked—Worst disruption of terrestrial environments postdates the Permian–Triassic mass extinction

    Science.gov (United States)

    Hochuli, Peter A.; Sanson-Barrera, Anna; Schneebeli-Hermann, Elke; Bucher, Hugo

    2016-06-01

    Generally Early Triassic floras are believed to be depauperate, suffering from protracted recovery following the Permian–Triassic extinction event. Here we present palynological data of an expanded East Greenland section documenting recovered floras in the basal Triassic (Griesbachian) and a subsequent fundamental floral turnover, postdating the Permian–Triassic boundary extinction by about 500 kyrs. This event is marked by a swap in dominating floral elements, changing from gymnosperm pollen-dominated associations in the Griesbachian to lycopsid spore-dominated assemblages in the Dienerian. This turnover coincides with an extreme δ13Corg negative shift revealing a severe environmental crisis, probably induced by volcanic outbursts of the Siberian Traps, accompanied by a climatic turnover, changing from cool and dry in the Griesbachian to hot and humid in the Dienerian. Estimates of sedimentation rates suggest that this environmental alteration took place within some 1000 years. Similar, coeval changes documented on the North Indian Margin (Pakistan) and the Bowen Basin (Australia) indicate the global extent of this crisis. Our results evidence the first profound disruption of the recovery of terrestrial environments about 500kyrs after the Permian–Triassic extinction event. It was followed by another crisis, about 1myrs later thus, the Early Triassic can be characterised as a time of successive environmental crises.

  16. Evolutionary and Ecological Sequelae of Mass Extinctions: Examples From the Continental Triassic-Jurassic Boundary

    Science.gov (United States)

    Olsen, P. E.; Whiteside, J. H.

    2003-12-01

    The Triassic-Jurassic boundary at ˜200 Ma marks one of the five major mass-extinctions of the Phanerozoic and, depending on the metrics used, was similar in magnitude to the K-T mass extinction. In continental environments about 50% of all tetrapod families are eliminated and although floral diversity change is difficult to gauge, a similar proportion of palynomorph taxa disappear at the boundary. The extinction event appears to have been very abrupt, followed by a roughly 900 ky super-greenhouse period characterized by increased precipitation. We hypothesize a series of biological consequences of the drop in diversity and associated super-greenhouse based on observations of the earliest Jurassic assemblages, largely from eastern North America. 1) The drop in diversity results in a collapse of ecological interactions that tend to stabilize the composition of regional biotas and buffer them from invading forms. Triassic assemblages show considerable biogeographic provinciality despite the existence of Pangea, but the earliest Jurassic assemblages were extraordinarily homogenous with many vertebrate genera being essentially global in distribution. 2) Initially the post-boundary terrestrial assemblages were comprised of eurytopic trophic generalists, with animal communities with few herbivores, but abundant carnivores and detritivores subsisting on aquatic-based food webs. The earliest Jurassic tetrapod footprint record is overwhelmingly dominated by the footprints of ceratosaurian theropod dinosaurs, the latter having skull characteristics usually associated at least in part with piscivory. 3) The dramatic size changes over very short periods of time were likely due to an absence of competition (i.e., ecological release). The maximum size of theropod dinosaur footprints increased by about 25% within 10 ky following the boundary, corresponding to a doubling of mass. 4) Representatives of clades with intrinsically high rates of speciation tend to form species flocks

  17. Early Triassic fluctuations of the global carbon cycle: New evidence from paired carbon isotopes in the western USA basin

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    Caravaca, Gwénaël; Thomazo, Christophe; Vennin, Emmanuelle; Olivier, Nicolas; Cocquerez, Théophile; Escarguel, Gilles; Fara, Emmanuel; Jenks, James F.; Bylund, Kevin G.; Stephen, Daniel A.; Brayard, Arnaud

    2017-07-01

    In the aftermath of the catastrophic end-Permian mass extinction, the Early Triassic records recurrent perturbations in the carbon isotope signal, most notably during the Smithian and through the Smithian/Spathian Boundary (SSB; 1.5 myr after the Permian/Triassic boundary), which show some of the largest excursions of the Phanerozoic. The late Smithian also corresponds to major biotic turnovers and environmental changes, such as temperature fluctuations, that deeply impacted the recovery after the end-Permian mass extinction. Here we document the paired carbon isotope signal along with an analysis of the trace and major elements at the long-known Hot Springs section (southeastern Idaho, USA). This section records Early Triassic sediments from the Griesbachian-Dienerian up to the lower Spathian. We show that the organic and carbonate δ13C variations mirror the signals identified at a global scale. Particularly, the middle Smithian-SSB event represented by a negative-positive isotopic couplet is well identified and is not of diagenetic origin. We also document a positive excursion potentially corresponding to the Dienerian/Smithian Boundary. Observed Smithian-Spathian excursions are recorded similarly in both the organic and carbonate reservoirs, but the organic matter signal systematically shows unexpectedly dampened variations compared to its carbonate counterpart. Additionally, we show that variations in the net isotopic effect (i.e., Δ13C) probably resulted from a complex set of forcing parameters including either a mixing between terrestrial and marine organic matter depending on the evolution of the depositional setting, or variations in the biological fractionation. We establish that the Δ13C signal cannot be directly related to CO2-driven temperature variations at Hot Springs. Even though the carbon isotope signal mirrors the Early Triassic variations known at the global scale, the Hot Springs signal probably also reflects local influences on the carbon

  18. Guanling Biota: A Rare Biota in Sea Early Late Triassic

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    Guanling biota has been found at the bottom of Wayao Formation of Upper Triassic (Carnic stage) near Xinpu town, Guanling County, Guizhou Province, China. There are a lot of crinoids and marine reptiles, which is a characteristic of Guanling biota, including ammonites, bivalve, brachiopod, fish, conodont and plant. These fossils are featured not only with the large quantity, but also with their extraordinary perfect forms. This paper explores the meaning, geological background, present situation of study and scientific significance of Guanling biota.

  19. Timing of global regression and microbial bloom linked with the Permian-Triassic boundary mass extinction: implications for driving mechanisms

    Science.gov (United States)

    Baresel, Björn; Bucher, Hugo; Bagherpour, Borhan; Brosse, Morgane; Guodun, Kuang; Schaltegger, Urs

    2017-03-01

    New high-resolution U-Pb dates indicate a duration of 89 ± 38 kyr for the Permian hiatus and of 14 ± 57 kyr for the overlying Triassic microbial limestone in shallow water settings of the Nanpanjiang Basin, South China. The age and duration of the hiatus coincides with the Permian-Triassic boundary (PTB) and the extinction interval in the Meishan Global Stratotype Section and Point, and strongly supports a glacio-eustatic regression, which best explains the genesis of the worldwide hiatus straddling the PTB in shallow water records. In adjacent deep marine troughs, rates of sediment accumulation display a six-fold decrease across the PTB compatible with a dryer and cooler climate as indicated by terrestrial plants. Our model of the Permian-Triassic boundary mass extinction (PTBME) hinges on the synchronicity of the hiatus with the onset of the Siberian Traps volcanism. This early eruptive phase released sulfur-rich volatiles into the stratosphere, thus simultaneously eliciting a short-lived ice age responsible for the global regression and a brief but intense acidification. Abrupt cooling, shrunk habitats on shelves and acidification may all have synergistically triggered the PTBME. Subsequently, the build-up of volcanic CO2 induced a transient cool climate whose early phase saw the deposition of the microbial limestone.

  20. Timing of global regression and microbial bloom linked with the Permian-Triassic boundary mass extinction: implications for driving mechanisms

    Science.gov (United States)

    Baresel, Björn; Bucher, Hugo; Bagherpour, Borhan; Brosse, Morgane; Guodun, Kuang; Schaltegger, Urs

    2017-01-01

    New high-resolution U-Pb dates indicate a duration of 89 ± 38 kyr for the Permian hiatus and of 14 ± 57 kyr for the overlying Triassic microbial limestone in shallow water settings of the Nanpanjiang Basin, South China. The age and duration of the hiatus coincides with the Permian-Triassic boundary (PTB) and the extinction interval in the Meishan Global Stratotype Section and Point, and strongly supports a glacio-eustatic regression, which best explains the genesis of the worldwide hiatus straddling the PTB in shallow water records. In adjacent deep marine troughs, rates of sediment accumulation display a six-fold decrease across the PTB compatible with a dryer and cooler climate as indicated by terrestrial plants. Our model of the Permian-Triassic boundary mass extinction (PTBME) hinges on the synchronicity of the hiatus with the onset of the Siberian Traps volcanism. This early eruptive phase released sulfur-rich volatiles into the stratosphere, thus simultaneously eliciting a short-lived ice age responsible for the global regression and a brief but intense acidification. Abrupt cooling, shrunk habitats on shelves and acidification may all have synergistically triggered the PTBME. Subsequently, the build-up of volcanic CO2 induced a transient cool climate whose early phase saw the deposition of the microbial limestone. PMID:28262815

  1. The intrusive record of the CAMP and what it means for the end Triassic mass extinction

    Science.gov (United States)

    Davies, Joshua; Marzoli, Andrea; Bertrand, Hervé; Youbi, Nasrrddine; Ernesto, Marcia; Schaltegger, Urs

    2017-04-01

    The end-Triassic mass extinction is one of the Phanerozoic's five largest mass extinctions. The extinction is usually attributed to climate change associated with degassing of erupting basalt from the Central Atlantic Magmatic Province (CAMP). However, recent work has shown that the earliest known CAMP basaltic flows occur stratigraphically above the extinction horizon indicating that the relationship between the CAMP and the extinction is more complex when resolved at higher temporal resolution. Here we present new high-precision U-Pb age determinations from intrusive units, which show that CAMP magmatic activity was occurring 100 ka before the oldest known eruptions. We show that the early magmatic activity correlates temporally with the onset of globally recognized changes to climatic and biotic records. We also report ages from sills in the Amazonas basin in Brazil that intrude synchronously with the extinction. We suggest that the release of thermogenic gases from the contact metamorphism of these sediments induced by injection of mafic sills may have contributed to the climate change that drove the extinction. Our results indicate that the intrusive record from large igneous provinces may be more important for linking to mass extinctions than the eruptive record.

  2. Siderite deposits in northern Italy: Early Permian to Early Triassic hydrothermalism in the Southern Alps

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    Martin, Silvana; Toffolo, Luca; Moroni, Marilena; Montorfano, Carlo; Secco, Luciano; Agnini, Claudia; Nimis, Paolo; Tumiati, Simone

    2017-07-01

    We present a minero-petrographic, geochemical and geochronological study of siderite orebodies from different localities of the Southern Alps (northern Italy). Siderite occurs as veins cutting the Variscan basement and the overlying Lower Permian volcano-sedimentary cover (Collio Fm.), and as both veins and conformable stratabound orebodies in the Upper Permian (Verrucano Lombardo and Bellerophon Fms.) and Lower Triassic (Servino and Werfen Fms.) sedimentary sequences of the Lombardian and the Venetian Alps. All types of deposits show similar major- and rare-earth (REE)-element patterns, suggesting a common iron-mineralizing event. The compositions of coexisting siderite, Fe-rich dolomite and calcite suggest formation from hydrothermal fluids at relatively high temperature conditions (≥ 250 °C). Geochemical modelling, supported by REE analyses and by literature and new δ13C and δ18O isotopic data, suggests that fluids responsible for the formation of siderite in the Variscan basement and in the overlying Lower Permian cover were derived from dominant fresh water, which leached Fe and C from volcanic rocks (mainly rhyolites/rhyodacites) and organic carbon-bearing continental sediments. On the basis of U-Th-Pb microchemical dating of uraninite associated with siderite in the Val Vedello and Novazza deposits (Lombardian Alps), the onset of hydrothermalism is constrained to 275 ± 13 Ma (Early-Mid Permian), i.e., it was virtually contemporaneous to the plutonism and the volcanic-sedimentary cycle reported in the same area (Orobic Basin). The youngest iron-mineralizing event is represented by siderite veins and conformable orebodies hosted in Lower Triassic shallow-marine carbonatic successions. In this case, the siderite-forming fluids contained a seawater component, interacted with the underlying Permian successions and eventually replaced the marine carbonates at temperatures of ≥ 250 °C. The absence of siderite in younger rocks suggests an Early Triassic

  3. High precision time calibration of the Permian-Triassic boundary mass extinction event in a deep marine context

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    Baresel, Björn; Bucher, Hugo; Brosse, Morgane; Bagherpour, Borhan; Schaltegger, Urs

    2015-04-01

    To construct a revised and high resolution calibrated time scale for the Permian-Triassic boundary (PTB) we use (1) high-precision U-Pb zircon age determinations of a unique succession of volcanic ash layers interbedded with deep water fossiliferous sediments in the Nanpanjiang Basin (South China) combined with (2) accurate quantitative biochronology based on ammonoids, conodonts, radiolarians, and foraminifera and (3) tracers of marine bioproductivity (carbon isotopes) across the PTB. The unprecedented precision of the single grain chemical abrasion isotope-dilution thermal ionization mass spectrometry (CA-ID-TIMS) dating technique at sub-per mil level (radio-isotopic calibration of the PTB at the Permian and Early Triassic. Here, we present new single grain U-Pb zircon data of volcanic ash layers from two deep marine sections (Dongpan and Penglaitan) revealing stratigraphic consistent dates over several volcanic ash layers bracketing the PTB. These analyses define weighted mean 206Pb/238U ages of 251.956±0.033 Ma (Dongpan) and 252.062±0.043 Ma (Penglaitan) for the last Permian ash bed. By calibration with detailed litho- and biostratigraphy new U-Pb ages of 251.953±0.038 Ma (Dongpan) and 251.907±0.033 Ma (Penglaitan) are established for the onset of the Triassic.

  4. Dobrogeria aegyssensis, a new early Spathian (Early Triassic) coelacanth from North Dobrogea (Romania)

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    Cavin, Lionel; Grădinaru, Eugen

    2014-06-01

    The Early Triassic witnessed the highest taxic diversity of coelacanths (or Actinistia), a clade with a single living genus today. This peak of diversity is accentuated here with the description of a new coelacanth discovered in the lower Spathian (Upper Olenekian, Lower Triassic) cropping out in the Tulcea Veche (Old Tulcea) promontory, in the city of Tulcea, in North Dobrogea, Romania. The bone remains were preserved in a block of limestone, which was chemically dissolved. The resulting 3D and matrix-free ossifications correspond mostly to elements of the skull and branchial apparatus. Posterior parietals, postparietal with associated prootic and basisphenoid allow a precise description of the neurocranium. Ossifications of the lower jaw, together with branchial and pectoral elements, complete the description of this coelacanth and support the coining of a new generic and specific name, Dobrogeria aegyssensis. A phylogenetic analysis of actinistians with the new species recovers clades which were found in most recent analyses, i.e. the Sasseniidae, the Laugiidae, the Coelacanthiformes, the Latimerioidei, the Mawsoniidae and the Latimeriidae, and identifies the new taxon as a non-latimerioid coelacanthiform.

  5. [Insects at the borderline between the Permian and the early triassic (Urzhum - Olenek age) and the problem of Permian-Triassic biodiversity crisis].

    Science.gov (United States)

    Rasnitsyn, A P; Aristov, D S; Rasnitsyn, D A

    2013-01-01

    Distribution of 115 insect families is considered in 15 local assemblages of European Russia, Siberia, Australia and South Africa. The assemblage ages embrace the Urzhum stage of the Middle Permian, the Late Permian, and the transitional Permian-Triassic interval. The assemblages are ordered statistically using two criteria. Ordination after the appearance of a fauna, that is, relation of the number of younger vs. older families, is found to be generally consistent with the stratigraphic data. The method of minimizing the gaps (ghost ranges) in distribution of the families is useful in interpreting the results. Urzhum time is characterized by the balance of emergence and extinction of families (counted as their first and latest appearances, respectively). In Severodvinsk and particularly in Vyatka time, the number of first appearances was decreasing resulted in prevailing extinction. In the transitional Permian-Triassic interval, the emergence of new families accelerated. Initially, the appearance of assemblages was typically Paleozoic (with older families prevailed). It changed gradually, so as by the end of Vyatka time it turned to be quite post-Paleozoic. Diversity was the highest in Severodvinsk time, and it halved at Vyatka time and at the transition interval. However, if we consider transitional families (those not found on a particular interval, but known before and after), the extinction rate reduces to one-third. And when normalized after the material volume, the diversity drop decreases up to a quarter. There was no mass extinction found at the end of the Permian, and the less so at the Permian-Triassic boundary and during the Lower Triassic. Structure of the Permian-Triassic diversity crisis is similar to that of the Cretaceous crisis in many respects. Since the Middle Triassic and up to now, the biodiversity kept increasing quickly and continuously. This implies that the Permian-Triassic crisis resulted in profound modification of the biosphere

  6. Terrestrial origin of viviparity in mesozoic marine reptiles indicated by early triassic embryonic fossils.

    Science.gov (United States)

    Motani, Ryosuke; Jiang, Da-yong; Tintori, Andrea; Rieppel, Olivier; Chen, Guan-bao

    2014-01-01

    Viviparity in Mesozoic marine reptiles has traditionally been considered an aquatic adaptation. We report a new fossil specimen that strongly contradicts this traditional interpretation. The new specimen contains the oldest fossil embryos of Mesozoic marine reptile that are about 10 million years older than previous such records. The fossil belongs to Chaohusaurus (Reptilia, Ichthyopterygia), which is the oldest of Mesozoic marine reptiles (ca. 248 million years ago, Early Triassic). This exceptional specimen captures an articulated embryo in birth position, with its skull just emerged from the maternal pelvis. Its headfirst birth posture, which is unlikely to be a breech condition, strongly indicates a terrestrial origin of viviparity, in contrast to the traditional view. The tail-first birth posture in derived ichthyopterygians, convergent with the conditions in whales and sea cows, therefore is a secondary feature. The unequivocally marine origin of viviparity is so far not known among amniotes, a subset of vertebrate animals comprising mammals and reptiles, including birds. Therefore, obligate marine amniotes appear to have evolved almost exclusively from viviparous land ancestors. Viviparous land reptiles most likely appeared much earlier than currently thought, at least as early as the recovery phase from the end-Permian mass extinction.

  7. Terrestrial origin of viviparity in mesozoic marine reptiles indicated by early triassic embryonic fossils.

    Directory of Open Access Journals (Sweden)

    Ryosuke Motani

    Full Text Available Viviparity in Mesozoic marine reptiles has traditionally been considered an aquatic adaptation. We report a new fossil specimen that strongly contradicts this traditional interpretation. The new specimen contains the oldest fossil embryos of Mesozoic marine reptile that are about 10 million years older than previous such records. The fossil belongs to Chaohusaurus (Reptilia, Ichthyopterygia, which is the oldest of Mesozoic marine reptiles (ca. 248 million years ago, Early Triassic. This exceptional specimen captures an articulated embryo in birth position, with its skull just emerged from the maternal pelvis. Its headfirst birth posture, which is unlikely to be a breech condition, strongly indicates a terrestrial origin of viviparity, in contrast to the traditional view. The tail-first birth posture in derived ichthyopterygians, convergent with the conditions in whales and sea cows, therefore is a secondary feature. The unequivocally marine origin of viviparity is so far not known among amniotes, a subset of vertebrate animals comprising mammals and reptiles, including birds. Therefore, obligate marine amniotes appear to have evolved almost exclusively from viviparous land ancestors. Viviparous land reptiles most likely appeared much earlier than currently thought, at least as early as the recovery phase from the end-Permian mass extinction.

  8. Integrated Sr isotope variations and global environmental changes through the Late Permian to early Late Triassic

    Science.gov (United States)

    Song, Haijun; Wignall, Paul B.; Tong, Jinnan; Song, Huyue; Chen, Jing; Chu, Daoliang; Tian, Li; Luo, Mao; Zong, Keqing; Chen, Yanlong; Lai, Xulong; Zhang, Kexin; Wang, Hongmei

    2015-08-01

    New 87Sr/86Sr data based on 127 well-preserved and well-dated conodont samples from South China were measured using a new technique (LA-MC-ICPMS) based on single conodont albid crown analysis. These reveal a spectacular climb in seawater 87Sr/86Sr ratios during the Early Triassic that was the most rapid of the Phanerozoic. The rapid increase began in Bed 25 of the Meishan section (GSSP of the Permian-Triassic boundary, PTB), and coincided closely with the latest Permian extinction. Modeling results indicate that the accelerated rise of 87Sr/86Sr ratios can be ascribed to a rapid increase (>2.8×) of riverine flux of Sr caused by intensified weathering. This phenomenon could in turn be related to an intensification of warming-driven runoff and vegetation die-off. Continued rise of 87Sr/86Sr ratios in the Early Triassic indicates that continental weathering rates were enhanced >1.9 times compared to those of the Late Permian. Continental weathering rates began to decline in the middle-late Spathian, which may have played a role in the decrease of oceanic anoxia and recovery of marine benthos. The 87Sr/86Sr values decline gradually into the Middle Triassic to an equilibrium values around 1.2 times those of the Late Permian level, suggesting that vegetation coverage did not attain pre-extinction levels thereby allowing higher runoff.

  9. Prolonged and recurrent global seafloor anoxia in the Early Triassic from uranium isotopic evidence

    Science.gov (United States)

    Lau, K. V.; Maher, K.; Kelley, B. M.; Yu, M.; Lehrmann, D. J.; Payne, J.

    2013-12-01

    The end-Permian extinction and prolonged Early Triassic recovery of marine ecosystems have been attributed in part to marine anoxia. However, the spatial and temporal extent of anoxic waters during Early Triassic time remains poorly understood. To better constrain the evolution of seawater conditions, we present a record of δ238/235U and uranium concentrations collected from the Great Bank of Guizhou, a Late Permian to Late Triassic isolated carbonate platform in the Nanpanjiang Basin, South China. The isotopic composition and concentration of uranium are independent constraints on paleoredox conditions and can be used as indicators for the global extent of ocean anoxia. Our δ238/235U results demonstrate that two large negative excursions of up to ~-0.4‰ occurred in the Induan and in the Spathian, before stabilizing in the Middle Triassic at Late Permian values. Uranium concentrations mirror the isotopic trends, reaching sustained minima of less than 0.2 ppm that correspond to the most negative isotopic values. By placing these observational constraints on a box model of the geological uranium cycle, we calculate that up to half of the continental shelves may have been affected during the two pulses of bottom-water anoxia. The expansion, contraction, and re-expansion of extreme low-oxygen conditions could explain many unresolved aspects of the prolonged recovery of marine ecosystems. The recurrence of widespread anoxia during Spathian time may have interrupted the recovery of marine organisms that began in the more oxic waters of the Smithian. These episodes of significant and prolonged bottom-water anoxia coincide with the most negative δ13C values, suggesting that Early Triassic perturbations to the global carbon cycle were tightly coupled to changes in ocean redox chemistry.

  10. Relationships between ocean anoxia, the biological pump, and marine animal life during the Permian-Triassic mass extinction (Invited)

    Science.gov (United States)

    Meyer, K. M.; Schaal, E. K.; Payne, J.

    2013-12-01

    Ocean anoxia/euxinia and carbon cycle instability have long been linked to the end-Permian mass extinction and the Early Triassic interval of delayed or interrupted biotic recovery. Many hypotheses to explain this extinction event invoke the release of greenhouse gases during the emplacement of the Siberian Traps, which likely triggered abrupt changes in marine biogeochemical cycling, atmospheric chemistry, and biodiversity. However, the precise ways in which volcanism and these perturbations are linked and how they governed the tempo and mode of biotic recovery remain poorly understood. Here we highlight new C, Ca, and Sr isotopic data that serve to link volcanic CO2 inputs to changes in marine biogeochemistry and environmental change. We then examine the relationship between ocean biogeochemistry, the biological pump, and marine animal ecosystems during the end-Permian mass extinction and Early Triassic recovery. Finally, we use numerical simulations to probe whether these relationships also explain broad Phanerozoic trends in ocean nutrient status, anoxia, and productivity of marine ecosystems.

  11. Mercury anomalies and the timing of biotic recovery following the end-Triassic mass extinction.

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    Thibodeau, Alyson M; Ritterbush, Kathleen; Yager, Joyce A; West, A Joshua; Ibarra, Yadira; Bottjer, David J; Berelson, William M; Bergquist, Bridget A; Corsetti, Frank A

    2016-04-06

    The end-Triassic mass extinction overlapped with the eruption of the Central Atlantic Magmatic Province (CAMP), and release of CO2 and other volcanic volatiles has been implicated in the extinction. However, the timing of marine biotic recovery versus CAMP eruptions remains uncertain. Here we use Hg concentrations and isotopes as indicators of CAMP volcanism in continental shelf sediments, the primary archive of faunal data. In Triassic-Jurassic strata, Muller Canyon, Nevada, Hg levels rise in the extinction interval, peak before the appearance of the first Jurassic ammonite, remain above background in association with a depauperate fauna, and fall to pre-extinction levels during significant pelagic and benthic faunal recovery. Hg isotopes display no significant mass independent fractionation within the extinction and depauperate intervals, consistent with a volcanic origin for the Hg. The Hg and palaeontological evidence from the same archive indicate that significant biotic recovery did not begin until CAMP eruptions ceased.

  12. Contrasting microbial community changes during mass extinctions at the Middle/Late Permian and Permian/Triassic boundaries

    Science.gov (United States)

    Xie, Shucheng; Algeo, Thomas J.; Zhou, Wenfeng; Ruan, Xiaoyan; Luo, Genming; Huang, Junhua; Yan, Jiaxin

    2017-02-01

    Microbial communities are known to expand as a result of environmental deterioration during mass extinctions, but differences in microbial community changes between extinction events and their underlying causes have received little study to date. Here, we present a systematic investigation of microbial lipid biomarkers spanning ∼20 Myr (Middle Permian to Early Triassic) at Shangsi, South China, to contrast microbial changes associated with the Guadalupian-Lopingian boundary (GLB) and Permian-Triassic boundary (PTB) mass extinctions. High-resolution analysis of the PTB crisis interval reveals a distinct succession of microbial communities based on secular variation in moretanes, 2-methylhopanes, aryl isoprenoids, steranes, n-alkyl cyclohexanes, and other biomarkers. The first episode of the PTB mass extinction (ME1) was associated with increases in red algae and nitrogen-fixing bacteria along with evidence for enhanced wildfires and elevated soil erosion, whereas the second episode was associated with expansions of green sulfur bacteria, nitrogen-fixing bacteria, and acritarchs coinciding with climatic hyperwarming, ocean stratification, and seawater acidification. This pattern of microbial community change suggests that marine environmental deterioration was greater during the second extinction episode (ME2). The GLB shows more limited changes in microbial community composition and more limited environmental deterioration than the PTB, consistent with differences in species-level extinction rates (∼71% vs. 90%, respectively). Microbial biomarker records have the potential to refine our understanding of the nature of these crises and to provide insights concerning possible outcomes of present-day anthropogenic stresses on Earth's ecosystems.

  13. A NEW SAURICHTHYS (ACTINOPTERYGII FROM THE SPATHIAN (EARLY TRIASSIC OF CHAOHU (ANHUI PROVINCE, CHINA

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    ANDREA TINTORI

    2014-07-01

    Full Text Available A new species of Saurichthys, S. majiashanensis , is described. It comes from a series of marine vertebrate-bearing beds of the upper member of the Nanlinghu Formation outcropping in the large quarry at the top of Majiashan (Majia Hill near Chaohu (Hefei City, Anhui Province, China. Its age is Middle Spathian (Olenekian, Early Triassic. This new species deeply differs from the several pre-Spathian species of Saurichthys mainly for having only two longitudinal scale rows together with a reduced grid-like structure for the neural elements in the vertebral column. Further derived characters are in the endoskeleton of the dorsal and anal fin, where radials articulate only to anterior lepidotrichia, the posterior ones being supported by the first scale from the caudal pedicle mid-dorsal and mid-ventral rows, deeply imbedded in the body. In addition, the haemal spines of the caudal region are much enlarged and reversed, with their distal parts pointing forwards. Though the skull is lacking, postcranial characters are enough to justify the erection of a new species. This new Saurichthys species, together with other few actinopterygians, can be considered as the oldest assemblage of the Triassic Middle Fish Fauna, which bloomed probably in the early Anisian and widespread especially all over the Tethys for the Middle Triassic and at least the Carnian in the Late Triassic. This new fish assemblage, together with some of the oldest marine reptiles, is considered as the beginning of the actual Triassic recovery among marine vertebrates.

  14. A terrestrial vegetation turnover in the middle of the Early Triassic

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    Saito, Ryosuke; Kaiho, Kunio; Oba, Masahiro; Takahashi, Satoshi; Chen, Zhong-Qiang; Tong, Jinnan

    2013-06-01

    Land-plant productivity was greatly reduced after the end-Permian mass extinction, causing a pronounced "coal gap" worldwide during the Early Triassic. Newly obtained organic geochemistry data from the Chaohu area, south China, indicated an abrupt and profound terrestrial vegetation change over the middle part of the Early Triassic Smithian-Spathian (S-S) interval. Herbaceous lycopsids and/or bryophytes dominated terrestrial vegetation from Griesbachian to Smithian times. The terrestrial ecosystem underwent an abrupt change, and woody conifers became dominant over the S-S interval. Several important biomarkers, namely retene, simonellite, and dehydroabietane (with multiple sources: conifer, lycopsid, and/or herbaceous bryophyte), were relatively abundant during Griesbachian, Dienerian, and Smithian times. The relatively low C/N ratio values during the Griesbachian-Smithian interval indicate that these biomarkers were likely sourced from herbaceous lycopsids and/or bryophytes. The extremely abundant conifer-sourced pimanthrene, combined with relatively high C/N ratio values, suggested the recovery of woody conifers after the S-S boundary. The new data revealed that the switch from herbaceous vegetation to woody coniferous vegetation marked a terrestrial plant recovery, which occurred globally within 3 million years after the end-Permian crisis rather than at a later date estimated in previous studies. In Chaohu, the S-S terrestrial event was marked by a reappearance of woody vegetation, while the S-S marine event was marked by an increase in ichnodiversity, trace complexity, burrow size, infaunal tiering level, and bioturbation level, and a possible intense upwelling event indicated by the extended tricyclic terpane ratios (ETR). Coeval vegetation changes with comparable patterns have also been documented in Europe and Pakistan based on palynologic studies. The S-S boundaries in Asia and Europe are associated with a positive δ13C excursion, the rebound of woody

  15. Milankovitch and sub-Milankovitch cycles of the Early Triassic Daye Formation, South China and their geochronological and paleoclimatic implications

    Science.gov (United States)

    Wu, H.; Zhang, S.; Feng, Q.; Jiang, G.; Li, H.; Yang, T.

    2011-12-01

    The most profound mass extinction in the Phanerozoic occurred at the end of the Permian, with global loss of nearly 90% of marine invertebrate species and 70% of terrestrial vertebrate genera. Recent studies suggested that volcanisms represented by the Siberian Trap were most likely cause of the end-Permian extinction. The post-extinction periods in the Early Triassic was characterized by low biodiversity, reduced abundance and size of invertebrates, hiatus in coal deposition, anomalously high sediment fluxes, and large perturbations of the carbon cycle, which have been interpreted as the consequence of persistently unfavorable environmental conditions. However, the time framework for the Early Triassic geological, biological and geochemical events is traditionally established by conodont biostratigraphy, but the absolute duration of condont biozones are not well constrained. In this study, a rock magnetic cyclostratigraphy, based on high-resolution analysis (2440 samples) of magnetic susceptibility (MS) and anhysteretic remanent magnetization (ARM) intensity variations, was developed for the 55.1-m-thick, Early Triassic Daye Formation at the Daxiakou section, Hubei province in South China. The Daye Formation shows exceptionally well-preserved lithological cycles with alternations of thin-bedded mudstone, marl and limestone, which are closely tracked by the MS and ARM variations. Power spectral, wavelet and amplitude modulation (AM) analysis of the ARM and MS series reveal strong evidence for the presence of Milankovitch to sub-Milankovitch frequencies dominated by precession index signal and 4-5 ka cycles. Cycles expressed by variations in MS and ARM were likely controlled by the input of fine-grained detrital magnetite, which in turn may be driven by astronomically induced changes in monsoon intensity in the equatorial eastern Tethys during the Early Triassic greenhouse period. On the basis of the 100-ka tuning results, the astronomically constrained duration of

  16. The Orthoceltites beds - a case study on a Triassic mass-occurrence (Carnian, Taurus, Turkey)

    Science.gov (United States)

    Lukeneder, A.; Lukeneder, S.

    2012-04-01

    Mass-occurrences in the palaeontological record can act as proxy for the environmental activities and biotic crisis through time. It has to be noted that the ultimate causes are often unknown and not well understood and are still under comprehensive discussion. The formation of the ammonite beds (e.g. Orthoceltites) is either autochthonous or allochthonous (transported). Expected 3D modelling results will be essential to reach geodynamic, palaeooceanographic and palaeobiological conclusions. 3D reconstructed faunas, representing environmental changes as displayed by the sea-level and climate can become more obvious and the 'motor' behind the demise better understood. While the Carnian, an ammonite mass-occurrence (Anatolia, Turkey) was deposited within an intrashelf area on the western end of the Cimmerian System, with intermediate connection to both, the Neo-Tethys and the Palaeo-Thetys Oceans. The mass-occurrence can be observed over several square kilometers around Aşağiyaylabel and Karapinar. This ammonite mass occurrence (Orthoceltites sp.) is now located at the boundary from the Kartoz and the Kasimlar Formation. The ceratitid ammonite Orthoceltites dominated the ammonite fauna (approx. 99.9%; n > 1 000 000) and is accompanied by rare individuals of Klipsteina and Sirenites. Statistical analysis of the orientation and relative position of the ammonite shells hint to current or transport directions. 3D modelling of ammonites will lead to a geometrical reconstruction and shed light on the biostratinomic and additional diagentic processes. The proposed research integrates well established 3D visualisation and geometrical modelling techniques in an exciting palaeontological task of reconstructing the distribution and alignment of ammonite in a Triassic mass-occurrence from Turkey. Computed tomography and laser surface-scans of ammonites and computed tomography provide additional information on shape and internal structures, which will in a further step be

  17. A gigantic nothosaur (Reptilia: Sauropterygia) from the Middle Triassic of SW China and its implication for the Triassic biotic recovery

    Science.gov (United States)

    Liu, Jun; Hu, Shi-Xue; Rieppel, Olivier; Jiang, Da-Yong; Benton, Michael J.; Kelley, Neil P.; Aitchison, Jonathan C.; Zhou, Chang-Yong; Wen, Wen; Huang, Jin-Yuan; Xie, Tao; Lv, Tao

    2014-11-01

    The presence of gigantic apex predators in the eastern Panthalassic and western Tethyan oceans suggests that complex ecosystems in the sea had become re-established in these regions at least by the early Middle Triassic, after the Permian-Triassic mass extinction (PTME). However, it is not clear whether oceanic ecosystem recovery from the PTME was globally synchronous because of the apparent lack of such predators in the eastern Tethyan/western Panthalassic region prior to the Late Triassic. Here we report a gigantic nothosaur from the lower Middle Triassic of Luoping in southwest China (eastern Tethyan ocean), which possesses the largest known lower jaw among Triassic sauropterygians. Phylogenetic analysis suggests parallel evolution of gigantism in Triassic sauropterygians. Discovery of this gigantic apex predator, together with associated diverse marine reptiles and the complex food web, indicates global recovery of shallow marine ecosystems from PTME by the early Middle Triassic.

  18. Taphonomic implications from Upper Triassic mass flow deposits: 2-dimensional reconstructions of an ammonoid mass occurrence (Carnian, Taurus Mountains, Turkey

    Directory of Open Access Journals (Sweden)

    Mayrhofer Susanne

    2014-10-01

    Full Text Available Ammonoid mass occurrences of Late Triassic age were investigated in sections from A şağlyaylabel and Yukarlyaylabel, which are located in the Taurus Platform-Units of eastern Turkey. The cephalopod beds are almost monospecific, with > 99.9 % of individuals from the ceratitic genus Kasimlarceltites, which comprises more than hundreds of millions of ammonoid specimens. The ontogenetic composition of the event fauna varies from bed to bed, suggesting that these redeposited shell-rich sediments had different source areas. The geographical extent of the mass occurrence can be traced over large areas up to 10 km2. Each of the Early Carnian (Julian 2 ammonoid mass occurrences signifies a single storm (e.g. storm-wave action or tectonic event (e.g. earthquake that caused gravity flows and turbidity currents. Three types of ammonoid accumulation deposits are distinguished by their genesis: 1 matrix-supported floatstones, produced by low density debris flows, 2 mixed floatstones and packstones formed by high density debris flows, and 3 densely ammonoid shell-supported packstones which result from turbidity currents. Two-dimensional calculations on the mass occurrences, based on sectioning, reveal aligned ammonoid shells, implying transport in a diluted sediment. The ammonoid shells are predominantely redeposited, preserved as mixed autochthonous/parautochnonous/ allochthonous communities based on biogenic and sedimentological concentration mechanisms ( = in-situ or post-mortem deposited. This taphonomic evaluation of the Kasimlarceltites beds thus reveals new insights into the environment of deposition of the Carnian section, namely that it had a proximal position along a carbonate platform edge that was influenced by a nearby shallow water regime. The Kasimlarceltites-abundance zone is a marker-zone in the study area, developed during the drowning of a shallow water platform, which can be traceable over long distances.

  19. Taphonomic implications from Upper Triassic mass flow deposits: 2-dimensional reconstructions of an ammonoid mass occurrence (Carnian, Taurus Mountains, Turkey)

    Science.gov (United States)

    Mayrhofer, Susanne; Mayrhofer, Susanne

    2014-10-01

    Ammonoid mass occurrences of Late Triassic age were investigated in sections from A şağlyaylabel and Yukarlyaylabel, which are located in the Taurus Platform-Units of eastern Turkey. The cephalopod beds are almost monospecific, with > 99.9 % of individuals from the ceratitic genus Kasimlarceltites, which comprises more than hundreds of millions of ammonoid specimens. The ontogenetic composition of the event fauna varies from bed to bed, suggesting that these redeposited shell-rich sediments had different source areas. The geographical extent of the mass occurrence can be traced over large areas up to 10 km2. Each of the Early Carnian (Julian 2) ammonoid mass occurrences signifies a single storm (e.g. storm-wave action) or tectonic event (e.g. earthquake) that caused gravity flows and turbidity currents. Three types of ammonoid accumulation deposits are distinguished by their genesis: 1) matrix-supported floatstones, produced by low density debris flows, 2) mixed floatstones and packstones formed by high density debris flows, and 3) densely ammonoid shell-supported packstones which result from turbidity currents. Two-dimensional calculations on the mass occurrences, based on sectioning, reveal aligned ammonoid shells, implying transport in a diluted sediment. The ammonoid shells are predominantely redeposited, preserved as mixed autochthonous/parautochnonous/ allochthonous communities based on biogenic and sedimentological concentration mechanisms ( = in-situ or post-mortem deposited). This taphonomic evaluation of the Kasimlarceltites beds thus reveals new insights into the environment of deposition of the Carnian section, namely that it had a proximal position along a carbonate platform edge that was influenced by a nearby shallow water regime. The Kasimlarceltites-abundance zone is a marker-zone in the study area, developed during the drowning of a shallow water platform, which can be traceable over long distances.

  20. Ocean redox change at the Permian-Triassic mass extinction

    DEFF Research Database (Denmark)

    Ruhl, Micha; Bjerrum, Christian J.; Canfield, Donald Eugene

    2013-01-01

    and marine (mass) ex¬tinction. The geographic and temporal extend and the intensity (ferruginous vs. euxinic) of anoxic con¬ditions is, however, strongly debated and not well constraint. This complicates understanding of close coupling between Earth’s physical, chemical and bi¬ological processes. We studied...... ocean redox change over the largest mass extinction event in Earth history, at the Permian-Tri¬assic boundary (at ~252 Ma). This event is marked by a major perturbation in the global exogenic carbon cycle (and associated major negative carbon isotope excursion (CIE)), likely initiated by carbon...... (anoxic but not euxinic) coinciding with the main extinction event. Molybdenum enrichments, often indicative for freely available sulfide in the water-column, only occur dur¬ing the second phase of euxinia. This pattern of ocean redox-change in Svalbard direct¬ly reflects similar trends in Greenland...

  1. Ocean redox change at the Permian-Triassic mass extinction

    DEFF Research Database (Denmark)

    Ruhl, Micha; Bjerrum, Christian J.; Canfield, Donald Eugene

    2013-01-01

    Earth’s history is marked by multiple events of ocean anoxia developing along continental margins and po¬tentially into the open ocean realm. These events of¬ten coincide with the emplacement of large igneous provinces (LIPs) on continents, major perturbations of global geochemical cycles...... ocean redox change over the largest mass extinction event in Earth history, at the Permian-Tri¬assic boundary (at ~252 Ma). This event is marked by a major perturbation in the global exogenic carbon cycle (and associated major negative carbon isotope excursion (CIE)), likely initiated by carbon...... and marine (mass) ex¬tinction. The geographic and temporal extend and the intensity (ferruginous vs. euxinic) of anoxic con¬ditions is, however, strongly debated and not well constraint. This complicates understanding of close coupling between Earth’s physical, chemical and bi¬ological processes. We studied...

  2. Early Triassic stromatolites in a siliciclastic nearshore setting in northern Perth Basin, Western Australia: Geobiologic features and implications for post-extinction microbial proliferation

    Science.gov (United States)

    Chen, Zhong-Qiang; Wang, Yongbiao; Kershaw, Stephen; Luo, Mao; Yang, Hao; Zhao, Laishi; Feng, Yuheng; Chen, Jianbo; Yang, Li; Zhang, Lei

    2014-10-01

    inhabited not only carbonate settings, but also siliciclastic nearshore settings. All features of these Early Triassic stromatolites indicate a microbial bloom in the aftermath of the P-Tr mass extinction.

  3. Community stability and selective extinction during the Permian-Triassic mass extinction

    Science.gov (United States)

    Roopnarine, Peter D.; Angielczyk, Kenneth D.

    2015-10-01

    The fossil record contains exemplars of extreme biodiversity crises. Here, we examined the stability of terrestrial paleocommunities from South Africa during Earth's most severe mass extinction, the Permian-Triassic. We show that stability depended critically on functional diversity and patterns of guild interaction, regardless of species richness. Paleocommunities exhibited less transient instability—relative to model communities with alternative community organization—and significantly greater probabilities of being locally stable during the mass extinction. Functional patterns that have evolved during an ecosystem's history support significantly more stable communities than hypothetical alternatives.

  4. Progress and review of the studies on the end-Triassic mass extinction event

    Institute of Scientific and Technical Information of China (English)

    DENG Shenghui; LU Yuanzheng; XU Daoyi

    2005-01-01

    The mass extinction at the end-Triassic is one of the five biggest in the Phanerozoic. However,it is the least well understood among these five events, and only till last decade it became a great academic interesting subject to geologists. The evidences for this event come obviously from bivalves, brachiopods, ammonites, corals, radiolaria, ostracods and foraminifera of marine habitats, and plants and tetrapods of terrestrial realm. By contrast, for some of other groups, such as marine gastropods and marine vertebrates, no mass extinction has been recognized yet. The extinction event is strongly marked at specific level but shown a complicated situation at generic and family levels. Dramatic changing of the environment, such as the temperature raise due to the greenhouse effect, the marine anoxic habitats caused by a sudden transgression after the regression at the end of Triassic, has been claimed to be the main cause of the extinction. Many hypotheses have been suggested to demonstrate the mechanisms of the environment changing, among which two popular ones are the bolide impact and volcanic eruption. The Triassic-Jurassic (Tr-J) boundary mass extinction event is still poorly understood because no enough data have been obtained from the Tr-J boundary successional sections of both marine and terrestrial sediments, and most of these studies were regionally restricted. The basic aspects of the event and its associated environmental conditions remain poorly characterized and the causal mechanism or mechanisms are equivocal. Some authors even doubt its occurrence. China has many successionally developed terrestrial and marine Tr-J sections. Detailed studies of these sections may be important and significant for well understanding of the event.

  5. Pronounced carbonate deposition in the Early Triassic Dienerian substage: Who was the carbonate producer?

    Science.gov (United States)

    Horacek, Micha; Brandner, Rainer

    2014-05-01

    and shaping the Early Triassic environment.

  6. Volatile earliest Triassic sulfur cycle

    DEFF Research Database (Denmark)

    Schobben, Martin; Stebbins, Alan; Algeo, Thomas J.

    2017-01-01

    Marine biodiversity decreases and ecosystem destruction during the end-Permian mass extinction (EPME) have been linked to widespread marine euxinic conditions. Changes in the biogeochemical sulfur cycle, microbial sulfate reduction (MSR), and marine dissolved sulfate concentrations during the Per...... of widespread euxinic conditions, posing a sustained threat to marine life during the Early Triassic....

  7. Late Triassic - Early Jurassic successions of the Atuel depocenter: sequence stratigraphy and tectonic controls

    Directory of Open Access Journals (Sweden)

    Silvia Lanés

    2008-12-01

    Full Text Available Biostratigraphic correlations of the Late Triassic - Early Jurassic successions of the Atuel depocenter allowed determining the accommodation changes and the possible tectonic controls on sedimentation. The Rhaetian - late Early Sinemurian deposits contain facies of slope-type fan deltas, braided fluvial systems and low sinuosity rivers with alternate bars deposited during a synrift phase. The late Early Sinemurian - Toarcian series host facies of intermediate (Gilbert to shelf type fan deltas, braided and low sinuosity fluvial systems, wave-dominated estuaries, transgressive storm-dominated and turbidite-influenced marine shelves which record the sag phase. According to different criteria two stratigraphic schemes are proposed, the first one considering tectosedimentary units (TSU and the second one using "Exxon-like" sequences. In the first scheme the synrift TSU matches the actual Precuyo Mesosequence and the sag TSU is partly equivalent to the Cuyo Mesosequence, mainly keeping the current mesosequence scheme for the Neuquén basin but assigning the fandeltaic deposits to the Precuyo Mesosequence. The second sequence scheme considers the whole Late Triassic - Early Jurassic succession as a part of the Cuyo Mesosequence, where the synrift deposits composes the detached lowstand system tract (LST and most of the sag deposits makes the transgressive system tract (TST. The basal sequence boundary does not crop out, the flooding surface at the TST base and the maximum flooding surface at the TST top are respectively marked by the lowest estuarine levels and by black shales with suboxic-compatible bivalves (Bositra sp..

  8. Early to Middle Triassic sedimentary records in the Youjiang Basin, South China: Implications for Indosinian orogenesis

    Science.gov (United States)

    Qiu, Liang; Yan, Dan-Ping; Yang, Wen-Xin; Wang, Jibin; Tang, Xiangli; Ariser, Shahnawaz

    2017-06-01

    The Indosinian orogeny marks the termination of marine deposition and the accumulation of lower Permian to Late Triassic clastic sediments in the Youjiang Basin, South China Block. Major and trace element compositions of Early to Middle Triassic sedimentary clastic rocks from Youjiang Basin were analysed to constrain their provenance and tectonic setting. Argillaceous samples have low SiO2 (average 56.95 wt.%), Al2O3 (average 15.15 wt.%), and Fe2O3T + MgO (average 11.54 wt.%) contents, and high K2O/Na2O (average 15.61) and Al2O3/SiO2 (average 0.27) ratios, similar to mudstones from continental arc basins. Arenaceous samples have moderate SiO2 (average 76.98 wt.%), Al2O3 (average 8.41 wt.%), and Fe2O3T + MgO (average 5.29 wt.%) contents, and moderate Al2O3/SiO2 (average 0.11) and K2O/Na2O (average 15.26) ratios, identical to those of graywackes from continental island arcs or active continental margins. Both the argillaceous and arenaceous samples have low CIA values (57-85) and relatively high ICV values (0.69-2.11), indicating that the source rocks experienced weak chemical weathering and the sedimentary detritus was derived from an immature source. Compared with late Permian to Early Triassic South China granitoids and upper crust, the samples have lower contents of high-field-strength elements (e.g., Zr, Hf, Nb, and Ta) and large ion lithophile elements (e.g., Rb, Sr, Ba, Th, U, and Pb). However, their relatively high Rb concentrations (>51 ppm), and low Rb/Sr (0.16-4.19) and Th/U (2.66-5.21) ratios, are indicative of an igneous source from a continental arc that underwent weak chemical weathering. Both the argillaceous and arenaceous samples are moderately enriched in light rare earth elements and show relatively flat chondrite-normalized heavy rare earth element patterns (LaN/YbN = 6.61-17.35; average 10.61) with strong negative Eu anomalies (Eu/Eu* = 0.54-0.89; average 0.73). In tectonic discrimination diagrams, including Th-Sc-Zr/10 and La-Th-Sc plots, the

  9. Biostratigraphic correlation and mass extinction during the Permian-Triassic transition in terrestrial-marine siliciclastic settings of South China

    Science.gov (United States)

    Chu, Daoliang; Yu, Jianxin; Tong, Jinnan; Benton, Michael J.; Song, Haijun; Huang, Yunfei; Song, Ting; Tian, Li

    2016-11-01

    The Permian-Triassic boundary marks the greatest mass extinction during the Phanerozoic, which was coupled with major global environmental changes, and is known especially from well-preserved marine fossil records and continuous carbonate deposits. However, the placement of the Permian-Triassic boundary in terrestrial sections and accurate correlation with the marine strata are difficult due to the absence of the key marine index fossils in terrestrial-marine siliciclastic settings. Here, we present detailed fossil data from four terrestrial sections, two paralic sections and one shallow marine section in South China. Our data show that the rapid mass disappearance of the Gigantopteris flora in various sections represents the end-Permian mass extinction and the base of the Permian-Triassic transitional beds in terrestrial-marine siliciclastic settings of South China. In particular, we find a mixed marine and terrestrial biota from the coastal transitional sections of the Permian-Triassic transitional Kayitou Formation, which provides a unique intermediate link for biostratigraphic correlation between terrestrial and marine sequences. Accordingly, the Euestheria gutta-bearing conchostracan fauna and the Pteria ussurica variabilis-Towapteria scythica-Eumorphotis venetiana bivalve assemblage are proposed as markers of the Permian-Triassic transitional beds in terrestrial-marine siliciclastic settings of South China.

  10. Palynofloral associations before and after the Permian-Triassic mass extinction, Kap Stosch, East Greenland

    Science.gov (United States)

    Schneebeli-Hermann, Elke; Hochuli, Peter A.; Bucher, Hugo

    2017-08-01

    The Permian-Triassic boundary (PTB) interval is known to document a major biodiversity crisis in the history of life. It is generally accepted that this crisis had a significant impact on marine invertebrates. The consequences for terrestrial ecosystems are still controversially discussed. Based on palynological analysis we present a high time resolution microfloral succession of the expanded Late Permian (Wuchiapingian)-Early Triassic (Dienerian) section from Kap Stosch, East Greenland. The quantitative distribution of palynomorphs (range charts and relative abundance data) allows for the differentiation of six distinct palynofloral associations. Ammonoids and conodonts provide independent age control for these assemblages. The Wuchiapingian association I, documented from the Ravnefjeld Formation, shows a typical Late Permian assemblage dominated by bisaccate and monosaccate pollen grains and Vittatina spp. It is separated from association II, present in the basal part of the Wordie Creek Formation, by an important hiatus. This association of Changhsingian or earliest Griesbachian age is characterised by the common occurrence of Ephedripites spp. and reduced abundance and diversity of Vittatina spp. Association III, dated as Griesbachian by the presence of ammonoids, is marked by high relative abundances of taeniate bisaccate pollen grains and high spore diversity. A distinct floral break occurs between the gymnosperm dominated Permian and Griesbachian floras and the lycopsid spore dominated Dienerian associations IV-VI. Ammonoid occurrences verify a Dienerian age for the latter associations. Association V is marked by the absence of non-taeniate bisaccate, striate monosaccate pollen grains, and Vittatina spp. Aratrisporites spp. a typical Triassic lycopsid spore occur consistently from this level onwards. Association VI is characterised by highest lycopsid spore abundances. Cluster analysis demonstrates that Griesbachian assemblages (associations II?-III) are

  11. A primitive ornithischian dinosaur from the Late Triassic of South Africa, and the early evolution and diversification of Ornithischia.

    Science.gov (United States)

    Butler, Richard J; Smith, Roger M H; Norman, David B

    2007-08-22

    Although the group played an important role in the evolution of Late Mesozoic terrestrial ecosystems, the early evolutionary history of the ornithischian dinosaurs remains poorly understood. Here, we report on a new primitive ornithischian, Eocursor parvus gen. et sp. nov. from the Late Triassic (?Norian) Lower Elliot Formation of South Africa. Eocursor is known from a single specimen comprising substantial cranial and postcranial material and represents the most complete Triassic member of Ornithischia, providing the earliest evidence for the acquisition of many key ornithischian postcranial characters, including an opisthopubic pelvis. A new phylogenetic analysis positions this taxon near the base of Ornithischia, as the sister taxon to the important and diverse clade Genasauria. The problematic clade Heterodontosauridae is also positioned basal to Genasauria, suggesting that an enlarged grasping manus may represent a plesiomorphic ornithischian condition. This analysis provides additional phylogenetic support for limited ornithischian diversity during the Late Triassic, and suggests that several major ornithischian clades may have originated later than generally believed. There are few morphological differences between Late Triassic and Early Jurassic ornithischians, supporting previous suggestions that the Early Jurassic ornithischian radiation may simply represent the filling of vacant ecological space following Late Triassic terrestrial extinctions.

  12. Testing the limits in a greenhouse ocean: Did low nitrogen availability limit marine productivity during the end-Triassic mass extinction?

    Science.gov (United States)

    Schoepfer, Shane D.; Algeo, Thomas J.; Ward, Peter D.; Williford, Kenneth H.; Haggart, James W.

    2016-10-01

    The end-Triassic mass extinction has been characterized as a 'greenhouse extinction', related to rapid atmospheric warming and associated changes in ocean circulation and oxygenation. The response of the marine nitrogen cycle to these oceanographic changes, and the extent to which mass extinction intervals represent a deviation in nitrogen cycling from other ice-free 'greenhouse' periods of Earth history, remain poorly understood. The well-studied Kennecott Point section in Haida Gwaii, British Columbia, Canada, was deposited in the open Panthalassic Ocean, and is used here as a test case to better understand changes in the nitrogen cycle and marine productivity from the pre-crisis greenhouse of the Rhaetian to the latest-Rhaetian crisis interval. We estimated marine productivity from the late Norian to the early Hettangian using TOC- and P-based paleoproductivity transform equations, and then compared these estimates to records of sedimentary nitrogen isotopes, redox-sensitive trace elements, and biomarker data. Major negative excursions in δ15N (to ≤ 0 ‰) correspond to periods of depressed marine productivity. During these episodes, the development of a stable pycnocline below the base of the photic zone suppressed vertical mixing and limited N availability in surface waters, leading to low productivity and increased nitrogen fixation, as well as ecological stresses in the photic zone. The subsequent shoaling of euxinic waters into the ocean surface layer was fatal for most Triassic marine fauna, although the introduction of regenerated NH4+ into the photic zone may have allowed phytoplankton productivity to recover. These results indicate that the open-ocean nitrogen cycle was influenced by climatic changes during the latest Triassic, despite having existed in a greenhouse state for over 50 million years previously, and that low N availability limited marine productivity for hundreds of thousands of years during the end-Triassic crisis.

  13. Early Triassic wrinkle structures on land: stressed environments and oases for life

    Science.gov (United States)

    Chu, Daoliang; Tong, Jinnan; Song, Haijun; Benton, Michael J.; Bottjer, David J.; Song, Huyue; Tian, Li

    2015-06-01

    Wrinkle structures in rocks younger than the Permian-Triassic (P-Tr) extinction have been reported repeatedly in marine strata, but rarely mentioned in rocks recording land. Here, three newly studied terrestrial P-Tr boundary rock succession in North China have yielded diverse wrinkle structures. All of these wrinkles are preserved in barely bioturbated shore-shallow lacustrine siliciclastic deposits of the Liujiagou Formation. Conversely, both the lacustrine siliciclastic deposits of the underlying Sunjiagou Formation and the overlying Heshanggou Formation show rich bioturbation, but no wrinkle structures or other microbial-related structures. The occurrence of terrestrial wrinkle structures in the studied sections reflects abnormal hydrochemical and physical environments, presumably associated with the extinction of terrestrial organisms. Only very rare trace fossils occurred in the aftermath of the P-Tr extinction, but most of them were preserved together with the microbial mats. This suggests that microbial mats acted as potential oases for the surviving aquatic animals, as a source of food and oxygen. The new finds suggests that extreme environmental stresses were prevalent both in the sea and on land through most of the Early Triassic.

  14. Long-term oceanic changes prior the end-Triassic mass extinction

    DEFF Research Database (Denmark)

    Clemence, Marie-Emilie; Mette, Wolfgang; Thibault, Nicolas Rudolph;

    2014-01-01

    A number of potential causes and kill mechanisms have been proposed for the end-Triassic mass extinction such as palaeoclimatic and sea-level variations, massive volcanism and ocean acidification. Recent analysis of the stomatal index and density of fossil leaves and geochemical research...... of marls and shales of the Zlambach Formation were deposited at the same time on the other side of this reef, in the oceanic Halstatt Basin, which was in direct connection to the Tethys. Here, we present new results on sedimentology, stable isotope and trace element analysis of both intraplatform...... and oceanic basin deposits in the NCA. Intraplatform Rhaetian sections from the Koessen Formation bear a few minor intervals of shales with enrichments in organic matter, some of which are associated to carbon isotopic excursions. Oceanic sections from the Halstatt Basin are characterized at the base by very...

  15. Rapid Carbonate Depositional Changes Following the Permian-Triassic Mass Extinction:Sedimentary Evidence from South China

    Institute of Scientific and Technical Information of China (English)

    Li Tian; Jinnan Tong; David Bottjer; Daoliang Chu; Lei Liang; Huyue Song; Haijun Song

    2015-01-01

    Various environmental changes were associated with the Permian-Triassic mass extinc-tion at 252.2 Ma. Diverse unusual sediments and depositional phenomena have been uncovered as re-sponses to environmental and biotic changes. Lithological and detailed conodont biostratigraphic cor-relations within six Permian-Triassic boundary sections in South China indicate rapid fluctuations in carbonate deposition. Four distinct depositional phases can be recognized:(1) normal carbonate depo-sition on the platform and slope during the latest Permian;(2) reduced carbonate deposition at the on-set of the main extinction horizon; (3) expanded areas of carbonate deposition during the Hindeodus changxingsensis Zone to the H. parvus Zone;and (4) persistent mud-enriched carbonate deposition in the aftermath of the Permian-Triassic transition. Although availability of skeletal carbonate was sig-nificantly reduced during the mass extinction, the increase in carbonate deposition did not behave the same way. The rapid carbonate depositional changes, presented in this study, suggest that diverse envi-ronmental changes played key roles in the carbonate deposition of the Permian-Triassic mass extinction and onset of its aftermath. An overview of hypotheses to explain these changes implies enhanced terres-trial input, abnormal ocean circulation and various geobiological processes contributed to carbonate saturation fluctuations, as the sedimentary response to large volcanic eruptions.

  16. Trajectories of Late Permian – Jurassic radiolarian extinction rates: no evidence for an end-Triassic mass extinction

    Directory of Open Access Journals (Sweden)

    W. Kiessling

    2011-02-01

    Full Text Available The hypothesis that ocean acidification was a proximate trigger of the marine end-Triassic mass extinction rests on the assumption that taxa that strongly invest in the secretion of calcium-carbonate skeletons were significantly more affected by the crisis than other taxa. An argument against this hypothesis is the great extinction toll of radiolarians that has been reported from work on local sections. Radiolarians have siliceous tests and thus should be less affected by ocean acidification. We compiled taxonomically vetted occurrences of late Permian and Mesozoic radiolarians and analyzed extinction dynamics of radiolarian genera. Although extinction rates were high at the end of the Triassic, there is no evidence for a mass extinction in radiolarians but rather significantly higher background extinction in the Triassic than in the Jurassic. Although the causes for this decline in background extinction levels remain unclear, the lack of a major evolutionary response to the end-Triassic event, gives support for the hypothesis that ocean acidification was involved in the dramatic extinctions of many calcifying taxa. doi:10.1002/mmng.201000017

  17. A NEW, EARLY CROWN-GROUP ASTEROID (ECHINODERMATA) FROM THE NORIAN (TRIASSIC) OF NORTHERN ITALY

    OpenAIRE

    2000-01-01

    Noriaster barberoi gen. et. sp. n. is based on a single specimen from the Calcare di Zorzino (Norian, Triassic) of northern Italy. A member of the surviving Poraniidae (Valvatida; Echinodermata), N. barberoi is the oldest-known species assignable to a Jurassic and younger family and the first such species known from the Triassic. No Paleozoic species with close affinities with crown-group families has been recognized. Noriaster and the slightly older Triassic genus Trichasteropsis from the Mu...

  18. An early Middle Anisian (Middle Triassic) Tubiphytes and cement crusts-dominated reef from North Dobrogea (Romania): facies, depositional environment and diagenesis

    Science.gov (United States)

    Popa, Livia; Panaiotu, Cristina E.; Grădinaru, Eugen

    2014-06-01

    A well-developed Triassic carbonate platform is exposed in the eastern part of the Tulcea Unit, in the Cimmerian North Dobrogean Orogen, southeastern Romania. Facies analysis of the 200 m thick succession of lower Middle Anisian limestones exposed in a large limestone quarry south of the village of Mahmudia suggests a transition from upper slope towards toe-of-slope carbonate facies, reflecting sea-level fluctuations and tectonic tilting. The slope is dominated by in situ microbialites in the upper portion, consisting of reefal boundstone facies, and by molluscan coquina and cement boundstones. A key role is played by the cosmopolitan micro-encruster Tubiphytes, which became common in the aftermath of the mass extinction at the Permian/Triassic boundary, and by autochthonous micrite and synsedimentary marine cement. The absence of metazoan reef builders, such as sponges and corals, reflects the fact that microbes were the first organisms to recover after the Permian/Triassic crisis under unusual marine conditions and that their main role in reef formation was sediment stabilization along the upper slopes. The lower slope is mostly detrital, being dominated by platform-derived bioclastic rudstones and crinoidal floatstones, which are interbedded with basinal carbonate hemipelagics. The toe-of-slope is composed of pelagic wackestones framed by thin tongues of intraclast breccia. All these observations are in agreement with the slopeshedding model described for the Pennsylvanian microbial margin in Asturias (northern Spain) and the Anisian- Ladinian flat-topped, steep-rimmed Latemar platform (Dolomites, Italy). As most of the Anisian reefs were described from western and eastern Tethys (Southern Alps, Hungary, China), the occurrence of the early Middle Anisian Tubiphytes-reef from North Dobrogea (Romania) contributes to resolving the puzzle of the geographic distribution of reef recovery in the Middle Triassic.

  19. Intense and widespread seismicity during the end-Triassic mass extinction due to emplacement of a large igneous province

    DEFF Research Database (Denmark)

    Lindström, Sofie; Pedersen, Gunver Krarup; van de Schootbrugge, Bas

    2015-01-01

    Multiple levels of earthquake-induced soft-sediment deformations (seismites) are concentrated in the end-Triassic mass extinction interval across Europe. The repetitive nature of the seismites rules out an origin by an extraterrestrial impact. Instead, this intense seismic activity is linked to t...... emission of gases (SO2, halocarbons, polycyclic aromatic hydrocarbons) that may have played a major part in the biotic crisis....

  20. Permian-Early Triassic tectonics and stratigraphy of the Karoo Supergroup in northwestern Mozambique

    Science.gov (United States)

    Bicca, Marcos Müller; Philipp, Ruy Paulo; Jelinek, Andrea Ritter; Ketzer, João Marcelo Medina; dos Santos Scherer, Claiton Marlon; Jamal, Daúd Liace; dos Reis, Adriano Domingos

    2017-06-01

    The Gondwana continent was the base of great basin inception, sedimentation and magmatism throughout the Cambrian to Middle Jurassic periods. The northwestern Mozambique igneous and metamorphic basement assemblages host the NW-trending Moatize Minjova Basin, which has great economic potential for coal and gas mining. This rift basin was activated by an S-SW stress field during the Early Permian period, as constrained by regional and field scale structural data. Tectonically induced subsidence in the basin, from the reactivation of NW-SE and NNE-SSW regional structures is well recorded by faults, folds and synsedimentary fractures within the Early Late Permian Moatize Formation. NW-SE, N-S and NE-SW field structures consist of post-Karoo reactivation patterns related to a NNE-SSW extension produced by the Pangea breakup and early inception stages of the Great East African Rift System. The Early Late Permian sequences of the Moatize-Minjova Basin are composed of fluvial meandering, coal-bearing beds of the Moatize Formation, which comprises mostly floodplain, crevasse splay and fluvial channel lithofacies associations, deposited in a cyclic pattern. This sequence was overlapped by a multiple-story, braided fluvial plain sequence of the Matinde Formation (Late Permian - Early Triassic). Lithofacies associations in the Matinde Formation and its internal relationships suggest deposition of poorly channelized braided alluvial plain in which downstream and probably lateral accretion macroforms alternate with gravity flow deposits. NW paleoflow measurements suggest that Permian fluvial headwaters were located somewhere southeast of the study area, possibly between the African and Antarctic Precambrian highlands.

  1. Globacrochordiceras gen. nov. (Acrochordiceratidae, late Early Triassic and its significance for stress-induced evolutionary jumps in ammonoid lineages (cephalopods

    Directory of Open Access Journals (Sweden)

    C. Monnet

    2013-08-01

    Full Text Available Globacrochordiceras transpacificum gen. et sp. nov. is an ammonoid (Ammonoidea, Cephalopoda with a shell characterized by plicate ribbing (rounded and undulating ribs strengthening on the venter without interruption, increasing involution through ontogeny, overhanging and deep umbilical wall, absence of tuberculation, subtriangular whorl section, globose adult shape with a closed umbilicus followed by an abrupt egressive coiling, and a subammonitic adult suture line. This new taxon occurs in Nevada (USA and in Guangxi (South China. It has its typical occurrence within the Neopopanoceras haugi Zone of late Spathian age (Early Triassic. The plicate ribbing, suture line and general shell shape are diagnostic of the family Acrochordiceratidae. The large adult size, high degree of involution and subammonitic suture line of Globacrochordiceras markedly contrast with the next younger genus of the family (Paracrochordiceras of early Anisian age, Middle Triassic, which is evolute and displays a ceratitic suture shape. Shell coiling and suture line of Globacrochordiceras are closer to that of the youngest member of the family: Acrochordiceras carolinae (late middle Anisian. The latter is the end-member of a long-term morphological evolutionary trend of the family during the early and middle Anisian. This trend composed of classical increases in adult size (Cope's rule, shell involution and suture indentation, lasted ca. four Myr. The sudden morphological evolutionary jump between Globacrochordiceras and Paracrochordiceras at the Spathian/Anisian (Early/Middle Triassic boundary may correspond to a generalized morphological reset of long-term trends, a process that differs from classic paedomorphic transformations. A dramatic global sea level change and carbon isotope positive excursion at the Early/Middle Triassic boundary both indicate stressful environmental changes that may have triggered this evolutionary jump. doi:10.1002/mmng.201300010

  2. Excursions in Stable Carbon Isotopes at the End-Triassic Mass Extinction: Eastern North America and Morocco

    Science.gov (United States)

    Whiteside, J. H.; Et-Touhami, M.

    2012-04-01

    The end-Triassic mass extinction (ETE) at 201.4 million years ago is one of the five largest ecological disasters of the last 600 million years. Its cause is thought to be related to flood basalt eruptions of the Central Atlantic Magmatic Province (CAMP). In eastern North America, non-marine deposits recording this extinction occur below the oldest basalts (1), whereas in Morocco the extinction appears to be synchronous or possibly above the oldest basalt flow (2). In marine and paralic strata of Europe, the extinction is marked by a distinct negative carbon isotopic (δ13C) excursion (CIE) (3). This CIE is also apparent in organic carbon records from eastern North America (4,5). Here we present new δ13C data from organic carbon and terrestrial plant derived n-alkanes from the Central High Atlas and Argana basins [6] of Morocco). These data also suggest that the CIE is coincident with the ETE. In the Passaic Formation of the Newark basin, the negative excursion is associated with the palynofloral extinction level and a fern spore abundance anomaly (fern spike) (7). In the Silver Ridge core (B-2) from the Hartford basin (Connecticut), the negative excursion is also associated with an equisetalian spore spike. In the Fundy basin, at Partridge Island, Nova Scotia, the negative excursion occurs at the palynofloral extinction level, below the oldest basalts [here and (5)], and in Morocco it occurs just below the oldest basalts where Triassic pollen taxa are still present [here and 6)]. One interpretation is that the CIE is synchronous globally and reflects a major anomaly in the Earth's carbon cycle (e.g., 8). However, it is also possible that this pattern is a coincidence of artifactual enrichments of 12C in depositional and early diagenetic environments cut off from the exchangeable global reservoirs, such as in eastern North American lakes (4) and possibly in the canonical shallow marine sections from the UK. Distinguishing between these two classes of hypotheses is

  3. Plants of Leptostrobus Heer (Czekanowskiales) from the Early Cretaceous and Late Triassic of China, with Discussion of the Genus

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    Inveetlgation of the Meeozoic seed plant Leptostrobus Heer from the Yangcaogou Formation of the Late Triassic and the Yixian Formation of the Early Cretaceous, Liaoning Province, China, provides new insight into its general morphology and geographical distribution. The materials of L. cancer from the Yixian Formation described herein are later than all the past findings of this species and add to the record of L. cancerduring the Early Cretaceous. Based on well-preserved specimens, the specific diagnosis is slightly emended and the reconstruction of L. cancer is perfected. The materials from the Yangcaogou Formation of the Late Triassic are placed in L. sphaericus. in addition, we review the history of investigation of the genus Leptostrobus since its establishment in 1876 and discuss the main characteristics of each species.

  4. Proliferation of MISS-related microbial mats following the end-Permian mass extinction in terrestrial ecosystems: Evidence from the Lower Triassic of the Yiyang area, Henan Province, North China

    Science.gov (United States)

    Tu, Chenyi; Chen, Zhong-Qiang; Retallack, Gregory J.; Huang, Yuangeng; Fang, Yuheng

    2016-03-01

    Microbially induced sedimentary structures (MISSs) are commonly present in siliciclastic shallow marine settings following the end-Permian mass extinction, but have been rarely reported in the post-extinction terrestrial ecosystems. Here, we present six types of well-preserved MISSs from the upper Sunjiagou Formation and lower Liujiagou Formation of Induan (Early Triassic) age in the Yiyang area, Henan Province, North China. These MISSs include: polygonal sand cracks, worm-like structures, wrinkle structures, sponge pore fabrics, gas domes, and leveled ripple marks. Microanalysis shows that these MISSs are characterized by thin clayey laminae and filamentous mica grains arranged parallel to bedding plane as well as oriented matrix supported quartz grains, which are indicative of biogenic origin. Facies analysis suggests that the MISS-hosting sediments were deposited in a fluvial sedimentary system during the Early Triassic, including lake delta, riverbeds/point bars, and flood plain paleoenvironments. Abundant MISSs from Yiyang indicate that microbes also proliferated in terrestrial ecosystems in the aftermath of the Permian-Triassic (P-Tr) biocrisis, like they behaved in marine ecosystems. Microbial blooms, together with dramatic loss of metazoans, may reflect environmental stress and degradation of terrestrial ecosystems or arid climate immediately after the severe Permian-Triassic ecologic crisis.

  5. High-precision U-Pb zircon geochronological constraints on the End-Triassic Mass Extinction, the late Triassic Astronomical Time Scale and geochemical evolution of CAMP magmatism

    Science.gov (United States)

    Blackburn, T. J.; Olsen, P. E.; Bowring, S. A.; McLean, N. M.; Kent, D. V.; Puffer, J. H.; McHone, G.; Rasbury, T.

    2012-12-01

    Mass extinction events that punctuate Earth's history have had a large influence on the evolution, diversity and composition of our planet's biosphere. The approximate temporal coincidence between the five major extinction events over the last 542 million years and the eruption of Large Igneous Provinces (LIPs) has led to the speculation that climate and environmental perturbations generated by the emplacement of a large volume of magma in a short period of time triggered each global biologic crisis. Establishing a causal link between extinction and the onset and tempo of LIP eruption has proved difficult because of the geographic separation between LIP volcanic deposits and stratigraphic sequences preserving evidence of the extinction. In most cases, the uncertainties on available radioisotopic dates used to correlate between geographically separated study areas often exceed the duration of both the extinction interval and LIP volcanism by an order of magnitude. The "end-Triassic extinction" (ETE) is one of the "big five" and is characterized by the disappearance of several terrestrial and marine species and dominance of Dinosaurs for the next 134 million years. Speculation on the cause has centered on massive climate perturbations thought to accompany the eruption of flood basalts related to the Central Atlantic Magmatic Province (CAMP), the most aerially extensive and volumetrically one of the largest LIPs on Earth. Despite an approximate temporal coincidence between extinction and volcanism, there lacks evidence placing the eruption of CAMP prior to or at the initiation of the extinction. Estimates of the timing and/or duration of CAMP volcanism provided by astrochronology and Ar-Ar geochronology differ by an order of magnitude, precluding high-precision tests of the relationship between LIP volcanism and the mass extinction, the causes of which are dependent upon the rate of magma eruption. Here we present high precision zircon U-Pb ID-TIMS geochronologic data

  6. Geochemical and palynological records for the end-Triassic Mass-Extinction Event in the NE Paris Basin (Luxemburg)

    Science.gov (United States)

    Kuhlmann, Natascha; van de Schootbrugge, Bas; Thein, Jean; Fiebig, Jens; Franz, Sven-Oliver; Hanzo, Micheline; Colbach, Robert; Faber, Alain

    2016-04-01

    The End-Triassic mass-extinction event is one of the "big five" mass extinctions in Earth's history. Large scale flood basalt volcanism associated with the break-up of Pangaea, which resulted in the opening of the central Atlantic Ocean, is considered as the leading cause. In addition, an asteroid impact in Rochechouart (France; 201 ± 2 Ma) may have had a local influence on ecosystems and sedimentary settings. The Luxembourg Embayment, in the NE Paris Basin, offers a rare chance to study both effects in a range of settings from deltaic to lagoonal. A multidisciplinary study (sedimentology, geochemistry, palynology) has been carried out on a number of outcrops and cores that span from the Norian to lower Hettangian. Combined geochemical and palynological records from the Boust core drilled in the NE Paris Basin, provide evidence for paleoenvironmental changes associated with the end-Triassic mass-extinction event. The Triassic-Jurassic stratigraphy of the Boust core is well constrained by palynomorphs showing the disappaerance of typical Triassic pollen taxa (e.g. Ricciisporites tuberculates) and the occurrence of the marker species Polypodiisporites polymicroforatus within the uppermost Rhaetian, prior to the Hettangian dominance of Classopollis pollen. The organic carbon stable isotope record (δ13Corg) spanning the Norian to Hettangian, shows a series of prominent negative excursions within the middle Rhaetian, followed by a trend towards more positive values (approx -24 per mille) within the uppermost Rhaetian Argiles de Levallois Member. The lowermost Hettangian is characterized by a major negative excursion, reaching - 30 per mille that occurs in organic-rich sediments. This so-called "main negative excursion" is well-known from other locations, for example from Mariental in Northern Germany and from St Audrie's Bay in England, and Stenlille in Denmark. Based on redox-sensitive trace element records (V, Cr, Ni, Co, Th, U) the lowermost Hettangian in most of

  7. Duration of and decoupling between carbon isotope excursions during the end-Triassic mass extinction and Central Atlantic Magmatic Province emplacement

    Science.gov (United States)

    Yager, Joyce A.; West, A. Joshua; Corsetti, Frank A.; Berelson, William M.; Rollins, Nick E.; Rosas, Silvia; Bottjer, David J.

    2017-09-01

    Changes in δ13Ccarb and δ13Corg from marine strata occur globally in association with the end-Triassic mass extinction and the emplacement of the Central Atlantic Magmatic Province (CAMP) during the break up of Pangea. As is typical in deep time, the timing and duration of these isotopic excursions has remained elusive, hampering attempts to link carbon cycle perturbations to specific processes. Here, we report δ13Ccarb and δ13Corg from Late Triassic and Early Jurassic strata near Levanto, Peru, where intercalated dated ash beds permit temporal calibration of the carbon isotope record. Both δ13Ccarb and δ13Corg exhibit a broad positive excursion through the latest Triassic into the earliest Jurassic. The first order positive excursion in δ13Corg is interrupted by a negative shift noted in many sections around the world coincident with the extinction horizon. Our data indicate that the negative excursion lasts 85 ± 25 kyrs, longer than inferred by previous studies based on cyclostratigraphy. A 260 ± 80 kyr positive δ13Corg shift follows, during which the first Jurassic ammonites appear. The overall excursion culminates in a return to pre-perturbation carbon isotopic values over the next 1090 ± 70 kyrs. Via chronologic, isotopic, and biostratigraphic correlation to other successions, we find that δ13Ccarb and δ13Corg return to pre-perturbation values as CAMP volcanism ceases and in association with the recovery of pelagic and benthic biota. However, the initiation of the carbon isotope excursion at Levanto predates the well-dated CAMP sills from North America, indicating that CAMP may have started earlier than thought based on these exposures, or that the onset of carbon cycle perturbations was not related to CAMP.

  8. A new sphenodontian (Lepidosauria: Rhynchocephalia) from the Late Triassic of Argentina and the early origin of the herbivore opisthodontians.

    Science.gov (United States)

    Martínez, Ricardo N; Apaldetti, Cecilia; Colombi, Carina E; Praderio, Angel; Fernandez, Eliana; Santi Malnis, Paula; Correa, Gustavo A; Abelin, Diego; Alcober, Oscar

    2013-12-07

    Sphenodontians were a successful group of rhynchocephalian reptiles that dominated the fossil record of Lepidosauria during the Triassic and Jurassic. Although evidence of extinction is seen at the end of the Laurasian Early Cretaceous, they appeared to remain numerically abundant in South America until the end of the period. Most of the known Late Cretaceous record in South America is composed of opisthodontians, the herbivorous branch of Sphenodontia, whose oldest members were until recently reported to be from the Kimmeridgian-Tithonian (Late Jurassic). Here, we report a new sphenodontian, Sphenotitan leyesi gen. et sp. nov., collected from the Upper Triassic Quebrada del Barro Formation of northwestern Argentina. Phylogenetic analysis identifies Sphenotitan as a basal member of Opisthodontia, extending the known record of opisthodontians and the origin of herbivory in this group by 50 Myr.

  9. Pattern of marine mass extinction near the Permian-Triassic boundary in South China.

    Science.gov (United States)

    Jin, Y G; Wang, Y; Wang, W; Shang, Q H; Cao, C Q; Erwin, D H

    2000-07-21

    The Meishan section across the Permian-Triassic boundary in South China is the most thoroughly investigated in the world. A statistical analysis of the occurrences of 162 genera and 333 species confirms a sudden extinction event at 251.4 million years ago, coincident with a dramatic depletion of delta13C(carbonate) and an increase in microspherules.

  10. Aggregations and parental care in the Early Triassic basal cynodonts Galesaurus planiceps and Thrinaxodon liorhinus

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    Sandra C. Jasinoski

    2017-01-01

    Full Text Available Non-mammaliaform cynodonts gave rise to mammals but the reproductive biology of this extinct group is still poorly known. Two exceptional fossils of Galesaurus planiceps and Thrinaxodon liorhinus, consisting of juveniles closely associated with an adult, were briefly described more than 50 years ago as examples of parental care in non-mammaliaform cynodonts. However, these two Early Triassic fossils have largely been excluded from recent discussions of parental care in the fossil record. Here we re-analyse these fossils in the context of an extensive survey of other aggregations found in these two basal cynodont taxa. Our analysis revealed six other unequivocal cases of aggregations in Thrinaxodon, with examples of same-age aggregations among immature or adult individuals as well as mixed-age aggregations between subadult and adult individuals. In contrast, only one additional aggregation of Galesauruswas identified. Taking this comprehensive survey into account, the two previously described cases of parental care in Galesaurus and Thrinaxodon are substantiated. The juveniles are the smallest specimens known for each taxon, and the size difference between the adult and the two associated juveniles is the largest found for any of the aggregations. The juveniles of Thrinaxodon are approximately only 37% of the associated adult size; whereas in Galesaurus, the young are at least 60% of the associated adult size. In each case, the two juvenile individuals are similar in size, suggesting they were from the same clutch. Even though parental care was present in both Galesaurus and Thrinaxodon, intraspecific aggregations were much more common in Thrinaxodon, suggesting it regularly lived in aggregations consisting of both similar and different aged individuals.

  11. A Middle Triassic thoracopterid from China highlights the evolutionary origin of overwater gliding in early ray-finned fishes.

    Science.gov (United States)

    Xu, Guang-Hui; Zhao, Li-Jun; Shen, Chen-Chen

    2015-01-01

    Gliding adaptations in thoracopterid flying fishes represent a remarkable case of convergent evolution of overwater gliding strategy with modern exocoetid flying fishes, but the evolutionary origin of this strategy was poorly known in the thoracopterids because of lack of transitional forms. Until recently, all thoracopterids, from the Late Triassic of Austria and Italy and the Middle Triassic of South China, were highly specialized 'four-winged' gliders in having wing-like paired fins and an asymmetrical caudal fin with the lower caudal lobe notably larger than the upper lobe. Here, we show that the new genus Wushaichthys and the previously alleged 'peltopleurid' Peripeltopleurus, from the Middle Triassic (Ladinian, 235-242 Ma) of South China and near the Ladinian/Anisian boundary of southern Switzerland and northern Italy, respectively, represent the most primitive and oldest known thoracopterids. Wushaichthys, the most basal thoracopterid, shows certain derived features of this group in the skull. Peripeltopleurus shows a condition intermediate between Wushaichthys and Thoracopterus in having a slightly asymmetrical caudal fin but still lacking wing-like paired fins. Phylogenetic studies suggest that the evolution of overwater gliding of thoracopterids was gradual in nature; a four-stage adaption following the 'cranial specialization-asymmetrical caudal fin-enlarged paired fins-scale reduction' sequence has been recognized in thoracopterid evolution. Moreover, Wushaichthys and Peripeltopleurus bear hooklets on the anal fin of supposed males, resembling those of modern viviparious teleosts. Early thoracopterids probably had evolved a live-bearing reproductive strategy.

  12. An Early Triassic evolving erg system (Iberian Chain, NE Spain): palaeoclimate implications

    NARCIS (Netherlands)

    Soria, A.R.; Liesa, C.L.; Rodriguez-Lopez, J.P.; Melendez, N.; Boer, P.L. de; Melendez, A.

    2011-01-01

    The Triassic Buntsandstein facies in the north-eastern Iberian Chain (central eastern Spain), previously considered to be fluvial in origin, is shown to contain an evolving erg system. The preserved erg accumulation comprises a succession that represents the transition from a wadi belt via inner erg

  13. A NEW, EARLY CROWN-GROUP ASTEROID (ECHINODERMATA FROM THE NORIAN (TRIASSIC OF NORTHERN ITALY

    Directory of Open Access Journals (Sweden)

    DANIEL B. BLAKE

    2000-07-01

    Full Text Available Noriaster barberoi gen. et. sp. n. is based on a single specimen from the Calcare di Zorzino (Norian, Triassic of northern Italy. A member of the surviving Poraniidae (Valvatida; Echinodermata, N. barberoi is the oldest-known species assignable to a Jurassic and younger family and the first such species known from the Triassic. No Paleozoic species with close affinities with crown-group families has been recognized. Noriaster and the slightly older Triassic genus Trichasteropsis from the Muschelkalk of Germany together indicate that the diversification of crown-group asteroids was well underway at least by Middle and Late Triassic time. Phylogeny of crown-group asteroids is problematic because extant familial-level taxa are morphologically divergent, and they exhibit comparatively few uncontested characters that clearly indicate phylogenetic affinities and sequence. Familial assignment of Noriaster is supported by a new cladistic analysis. To the student of living asteroids, the appearance of a living Noriaster would be remarkable only because it would seem so commonplace. To the extent that form correlates with function, Noriaster suggests that modern asteroid life modes emerged quite promptly during the Mesozoic asteroid diversification. 

  14. Triggers of Permo-Triassic boundary mass extinction in South China: The Siberian Traps or Paleo-Tethys ignimbrite flare-up?

    Science.gov (United States)

    He, Bin; Zhong, Yu-Ting; Xu, Yi-Gang; Li, Xian-Hua

    2014-09-01

    Assessment of the synchroneity between the Siberian Traps and the Permo-Triassic boundary (PTB) mass extinction has led to the proposition that the Siberian flood volcanism was responsible for the severest biotic crisis in the Phanerozoic. However, recent studies suggest that the Siberian Traps may have postdated the main extinction horizon. In this paper, we demonstrate, using stratigraphy, a time and intensity coincidence between PTB volcanic ash and the main extinction horizon. Geochemistry of the PTB volcanic ashes in five sections in South China indicates that they were derived from continental magmatic arc. Zircons extracted from the PTB volcanic ashes have negative εHf(t) (- 12.9 to - 2.0) and δ18O (6.8 to 10.9‰), consistent with an acidic volcanism and a crustal-derived origin, and therefore exclude a genetic link between the PTB mass extinction and the Siberian Traps. On the basis of spatial variation in the number of the PTB volcanic ash layers and the thickness of the ash layers in South China, we propose that the PTB volcanic ash may be related to Paleo-Tethys continental arc magmatism in the Kunlun area. Ignimbrite flare-up related to rapid plate subduction during the final assemblage of the Pangea super-continent may have generated a volcanic winter, which eventually triggered the collapse of ecosystem and ultimately mass extinction at the end of the Permian. The Siberian Traps may have been responsible for a greenhouse effect and so have been responsible for both a second pulse of the extinction event and Early Triassic ecological evolution.

  15. The beginning of the Buntsandstein cycle (Early-Middle Triassic) in the Catalan Ranges, NE Spain: Sedimentary and palaeogeographic implications

    Science.gov (United States)

    Galán-Abellán, Belén; López-Gómez, José; Barrenechea, José F.; Marzo, Mariano; De la Horra, Raúl; Arche, Alfredo

    2013-10-01

    The Early-Middle Triassic siliciclastic deposits of the Catalan Ranges, NE Spain, are dominated by aeolian sediments indicating a predominance of arid climate during this time span, in sharp contrast with the coeval fluvial sediments found in the Castilian Branch of the Iberian Ranges, 300 km to the SW. The NE-SW-oriented Catalan Basin evolved during the Middle-Late Permian as the result of widespread extension in the Iberian plate. This rift basin was bounded by the Pyrenees, Ebro and Montalbán-Oropesa highs. The Permian-Early Triassic-age sediments of the Catalan Basin were deposited in three isolated subbasins (Montseny, Garraf, Prades), separated by intrabasinal highs, but linked by transversal NW-SE oriented faults. The three subbasins show evidence of diachronic evolution with different subsidence rates and differences in their sedimentary records. The Buntsandstein sedimentary cycle started in the late Early Triassic (Smithian-Spathian) in the central and southern domains (Garraf and Prades), with conglomerates of alluvial fan origin followed by fluvial and aeolian sandstones. Source area of the fluvial sediments was nearby Paleozoic highs to the north and west, in contrast with the far-away source areas of the fluvial sediments in the Iberian Ranges, to the SW. These fluvial systems were interacting with migrating aeolian dune fields located towards the S, which developed in the shadow areas behind the barriers formed by the Paleozoic highs. These highs were separating the subbasins under arid and semi-arid climate conditions. The dominating winds came from the east where the westernmost coast of the Tethys Sea was located, and periods of water run-off and fields of aeolian dunes development alternated. Some of the fluvial systems were probably evaporating as they were mixed into the interdune areas, never reaching the sea. From the end of the Smithian to the Spathian, the Catalan Basin and neighbour peri-Tethys basins of the present-day southern France

  16. A carapace-like bony 'body tube' in an early triassic marine reptile and the onset of marine tetrapod predation.

    Directory of Open Access Journals (Sweden)

    Xiao-hong Chen

    Full Text Available Parahupehsuchus longus is a new species of marine reptile from the Lower Triassic of Yuan'an County, Hubei Province, China. It is unique among vertebrates for having a body wall that is completely surrounded by a bony tube, about 50 cm long and 6.5 cm deep, comprising overlapping ribs and gastralia. This tube and bony ossicles on the back are best interpreted as anti-predatory features, suggesting that there was predation pressure upon marine tetrapods in the Early Triassic. There is at least one sauropterygian that is sufficiently large to feed on Parahupehsuchus in the Nanzhang-Yuan'an fauna, together with six more species of potential prey marine reptiles with various degrees of body protection. Modern predators of marine tetrapods belong to the highest trophic levels in the marine ecosystem but such predators did not always exist through geologic time. The indication of marine-tetrapod feeding in the Nanzhang-Yuan'an fauna suggests that such a trophic level emerged for the first time in the Early Triassic. The recovery from the end-Permian extinction probably proceeded faster than traditionally thought for marine predators. Parahupehsuchus has superficially turtle-like features, namely expanded ribs without intercostal space, very short transverse processes, and a dorsal outgrowth from the neural spine. However, these features are structurally different from their turtle counterparts. Phylogeny suggests that they are convergent with the condition in turtles, which has a fundamentally different body plan that involves the folding of the body wall. Expanded ribs without intercostal space evolved at least twice and probably even more among reptiles.

  17. Boreal earliest Triassic biotas elucidate globally depauperate hard substrate communities after the end-Permian mass extinction

    Science.gov (United States)

    Zatoń, Michał; Niedźwiedzki, Grzegorz; Blom, Henning; Kear, Benjamin P.

    2016-11-01

    The end-Permian mass extinction constituted the most devastating biotic crisis of the Phanerozoic. Its aftermath was characterized by harsh marine conditions incorporating volcanically induced oceanic warming, widespread anoxia and acidification. Bio-productivity accordingly experienced marked fluctuations. In particular, low palaeolatitude hard substrate communities from shallow seas fringing Western Pangaea and the Tethyan Realm were extremely impoverished, being dominated by monogeneric colonies of filter-feeding microconchid tubeworms. Here we present the first equivalent field data for Boreal hard substrate assemblages from the earliest Triassic (Induan) of East Greenland. This region bordered a discrete bio-realm situated at mid-high palaeolatitude (>30°N). Nevertheless, hard substrate biotas were compositionally identical to those from elsewhere, with microconchids encrusting Claraia bivalves and algal buildups on the sea floor. Biostratigraphical correlation further shows that Boreal microconchids underwent progressive tube modification and unique taxic diversification concordant with changing habitats over time. We interpret this as a post-extinction recovery and adaptive radiation sequence that mirrored coeval subequatorial faunas, and thus confirms hard substrate ecosystem depletion as a hallmark of the earliest Triassic interval globally.

  18. Sedimentology and ichnology of two Lower Triassic sections in South China: Implications for the biotic recovery following the end-Permian mass extinction

    Science.gov (United States)

    Luo, Mao; George, Annette D.; Chen, Zhong-Qiang

    2016-09-01

    Biotic recovery following the end-Permian mass extinction was investigated using trace fossil and facies analysis of two Lower-Middle Triassic sections in South China. The Susong section (Lower Yangtze Sedimentary Province) comprises a range of carbonate and mudstone facies that record overall shallowing from offshore to intertidal settings. The Tianshengqiao section (Upper Yangtze Sedimentary Province) consists of mixed carbonate and siliciclastic facies deposited in shallow marine to offshore settings. Griesbachian to Dienerian ichnological records in both sections are characterized by low ichnodiversity, low ichnofabric indices (1-2) and low bedding plane bioturbation indices (1-2). Higher ichnofabric indices (3 and 4), corresponding to a dense population of diminutive ichnotaxon, in the Tianshengqiao section suggest opportunistic infaunal biotic activity during the earliest Triassic. Ichnological data from the Susong section show an increase in ichnodiversity during the late Smithian with 11 ichnogenera identified and increased ichnofabric indices of 4-5 and bedding plane bioturbation indices of 3-5. Although complex traces such as Rhizocorallium are present in Spathian-aged strata in this section, low ichnodiversity and ichnofabric indices and diminutive Planolites suggest a decline in recovery. In the Tianshengqiao section, ichnofabric indices are moderate to high (3-5) although only six ichnogenera are present and Planolites burrows are consistently small in Smithian and Spathian strata. Complex traces, such as large Rhizocorallium and Thalassinoides, and large Planolites, did not appear until the Anisian. Ichnological results from both sections record the response of organisms to unfavourable environmental conditions although the Susong section shows earlier recovery during the Smithian prior to latest Smithian-Spathian decline. This decline may have resulted from a resurgence of euxinic to anoxic marine environment in various regions of South China

  19. Sedimentary-volcanic tuffs formed during the early Middle Triassic volcanic event in Guizhou Province and their stratigraphic significance

    Institute of Scientific and Technical Information of China (English)

    XIAO Jiafei; HU Ruizhong

    2005-01-01

    The sedimentary-volcanic tuff (locally called "green-bean rock") formed during the early Middle Triassic volcanic event in Guizhou Province is characterized as being thin, stable, widespread, short in forming time and predominantly green in color. The green-bean rock is a perfect indicator for stratigraphic division. Its petrographic and geochemical features are unique, and it is composed mainly of glassy fragments and subordinately of crystal fragments and volcanic ash balls. Analysis of the major and trace elements and rare-earth elements (REE), as well as the related diagrams, permits us to believe that the green-bean rock is acidic volcanic material of the calc-alkaline series formed in the Indosinian orogenic belt on the Sino-Vietnam border, which was atmospherically transported to the tectonically stable areas and then deposited as sedimentary-volcanic rocks there. According to the age of green-bean rock, it is deduced that the boundary age of the Middle-Lower Triassic overlain by the sedimentary-volcanic tuff is about 247 Ma.

  20. Osteology of Pseudochampsa ischigualastensis gen. et comb. nov. (Archosauriformes: Proterochampsidae) from the early late triassic ischigualasto formation of Northwestern Argentina.

    Science.gov (United States)

    Trotteyn, M Jimena; Ezcurra, Martín D

    2014-01-01

    Proterochampsids are crocodile-like, probably semi-aquatic, quadrupedal archosauriforms characterized by an elongated and dorsoventrally low skull. The group is endemic from the Middle-Late Triassic of South America. The most recently erected proterochampsid species is "Chanaresuchus ischigualastensis", based on a single, fairly complete skeleton from the early Late Triassic Ischigualasto Formation of northwestern Argentina. We describe here in detail the non-braincase cranial and postcranial anatomy of this species and revisit its taxonomy and phylogenetic relationships. The phylogenetic analysis recovered 'Chanaresuchus ischigualastensis' as part of a trichotomy together with Gualosuchus reigi and Chanaresuchus bonapartei. Accordingly, "Chanaresuchus ischigualastensis" can be potentially more closely related to Gualosuchus reigi, or even Rhadinosuchus gracilis, than to Chanaresuchus bonapartei. In addition, after discussing previously claimed synapomorphies of Chanaresuchus, we could not find unambiguous support for the monophyly of the genus. As a result, we propose here the erection of the new genus Pseudochampsa for 'Chanaresuchus ischigualastensis', which results in the new combination Pseudochampsa ischigualastensis. The information provided here about the anatomy and taxonomy of Pseudochampsa ischiguaslastensis will be useful for future quantitative analyses focused on the biogeography and macroevolutionary history of proterochampsids.

  1. Osteology of Pseudochampsa ischigualastensis gen. et comb. nov. (Archosauriformes: Proterochampsidae from the early late triassic ischigualasto formation of Northwestern Argentina.

    Directory of Open Access Journals (Sweden)

    M Jimena Trotteyn

    Full Text Available Proterochampsids are crocodile-like, probably semi-aquatic, quadrupedal archosauriforms characterized by an elongated and dorsoventrally low skull. The group is endemic from the Middle-Late Triassic of South America. The most recently erected proterochampsid species is "Chanaresuchus ischigualastensis", based on a single, fairly complete skeleton from the early Late Triassic Ischigualasto Formation of northwestern Argentina. We describe here in detail the non-braincase cranial and postcranial anatomy of this species and revisit its taxonomy and phylogenetic relationships. The phylogenetic analysis recovered 'Chanaresuchus ischigualastensis' as part of a trichotomy together with Gualosuchus reigi and Chanaresuchus bonapartei. Accordingly, "Chanaresuchus ischigualastensis" can be potentially more closely related to Gualosuchus reigi, or even Rhadinosuchus gracilis, than to Chanaresuchus bonapartei. In addition, after discussing previously claimed synapomorphies of Chanaresuchus, we could not find unambiguous support for the monophyly of the genus. As a result, we propose here the erection of the new genus Pseudochampsa for 'Chanaresuchus ischigualastensis', which results in the new combination Pseudochampsa ischigualastensis. The information provided here about the anatomy and taxonomy of Pseudochampsa ischiguaslastensis will be useful for future quantitative analyses focused on the biogeography and macroevolutionary history of proterochampsids.

  2. An early Late Triassic long-necked reptile with a bony pectoral shield and gracile appendages

    Directory of Open Access Journals (Sweden)

    Jerzy Dzik

    2016-12-01

    Full Text Available Several partially articulated specimens and numerous isolated bones of Ozimek volans gen. et sp. nov., from the late Carnian lacustrine deposits exposed at Krasiejów in southern Poland, enable a reconstruction of most of the skeleton. The unique character of the animal is its enlarged plate-like coracoids presumably fused with sterna. Other aspects of the skeleton seem to be comparable to those of the only known specimen of Sharovipteryx mirabilis from the latest Middle Triassic of Kyrgyzstan, which supports interpretation of both forms as protorosaurians. One may expect that the pectoral girdle of S. mirabilis, probably covered by the rock matrix in its only specimen, was similar to that of O. volans gen. et sp. nov. The Krasiejów material shows sharp teeth, low crescent scapula, three sacrals in a generalized pelvis (two of the sacrals being in contact with the ilium and curved robust metatarsal of the fifth digit in the pes, which are unknown in Sharovipteryx. Other traits are plesiomorphic and, except for the pelvic girdle and extreme elongation of appendages, do not allow to identify any close connection of the sharovipterygids within the Triassic protorosaurians.

  3. Evolution of strontium isotopic composition of sea-water from Late Permian to Early Triassic based on study of marine carbonates,Zhongliang Mountain,Chongqing,China

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    Collected from a Late Permian to Early Triassic sedimentary section in the Zhongliang Mountain of Chongqing, Southwest China, sixty marine carbonate samples were measured for the 87Sr/86Sr ratios, and corresponding evolution curve was constructed. The concentrations of SiO2, CaO, MgO, Mn and Sr are used to evaluate reservation of strontium isotopic composition for original seawater and the credi-bility of the dissolution method for sample preparation. The results show that most of the samples (except seven samples with the Mn/Sr ratios higher than 2) contain the original geochemistry signa-tures of ancient seawater. Compared to the published 87Sr/86Sr ratios from the Late Permian to Early Triassic, our database reported here is the largest and the curve constructed is the most complete. The strontium isotopic curve from Late Permian to Early Triassic is consistent globally and exhibits a gen-eral trend of steady increase during this period. The minimum of 87Sr/86Sr ratios (0.707011) occurs in the Late Permian (30 m in thickness below the Permian-Triassic boundary), and the maximum (0.708281), near the Early-Middle Triassic boundary. The lack of land plants and the rapid continental weathering result in the increase of 87Sr/86Sr ratios during the interval. The Permian-Triassic boundary in Zhongli-ang Mountain Section has been accepted internationally. The 87Sr/86Sr ratios of six samples near the boundary vary from 0.70714 to 0.70715 with an average of 0.70714, which is consistent with the value of 0.70715 (samples are from articulate brachiopod shells) from Korte et al. published in 2006 (within the error range in experiment). Accordingly, the strontium isotope composition in the Permian-Triassic boundary in this paper is of global significance. It can be confirmed that the 87Sr/86Sr ratios of the sea-water in the Permian-Triassic transition are in the range of 0.70714―0.70715.

  4. Preliminary study on Late Triassic to Early Jurassic strata and floral variation in Hechuan region of Chongqing,southern Sichuan Basin

    Institute of Scientific and Technical Information of China (English)

    Ning TIAN; Yongdong WANG; Xiaoju YANG; Qing NI; Zikun JIANG

    2008-01-01

    The end-Triassic mass extinction event is extensively known, however, the terrestrial response of this event is still poorly understood. Here we briefly report our preliminary results on the variation of floral diversity through the Triassic/Jurassic boundary deposits in the Tanba section of Hechuan region, Chongqing, southern China. It is recognized that the floral biodiversity of the Hechuan region shows a distinct change through the Triassic and Jurassic transition; and the floral diversity loss reaches up to 92 5% at species level. Meanwhile, in northeastern region of the Sichuan Basin, the floral diversity declines by about 50% across the T/J boundary at species level with a remarkable turnover of genera and species. The potential reasons and mechanisms that cause the floral diversity differentiation of the T/J boundary in the Sichuan Basin are briefly discussed in this note.

  5. A basal sauropodomorph (Dinosauria: Saurischia from the Ischigualasto Formation (Triassic, Carnian and the early evolution of Sauropodomorpha.

    Directory of Open Access Journals (Sweden)

    Ricardo N Martinez

    Full Text Available BACKGROUND: The earliest dinosaurs are from the early Late Triassic (Carnian of South America. By the Carnian the main clades Saurischia and Ornithischia were already established, and the presence of the most primitive known sauropodomorph Saturnalia suggests also that Saurischia had already diverged into Theropoda and Sauropodomorpha. Knowledge of Carnian sauropodomorphs has been restricted to this single species. METHODOLOGY/PRINCIPAL FINDINGS: We describe a new small sauropodomorph dinosaur from the Ischigualsto Formation (Carnian in northwest Argentina, Panphagia protos gen. et sp. nov., on the basis of a partial skeleton. The genus and species are characterized by an anteroposteriorly elongated fossa on the base of the anteroventral process of the nasal; wide lateral flange on the quadrate with a large foramen; deep groove on the lateral surface of the lower jaw surrounded by prominent dorsal and ventral ridges; bifurcated posteroventral process of the dentary; long retroarticular process transversally wider than the articular area for the quadrate; oval scars on the lateral surface of the posterior border of the centra of cervical vertebrae; distinct prominences on the neural arc of the anterior cervical vertebra; distal end of the scapular blade nearly three times wider than the neck; scapular blade with an expanded posterodistal corner; and medial lamina of brevis fossa twice as wide as the iliac spine. CONCLUSIONS/SIGNIFICANCE: We regard Panphagia as the most basal sauropodomorph, which shares the following apomorphies with Saturnalia and more derived sauropodomorphs: basally constricted crowns; lanceolate crowns; teeth of the anterior quarter of the dentary higher than the others; and short posterolateral flange of distal tibia. The presence of Panphagia at the base of the early Carnian Ischigualasto Formation suggests an earlier origin of Sauropodomorpha during the Middle Triassic.

  6. Cyclostratigraphy of the Induan (Early Triassic) in West Pingdingshan Section, Chaohu, Anhui Province

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    The Induan sequence in the West Pingdingshan Section, Chaohu, Anhui Province, displays a series of superimposed mudstone/limestone cycles. The lithological character of the cycles, combined with power spectral and wavelet analysis of magnetic susceptibility readings, reveals 12 short eccentricity and 56 precession Milankovitch cycles - obliquity cycles are not apparent. The uniformity of cycle thicknesses indicates a stable depositional setting making this section ideal to perform various geological studies. Accordingly, the Induan Stage is estimated to have lasted 1.1 Ma, and the depositional rate for this part of the section is about 3.7 cm/ka. This places the Induan-Olenekian boundary in the West Pingdingshan Section at about 251.5 Ma based on an age of 252.6 Ma for the Permian-Triassic boundary.

  7. Cyclostratigraphy of the Induan (Early Triassic) in West Pingdingshan Section,Chaohu,Anhui Province

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    The Induan sequence in the West Pingdingshan Section, Chaohu, Anhui Province, displays a series of superimposed mudstone/limestone cycles. The lithological character of the cycles, combined with power spectral and wavelet analysis of magnetic susceptibility readings, reveals 12 short eccentricity and 56 precession Milankovitch cycles - obliquity cycles are not apparent. The uniformity of cycle thicknesses indicates a stable depositional setting making this section ideal to perform various geo-logical studies. Accordingly, the Induan Stage is estimated to have lasted 1.1 Ma, and the depositional rate for this part of the section is about 3.7 cm/ka. This places the Induan-Olenekian boundary in the West Pingdingshan Section at about 251.5 Ma based on an age of 252.6 Ma for the Permian-Triassic boundary.

  8. Compound-specific carbon isotopes from Earth's largest flood basalt eruptions directly linked to the end-Triassic mass extinction.

    Science.gov (United States)

    Whiteside, Jessica H; Olsen, Paul E; Eglinton, Timothy; Brookfield, Michael E; Sambrotto, Raymond N

    2010-04-13

    A leading hypothesis explaining Phanerozoic mass extinctions and associated carbon isotopic anomalies is the emission of greenhouse, other gases, and aerosols caused by eruptions of continental flood basalt provinces. However, the necessary serial relationship between these eruptions, isotopic excursions, and extinctions has never been tested in geological sections preserving all three records. The end-Triassic extinction (ETE) at 201.4 Ma is among the largest of these extinctions and is tied to a large negative carbon isotope excursion, reflecting perturbations of the carbon cycle including a transient increase in CO(2). The cause of the ETE has been inferred to be the eruption of the giant Central Atlantic magmatic province (CAMP). Here, we show that carbon isotopes of leaf wax derived lipids (n-alkanes), wood, and total organic carbon from two orbitally paced lacustrine sections interbedded with the CAMP in eastern North America show similar excursions to those seen in the mostly marine St. Audrie's Bay section in England. Based on these results, the ETE began synchronously in marine and terrestrial environments slightly before the oldest basalts in eastern North America but simultaneous with the eruption of the oldest flows in Morocco, a CO(2) super greenhouse, and marine biocalcification crisis. Because the temporal relationship between CAMP eruptions, mass extinction, and the carbon isotopic excursions are shown in the same place, this is the strongest case for a volcanic cause of a mass extinction to date.

  9. Organic geochemical characterization of the Lower-Middle Triassic sedimentary rocks from south China

    Science.gov (United States)

    Saito, R.

    2015-12-01

    The most devastated environments and depleted biodiversity on Earth occurred during the Early Triassic epoch following the latest Permian mass extinction. Complete biotic recovery, characterized by a return to pre-extinction diversity levels, took an extraordinarily long time (ca. 5 x 106 yr), probably because harsh conditions developed repeatedly during the Early Triassic. Newly obtained organic geochemistry data from south China area, indicated a variety of biotic (eukaryotic algae, cyanobacteria, bacteria, and archaea) and environmental fluctuations (redox) during the Early Triassic. Remarkably, some sedimentary rocks from Lower Triassic strata contain rare biomarkers such as biphytanes and okenane, whch are biomarkers for archaea and purple sulfur bacteria, respectively. This is the first study to describe in detail primary producers, microbes, and redox conditions in the Early-Early Middle Triassic, on the basis of biomarkers such as steranes, 2-methyl hopanes, hopanes, biphytanes, regular isoprenoids, n-alkanes, okenane, chlorobactane, β-carotane, and γ-carotane. The results greatly not only increase our understanding of the recovery processes that occurred following the Permian mass extinction, but also emphasize an effectiveness of organic geochemistry against the Early Triassic.

  10. The Early Triassic magmatism of the Alto Paraguay Province, Central South America: Paleomagnetic and ASM data

    Science.gov (United States)

    Ernesto, Marcia; Comin-Chiaramonti, Piero; Gomes, Celso de Barros

    2015-10-01

    A paleomagnetic studystudywork was carried out on the Alto Paraguay Province (APP), a belt of alkaline complexes that parallel the Paraguay river for more than 40 km at the border of Brazil and Paraguay. The province is well dated by 40Ar/39Ar method giving ages in the range 240-250 Ma with a preferred age of 241 Ma. Intrusive rocks are predominant but the stocks may be topped by lava flows and ignimbrites. Paleomagnetic work on stocks, dikes and flows of the APP identified normal and reversed magnetic components which are carried mainly by titanomagnetites. The calculated paleomagnetic pole located at 319ºE 78ºS (α95 = 6º; k = 23) is in agreement with other South American poles of Permo-Triassic age. Most of the sampling sites showed large variations in rock magnetization, but similar patterns in the variation of the within-site magnetizations, mainly in dikes, suggest geomagnetic polarity transition records. The magnetization data along with the anisotropy of magnetic susceptibility determinations suggested that the South and North areas of the province have different evolution characteristics.

  11. Role of degassing of the Noril'sk nickel deposits in the Permian-Triassic mass extinction event.

    Science.gov (United States)

    Le Vaillant, Margaux; Barnes, Stephen J; Mungall, James E; Mungall, Emma L

    2017-03-07

    The largest mass extinction event in Earth's history marks the boundary between the Permian and Triassic Periods at circa 252 Ma and has been linked with the eruption of the basaltic Siberian Traps large igneous province (SLIP). One of the kill mechanisms that has been suggested is a biogenic methane burst triggered by the release of vast amounts of nickel into the atmosphere. A proposed Ni source lies within the huge Noril'sk nickel ore deposits, which formed in magmatic conduits widely believed to have fed the eruption of the SLIP basalts. However, nickel is a nonvolatile element, assumed to be largely sequestered at depth in dense sulfide liquids that formed the orebodies, preventing its release into the atmosphere and oceans. Flotation of sulfide liquid droplets by surface attachment to gas bubbles has been suggested as a mechanism to overcome this problem and allow introduction of Ni into the atmosphere during eruption of the SLIP lavas. Here we use 2D and 3D X-ray imagery on Noril'sk nickel sulfide, combined with simple thermodynamic models, to show that the Noril'sk ores were degassing while they were forming. Consequent "bubble riding" by sulfide droplets, followed by degassing of the shallow, sulfide-saturated, and exceptionally volatile and Cl-rich SLIP lavas, permitted a massive release of nickel-rich volcanic gas and subsequent global dispersal of nickel released from this gas as aerosol particles.

  12. Two New Cynodonts (Therapsida) from the Middle-Early Late Triassic of Brazil and Comments on South American Probainognathians

    Science.gov (United States)

    Soares, Marina Bento; Schwanke, Cibele

    2016-01-01

    We describe two new cynodonts from the early Late Triassic of southern Brazil. One taxon, Bonacynodon schultzi gen. et sp. nov., comes from the lower Carnian Dinodontosaurus AZ, being correlated with the faunal association at the upper half of the lower member of the Chañares Formation (Ischigualasto-Villa Unión Basin, Argentina). Phylogenetically, Bonacynodon is a closer relative to Probainognathus jenseni than to any other probainognathian, bearing conspicuous canines with a denticulate distal margin. The other new taxon is Santacruzgnathus abdalai gen. et sp. nov. from the Carnian Santacruzodon AZ. Although based exclusively on a partial lower jaw, it represents a probainognathian close to Prozostrodon from the Hyperodapedon AZ and to Brasilodon, Brasilitherium and Botucaraitherium from the Riograndia AZ. The two new cynodonts and the phylogenetic hypothesis presented herein indicate the degree to which our knowledge on probainognathian cynodonts is incomplete and also the relevance of the South American fossil record for understanding their evolutionary significance. The taxonomic diversity and abundance of probainognathians from Brazil and Argentina will form the basis of deep and complex studies to address the evolutionary transformations of cynodonts leading to mammals. PMID:27706191

  13. Two New Cynodonts (Therapsida) from the Middle-Early Late Triassic of Brazil and Comments on South American Probainognathians.

    Science.gov (United States)

    Martinelli, Agustín G; Soares, Marina Bento; Schwanke, Cibele

    2016-01-01

    We describe two new cynodonts from the early Late Triassic of southern Brazil. One taxon, Bonacynodon schultzi gen. et sp. nov., comes from the lower Carnian Dinodontosaurus AZ, being correlated with the faunal association at the upper half of the lower member of the Chañares Formation (Ischigualasto-Villa Unión Basin, Argentina). Phylogenetically, Bonacynodon is a closer relative to Probainognathus jenseni than to any other probainognathian, bearing conspicuous canines with a denticulate distal margin. The other new taxon is Santacruzgnathus abdalai gen. et sp. nov. from the Carnian Santacruzodon AZ. Although based exclusively on a partial lower jaw, it represents a probainognathian close to Prozostrodon from the Hyperodapedon AZ and to Brasilodon, Brasilitherium and Botucaraitherium from the Riograndia AZ. The two new cynodonts and the phylogenetic hypothesis presented herein indicate the degree to which our knowledge on probainognathian cynodonts is incomplete and also the relevance of the South American fossil record for understanding their evolutionary significance. The taxonomic diversity and abundance of probainognathians from Brazil and Argentina will form the basis of deep and complex studies to address the evolutionary transformations of cynodonts leading to mammals.

  14. Shallow marine ecosystem feedback to the Permian/Triassic mass extinction

    Institute of Scientific and Technical Information of China (English)

    Yongbiao WANG; Zheng MENG; Wei LIAO; Zeting WENG; Hao YANG

    2011-01-01

    Late Permian reefs developed widely on shallow marine carbonate platforms in South China but disappeared far below the main mass extinction level of the latest Permian. The collapse of reef ecosystem may be related to the enhanced volcanism at the end of Late Permian. Notably, some colony corals and reef-building sponges were found to occur near the mass extinction boundary, inferring the eclipse of reef ecosystem is ahead of the disappearance of reef-building organisms, and the triggers would be present long before the main mass extinction. As the primary producers, the calcareous algae are rich in platform limestones of Late Permian and played a very important role in maintaining the shallow benthic ecosystems. The calcareous algae were found to disappear synchronously with the great reduction of foraminifers,which were ecologically associated with these algae. The extinction of Late Permian calcareous algae greatly reduced the biodiversity of primary producers in the shallow marine environment and destroyed in part the structure and the base of the shallow marine ecosystems,which in turn cause the extinction of ecologically associated metazoan. Microbialites developed on carbonate platforms immediately after the end-Permian mass extinction, representing a simple and unique microbial ecosystem. Widespread occurrence of microbialites symbolized the deterioration of marine environmental conditions and the dramatic revolution of marine ecosystems. As the new primary producers instead of the extinguished calcareous algae, cyanobacteria in the microbialites were an important base of this peculiar ecosystem and contributed greatly to the survival of the remnant faunas after the mass extinction. Widespread occurrence of microbialites in shallow marine environment is suggested to be related to the elevated level of volcanism-induced greenhouse gases and enhanced evaporation and hypersaline condition in addition to the decrease of metazoan grazing pressure. The change

  15. Taphonomy of Early Triassic fish fossils of the Vega-Phroso Siltstone Member of the Sulphur Mountain Formation near Wapiti Lake, British Columbia, Canada

    Directory of Open Access Journals (Sweden)

    Karen Anderson

    2013-10-01

    Full Text Available The taphonomy of fishes living in lacustrine environments has been extensively studied in both the laboratory and the fossil record; the taphonomy of marine fishes, however, is poorly known. Triassic marine fishes with heavy ganoid and cosmoid scales, which provided protection from rapid taphonomic loss, offer a means to examine marine fish taphonomy in the fossil record. Four genera of Early Triassic fishes (the ray-finned actinopterygians Albertonia, Bobasatrania, Boreosomus, and the lobe-finned coelacanth (sarcopterygian, Whiteia from the Wapiti Lake, British Columbia locality of the Lower Triassic Sulphur Mountain Formation were examined in order to gain a better understanding of the taphonomy of fish in marine environments, determine ambient environmental conditions in the region during the Early Triassic, and ascertain the habitat and mode of life of the fish. Results indicate that environmental conditions that contributed to the preservation of the fossil fishes of the current study included deposition in deep, quiet waters, which reduced the odds of disarticulation, colder waters under higher pressure, which slowed decay and limited postmortem floatation, and waters that were anoxic, which discouraged predators and scavengers. In addition, the thickness of the primitive ganoid and cosmoid scales of the fossil fishes also increased their preservation potential. Taphonomic, physiological and environmental indicators suggest that Whiteia, Albertonia, and possibly Bobasatrania lived in deep, cold waters near the oxygen minimum zone, while Boreosomus lived higher in the water column. While the anatomical and physiological characteristics of modern fishes will likely continue to inhibit marine taphonomy studies, examination of ancient fish, particularly those with ganoid or cosmoid scales, may provide future avenues of research to gain a better understanding of marine fish taphonomy and provide a powerful tool to examine ancient fish behavior

  16. A Re-Examination of the Bedout High, Offshore Canning Basin, Western Australia - Possible Impact Site for the Permian-Triassic Mass Extinction Event?

    Science.gov (United States)

    Becker, L.; Nicholson, C.; Poreda, R. J.

    2002-12-01

    The Bedout High, located offshore Canning basin in Western Australia, is an unusual structure and its origin remains problematic. K-Ar dating of volcanic samples encountered at total depth in the Lagrange-1 exploration well indicated an age of about 253+/-5 Ma consistent with the Permian-Triassic boundary event. Gorter (PESA News, pp. 33-34, 1996) speculates that the Bedout High is the uplifted core (30 km) of a circular feature, some 220 km across, formed by the impact of a large bolide (cometary or asteroidal) with the Earth near the end-Permian. Accepting a possible impact origin for the Bedout structure, with the indicated dimensions, would have had profound effects on global climate as well as significant changes in lithotratigraphic, biostratigraphic and chemostratigraphic indicators as seen in several Permian-Triassic boundary locations worldwide. In this work, we re-examine some of the structural data previously presented by Gorter (1996) using some additional seismic lines. We have also evaluated several impact tracers including iridium, shocked quartz, productivity collapse, helium-3, chromium-53 and fullerenes with trapped noble gases from some Permian-Triassic boundary sites in the Tethys and Circum-Pacific regions. Our findings suggest that the Bedout structure is a good candidate for an oceanic impact at the end Permian, triggering the most severe mass extinction in the history of life on Earth.

  17. Lithofacies palaeogeography and sedimentology Beef and cone-in-cone calcite fibrous cements associated with the end-Permian and end-Triassic mass extinctions:Reassessment of processes of formation

    Institute of Scientific and Technical Information of China (English)

    Stephen Kershaw; Li Guo

    2016-01-01

    This paper reassesses published interpretation that beef and cone-in-cone (B-CIC) fibrous calcite cements were precipitated contemporaneously just below the sea floor in uncon-solidated sediment, in limestones associated with the end-Permian (P/T) and end-Triassic (T/J) mass extinctions. That interpretation introduced the concept of a sub-seafloor car-bonate factory associated with ocean acidification by raised carbon dioxide driven by volcanic eruption, coinciding with mass extinction. However, our new fieldwork and petrographic analysis, with literature comparison, reveals several problems with this concept. Two key points based on evidence in the T/J transition of the UK are:(1) that B-CIC calcite deposits form thin scattered layers and lenses at several horizons, not a distinct deposit associated with volcanic activity; and (2) B-CIC calcite is more common in Early Jurassic sediments after the extinction and after the end of the Central Atlantic Magmatic Province volcanism proposed to have supplied the carbon dioxide required. Our samples from Late Triassic, Early Jurassic and Early Cretaceous limestones in southern UK show that B-CIC calcite occurs in both marine and non-marine sediments, therefore ocean processes are not mandatory for its formation. There is no proof that fibrous calcite was formed before lithification, but our Early Jurassic samples do prove fibrous calcite formed after compaction, thus interpretation of crystal growth in uncon-solidated sediment is problematic. Furthermore, B-CIC crystals mostly grew both upwards and downwards equally, contradicting the interpretation of the novel carbonate factory that they grew preferentially upwards in soft sediment. Finally, Early Jurassic and Early Cretaceous examples are not associated with mass extinction. Three further key points derived from the literature include: (1) B-CIC calcite is wide-spread geographically and stratigraphically, not clustered around mass extinctions or the Paleocene

  18. Late Olenekian Radiolarians from Bedded Chert of Ashio Terrane, Northeast Japan,and Faunal Turnovers in Western Panthalassa during Early Triassic

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    Late Olenekian assemblages in the western Panthalassa have been recovered from bedded radiolarian chert sequences of an accretionary complex, the Ashio belt. These faunas are documented and considered in terms of radiolarian diversity and faunal turnover during the latest Permian to Middle Triassic time. The fauna includes 30 radiolarians belonging to Spumellaria or Entactinaria, with two relicts from the Late Permian. This late Olenekian fauna is markedly different from Permian and Anisian faunas, respectively, and is herein named the Minowa fauna. Study of the literature indicates that radiolarian provinces were significantly disconnected between the western Panthalassa and eastern Tethys during late Olenekian time. Furthermore, 121 of 143 species disappeared during late Olenekian time, and in turn 118 new species appeared in the western Panthalassa around the Olenekian-Anisian boundary. It is concluded that faunal turnover occurred at least three times between the latest Permian and Middle Triassic. The first turnover is the Paleozoic-type radiolarian extinction at the Permian-Triassic boundary, the second is the diversification of spheroidal Spumellaria and Entactinaria between early and late Olenekian time, and the third is a faunal turnover from the Minowa fauna to the true Mesozoic-type radiolarian faunas that are characterized by multi-segmented Nassellaria.

  19. High precision dating of mass extinction events: a combined zircon geochronology, apatite tephrochronology, and Bayesian age modelling approach of the Permian-Triassic boundary extinction

    Science.gov (United States)

    Baresel, Björn; Bucher, Hugo; Brosse, Morgane; Bagherpour, Borhan; Schaltegger, Urs

    2016-04-01

    Chemical abrasion isotope dilution thermal ionization mass spectrometry (CA-ID-TIMS) U-Pb dating of single-zircon crystals is preferably applied to tephra beds intercalated in sedimentary sequences. By assuming that the zircon crystallization age closely approximate that of the volcanic eruption and ash deposition, U-Pb zircon geochronology is the preferred approach for dating mass extinction events (such as the Permian-Triassic boundary mass extinction) in the sedimentary record. As tephra from large volcanic eruptions is often transported over long distances, it additionally provide an invaluable tool for stratigraphic correlation across distant geologic sections. Therefore, the combination of high-precision zircon geochronology with apatite chemistry of the same tephra bed (so called apatite tephrochronology) provides a robust fingerprint of one particular volcanic eruption. In addition we provide coherent Bayesian model ages for the Permian-Triassic boundary (PTB) mass extinction, then compare it with PTB model ages at Meishan after Burgess et al. (2014). We will present new high-precision U-Pb zircon dates for a series of volcanic ash beds in deep- and shallow-marine Permian-Triassic sections in the Nanpanjiang Basin, South China. In addition, apatite crystals out of the same ash beds were analysed focusing on their halogen (F, Cl) and trace-element (e.g. Fe, Mg, REE) chemistry. We also show that Bayesian age models produce reproducible results from different geologic sections. On the basis of these data, including litho- and biostratigraphic correlations, we can precisely and accurately constrain the Permian-Triassic boundary in an equatorial marine setting, and correlate tephra beds over different sections and facies in the Nanpanjiang Basin independently from litho-, bio- or chemostratigraphic criteria. The results evidence that data produced in laboratories associated to the global EARTHTIME consortium can provide age information at the 0.05% level of 206

  20. Palaeoclimatic conditions in the Late Triassic-Early Jurassic of southern Africa: A geochemical assessment of the Elliot Formation

    Science.gov (United States)

    Sciscio, Lara; Bordy, Emese M.

    2016-07-01

    The Triassic-Jurassic boundary marks a global faunal turnover event that is generally considered as the third largest of five major biological crises in the Phanerozoic geological record of Earth. Determining the controlling factors of this event and their relative contributions to the biotic turnover associated with it is on-going globally. The Upper Triassic and Lower Jurassic rock record of southern Africa presents a unique opportunity for better constraining how and why the biosphere was affected at this time not only because the succession is richly fossiliferous, but also because it contains important palaeoenvironmental clues. Using mainly sedimentary geochemical proxies (i.e., major, trace and rare earth elements), our study is the first quantitative assessment of the palaeoclimatic conditions during the deposition of the Elliot Formation, a continental red bed succession that straddles the Triassic-Jurassic boundary in southern Africa. Employing clay mineralogy as well as the indices of chemical alteration and compositional variability, our results confirm earlier qualitative sedimentological studies and indicate that the deposition of the Upper Triassic and Lower Jurassic Elliot Formation occurred under increasingly dry environmental conditions that inhibited chemical weathering in this southern part of Pangea. Moreover, the study questions the universal validity of those studies that suggest a sudden increase in humidity for the Lower Jurassic record and supports predictions of long-term global warming after continental flood basalt emplacement.

  1. Record of Permian-Early Triassic continental arc magmatism in the western margin of the Jiamusi Block, NE China: petrogenesis and implications for Paleo-Pacific subduction

    Science.gov (United States)

    Yang, Hao; Ge, Wenchun; Dong, Yu; Bi, Junhui; Wang, Zhihui; Ji, Zheng; Yang, H.; Ge, W. C.; Dong, Y.; Bi, J. H.; Wang, Z. H.; Ji, Z.

    2016-09-01

    In this paper, we report zircon U-Pb ages, Hf isotopes and whole-rock geochemical data for the Permian to Early Triassic granitoids from the western margin of the Jiamusi Block (WJB), NE China. The intermediate to felsic (SiO2 = 59.67-74.04 wt%) granitoids belong to calc-alkaline series and are characterized by enrichments in light rare earth elements and large ion lithophile elements with pronounced negative Nb, Ta and Ti anomalies, revealing typical continental magmatic arc geochemical signatures. The zircon U-Pb determinations on the granodiorite, monzogranite, syenogranite and quartz diorite samples yielded ages between ca. 275-245 Ma, which, together with the published coeval intrusive rocks, indicates that Permian to Early Triassic continental arc magmatism occurred extensively in the WJB. The low and mainly negative zircon ɛ Hf(t) values between -7.6 and +1.6 and the zircon Hf model ages of 1.2-1.8 Ga, which are significantly older than their crystallization ages, suggest that they were mainly derived from reworking of ancient crustal materials with a limited input of juvenile components. The geochemical systematics and petrogenetic considerations indicate that the studied granitoids were generated from a zone of melting, assimilation, storage, and homogenization, i.e., a MASHed zone at the base of Paleo- to Mesoproterozoic continental crust, where large portions of igneous rocks and minor clay-poor sediments involved in the source region. In combination with regional geological data, we argue that the Jiamusi Block was unlikely the rifted segment of the Songliao Block and two possible geodynamical models were proposed to interpret the formation of the ca. 275-245 Ma granitoids in the WJB. In the context of Permian global plate reconstruction, we suggest that Paleo-Pacific plate subduction was initiated in the Permian to Early Triassic beneath the Jiamusi Block, and even whole eastern NE China.

  2. Support for an “A-type” Pangea reconstruction from high-fidelity Late Permian and Early to Middle Triassic paleomagnetic data from Argentina

    Science.gov (United States)

    Domeier, Mathew; van der Voo, Rob; Tomezzoli, Renata N.; Tohver, Eric; Hendriks, Bart W. H.; Torsvik, Trond H.; Vizan, Haroldo; Dominguez, Ada

    2011-12-01

    A major disparity is observed between the late Paleozoic-early Mesozoic apparent polar wander paths (APWPs) of Laurussia and Gondwana when the landmasses are re-assembled in a conventional "A-type" Pangea. This discrepancy has endured from the earliest paleomagnetic reconstructions of the supercontinent, and has prompted discussions of non-dipole paleomagnetic fields and alternative paleogeographic models. Here we report on a joint paleomagnetic-geochronologic study of Late Permian and Early to Middle Triassic volcanic and volcaniclastic rocks from Argentina, which demonstrates support for an A-type model, without requiring modification to the geocentric axial dipole hypothesis. New SHRIMP U-Pb and 40Ar-39Ar isotopic dating has reinforced the inferred age of the sequences, which we estimate at ˜264 Ma (Upper Choiyoi Group) and ˜245 Ma (Puesto Viejo Group). Field-stability tests demonstrate that the volcanic rocks are carrying early/primary magnetizations, which yield paleopoles: 73.7°S, 315.6°E, A95: 4.1°, N: 40 (Upper Choiyoi) and 76.7°S, 312.4°E, A95: 7.3°, N: 14 (Puesto Viejo). A comprehensive magnetic fabric analysis is used to evaluate structural restorations and to correct for magnetization anisotropy. The paleomagnetic results derived from volcaniclastic rocks are interpreted to be affected by inclination shallowing, and corrections are discussed. A comparison of these new results with the existing Permian-Triassic paleomagnetic data from Gondwana suggests the presence of widespread bias in the latter. We contend that such bias can explain the observed APWP disparity, at least for Late Permian-Middle Triassic time, and that alternative paleogeographic reconstructions or non-dipole paleomagnetic fields do not need to be invoked to resolve the discrepancy.

  3. Permian-Triassic Conodonts from Dajiang (Guizhou, South China) and Their Implication for the Age of Microbialite Deposition in the Aftermath of the End-Permian Mass Extinction

    Institute of Scientific and Technical Information of China (English)

    Haishui Jiang; Xulong Lai; Yadong Sun; Paul B Wignall; Jianbo Liu; Chunbo Yan

    2014-01-01

    The widespread microbialites deposition that followed the End-Permian mass extinction in the Tethyan realm have been intensively studied because of the evidence they provide on the nature of this crisis and its aftermath. However, the age of the microbialite event remains controversial. New conodont collection across the Permian-Triassic (P-T) transition from Dajiang (Guizhou Province, South China) in this study enable us to discriminate four conodont zones, in ascending order, they are:Hindeodus parvus zone, Isarcicella lobata zone, Isarcicella isarcica zone and Hindeodus sosioensis zone. The age of microbialite in the P-T transition at the Dajiang Section is considered to be within the Hindeodus parvus zone and thus to clearly post-date the main extinction crisis. Reviewing the age of onset of microbialites throughout the Tethyan regions reveals two different ages: a Hindeodus changxingensis zone age is dominant in south-western and westernmost Tethys, whilst most other re-gions show microbialite deposition began in the Hindeodus parvus zone. Our investigation also indicates that two conodont changes occur at this time:an increase of hindeodid species immediately following a sequence boundary and the mass extinction, and a phase of extinction losses in the earliest Triassic Isarcicella isarcica zone during highstand development.

  4. Current Status of the Late Triassic and Early Jurassic APTS from Continental Sediments and Correlation with Standard Marine Stages

    Science.gov (United States)

    Kent, D. V.; Olsen, P. E.; Muttoni, G.

    2014-12-01

    A reproducible geomagnetic polarity template for the Late Triassic and earliest Jurassic continues to be that determined from ~5,000 meters of cored section in the Newark basin and ~2,500 meters of outcrop section in the Hartford basin, sampled at nominal ~20 kyr intervals according to a well-developed climate cyclicity that characterizes the lacustrine strata present in all but the fluviatile portions of the basins [Kent & Olsen, 1999, 2008 JGR]. The age model is based on the 405 kyr Milankovich climate cycle and pegging the sequence to high precision U-Pb dating of the Central Atlantic Magmatic Province (CAMP) at 201.6 to 200.9 Ma [Blackburn+2013 Science], the initiation of which is practically coincident with the end-Triassic extinction level (formerly set to 202 Ma) and within a climatic precession cycle after magnetochron E23r. The resulting astrochronostratigraphic polarity time scale (APTS) has 66 Poisson-distributed polarity intervals from chrons E8r (~225 Ma) to H27n (~199 Ma) with a constant sediment-accumulation rate extrapolation to chron E1r (~233 Ma). Magnetostratigraphic correlations from the most complete and usually the thickest Tethyan marine sections suggest that the Carnian/Norian boundary occurs within ~E7n [Channell+2003 PPP; Muttoni+2004 GSAB] at an APTS age of 227.5 Ma and for the Norian/Rhaetian boundary anywhere from E16n [Husing+2011 EPSL] at ~210.5 Ma to E20r [Maron+2014 Geology] at ~205.4 Ma depending on choice of conodont taxa, whereas the Hettangian/Sinemurian boundary can be placed at ~199.5 Ma within the marine equivalent of H25r [Husing+2014 EPSL]. These APTS ages are in substantive agreement with available high-precision dates in marine strata for the late Carnian [231 Ma: Furin+2006 Geology], latest Norian [205.5 Ma: Wotslaw+2014 Geology], and the boundaries of the Triassic/Jurassic [201.3 Ma: Guex+2012 PPP] and the Hettangian/Sinemurian [199.5 Ma: Schaltegger+2008 EPSL]. Carnian magnetostratigraphy needs to be improved but

  5. Permian-Triassic Osteichthyes (bony fishes): diversity dynamics and body size evolution.

    Science.gov (United States)

    Romano, Carlo; Koot, Martha B; Kogan, Ilja; Brayard, Arnaud; Minikh, Alla V; Brinkmann, Winand; Bucher, Hugo; Kriwet, Jürgen

    2016-02-01

    The Permian and Triassic were key time intervals in the history of life on Earth. Both periods are marked by a series of biotic crises including the most catastrophic of such events, the end-Permian mass extinction, which eventually led to a major turnover from typical Palaeozoic faunas and floras to those that are emblematic for the Mesozoic and Cenozoic. Here we review patterns in Permian-Triassic bony fishes, a group whose evolutionary dynamics are understudied. Based on data from primary literature, we analyse changes in their taxonomic diversity and body size (as a proxy for trophic position) and explore their response to Permian-Triassic events. Diversity and body size are investigated separately for different groups of Osteichthyes (Dipnoi, Actinistia, 'Palaeopterygii', 'Subholostei', Holostei, Teleosteomorpha), within the marine and freshwater realms and on a global scale (total diversity) as well as across palaeolatitudinal belts. Diversity is also measured for different palaeogeographical provinces. Our results suggest a general trend from low osteichthyan diversity in the Permian to higher levels in the Triassic. Diversity dynamics in the Permian are marked by a decline in freshwater taxa during the Cisuralian. An extinction event during the end-Guadalupian crisis is not evident from our data, but 'palaeopterygians' experienced a significant body size increase across the Guadalupian-Lopingian boundary and these fishes upheld their position as large, top predators from the Late Permian to the Late Triassic. Elevated turnover rates are documented at the Permian-Triassic boundary, and two distinct diversification events are noted in the wake of this biotic crisis, a first one during the Early Triassic (dipnoans, actinistians, 'palaeopterygians', 'subholosteans') and a second one during the Middle Triassic ('subholosteans', neopterygians). The origination of new, small taxa predominantly among these groups during the Middle Triassic event caused a

  6. Remnants of a Late Triassic ocean island in the Gufeng area, northern Tibet: Implications for the opening and early evolution of the Bangong-Nujiang Tethyan Ocean

    Science.gov (United States)

    Fan, Jian-Jun; Li, Cai; Wang, Ming; Liu, Yi-Ming; Xie, Chao-Ming

    2017-03-01

    In this paper we present new major and trace element compositions of basaltic rocks in the Gufeng ocean island (GFOI) area in the western segment of the Bangong-Nujiang Suture Zone, northern Tibet. Our aim was to assess the genesis of these rocks and discuss the implications of this new dataset for the evolution of the Bangong-Nujiang Tethyan Ocean. An ocean-island-type double-layer structure comprising a basaltic basement and an oceanic sedimentary cover sequence found within the GFOI provides direct evidence for the interpretation that the assemblage is a typical ocean island. The basalts in the GFOI can be divided into three types (named G1, G2 and G3 basalts), and these basalts range in composition from MORB to OIB types, which is typical of ocean islands. The G1 basalts have MORB-type affinities, possibly indicating the existence of MORB oceanic crust under the GFOI. The G2 basalts represent the early stage of formation of the GFOI, and are produced by the interaction of rising OIB-type basaltic magma and the existing MORB oceanic crust. The G3 basalts are typical OIB basalts and they are the products of the direct eruption of OIB-type basaltic magmas. The G3 basalts have high (La/Yb)N (12.3-14.4), (Ce/Yb)N (10.8-11.8), (La/Sm)N (2.39-2.76), and (Sm/Yb)N (4.89-5.23) ratios, indicating the presence of oceanic lithosphere below the GFOI with a thickness of 50-60 km. Geochemical analyses of the GFOI cherts show that they contain terrigenous material, indicating the GFOI formed close to a continental margin. Norian conodont fossils within the GFOI limestones indicate the GFOI formed during the Late Triassic. These data, combined with geological evidence and a half-space model of lithosphere cooling, where the thickness of the oceanic lithosphere is determined from the age of the lithosphere, indicate that the western segment of the Bangong-Nujiang Tethyan Ocean opened initially in the late Permian, expanded rapidly during the Early-Middle Triassic, and was a

  7. Ostracod fauna across the Permian-Triassic boundary at Chongyang, Hubei Province, and its implication for the process of the mass extinction

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    Thirty species of 10 ostracod genera were identified from 440 fossil specimens isolated through the hot acetolysis of the rock samples collected across the Permian-Triassic boundary at Chongyang section. Twenty species of 6 genera are found to occur in the limestone of Changxing Formation, and 11 species of 7 genera above the main faunal mass extinction horizon. The os-tracod assemblages identified at the Chongyang section are obviously different from those previously reported in the contem-poraneous microbialites in Guangxi and Chongqing regions, not only in the ostracod components but also in the abundance of filter-feeding ostracods relative to the deposit-feeding ostracods, an indicator of the oxygen level of the seawater. This spatial difference in ostracod assemblages might reflect the diversity of oceanic environmental conditions after the end-Permian mass extinction. Ostracods disappear at 200 cm below and near the main mass extinction horizon, and on the top of the microbialites, respectively, showing an episodic and gradual collapse process at the Chongyang section. The carbon isotope composition is found to appear at 200 cm below the main mass extinction horizon, indicating the initial deterioration of oceanic environment. Fluctuation of the carbon isotope composition is obviously related with the episodic evolution of ostracod species, but not with the abundance of ostracods.

  8. Comparison of mantle lithosphere beneath early Triassic kimberlite fields in Siberian craton reconstructed from deep-seated xenocrysts

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    I.V. Ashchepkov

    2016-07-01

    Kharamai mantle clinopyroxenes represent three geochemical types: (1 harzburgitic with inclined linear REE, HFSE troughs and elevated Th, U; (2 lherzolitic or pyroxenitic with round TRE patterns and decreasing incompatible elements; (3 eclogitic with Eu troughs, Pb peak and high LILE content. Calculated parental melts for garnets with humped REE patterns suggest dissolution of former Cpx and depression means Cpx and garnets extraction. Clinopyroxenes from Ary-Mastakh fields show less inclined REE patterns with HMREE troughs and an increase of incompatible elements. Clinopyroxenes from Kuranakh field show flatter spoon-like REE patterns and peaks in Ba, U, Pb and Sr, similar to those in ophiolitic harzburgites. The PT diagrams for the mantle sections show high temperature gradients in the uppermost SCLM accompanied by an increase of P-Fe#Ol upward and slightly reduced thickness of the mantle keel of the Siberian craton, resulting from the influence of the Permian–Triassic superplume, but with no signs of delamination.

  9. Compound-specific carbon isotopes from Earth’s largest flood basalt eruptions directly linked to the end-Triassic mass extinction

    Science.gov (United States)

    Whiteside, Jessica H.; Olsen, Paul E.; Eglinton, Timothy; Brookfield, Michael E.; Sambrotto, Raymond N.

    2010-01-01

    A leading hypothesis explaining Phanerozoic mass extinctions and associated carbon isotopic anomalies is the emission of greenhouse, other gases, and aerosols caused by eruptions of continental flood basalt provinces. However, the necessary serial relationship between these eruptions, isotopic excursions, and extinctions has never been tested in geological sections preserving all three records. The end-Triassic extinction (ETE) at 201.4 Ma is among the largest of these extinctions and is tied to a large negative carbon isotope excursion, reflecting perturbations of the carbon cycle including a transient increase in CO2. The cause of the ETE has been inferred to be the eruption of the giant Central Atlantic magmatic province (CAMP). Here, we show that carbon isotopes of leaf wax derived lipids (n-alkanes), wood, and total organic carbon from two orbitally paced lacustrine sections interbedded with the CAMP in eastern North America show similar excursions to those seen in the mostly marine St. Audrie’s Bay section in England. Based on these results, the ETE began synchronously in marine and terrestrial environments slightly before the oldest basalts in eastern North America but simultaneous with the eruption of the oldest flows in Morocco, a CO2 super greenhouse, and marine biocalcification crisis. Because the temporal relationship between CAMP eruptions, mass extinction, and the carbon isotopic excursions are shown in the same place, this is the strongest case for a volcanic cause of a mass extinction to date. PMID:20308590

  10. Petrography and geochemistry of the Permian-Triassic boundary interval, Yangou section, South China: Implications for early Griesbachian seawater δ13CDIC gradient with depth

    Science.gov (United States)

    Li, Rong

    2017-04-01

    The carbon isotopic composition (δ13Ccarb) recorded in shelf carbonates has been widely used as a proxy for the isotopic composition (δ13CDIC) of surface ocean water to establish paleocean chemistry and circulation patterns. However, δ13Ccarb values do not necessarily preserve the δ13CDIC, due to post-depositional diagenetic alteration. In order to examine the early Griesbachian surface-to-deep δ13CDIC gradient with depth, the diagenetic features of the Permian-Triassic boundary interval (beds 18 to 35) from Yangou section, located in the Yangtze carbonate platform interior, South China, are delineated to compare with those of the slope GSSP Meishan section. The petrographic and geochemical observations show that the early Griesbachian carbonates in the Yangou section underwent pervasive dolomitization in its early diagenetic history. Three types of early replacement dolomites and one type of dolomite cement are present. The dolomite crystals display internal zonation, with high-Ca calcian dolomite (HCD) core being encased successively by calcite and an outermost Fe-rich HCD cortex. The initial dolomitization took place in anoxic seawater, and underwent subsequent diagenetic system involved with meteoric water. The two most negative δ13C values in claystones of Beds 21-3 and 35 are probably related to meteoric diagenesis. Above and/or below the meteorically influenced beds, the dolomite and calcite have uniformly positive δ13C values. The primary carbon isotopic compositions are probably preserved in the early Griesbachian carbonate from the platform Yangou section, which could probably be related to the poor formation of the outermost Fe-rich HCD cortex. Compared to the slope carbonate from the Meishan section, the platform carbonate from the Yangou section has lower primary δ13Ccarb values. It is estimated that the δ13CDIC gradient with depth between Yangou and Meishan is less than the previously suggested. The results highlight the need for evaluation

  11. Petrogenesis of Middle-Late Triassic volcanic rocks from the Gangdese belt, southern Lhasa terrane: Implications for early subduction of Neo-Tethyan oceanic lithosphere

    Science.gov (United States)

    Wang, Chao; Ding, Lin; Zhang, Li-Yun; Kapp, Paul; Pullen, Alex; Yue, Ya-Hui

    2016-10-01

    The Gangdese belt is dominantly composed of igneous rocks that formed during the northward subduction of Neo-Tethyan oceanic lithosphere beneath the Lhasa terrane and has played a crucial role in understanding the pre-collisional evolution of southern Tibet. This paper presents new geochronological and geochemical (whole-rock major and trace element and Sr-Nd and zircon Hf isotope) data for recently identified volcanic rocks exposed in Changguo area, southernmost part of the Lhasa terrane. Zircon U-Pb dating from six samples yields consistent ages of 237.1 ± 1.1 Ma to 211.7 ± 1.5 Ma for magma emplacement through volcanic eruption, showing the Middle-Late Triassic magmatic activity in the southernmost Gangdese Belt. The Changguo volcanic rocks are mainly composed of basaltic and andesitic rocks and exhibit LILE enrichment and HFSE depletion. They also exhibit relatively uniform Nd-Hf isotopic compositions (εNd(t) = + 5.20 to + 7.74 and εHf(t)zircon = + 10.2 to + 15.9). The basaltic magmas were likely sourced from partial melting of sub-arc mantle wedge that was metasomatized by not only the aqueous fluid derived from subducting altered oceanic crust but also hydrous melt derived from subducting seafloor sediments, and subsequently experienced fractional crystallization and juvenile crustal contamination during ascent. The andesitic magmas were generated by partial melting of mafic-ultramafic metasomes through melt/fluid-peridotite reaction at slab-mantle interface. Taking into account the temporal and spatial distribution of the Early Mesozoic magmatic rocks and regional detrital zircon data, we further propose that the northward subduction of Neo-Tethyan oceanic lithosphere beneath the Lhasa terrane commenced by Middle Triassic.

  12. Silicified wood from the Permian and Triassic of Antarctica: Tree rings from polar paleolatitudes

    Science.gov (United States)

    Ryberg, P.E.; Taylor, E.L.

    2007-01-01

    The mass extinction at the Permian-Triassic boundary produced a floral turnover in Gondwana in which Paleozoic seed ferns belonging to the Glossopteridales were replaced by corystosperm seed ferns and other seed plant groups in the Mesozoic. Secondary growth (wood production) in both plant groups provides information on plant growth in relation to environment in the form of permineralized tree rings. Techniques utilized to analyze extant wood can be used on fossil specimens to better understand the climate from both of these periods. Late Permian and early Middle Triassic tree rings from the Beardmore Glacier area indicate an environment where extensive plant growth occurred at polar latitudes (~80–85°S, Permian; ~75°S, Triassic). A rapid transition to dormancy in both the Permian and Triassic woods suggests a strong influence of the annual light/dark cycle within the Antarctic Circle on ring production. Latewood production in each ring was most likely triggered by the movement of the already low-angled sun below the horizon. The plants which produced the wood have been reconstructed as seasonally deciduous, based on structural and sedimentologic evidence. Although the Late Permian climate has been reconstructed as cold temperate and the Middle Triassic as a greenhouse, these differences are not reflected in tree ring anatomy or wood production in these plant fossils from the central Transantarctic Mountains.

  13. Timing of the terrestrial Permian-Triassic boundary biotic crisis: Implications from U-Pb dating of authigenic zircons

    Institute of Scientific and Technical Information of China (English)

    YU JianXin; LI HuiMin; ZHANG SuXin; YANG FengQing; FENG QingLai

    2008-01-01

    The Late Permian to Early Triassic transition represents one of the most important Phanerozoic mass extinction episodes.The cause of this event is still in debate between catastrophic and gradual mechanisms.This study uses the U-Pb method on zircons from the uppermost Permian/lowermost Triassic clay deposits at Chahe (Guizhou Province,SW China) to examine time constraints for this event.The results of both this and previous studies show that the ages of Bed 68a and 68c (the upper clay bed of the terrestrial Permian-Triassic boundary (PTB)) respectively are 252.6~2.8 and 247.5±2.8 Ma.This age (within the margin of error) almost accords with the upper clay bed (Bed 28) age of Meishan and the eruption age of Tunguss Basalt,and is so far the most accurate age obtained from terrestrial PTB.The claystone of Bed 68 was formed in the earliest Triassic.The biotic crisis occurred at nearly the same time in terrestrial and marine environments during Permian-Triassic interval; however the extinction patterns and processes are different.The extinction pattern of the terrestrial plants shows a major decline at the PTB after long-term evolution,followed by a retarded extinction of the relicts in the earliest Triassic.

  14. Timing of the terrestrial Permian-Triassic boundary biotic crisis:Implications from U-Pb dating of authigenic zircons

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    The Late Permian to Early Triassic transition represents one of the most important Phanerozoic mass extinction episodes. The cause of this event is still in debate between catastrophic and gradual mechanisms. This study uses the U-Pb method on zircons from the uppermost Permian/lowermost Triassic clay deposits at Chahe (Guizhou Province, SW China) to examine time constraints for this event. The results of both this and previous studies show that the ages of Bed 68a and 68c (the upper clay bed of the terrestrial Permian-Triassic boundary (PTB)) respectively are 252.6±2.8 and 247.5±2.8 Ma. This age (within the margin of error) almost accords with the upper clay bed (Bed 28) age of Meishan and the eruption age of Tunguss Basalt, and is so far the most accurate age obtained from terrestrial PTB. The claystone of Bed 68 was formed in the earliest Triassic. The biotic crisis occurred at nearly the same time in terrestrial and marine environments during Permian-Triassic interval; however the extinction patterns and processes are different. The extinction pattern of the terrestrial plants shows a major decline at the PTB after long-term evolution, followed by a retarded extinction of the relicts in the earliest Triassic.

  15. A new Lower Triassic ichthyopterygian assemblage from Fossil Hill, Nevada

    Directory of Open Access Journals (Sweden)

    Neil P. Kelley

    2016-01-01

    Full Text Available We report a new ichthyopterygian assemblage from Lower Triassic horizons of the Prida Formation at Fossil Hill in central Nevada. Although fragmentary, the specimens collected so far document a diverse fauna. One partial jaw exhibits isodont dentition with blunt tipped, mesiodistally compressed crowns and striated enamel. These features are shared with the Early Triassic genus Utatsusaurus known from coeval deposits in Japan and British Columbia. An additional specimen exhibits a different dentition characterized by relatively small, rounded posterior teeth resembling other Early Triassic ichthyopterygians, particularly Grippia. This Nevada assemblage marks a southward latitudinal extension for Early Triassic ichthyopterygians along the eastern margin of Panthalassa and indicates repeated trans-hemispheric dispersal events in Early Triassic ichthyopterygians.

  16. Early Triassic change in the erosional level in the eastern part of the Bohemian Massif revealed by detrital garnet assemblages from the Buntsandstein siliciclastics of southern Poland

    Science.gov (United States)

    Kowal-Linka, Monika; Walczak, Klaudia

    2017-04-01

    Garnets, as constituents of various magmatic and metamorphic rocks, show different chemical compositions depending on the type of magma or primary rock, the temperature, and the pressure. This diversity of chemical compositions makes detrital garnets a very useful tool for provenance analysis and deciphering changes in erosional levels of source areas. Preliminary works reveal that the Lower and Middle Buntsandstein terrigenous and marine sandstones cropping out in southern Poland (50˚ 28'20"N, 18˚ 04'33"E and 50˚ 27'35"N, 18˚ 07'23"E) are characterized by very different heavy mineral assemblages (HMA) and types of detrital garnets. The aim of the research is to recognize the source areas and causes of these distinct variations using petrographic analysis, heavy mineral analysis, and electron probe microanalysis. During the Early Triassic, the area under study was located between two landmasses: the eastern margin of the Bohemian Massif (BM) to the west and Pre-Carpathian Land (PCL) to the east. Presently, the sampled area is situated ˜50 km from the NE margin of the BM, which consists of many garnet-bearing rocks and is a presumable source area for the examined grains. The PCL was hidden under the Carpathians during the Alpine orogeny and knowledge of its composition is very limited. Petrographic analysis shows that the older sandstones are red to rusty quartz arenites with a hematite-rich matrix and well-rounded grains (aeolian deposits). The younger sandstones are bicolored quartz wackes (dirty pink with grey patches) with a calcite matrix and angular to rounded grains (shallow marine deposits). The arenites contain zircon, tourmaline, and rutile grains accompanied by garnet, staurolite, apatite, and topaz. The opaque heavy minerals include ilmenite, ilmenite-rutile aggregates, magnetite and rarely chromian spinel. In contrast, the HMA from the wackes consist mostly of garnets, while the minerals listed above occur in subordinate amounts. The garnets from

  17. Geomicrobiological perspective on the pattern and causes of the 5-million-year Permo/Triassic biotic crisis

    Institute of Scientific and Technical Information of China (English)

    Shucheng XIE; Yongbiao WANG

    2011-01-01

    The pattern and causes of Permo/Triassic biotic crisis were mainly documented by faunal and terrestrial plant records. We reviewed herein the geomicrobiological perspective on this issue based on the reported cyanobacterial record. Two episodic cyanobacterial blooms were observed to couple with carbon isotope excursions and faunal mass extinction at Meishan section, suggestive of the presence of at least two episodic biotic crises across the Permian-Triassic boundary (PTB). The two episodes of cyanobacterial blooms, carbon isotope excursions and faunal mass extinction were, respectively, identified in several sections of the world, inferring the presence of two global changes across the PTB. Close associations among the three records (cyanobacterial bloom, shift in carbon isotope composition, and faunal extinction) were subsequently observed in three intervals in the Early Triassic, the protracted recovery period as previously thought, inferring the occurrence of more episodes of global changes.Spatiotemporal association of cyanobacterial blooms with volcanic materials in South China, and probably in South-east Asia, infers their causal relationship. Volcanism is believed to trigger the biotic crisis in several ways and to cause the close association among microbial blooms, the carbon isotope excursions and faunal mass extinctions in four intervals from the latest Permian to the Early Triassic.The major episodes of the well-known Siberian flood eruption are proposed to be responsible for the extinctions in the Early Triassic, but their synchronicity with the endPermian extinction awaits more precise dating data to confirm. Geomicrobial records are thus suggestive of a long-term episodic biotic crisis (at least four episodes)lasting from the latest Permian to the end of the Early Triassic, induced by the global volcanic eruptions and sea level changes during Pangea formation.

  18. Reassessment of the evidence for postcranial skeletal pneumaticity in Triassic archosaurs, and the early evolution of the avian respiratory system.

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    Richard J Butler

    Full Text Available Uniquely among extant vertebrates, birds possess complex respiratory systems characterised by the combination of small, rigid lungs, extensive pulmonary air sacs that possess diverticula that invade (pneumatise the postcranial skeleton, unidirectional ventilation of the lungs, and efficient crosscurrent gas exchange. Crocodilians, the only other living archosaurs, also possess unidirectional lung ventilation, but lack true air sacs and postcranial skeletal pneumaticity (PSP. PSP can be used to infer the presence of avian-like pulmonary air sacs in several extinct archosaur clades (non-avian theropod dinosaurs, sauropod dinosaurs and pterosaurs. However, the evolution of respiratory systems in other archosaurs, especially in the lineage leading to crocodilians, is poorly documented. Here, we use µCT-scanning to investigate the vertebral anatomy of Triassic archosaur taxa, from both the avian and crocodilian lineages as well as non-archosaurian diapsid outgroups. Our results confirm previous suggestions that unambiguous evidence of PSP (presence of internal pneumatic cavities linked to the exterior by foramina is found only in bird-line (ornithodiran archosaurs. We propose that pulmonary air sacs were present in the common ancestor of Ornithodira and may have been subsequently lost or reduced in some members of the clade (notably in ornithischian dinosaurs. The development of these avian-like respiratory features might have been linked to inferred increases in activity levels among ornithodirans. By contrast, no crocodile-line archosaur (pseudosuchian exhibits evidence for unambiguous PSP, but many of these taxa possess the complex array of vertebral laminae and fossae that always accompany the presence of air sacs in ornithodirans. These laminae and fossae are likely homologous with those in ornithodirans, which suggests the need for further investigation of the hypothesis that a reduced, or non-invasive, system of pulmonary air sacs may be have

  19. EARLIEST TRIASSIC CONODONTS FROM CHITRAL, NORTHERNMOST PAKISTAN

    Directory of Open Access Journals (Sweden)

    MARIA CRISTINA PERRI

    2004-07-01

    Full Text Available Extensive tracts of very shallow water carbonates in the valleys of the Yarkhun and Mastuj rivers of Chitral (northernmost Pakistan previously though to be Permian (or Cretaceous are shown by conodonts from two horizons in sequences 110 km apart—near Torman Gol (Mastuj valley and near Sakirmul (upper Yarkhun valley—to include earliest Triassic (Scythian—Induan horizons. Both faunas have Isarcicella staeschei Dai & Zhang, Is. lobata Perri, Is. turgida (Kozur et al. and Hindeodus parvus (Kozur & Pjatakova, whereas Is. Isarcica (Huckriede has been recognised only in the Torman Gol occurrence. The presence, respectively, of Is. staeschei in the Sakirmul and Is. isarcica in the Torman Gol occurrences, allows discrimination of the staeschei and isarcica zones respectively the third and the fourth conodont biozones of the Early Triassic conodont biozonation of Perri (in Perri & Farabegoli 2003. Such faunas, consisting mainly of isarcicellids and hindeodids but lacking gondolellids, are characteristic of restricted sea environments across the Permian–Triassic boundary and in the earliest Triassic in other Tethyan areas. The conodont faunas from these two occurrences are remarkably similar, nearly contemporaneous, and indicate shallow water biofacies. They are inferred to equate with the Ailak Dolomite, a sequence of Late Permian–?Late Triassic dolostones discriminated farther up the Yarkhun valley and extending eastwards into the upper Hunza region of northernmost Pakistan. The Zait Limestone and Sakirmul carbonate sequence are consistent with extension of the previously inferred Triassic carbonate platform at least 110 km farther to the SW than previously supposed.

  20. Mass Extinction and Survival during the Permian-Triassic Crisis%二叠纪-三叠纪之交生物大灭绝与残存

    Institute of Scientific and Technical Information of China (English)

    宋海军; 童金南

    2016-01-01

    当今人类正在面临大气二氧化碳浓度升高、全球变暖、海洋酸化等一系列气候环境问题,有科学家提出这可能导致第6次生物大灭绝.类似的灾难事件在地质历史上多次发生,因此以史为鉴、以古示今才能更好地认识、应对和解决这些问题.显生宙最大的一次生物灭绝事件发生在2.52亿年前的二叠纪-三叠纪之交,超过90%的海洋物种永久消失.此次生物灭绝的过程和原因一直是科学家关注和致力解决的关键科学问题之一.近年来的研究表明当前人类面临的这些极端的气候环境事件在2.52亿年前也都有发生,而且更为严重.本文重点围绕近年来有关二叠纪-三叠纪之交的生物和环境事件研究进展,结合化石和环境指标的地质记录以及生物与环境之间的相互作用关系,总结生物灭绝的过程和形式及相关环境因子的贡献,并探讨残存生物能够躲过这次灾难事件得以延续和发展的内在机制和外界原因.%Today we are facing a series of climatic problems such as elevation of PCO2 ,global warming,and ocean acidification, which may lead to the sixth mass extinction.The similar extreme climate has been happened repeatedly in the Earth history. Therefore,taking history as mirror will help us to better understand the nature of these problems and resolve them.The most severe extinction happened during the Permian-Triassic transition (252 Ma),eliminating over 90% species.In the past few dec-ades,the process and cause about this extinction event have become the key scientific questions that need to be uncovered.Re-cent studies show the extreme climatic events we are facing now have been occurred near the Permian-Triassic boundary.The main purpose of this paper is to summarize recent studies on biotic and environmental events during the Permian-Triassic transi-tion,including extinction process,pattern,and causes of the extinction

  1. Peritidal carbonate cycles induced by carbonate productivity variations:A conceptual model for an isolated Early Triassic greenhouse platform in South China

    Institute of Scientific and Technical Information of China (English)

    Wan Yang; Dan JLehrmann

    2014-01-01

    Eustasy has commonly been invoked to explain peritidal carbonate cyclicity, but is dififcult to explain cycles formed in a greenhouse climate when eustasy is minimal. We propose that peritidal cycles on an Early Triassic isolated carbonate platform in Guizhou, South China, were formed by hierarchical carbonate productivity variations. Most of the 149 shallowing-upward cycles are typically terminated by lfooding over intertidal facies and con-tain rare supratidal facies and no prolonged subaerial exposure. Low-diversity benthos in the platform interior during the post-end-Permian biotic recovery were sensitive to environmental perturbations, which caused variations in benthic sediment productivity in the subtidal carbon-ate factory. The perturbations may be driven by changes in salinity and degree of eutrophica-tion, or repeated platform mini-drowning by anoxic and/or CO2-charged deep water upwelled onto the banktop. They were modulated by Milankovitch orbitally-driven climatic and oceano-graphic factors as suggested by the hierarchical stacking pattern and spectral signals of these cycles. A one-dimensional conceptual model shows that hierarchical productivity variations alone may generate hierarchical peritidal carbonate cycles under conditions of constant sub-sidence and no sea-level lfuctuation.

  2. Peritidal carbonate cycles induced by carbonate productivity variations:A conceptual model for an isolated Early Triassic greenhouse platform in South China

    Institute of Scientific and Technical Information of China (English)

    Wan; Yang; Dan; J.Lehrmann

    2014-01-01

    Eustasy has commonly been invoked to explain peritidal carbonate cyclicity,but is difficult to explain cycles formed in a greenhouse climate when eustasy is minimal.We propose that peritidal cycles on an Early Triassic isolated carbonate platform in Guizhou,South China,were formed by hierarchical carbonate productivity variations.Most of the 149 shallowing-upward cycles are typically terminated by flooding over intertidal facies and contain rare supratidal facies and no prolonged subaerial exposure.Low-diversity benthos in the platform interior during the post-end-Permian biotic recovery were sensitive to environmental perturbations,which caused variations in benthic sediment productivity in the subtidal carbonate factory.The perturbations may be driven by changes in salinity and degree of eutrophication,or repeated platform mini-drowning by anoxic and/or CO2-charged deep water upwelled onto the banktop.They were modulated by Milankovitch orbitally-driven climatic and oceanographic factors as suggested by the hierarchical stacking pattern and spectral signals of these cycles.A one-dimensional conceptual model shows that hierarchical productivity variations alone may generate hierarchical peritidal carbonate cycles under conditions of constant subsidence and no sea-level fluctuation.

  3. Integrated Record of Terrestrial Biotic Change from the Upper Triassic Chinle Formation of northern New Mexico

    Science.gov (United States)

    Irmis, R. B.; Lindström, S.; Dunlavey, M.; Whiteside, J. H.

    2010-12-01

    The Triassic Period was an interval of major biotic and environmental changes sandwiched between two major mass extinctions. During the Late Triassic (235-201.3 Ma), dinosaurs originated and diversified across Pangaea, and several major extant vertebrate groups also appeared for the first time. Unfortunately, few detailed stratigraphically-precise local-regional paleontological records exist for continental Triassic strata, which hinders any attempt to understand the tempo and mode of biotic change through the Late Triassic. We present a new stratigraphically well-constrained fossil vertebrate and palynomorph record (10-15 Ma in duration) from the upper Chinle Formation of the Chama Basin, northern New Mexico, an area that is famous for preserving one of the best records of early dinosaurs in North America. Our data indicate that vertebrate faunas were generally stable, experiencing only one identifiable species turnover event. Dinosaurs, although relatively diverse, were never abundant components of the fauna. Contemporaneous palynological records indicate that floral composition fluctuated considerably. The drought-tolerant conifer pollen Enzonalasporites and other gymnosperms such as Alisporites and Protodiploxypinus dominate most palynofloral assemblages, but there is a distinct increase in fern spore abundance near the top of the section. In combination with evidence of variability from organic carbon stable isotopes, these data indicate that the vertebrate fauna, including early dinosaurs, remained stable over millions of years despite living within a dynamic ecosystem associated with rapidly changing environmental conditions.

  4. Anachronistic facies in the Lower Triassic of South China and their implications to the ecosystems during the recovery time

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    The end-Permian mass extinction not only severely distressed the Paleozoic ecosystems but also dramatically changed the sedimentary systems, resulting in a peculiar Early Triassic ecosystem and submarine environment during the recovery time following the mass extinction. The Lower Triassic is characteristic of the wide occurrence of various distinctive sediments and related sedimentary structures, such as flatpebble conglomerates, vermicular limestone, subtidal wrinkle structures, microbialite, carbonate seafloor fans, thin-bedded limestone and zebra limestone-mudstone. These sediments were common in the Precambrian to Early Ordovician marine settings, and then they occurred only in some extreme and unusual environments with the expansion of metazoan faunas. However, the Early Triassic witnessed an "anachronistic" reappearance of some distinctive sedimentary records in normal shallow marine settings. The study of these anachronistic facies should be of great importance for the understanding of the unique ecosystem and marine environment through the great Paleozoic-Mesozoic transition. The anachronistic facies characterized by vermicular limestone have been documented in many localities in South China and occur at various horizons of the Lower Triassic. Most types of re- ported distinctive sediments over the world have been observed in the Lower Triassic of South China. This provides an excellent opportunity for understanding the Early Triassic environment and its co- evolution with the biotic recovery. Among the anachronistic facies the vermicular limestone is the most characteristic and common distinctive sediments in the Lower Triassic of South China but has received relatively few investigations. Taking it as a case study, we will detail the variation of vermicular limestone and its stratigraphic distribution in the Three Gorges area, Hubei Province. The investigation on the vermicular limestone and other distinctive sediments from the Lower Triassic of South

  5. Anachronistic facies in the Lower Triassic of South China and their implications to the ecosystems during the recovery time

    Institute of Scientific and Technical Information of China (English)

    ZHAO XiaoMing; TONG JinNan; YAO HuaZhou; ZHANG KeXin; ZQ CHEN

    2008-01-01

    The end-Permian mass extinction not only severely distressed the Paleozoic ecosystems but also dramatically changed the sedimentary systems,resulting in a peculiar Early Triassic ecosystem and submarine environment during the recovery time following the mass extinction.The Lower Triassic is characteristic of the wide occurrence of various distinctive sediments and related sedimentary structures,such as flat-pebble conglomerates,vermicular limestone,subtidal wrinkle structures,microbialite,carbonate seafloor fans,thin-bedded limestone and zebra limestone-mudstone.These sediments were common in the Precambrian to Early Ordovician marine settings,and then they occurred only in some extreme and unusual environments with the expansion of metazoan faunas.However,the Early Triassic witnessed an "anachronistic" reappearance of some distinctive sedimentary records in normal shallow marine settings.The study of these anachronistic facies should be of great importance for the understanding of the unique ecosystem and marine environment through the great Paleozoic-Mesozoic transition.The anachronistic facies characterized by vermicular limestone have been documented in many localities in South China and occur at various horizons of the Lower Triassic.Most types of reported distinctive sediments over the world have been observed in the Lower Triassic of South China.This provides an excellent opportunity for understanding the Early Triassic environment and its coevolution with the biotic recovery.Among the anachronistic facies the vermicular limestone is the most characteristic and common distinctive sediments in the Lower Triassic of South China but has Received relatively few investigations.Taking it as a case study,we will detail the variation of vermicular limestone and its stratigraphic distribution in the Three Gorges area,Hubei Province.The investigation on the vermicular limestone and other distinctive sediments from the Lower Triassic of South China further indicates

  6. The influence of climate on early and burial diagenesis of Triassic and Jurassic sandstones from the Norwegian – Danish Basin

    DEFF Research Database (Denmark)

    Weibel, Rikke; Olivarius, Mette; Kjøller, Claus

    2017-01-01

    the humid climate, kaolinite precipitated due to leaching of feldspar and mica, and the abundant organic matter caused reducing conditions, which led to other Fe-rich phases, i.e. pyrite, Fe-chlorite and siderite. The inherited early diagenetic pore fluids and mineral assemblage also affect the mineral...

  7. Rare Earth Elements of the Permian-Triassic Conodonts from Shelf Basin to Shallow Platform: Implications for Oceanic Redox Conditions immediately After the End-Permian Mass Extinction

    Science.gov (United States)

    Li, Y.; Zhao, L.; Chen, Z.; Chen, J.; Chen, Y.

    2013-12-01

    Rare-earth elements (REEs) can provide information regarding the influence of weathering fluxes and hydrothermal inputs on seawater chemistry as well as processes that fractionate REEs between solid and aqueous phases. Of these, cerium (Ce) distributions may provide information about variations in dissolved oxygen in seawater, and thus assess the redox conditions. The short residence times of REEs in seawater (~300-1,000 yr) can result in unique REE signatures in local watermasses. REE patterns preserved in biogenic apatite such as conodonts are ideal proxies for revealing original seawater chemistry. Here, we measured the REE content of in-situ, single albid crowns using laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS) in combination with an ArF (λ=193 nm) excimer laser (Lambda Physiks GeoLas 2005) and quadrupole ICP-MS (Agilent 7500a). LA-ICP-MS is ideally suited for analyzing conodonts due to its ability to measure compositional variation within single conodont elements. It has the capability to determine, with high spatial resolution, continuous compositional depth profiles through the concentric layered structure of component histologies. To evaluate paleoceanographic conditions immediately after the Permian-Triassic (P-Tr) mass extinction in various depositional settings, we sampled a nearly contemporaneous strata unit, the P-Tr boundary bed, just above the extinction horizon from six sections in South China. They represent various depositional settings from shelf basin (Chaohu and Daxiakou sections), lower part of ramp (Meishan section), normal shallow platform (Yangou section), and platform microbialite (Chongyang and Xiushui sections). The sampled unit is constrained by conodonts Hindeodus changxingensis, H. parvus, and H. staeschei Zones in Meishan. REE results obtained from conodont albid crowns show that the seawater in lower ramp and shelf basin settings contains much higher REE concentrations than that in shallow platform. Ce

  8. The influence of climate on early and burial diagenesis of Triassic and Jurassic sandstones from the Norwegian – Danish Basin

    DEFF Research Database (Denmark)

    Weibel, Rikke; Olivarius, Mette; Kjøller, Claus

    2017-01-01

    to the Gassum Formation, which was characterized by quartz and more stable heavy minerals. The arid to semi-arid climate led to early oxidising conditions under which abundant iron-oxide/hydroxide coatings formed, while the evaporative processes occasionally resulted in caliche and gypsum precipitation. Under...... and geochemical study complemented by porosity and permeability measurements of cores widely distributed in the basin (1700 – 5900 m burial depth). The Skagerrak Formation had an immature composition with more abundant feldspar, rock fragments and a larger variability in the heavy mineral assemblage when compared...... the humid climate, kaolinite precipitated due to leaching of feldspar and mica, and the abundant organic matter caused reducing conditions, which led to other Fe-rich phases, i.e. pyrite, Fe-chlorite and siderite. The inherited early diagenetic pore fluids and mineral assemblage also affect the mineral...

  9. A Triassic Archosaur Preying in the Ocean

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    @@ The Archosaurian is an extinct reptile group that gave rise to very diverse lines in evolution, including dinosaurs, pterosaurs and crocodiles. Its early members, traditionally called "thecodonts," flourished all over the globe during the Triassic period, and have long been considered terrestrial (including freshwater) predators.

  10. Tempestite of Early Triassic Feixianguan Formation in Shangsi Section,Guanyuan: Are they extreme climatic event under megamonsoon system?%广元上寺剖面下三叠统飞仙关组风暴岩:巨型季风体制下的极端气候事件?

    Institute of Scientific and Technical Information of China (English)

    曾德勇; 时志强; 张华; 安红艳; 张慧娟

    2011-01-01

    surface structure. Storm tear structures included messy mud gravel, torn sutureline breccia and truncated structure amongst lays. Bedding structures included hummocky cross bedding, graded bedding,blocky bedding ,homogeneous bedding and parallel bedding. According to sedimentary structures and lithology, three kinds of sequence of Sa-Sb-Sc, Sb-Sd, Sa-Sc-Sd( Sa-stranded gravel deposition, Sb-graded bedding, Sc-hummocky cross-stratification, Sd-homogeneous bedding) were recognized. The storm deposits occurred in the shallow sea and the formation, development and characteristics of the tempestites have important significance on paleoclimate research. We think that tempstite in Shangsi (and even whole Upper-Yangtze region) was controlled likely by the strong monsoon system (Megamonsoon) in Early Triassic, and the P/T boundary mass extinction event let tempestite be preserved below the setting that organism burrows were few.

  11. Interpretation of "fungal spikes" in Permian-Triassic boundary sections

    Science.gov (United States)

    Hochuli, Peter A.

    2016-09-01

    Abundant occurrences of the palynomorph Reduviasporonites have been described as ;fungal spike; from several Permian/Triassic boundary sections and related to the supposed destruction of woody vegetation by fungal pathogens during the Permian/Triassic extinction event. The biological affinity of this taxa considered by some authors of fungal origin is still controversially discussed since there is geochemical evidence that it is most probably related to algae. The abundance peak of this species is used by some authors as a stratigraphic marker, notably in terrestrial Permian/Triassic boundary sections from South China. Illustrations of the reported fungal remains however show potentially erroneous taxonomic identification of Reduviasporonites, and, based on differences in thermal maturation, they may represent recent contamination. Here Reduviasporonites chalastus of Early Triassic age is illustrated together with recent fungal remains originating from a strongly weathered and otherwise barren sample from a Middle Triassic section.

  12. Post-Triassic para-autochthoneity of the Yukon-Tanana Terrane: paleomagnetism of the Early Cretaceous Quiet Lake batholith

    Science.gov (United States)

    Symons, D. T. A.; McCausland, P. J. A.; Kawasaki, K.; Hart, C. J. R.

    2015-10-01

    Was the Yukon-Tanana Terrane (YTT), a California-sized part of south-central Yukon, an autochthonous or para-autochthonous part of northern British Columbia in the Early Cretaceous or was it part of a proposed allochthonous `Baja B.C.' continent offshore of southern California? To answer this fundamental question, a paleomagnetic study has been completed on 347 specimens from 24 sites in the 114.7 ± 1.1 Ma Quiet Lake batholith. This 1300 km2 pluton is composed mostly of massive medium-to-coarse grained biotite quartz monzonite that exhibits no evidence of either deformation or metamorphism, and that intrudes metamorphosed pre-Cretaceous basement rocks of the YTT in southern Yukon. The paleomagnetic analysis utilized thermal and alternating field step demagnetization, and saturation isothermal remanence methods. A well-defined characteristic remanent magnetization (ChRM) direction was isolated throughout the 500-585 °C temperature range at Decl. = 340.6°, Incl. = 77.4° (N = 14 sites, k = 51.2, A95 = 5.6°). The ChRM resides in magnetite with a low titanium content and is interpreted to be a primary thermoremanent magnetization. After correction for 490 km of geologically demonstrable dextral displacement on the inboard Tintina fault zone, the Quiet Lake batholith's paleopole is not significantly different at 95 per cent confidence from the co-eval 115 Ma reference paleopole for North America, giving non-significant translation and rotation estimates of 1.4° ± 5.1° (1σ) northwestwards and 10° ± 13° (1σ) clockwise, respectively. Thus, this is the first Early Cretaceous paleopole to show clearly that the YTT in Yukon is a para-autochthon that was part of North America's continental margin at that time. Further, after correction for Tintina fault displacement, the eight available Mesozoic YTT paleopoles agree closely with the North American apparent polar wander path (APWP). In contrast, the 22 paleopoles from the Intermontane Belt show the expected

  13. Eccentricity and obliquity paced carbon cycling in the Early Triassic and implications for post-extinction ecosystem recovery

    Science.gov (United States)

    Fu, Wanlu; Jiang, Da-Yong; Montañez, Isabel P.; Meyers, Stephen R.; Motani, Ryosuke; Tintori, Andrea

    2016-06-01

    The timing of marine ecosystem recovery following the End Permian Mass Extinction (EPME) remains poorly constrained given the lack of radiometric ages. Here we develop a high-resolution carbonate carbon isotope (δ13Ccarb) record for 3.20 million years of the Olenekian in South China that defines the astronomical time-scale for the critical interval of major evolutionary and oceanic events in the Spathian. δ13Ccarb documents eccentricity modulation of carbon cycling through the period and a strong obliquity signal. A shift in phasing between short and long eccentricity modulation, and amplification of obliquity, is nearly coincident with a 2% decrease in seawater δ13CDIC, the last of a longer-term stepped decrease through the Spathian. The mid-Spathian shift in seawater δ13CDIC to typical thermocline values is interpreted to record a major oceanic reorganization with global climate amelioration. Coincidence of the phasing shift with the first occurrence of marine reptiles (248.81 Ma), suggests that their invasion into the sea and the onset of a complex ecosystem were facilitated by restoration of deep ocean ventilation linked mechanistically to a change in the response of the oceanic carbon reservoir to astronomical forcing. Together these records place the first constraints on the duration of the post-extinction recovery to 3.35 myr.

  14. Importance of carbon isotopic data of the Permian-Triassic boundary layers in the Verkhoyansk region for the global correlation of the basal Triassic layer

    Science.gov (United States)

    Zakharov, Yu. D.; Biakov, A. S.; Richoz, S.; Horacek, M.

    2015-01-01

    This paper is dedicated to a global correlation of marine Permian-Triassic boundary layers on the basis of partially published and original data on the δ13Corg and δ13Ccarb values of the Suol section (Setorym River, South Verkhoyansk region). The section consists of six carbon isotopic intervals, which are easily distinguishable in the carbon isotopic curves for a series of Permian-Triassic reference sections of Eurasia and Northern America, including paleontologically described sections of Central Iran, Kashmir, and Southern China. This suggests that the Permian-Triassic boundary in the Suol section is close to the carbon isotopic minimum of interval IV. In light of new data, we suggest considering the upper part of the Late Permian Changhsingian Stage and the lower substage of the Early Triassic Induan Stage of Siberia in the volumes of the rank Otoceras concavum zone and the Tompophiceras pascoei and Wordieoceras decipiens zones, respectively. The O. concavum zone of the Verkhoyansk region probably corresponds to the Late Changhsingian Hypophiceras triviale zone of Greenland. The carbon isotopic intervals II, III, IV, and V in the Permian-Triassic boundary layers of the Verkhoyansk region traced in a series of the reference sections of Eurasia correspond, most likely, to intensification of volcanic activity at the end of the Late Changhsingian and to the first massive eruptions of Siberian traps at the end of the Changhsingian and the beginning of the Induan Stages. New data indicate the possible survival of ammonoids of the Otoceratoidea superfamily at the species level after mass extinction of organisms at the end of the Permian.

  15. The early Cretaceous orogen-scale Dabieshan metamorphic core complex: implications for extensional collapse of the Triassic HP-UHP orogenic belt in east-central China

    Science.gov (United States)

    Ji, Wenbin; Lin, Wei; Faure, Michel; Shi, Yonghong; Wang, Qingchen

    2016-03-01

    The Dabieshan massif is famous as a portion of the world's largest HP-UHP metamorphic belt in east-central China that was built by the Triassic North-South China collision. The central domain of the Dabieshan massif is occupied by a huge migmatite-cored dome [i.e., the central Dabieshan dome (CDD)]. Origin of this domal structure remains controversial. Synthesizing previous and our new structural and geochronological data, we define the Cretaceous Dabieshan as an orogen-scale metamorphic core complex (MCC) with a multistage history. Onset of lithospheric extension in the Dabieshan area occurred as early as the commencement of crustal anatexis at the earliest Cretaceous (ca. 145 Ma), which was followed by primary (early-stage) detachment during 142-130 Ma. The central Dabieshan complex in the footwall and surrounding detachment faults recorded a consistently top-to-the-NW shearing. It is thus inferred that the primary detachment was initiated from a flat-lying detachment zone at the middle crust level. Removal of the orogenic root by delamination at ca. 130 Ma came into the extensional climax, and subsequently isostatic rebound resulted in rapid doming. Along with exhumation of the footwall, the mid-crustal detachment zone had been warped as shear zones around the CDD. After 120 Ma, the detachment system probably experienced a migration accommodated to the crustal adjustment, which led to secondary (late-stage) detachment with localized ductile shearing at ca. 110 Ma. The migmatite-gneiss with HP/UHP relicts in the CDD (i.e., the central Dabieshan complex) was product of the Cretaceous crustal anatexis that consumed the deep-seated part of the HP-UHP slices and the underlying para-autochthonous basement. Compared with the contemporaneous MCCs widely developed along the eastern margin of the Eurasian continent, we proposed that occurrence of the Dabieshan MCC shares the same tectonic setting as the "destruction of the North China craton". However, geodynamic trigger

  16. The early Cretaceous orogen-scale Dabieshan metamorphic core complex: implications for extensional collapse of the Triassic HP-UHP orogenic belt in east-central China

    Science.gov (United States)

    Ji, Wenbin; Lin, Wei; Faure, Michel; Shi, Yonghong; Wang, Qingchen

    2017-06-01

    The Dabieshan massif is famous as a portion of the world's largest HP-UHP metamorphic belt in east-central China that was built by the Triassic North-South China collision. The central domain of the Dabieshan massif is occupied by a huge migmatite-cored dome [i.e., the central Dabieshan dome (CDD)]. Origin of this domal structure remains controversial. Synthesizing previous and our new structural and geochronological data, we define the Cretaceous Dabieshan as an orogen-scale metamorphic core complex (MCC) with a multistage history. Onset of lithospheric extension in the Dabieshan area occurred as early as the commencement of crustal anatexis at the earliest Cretaceous (ca. 145 Ma), which was followed by primary (early-stage) detachment during 142-130 Ma. The central Dabieshan complex in the footwall and surrounding detachment faults recorded a consistently top-to-the-NW shearing. It is thus inferred that the primary detachment was initiated from a flat-lying detachment zone at the middle crust level. Removal of the orogenic root by delamination at ca. 130 Ma came into the extensional climax, and subsequently isostatic rebound resulted in rapid doming. Along with exhumation of the footwall, the mid-crustal detachment zone had been warped as shear zones around the CDD. After 120 Ma, the detachment system probably experienced a migration accommodated to the crustal adjustment, which led to secondary (late-stage) detachment with localized ductile shearing at ca. 110 Ma. The migmatite-gneiss with HP/UHP relicts in the CDD (i.e., the central Dabieshan complex) was product of the Cretaceous crustal anatexis that consumed the deep-seated part of the HP-UHP slices and the underlying para-autochthonous basement. Compared with the contemporaneous MCCs widely developed along the eastern margin of the Eurasian continent, we proposed that occurrence of the Dabieshan MCC shares the same tectonic setting as the "destruction of the North China craton". However, geodynamic trigger

  17. Evolution of the carbon cycle and seawater temperature from the Triassic-Jurassic boundary to the Early Toarcian based on brachiopod geochemistry

    Science.gov (United States)

    Müller, Tamás; Tomašových, Adam

    2017-04-01

    The ecological crisis and extinction at the end of the Triassic coincides with several environmental perturbations such as global temperature rise, ocean acidification and carbon isotope anomalies, with a large observed negative carbon isotope excursion (CIE) in the Late Rhaetian as well. Followed by the ETE, the Early Jurassic was characterized by marked fluctuations of the global seawater temperature and carbon cycle. Carbon isotope records are showing positive and remarkable negative excursions. A particular example of these phenomena is connected to the Toarcian Oceanic Anoxic Event (TOAE). The δ13C record of the TOAE is showing a negative excursion of a high magnitude, suggesting the injection of large amount of light carbon into the ocean-atmosphere system, coinciding with rapid global warming and widespread anoxia. Beside the TOAE there are many other, smaller scale carbon isotope anomalies and environmental perturbations at the Sinemurian-Pliensbachian transition or at the Pliensbachian-Toarcian boundary. In our study, we provide new brachiopod δ13C, δ18O, and Mg/Ca data from the time interval starting in the Rhaetian till the end of the Early Toarcian. Considering the strong resistance of brachiopod shells against diagenesis, our aim is to reconstruct seawater temperature, seawater Mg/Ca, and carbon cycle evolution based on a reliable geochemical proxy database of the studied time interval. The samples have been collected from various localities across Europe achieving a good, at least ammonite subzone scale resolution for the Rhaetian stage and for the Lower Jurassic. The geochemical preservation of the shell material have been tested by several approaches. Thin-sections were made from the shells and analyzed by electron microprobe and ICP-OES to evaluate their preservation by assessing concentrations of Fe, Mn, Sr, and their ratios (Mn/Ca, Sr/Ca). Considering the various elemental composition data of fossil and recent brachiopods published by several

  18. Lepidoptera (moths and butterflies) thrived in gymnosperm forests following the end-Triassic extinction

    Science.gov (United States)

    van de Schootbrugge, Bas; van Eldijk, Timo; Wappler, Torsten; Strother, Paul; van der Weijst, Carolien; Rajaei, Hossein; Visscher, Henk

    2017-04-01

    The oldest evidence for Lepidoptera (moths and butterflies) and the Coelolepida (hollow-scaled moths and butterflies) is presented based on an assemblage of fossilized scales encountered in uppermost Triassic and lowermost Jurassic sediments from a core drilled in northern Germany. The diverse assemblage of scales points to a Triassic origin of the Lepidoptera and a radiation of some lineages just before or right after the end-Triassic mass extinction (201 Ma). These findings confirm molecular clock estimates for splits within the Amphiesmenoptera that led to the evolution of true butterflies. Not only did Lepidoptera survive the end-Triassic extinction, they also appear to have radiated directly following this environmental crisis, which could be related to the dramatic changes in paleoclimate triggered by the eruption of the CAMP, especially an increase in humidity. Seen in combination with high-resolution palynological records that show an Early Jurassic dominance of conifer pollen, the presence of scales derived from angiospermivorous Coelolepida likely signifies a host-shift (for multiple lineages of crown group Lepidoptera) from gymnosperms to angiosperms during the Mesozoic.

  19. Early discovery drug screening using mass spectrometry.

    Science.gov (United States)

    Siegel, Marshall M

    2002-01-01

    Electrospray ionization (ESI) and matrix-assisted laser desorption/ionization (MALDI) mass spectrometric methods useful for early discovery drug screening are reviewed. All methods described involve studies of non-covalent complexes between biopolymer receptors and small molecule ligands formed in the condensed phase. The complexes can be sprayed intact directly into the gas phase by ESI-MS using gentle experimental conditions. Gas phase screening applications are illustrated for drug ligand candidates non-covalently interacting with peptides, proteins, RNA, and DNA. In the condensed phase, the complexes can be also isolated, denatured and analyzed by ESI-MS to identify the small molecule ligands. Condensed phase drug screening examples are illustrated for the ESI-MS ancillary techniques of affinity chromatography, ultrafiltration, ultracentrifugation, gel permeation chromatography (GPC), reverse phase-high performance liquid chromatography (RP-HPLC) and capillary electrophoretic methods. Solid phase drug screening using MALDI-MS is illustrated for small molecule ligands bound to MALDI affinity probe tips and to beads. Since ESI and MALDI principally produce molecular ions, high throughput screening is achieved by analyzing mass indexed mixtures.

  20. First Late Triassic Record of a Paleoentomofauna from South America(Malargüe Basin,Mendoza Province,Argentina)

    Institute of Scientific and Technical Information of China (English)

    Carsten BRAUCKMANN; Oscar F.GALLEGO; Norbert HAUSCHKE; Rafael G.MARTINS-NETO; Elke GROENING; Jan-M.ILGER; María B.LARA

    2010-01-01

    Late Middle Triassic to early Late Triassic insects from Argentina have been previously described from the Bermejo and Cuyana Basins where they have been recovered from the Ischichuca-Los Rastros and Potrerillos-Cacheuta Formations,respectively.The insect fauna discussed herein was collected during field studies in 1986/1987 from the Llantenes section(Norian to Rhaetian? Late Triassic),which is situated in the Malargtie Basin in southern Mendoza province.The insect remains were found in the upper part of the Llantenes section(Llantenes Formation),which is built up of two coarsening-upwards cycles reflecting a deltaic progradation of a fluvial into a lacustrine environment(lower part),succeeded by repeated progradations into a floodplaindominated environment(upper part; with finds of insects,conchostracans,fish remains,plant fragments,and drifted logs).The new finds represent the youngest Triassic insect records described from Argentina and even from South America in its entirety.There is only one contemporaneous fossil assemblage in Gondwana:in the Clarence/Moreton Basin(Aberdare Conglomerate; Late Norian)in Australia.The new Triassic insects include an impression of an isolated Mecopterida-like wing(Mendozachorista volkheimeri gen.et sp.nov.;Mendozachoristidae fam.nov.),coleopteran elytra of the Permosynidae(Ademosyne rosenfeldi sp.nov.and Ademosyne llantenesensis sp.nov.)and other isolated body fragments.This new Late Triassic entomofauna from Argentina is of considerable importance in the reconstruction of the biotic recovery of continental environments in Gondwana after the catastrophic mass extinction at the P/T boundary.

  1. End-Triassic nonmarine biotic events

    Institute of Scientific and Technical Information of China (English)

    Spencer G. Lucas; Lawrence H. Tanner

    2015-01-01

    The Late Triassic was a prolonged interval of elevated extinction rates and low origination rates that manifested themselves in a series of extinctions during Carnian, Norian and Rhaetian time. Most of these extinctions took place in the marine realm, particularly af-fecting radiolarians, conodonts, bivalves, ammonoids and reef-building organisms. On land, the case for a Late Triassic mass extinction is much more tenuous and has largely focused on tetrapod vertebrates (amphibians and reptiles), though some workers advocate a sudden end-Triassic (TJB) extinction of land plants. Nevertheless, an extensive literature does not identify a major extinction of land plants at the TJB, and a comprehensive review of palynological records concluded that TJB vegetation changes were non-uniform (different changes in dif-ferent places), not synchronous and not indicative of a mass extinction of land plants. Claims of a substantial perturbation of plant ecology and diversity at the TJB in East Greenland are indicative of a local change in the paleolfora largely driven by lithofacies changes resulting in changing taphonomic iflters. Plant extinctions at the TJB were palaeogeographically localized events, not global in extent. With new and more detailed stratigraphic data, the perceived TJB tetrapod extinction is mostly an artifact of coarse temporal resolution, the compiled cor-relation effect. The amphibian, archosaur and synapsid extinctions of the Late Triassic are not concentrated at the TJB, but instead occur stepwise, beginning in the Norian and extending into the Hettangian. There was a disruption of the terrestrial ecosystem across the TJB, but it was more modest than generally claimed. The ecological severity of the end-Triassic non-marine biotic events are relatively low on the global scale. Biotic turnover at the end of the Triassic was likely driven by the CAMP (Central Atlantic Magmatic Province) eruptions, which caused signiifcant environmental perturbations (cooling

  2. End-Triassic nonmarine biotic events

    Directory of Open Access Journals (Sweden)

    Spencer G. Lucas

    2015-10-01

    Full Text Available The Late Triassic was a prolonged interval of elevated extinction rates and low origination rates that manifested themselves in a series of extinctions during Carnian, Norian and Rhaetian time. Most of these extinctions took place in the marine realm, particularly affecting radiolarians, conodonts, bivalves, ammonoids and reef-building organisms. On land, the case for a Late Triassic mass extinction is much more tenuous and has largely focused on tetrapod vertebrates (amphibians and reptiles, though some workers advocate a sudden end-Triassic (TJB extinction of land plants. Nevertheless, an extensive literature does not identify a major extinction of land plants at the TJB, and a comprehensive review of palynological records concluded that TJB vegetation changes were non-uniform (different changes in different places, not synchronous and not indicative of a mass extinction of land plants. Claims of a substantial perturbation of plant ecology and diversity at the TJB in East Greenland are indicative of a local change in the paleoflora largely driven by lithofacies changes resulting in changing taphonomic filters. Plant extinctions at the TJB were palaeogeographically localized events, not global in extent. With new and more detailed stratigraphic data, the perceived TJB tetrapod extinction is mostly an artifact of coarse temporal resolution, the compiled correlation effect. The amphibian, archosaur and synapsid extinctions of the Late Triassic are not concentrated at the TJB, but instead occur stepwise, beginning in the Norian and extending into the Hettangian. There was a disruption of the terrestrial ecosystem across the TJB, but it was more modest than generally claimed. The ecological severity of the end-Triassic nonmarine biotic events are relatively low on the global scale. Biotic turnover at the end of the Triassic was likely driven by the CAMP (Central Atlantic Magmatic Province eruptions, which caused significant environmental

  3. The oldest post-Palaeozoic Crinoid and Permian-Triassic origins of the Articulata (Echinodermata).

    Science.gov (United States)

    Oji, Tatsuo; Twitchett, Richard J

    2015-04-01

    The Crinoidea are the most primitive class of living echinoderms, and suffered a severe crisis during the Late Permian mass extinction event. All post-Palaeozoic crinoids, including living species, belong to the Articulata, and morphological and recent molecular studies demonstrate that they form a monophyletic clade. The Articulata originated from Palaeozoic cladid crinoids, but the nature and timing of their origination remains obscure. Problems with understanding the origin and early evolution of the Articulata have arisen because the Permian-Triassic crinoid fossil record is particularly poor. We report on a new genus and species from the earliest Triassic, which is the oldest known post-Palaeozoic articulate crinoid and fundamentally alters our understanding of the early evolution of the Articulata. Prior to this study, the most primitive post-Palaeozoic articulate was thought to be Holocrinus of the order Isocrinida. Unexpectedly, the new taxon belongs to the order Encrinida, which reveals a previously hidden diversity of crinoids in the earliest Triassic. Its discovery implies either a dramatic radiation of crinoids in the immediate post-extinction aftermath, when environmental conditions were at their most severe, or a pre-extinction origin of the crown group articulates and survival of multiple lineages.

  4. Origin of masses in the Early Universe

    CERN Document Server

    Pervushin, Victor N; Cherny, Alexander Yu; Shilin, Vadim I; Nazmitdinov, Rashid G; Pavlov, Alexander E; Pichugin, Konstantin N; Zakharov, Alexander F

    2015-01-01

    New model is suggested, where the Casimir mechanism is the source of masses and conformal symmetry breaking at the Planck epoch in the beginning of the Universe. The mechanism is the Casimir energy and associated condensate, which are resulted from the vacuum postulate and normal ordering of the conformal invariant Hamiltonian with respect to the quantum elementary field operators. It is shown that the Casimir top-quark condensate specifies the value of the Higgs particle mass without involving the Higgs tachyon mass, which is put equal to zero. The Casimir mechanism yields another value of the coupling constant for the self-interaction of scalar field than the standard model does.

  5. Triassic carbonate rocks in the Phatthalung area, Peninsular Thailand

    Science.gov (United States)

    Ampornmaha, Apsorn

    Carbonate rocks in the Phatthalung area and others in Peninsular Thailand have been known as the Permian Rat Buri Limestone. The study area is characterized by several isolated limestone mountains and is located in Phatthalung province. Micropaleontological study of these carbonate rocks indicates that they should be assigned a late Early to Late Triassic age. The Chaiburi Formation is newly proposed and divided into three members: the Phukhaothong Dolomite, Chiak Limestone and Phanomwang Limestone in ascending order. The Phukhaothong Dolomite consists of thickly bedded to massive dolomite and yields Neospathodus kummeli Sweet, N. waageni Sweet, N. cfr. waageni Sweet and other conodonts that indicate Dienerian to Smithian (Early Triassic). The Chiak Limestone Member consists of bedded and laminated limestone with intercalated thin chert layers and nodules. This limestone commonly yields Early Triassic to Middle Triassic conodonts such as Neospathodus timorensis (Nogami) and Neospathodus kockeli (Tatge), both reliable indicators of latest Spathian to early Anisian, and rare occurrences of Neogondolella bulgarica (Budurov and Stefanov), an indicator of the middle Anisian. The Phanomwang Limestone Member is mostly massive limestone with intercalated reef limestone (coral buildups) and yields abundant fossils that indicate Carnian (Late Triassic). Microfacies analysis and stratigraphic sequences of carbonate rocks in this area show the gradual change of depositional environment from low to high energy conditions.

  6. Carbon cycle changes during the Triassic-Jurassic transition

    NARCIS (Netherlands)

    Ruhl, M.

    2010-01-01

    The end-Triassic is regarded as one of the five major mass extinction events of the Phanerozoic. This time interval is marked by up to 50% of marine biodiversity loss and major changes in terrestrial ecosystems. Mass extinction events are often marked by changes in the global carbon cycle. The reali

  7. Carbon cycle changes during the Triassic-Jurassic transition

    NARCIS (Netherlands)

    Ruhl, M.|info:eu-repo/dai/nl/304838357

    2010-01-01

    The end-Triassic is regarded as one of the five major mass extinction events of the Phanerozoic. This time interval is marked by up to 50% of marine biodiversity loss and major changes in terrestrial ecosystems. Mass extinction events are often marked by changes in the global carbon cycle. The

  8. 上扬子地区早三叠世异常碳酸盐岩的分类与特征%Classification and characters of the Early Triassic anomalous carbonate rocks in Upper Yangtze Area

    Institute of Scientific and Technical Information of China (English)

    时志强; 安红艳; 伊海生; 张华; 曾德勇

    2011-01-01

    The anomalous carbonates of the late period of Late Permian and Early Triassic in the Upper Yangtze Area can be divided into three main types by genesis: A—biogenic anomalous carbonate rocks, B—abiogenetic (chemical and hydrodynamic ) anomalous carbonate rocks, C—multi-genetic anomalous carbonate rocks. Eight specific sorts of the anomalous carbonate rocks can be further distinguished, including microbiolite, brecciform limestone, flat-pebble limestone, ribbon limestone, thinbedded or laminated argillaceous limestone, oolitic limestone and 2 kinds of vermiculate limestone ( Type a and Type b). The extreme palaeoceanic environment and paleoclimatic conditions are the basis of the development of the anomalous carbonate rocks (mainly anachronistic facies) around P/T boundary. After the P/T mass extinction, the destruction of benthonic animals living on the surface of marine sediments was nearly stopped and the ocean currents were almost stagnated, meanwhile the surface layer of the sea water suffered the disturbing of megamonsoon and cyclonic storms, the algo-fungus ecosystem of euphoriczone grew and formed the wave-resistance microbiolites on the biohermal facies or on the shallow water carbonate platform. Seafloor was often affected by frequent storms which tear up the unconsolidated syngenetic carbonate ooze and thus the syngenetic pebble formed. At the same time, the particular gradient of the paleotopography intensified the development of carbonate gravity flows which might also be triggered by the storms; moreover the calcium carbonate-supersaturated sea water allowed the carbonate directly precipitating in the forms of chemical precipitation on the seafloor and the clays brought by the megamonsoon deposited together with the carbonate chemical precipitation. All the mentioned process happened at the earliest Early Triassic specific palaeoenvironment, which resulted in the appearance of the diverse anomalous carbonate deposition in the Upper Yangzte Area

  9. Two episodic changes of trace fossils through the Permian-Triassic transition in the Meishan cores,Zhejiang Province

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    Six ichnogenera,Chondrites,Palaeophycus,Planolites,Rhizocorallium,Skolithos,and Thalassinoides,were identified from the drilling cores near the Global Stratotype Section and Point(GSSP) of Permian-Triassic boundary at Meishan,Zhejiang Province.The ichnological indices,including abundance,bioturbation index,and disturbed depth of trace fossils,show two episodes of intense changes near the Permian-Triassic Boundary(PTB).Episode I occurred in Beds 25-27b when the ecologically complicate forms such as Chondrites,Skolithos,Rhizocorallium,and Thalassinoides disappeared hereafter,the bioturbation index reduced from 1-5 to 1-3,and the disturbed depth declined from 5-66 to 2-5 cm.Episode II took place at the base of Bed 33 with the disappearance of Palaeophycus and Planolites,and subsequent absence of trace fossils and bioturbation till the middle-upper part of Bed 41 when the disturbed structures reoccurred,but they are only tiny Planolites and the bioturbation index was never higher than 3 and the disturbed depth less than 4 mm.Episode I shows an intense change,corresponding to the main stage of the end-Permian mass extinction,whereas Episode II is relatively weak,corresponding to the epilogue of the mass extinction of trace makers in the Early Triassic.Subsequently,ichnofossils were dominated by surface tracks in simple ecological habit and structures.This phenomenon indicates that the Early Triassic benthonic fauna is changed from sessile benthic system to mobile benthic system after the end-Permian mass extinction.In other words,the evolution of the trace fossils across the Permian-Triassic transition had an episodic process similar to the body fossils.In addition,the change of ichnofabrics is well coincided with the negative excursion of carbon isotopes and the expansion of cyanobacteria.As the results of physical and biogenic processes,trace fossils provided unique materials for the study of the biotic and environmental events,as well as their coupling evolution

  10. Spondarthritis in the triassic.

    Directory of Open Access Journals (Sweden)

    Juan Carlos Cisneros

    Full Text Available BACKGROUND: The evidence of several forms of arthritis has been well documented in the fossil record. However, for pre-Cenozoic vertebrates, especially regarding reptiles, this record is rather scarce. In this work we present a case report of spondarthritis found in a vertebral series that belonged to a carnivorous archosaurian reptile from the Lower Triassic (∼245 million years old of the South African Karoo. METHODOLOGY/PRINCIPAL FINDINGS: Neutron tomography confirmed macroscopic data, revealing the ossification of the entire intervertebral disc space (both annulus fibrosus and nucleus pulposus, which supports the diagnosis of spondarthritis. CONCLUSIONS/SIGNIFICANCE: The presence of spondarthritis in the new specimen represents by far the earliest evidence of any form of arthritis in the fossil record. The present find is nearly 100 million years older than the previous oldest report of this pathology, based on a Late Jurassic dinosaur. Spondarthritis may have indirectly contributed to the death of the animal under study.

  11. Spondarthritis in the Triassic

    Science.gov (United States)

    Cisneros, Juan Carlos; Gomes Cabral, Uiara; de Beer, Frikkie; Damiani, Ross; Costa Fortier, Daniel

    2010-01-01

    Background The evidence of several forms of arthritis has been well documented in the fossil record. However, for pre-Cenozoic vertebrates, especially regarding reptiles, this record is rather scarce. In this work we present a case report of spondarthritis found in a vertebral series that belonged to a carnivorous archosaurian reptile from the Lower Triassic (∼245 million years old) of the South African Karoo. Methodology/Principal Findings Neutron tomography confirmed macroscopic data, revealing the ossification of the entire intervertebral disc space (both annulus fibrosus and nucleus pulposus), which supports the diagnosis of spondarthritis. Conclusions/Significance The presence of spondarthritis in the new specimen represents by far the earliest evidence of any form of arthritis in the fossil record. The present find is nearly 100 million years older than the previous oldest report of this pathology, based on a Late Jurassic dinosaur. Spondarthritis may have indirectly contributed to the death of the animal under study. PMID:20976231

  12. Terrestrial paleoenvironment characterization across the Permian-Triassic boundary in South China

    Science.gov (United States)

    Bercovici, Antoine; Cui, Ying; Forel, Marie-Béatrice; Yu, Jianxin; Vajda, Vivi

    2015-02-01

    Well-preserved marine fossils in carbonate rocks permit detailed studies of the end-Permian extinction event in the marine realm. However, the rarity of fossils in terrestrial depositional environments makes it more challenging to attain a satisfactory degree of resolution to describe the biotic turnover on land. Here we present new sedimentological, paleontological and geochemical (X-ray fluorescence) analysis from the study of four terrestrial sections (Chahe, Zhejue, Mide and Jiucaichong) in Western Guizhou and Eastern Yunnan (Yangtze Platform, South China) to evaluate paleoenvironmental changes through the Permian-Triassic transition. Our results show major differences in the depositional environments between the Permian Xuanwei and the Triassic Kayitou formations with a change from fluvial-lacustrine to coastal marine settings. This change is associated with a drastic modification of the preservation mode of the fossil plants, from large compressions to small comminuted debris. Plant fossils spanning the Permian-Triassic boundary show the existence of two distinct assemblages: In the Xuanwei Formation, a Late Permian (Changhsingian) assemblage with characteristic Cathaysian wetland plants (mainly Gigantopteris dictyophylloides, Gigantonoclea guizhouensis, G. nicotianaefolia, G. plumosa, G. hallei, Lobatannularia heinanensis, L. cathaysiana, L. multifolia, Annularia pingloensis, A. shirakii, Paracalamites stenocostatus, Cordaites sp.) is identified. In the lowermost Kayitou Formation, an Early Triassic (Induan) Annalepis-Peltaspermum assemblage is shown, associated with very rare, relictual gigantopterids. Palynological samples are poor, and low yield samples show assemblages almost exclusively represented by spores. A ∼1 m thick zone enriched in putative fungal spores was identified near the top of the Xuanwei Formation, including diverse multicellular forms, such as Reduviasporonites sp. This interval likely corresponds to the PTB "fungal spike

  13. Return to Coalsack Bluff and the Permian Triassic boundary in Antarctica

    Science.gov (United States)

    Retallack, Gregory J.; Greaver, Tara; Jahren, A. Hope

    2007-01-01

    Coalsack Bluff was the first discovery site in Antarctica for the latest Permian to earliest Triassic reptile Lystrosaurus. This together with discovery of Permian Glossopteris leaves during the heroic age of Antarctic exploration, indicated not only that Antarctica was part of Gondwanaland, but also that Antarctic rocks recorded faunas from the greatest of all mass extinctions at the Permian-Triassic boundary. Pinpointing the exact stratigraphic level of this life crisis has recently become possible using δ 13C values in terrestrial organic matter. Multiple, short-lived events of 13C depletion may reflect carbon cycle crises, with the isotopic change a measure of terrestrial and atmospheric disequilibrium. Additional evidence for ecosystem reorganization came from changes in paleosol types and their root traces. Such studies previously completed at the Antarctic localities of Graphite Peak, Mount Crean, Portal Mountain, Shapeless Mountain and Allan Hills, are here extended to Coalsack Bluff. Carbon isotopic values in Permian rocks at Coalsack Bluff average - 23.08 ± 0.25‰, but begin to decline within the last coal with leaves ( Glossopteris), roots ( Vertebraria) and permineralized stumps ( Araucarioxylon) of glossopterids. The low point in ä 13C values is - 27.19‰ at 5.6 m above the last coal, which is capped by unusually abundant pyrite, and a claystone breccia with common clasts of redeposited clayey soils. Above this are massive quartz-rich sandstones of braided streams, considered a geomorphic response to deforestation and soil erosion following the mass extinction. Distinctive berthierine-bearing paleosols (Dolores pedotype) within these sandstones have unoxidized iron taken as evidence of severe groundwater hypoxia. Other paleosols at this stratigraphic level are like those in other Early Triassic rocks of Antarctica, which indicate unusually warm and humid conditions for such high paleolatitude lowlands. Waterlogging is also indicated by newly

  14. The Late Permian-Early Triassic cyclostratigraphy in Shangsi section of Guangyuan area, Sichuan Province: Implications for P-T geological event based on wavelet analysis%四川广元上寺剖面晚二叠世-早三叠世旋回地层:基于小波分析的P-T界线地质事件探讨

    Institute of Scientific and Technical Information of China (English)

    乔彦国; 时志强; 王艳艳; 张彪

    2012-01-01

    利用小波分析技术,对采集自四川广元上寺剖面上二叠统-下三叠统格里斯巴赫亚阶以碳酸盐岩为主的沉积序列的自然伽马(GR)能谱序列进行深入分析研究,结果表明,该沉积序列很大程度上受到410∶102.5∶42.6∶21.5的米兰科维奇旋回控制.晚二叠世上寺剖面位于古特提斯洋的深水环境,沉积速率较低,平均为5 cm/ka;二叠纪-三叠纪过渡时期研究区构造活动强烈,陆地及海洋生物发生大灭绝,由于酸雨以及植被缺乏等气候及生态因素影响,陆地表面风化速率急剧增加,大量陆源物质注入导致早三叠世早期浅海系统沉积速率提高至25 cm/ka,并强烈影响了海洋生态系统,抑制了海洋生物的多样性,延缓了海洋生态复苏进程.在二叠纪末期,上寺剖面沉积记录的旋回性较为明显且稳定,到三叠纪早期旋回性有所变差.早三叠世沉积速率的显著变化和旋回性差异与该时期动荡的古气候、古海洋环境密切相关,地球表层环境变化对海洋生态系统具有较强的影响,且可能成为早三叠世海洋生态系统复苏缓慢的主要控制因素之一.%Based on the analysis of the GR energy spectrum collected from the Upper Permian to Lower Triassic carbonate rocks in Shangsi section at Cuangyuan area, Sichuan Province, it was indicated that the sedimentary layers are controlled by Milankovitch cycles, whose scale ratio was 410: 102. 5 :42. 6 : 21. 5. During the Late Permian, the Shangsi area was in a deep-water environment of the paleo-Tethys and the deposition rate was low to 5 cm/ka. During the P-T transitional period the tectonic movement was strong and terrestrial and marine fauna experienced mass extinction. At the same time, weathering rate increased sharply because of the acid rain and lack of terrestrial vegetation and mass terrigenous material fluxed into shallow sea in turn, which resulted in a rapid deposition rate of 25 cm/ka in Shangsi section

  15. Life crises on land across the Permian-Triassic boundary in South China

    Science.gov (United States)

    Peng, Yuanqiao; Shi, G. R.

    2009-02-01

    The western Guizhou and eastern Yunnan area of southwest China commands a unique and significant position globally in the study of Permian-Triassic boundary (PTB) events as it contains well and continuously exposed PTB sections of marine, non-marine and marginal-marine origin in the same area. By using a range of high-resolution stratigraphic methods including biostratigraphy, eventostratigraphy, chronostratigraphy and chemostratigraphy, not only are the non-marine PTB sections correlated with their marine counterparts in the study area with high-resolution, the non-marine PTB sections of the study area can also be aligned with the PTB Global Stratotype Section and Point (GSSP) at Meishan in eastern China. Plant megafossils ("megaplants") in the study area indicate a major loss in abundance and diversity across the PTB, and no coal beds and/or seams have been found in the non-marine Lower Triassic although they are very common in the non-marine Upper Permian. The megaplants, however, did not disappear consistently across the whole area, with some elements of the Late Permian Cathaysian Gigantopteris flora surviving the PTB mass extinction and locally even extending up to the Lower Triassic. Palynomorphs exhibit a similar temporal pattern characterized by a protracted stepwise decrease from fern-dominated spores in the Late Permian to pteridosperm and gymnosperm-dominated pollen in the Early Triassic, which was however punctuated by an accelerated loss in both abundance and diversity across the PTB. Contemporaneous with the PTB crisis in the study area was the peculiar prevalence and dominance of some fungi and/or algae species. The temporal patterns of megaplants and palynomorphs across the PTB in the study area are consistent with the regional trends of plant changes in South China, which also show a long-term decrease in species diversity from the Late Permian Wuchiapingian through the Changhsingian to the earliest Triassic, with about 48% and 77% losses of

  16. Photic Zone Euxinia During the Permian-Triassic Superanoxic Event

    Science.gov (United States)

    Grice, Kliti; Cao, Changqun; Love, Gordon D.; Böttcher, Michael E.; Twitchett, Richard J.; Grosjean, Emmanuelle; Summons, Roger E.; Turgeon, Steven C.; Dunning, William; Jin, Yugan

    2005-02-01

    Carbon and sulfur isotopic data, together with biomarker and iron speciation analyses of the Hovea-3 core that was drilled in the Perth Basin, Western Australia, indicate that euxinic conditions prevailed in the paleowater column during the Permian-Triassic superanoxic event. Biomarkers diagnostic for anoxygenic photosynthesis by Chlorobiaceae are particularly abundant at the boundary and into the Early Triassic. Similar conditions prevailed in the contemporaneous seas off South China. Our evidence for widespread photic-zone euxinic conditions suggests that sulfide toxicity was a driver of the extinction and a factor in the protracted recovery.

  17. MAGNETITE-HEMATITE IRON ORE OCCURRENCES IN THE TRIASSIC-PALEOZOIC METAMORPHIC COMPLEX OF MEDVEDNICA MOUNTAIN, CROATIA

    Directory of Open Access Journals (Sweden)

    Ivan Jurković

    2005-12-01

    Full Text Available Iron ore occurrences are situated on the south-eastern slopes of the Medvednica Mountain. They occur as discontinous, decameters long and 2-3.5 m thick bedded, poorly mineralized (15-35 % Fe lenses. A narrow, 6 km long, ore zone strikes NE-SW from Tisova Peć to Pustodol-Adolfovac. It is spatially and genetically bounded to the basic volcanogenic-sedimentary series (SEDEX-type, metamorphosed in greenschists during Cretaceous under P 3-3.5 kbar and T 350-400°C. The main minerals of the paragenesis are: quartz, chlorite, hematite, magnetite, stilpnomelane, martite. Similar types of Neo-Proterozoic and Early Paleozoic iron deposits were found in eastern Bosnia - western Serbia, western Macedonia and in the Serbo-Macedonian Mass. In the Triassic period of the Dinarides, magnetite-hematite deposits occur only as iron skarns or as short veins and small sized bodies of pneumatolytic-hydrothermal origin genetically bounded to gabbro-diorite or syenite stock and dykes. In the Triassic vulcanogenic-sedimentary complexes pointing occur only bedded deposits of red hematite, siderite, as well as locally with Mn-oxide ores. The arguments for the Paleozoic age of the Mt. Medvednica iron deposits are more convincing than those proposing theoretically possible Triassic age. The structures, textures and parageneses of the Mt. Medvednica magnetite-hematite occurrences are very similar only to the iron ores situated in the Early Paleozoic metamorphic complexes.

  18. Heterogeneous volcanism across the Permian-Triassic Boundary in South China and implications for the Latest Permian Mass Extinction: New evidence from volcanic ash layers in the Lower Yangtze Region

    Science.gov (United States)

    Liao, Zhiwei; Hu, Wenxuan; Cao, Jian; Wang, Xiaolin; Yao, Suping; Wu, Haiguang; Wan, Ye

    2016-09-01

    Volcanism has been suggested to have occurred widely in South China across the Permian-Triassic boundary (PTB); this has important implications for understanding the cause of the Latest Permian Mass Extinction (LMPE). However, few volcanic deposits have been reported in the Lower Yangtze Region and the extent of volcanism is uncertain. Herein we report new discoveries of intensive volcanism in this region for the first time, as evidenced by multiple (n > 20) and thick (3-5 cm) claystones (volcanic ash layers, K-bentonite) found in three deep-water outcrops in Xuancheng city, southern Anhui Province. Detailed petrographic and geochemical analyses of the ash layers were conducted to understand their origin and implications for the cause of the LPME, including X-ray diffraction, scanning electronic microscopy, energy dispersive spectroscopy, and whole-rock geochemistry. The petrological and mineralogical results show that the claystones contain clastic minerals indicative of a volcanic origin, such as zircon, analcites, pentagonal dodecahedral pyrite, and micro-spherules. The whole-rock geochemical data of the claystones suggest that the source rock of the ash layers was intermediate-acidic rhyodacite. The claystones are different from previously known claystones in the Middle-Upper Yangtze regions, indicating the occurrence of chemically heterogeneous volcanism in South China at the PTB.

  19. The Initial Mass Function of Early-Type Galaxies

    NARCIS (Netherlands)

    Treu, Tommaso; Auger, Matthew W.; Koopmans, Léon V. E.; Gavazzi, Raphaël; Marshall, Philip J.; Bolton, Adam S.

    2010-01-01

    We determine an absolute calibration of the initial mass function (IMF) of early-type galaxies, by studying a sample of 56 gravitational lenses identified by the Sloan Lenses ACS Survey. Under the assumption of standard Navarro, Frenk, and White dark matter halos, a combination of lensing, dynamical

  20. THE EARLY TRIASSIC INTERMEDIATE- ACID VOLCANICS AND ITS TECTONIC ENVIRONMENT IN SOUTHWESTERN GUANGXI%桂西南早三叠世中酸性火山岩及其构造环境

    Institute of Scientific and Technical Information of China (English)

    梁金城; 邓继新; 陈懋弘; 蒋柏昌; 朱继姣

    2001-01-01

    There exists an extended set of early Triassic intermediate- acid volcanics closely related to microdot gold ore in Southwestern Guangxi.It is mainly distributed in the fourth part of the Beisi Formation of the lower Triassic,exhibiting tidal flat characteristics and located between the underlying HST and the upper TST.The rock types include rhyolite,dacite and sedimentary volcaniclastic rocks,among which the lava tuff breccia was newly discovered in the 1∶ 50 000 region.The three volcanics are of kalium alkaline series,with their chemical elements showing the same magma origin.The multi- geochemical data analysis shows that the occurring tectonic environment is an active continental margin.Caused by the underthrust of the Pacific Kula Plate towards the Asia Plate,the high energy thermal flow brought the magma in the great depth of the upper mantle to force its way through the huge thick crust rock layers and absorbed the melted materials.The ascending channel should be along the activated Pingxiang- Dongmen deep fault.%桂西南广泛发育一套与微粒型金矿密切相关的早三叠世中酸性火山岩。主要见于下三叠统北泗组第四段,具潮坪特点,层序上处于下伏的 HST和上覆的 TST之间。岩石类型为流纹岩、英安岩和沉火山碎屑岩,其中的熔结角砾凝灰岩是本次 1∶ 5万区调中的新发现。三种火山岩均属钾质钙碱性系列,岩石化学成分显示为同源岩浆产物。运用多种岩石地球化学数据判别:其产出的大地构造环境为活动陆缘。岩浆来源深度较大,与太平洋库拉板块向亚洲板块俯冲,高能热流导致上地幔部分熔融上涌,穿透巨厚壳层时吸收了部分壳源重熔物质有关,其上涌通道主要沿被激活的凭祥—东门深断裂。

  1. Provenance of the Upper Triassic siliciclastics of the Mecsek Mountains and Villány Hills (Pannonian Basin, Hungary): constraints to the Early Mesozoic paleogeography of the Tisza Megaunit

    Science.gov (United States)

    Pozsgai, Emília; Józsa, Sándor; Dunkl, István; Sebe, Krisztina; Thamó-Bozsó, Edit; Sajó, István; Dezső, József; von Eynatten, Hilmar

    2016-10-01

    The Tisza Megaunit in the Southern Pannonian Basin formed part of the southern margin of the European Plate in the Early Mesozoic era. Its exact paleo-position and relation to other structural blocks is disputed for a long time. Detrital zircon U-Pb dating, heavy mineral analysis and petrographical examination of Carnian to Pliensbachian sandstone members lead to better understanding of the provenance of clastic deposits after the Ladinian-Carnian carbonate to siliciclastic facies shift in the Southwestern Tisza Megaunit. Investigations allow for constraining its paleogeographic relation to adjacent units. The Carnian and Pliensbachian siliciclastics of the Villány Hills derive from inside the Southwestern Tisza Megaunit, i.e. the medium-grade polymetamorphic rocks of the adjacent Slavonian Mountains or similar basement fragments. The Upper Triassic clastic deposits of the Mecsek Mountains most likely derive from Variscan felsic plutonic rocks of the local basement or partially from the Southern/Southwestern Bohemian Massif. About 200 Ma zircon U-Pb ages are tentatively interpreted as traces of synsedimentary distal volcanism in the Central Atlantic Magmatic Province.

  2. Zircon U-Pb ages, Hf isotope data, and tectonic implications of Early-Middle Triassic granitoids in the Ailaoshan high-grade metamorphic belt of Southeast Tibet

    Science.gov (United States)

    Wu, Wenbin; Liu, Junlai; Chen, Xiaoyu; Zhang, Lisheng

    2017-04-01

    The Ailaoshan tectonic belt, where the effects of the Paleo-Tethyan ocean evolution and Indian-Eurasian plate collision are superimposed, is one of the most significant geological discontinuities in western Yunnan province of southeast Tibet. An Ailaoshan micro-block within the belt is bounded by the Ailaoshan suture zone to the west and the Red River Fault to the east, and consists of low- and high-grade metamorphic belts. Late Permian-Middle Triassic granitoids that are widely distributed to the west of the Ailaoshan suture zone and within the Ailaoshan micro-block may yield significant information on the Tethyan tectonic evolution of the Ailaoshan tectonic belt. This study reports new LA-ICP-MS zircon U-Pb geochronology and Hf isotope data of four granitoids from the Ailaoshan high-grade metamorphic belt. Zircon grains from the Yinjie granitoid do not have inherited cores and yield a weighted mean U-Pb age of 247.1 ± 2.0 Ma. The zircon ɛ Hf( t) values range from 7.8 to 12.1, and Hf model ages from 775 to 546 Ma, indicating that the granitoid was derived from juvenile crust. The rims of zircons from the Majie and Yuanjiang granitoids yield weighted mean U-Pb ages of 239.5 ± 1.8 and 237.9 ± 2.6 Ma, respectively, whereas the cores yield ages of 1608-352 Ma. The ɛ Hf( t) values of zircon rims range from -20.4 to -5.3, yielding Hf model ages from 2557 to 1606 Ma and suggesting that the source magma of the Majie and Yuanjiang granitoids was derived from ancient crust. An additional granitoid located near the Majie Village yields a zircon U-Pb age of 241.2 ± 1.0 Ma. Based on our geochronological and geochemical data, combined with geological observations, we propose that the Ailaoshan micro-block was derived from the western margin of the Yangtze block, and is comparable to the Zhongzan and Nam Co micro-blocks. The presence of late Permian mafic rocks with rift-related geochemical characteristics within the Ailaoshan micro-block, together with granitoids derived

  3. Zircon U-Pb ages, Hf isotope data, and tectonic implications of Early-Middle Triassic granitoids in the Ailaoshan high-grade metamorphic belt of Southeast Tibet

    Science.gov (United States)

    Wu, Wenbin; Liu, Junlai; Chen, Xiaoyu; Zhang, Lisheng

    2016-05-01

    The Ailaoshan tectonic belt, where the effects of the Paleo-Tethyan ocean evolution and Indian-Eurasian plate collision are superimposed, is one of the most significant geological discontinuities in western Yunnan province of southeast Tibet. An Ailaoshan micro-block within the belt is bounded by the Ailaoshan suture zone to the west and the Red River Fault to the east, and consists of low- and high-grade metamorphic belts. Late Permian-Middle Triassic granitoids that are widely distributed to the west of the Ailaoshan suture zone and within the Ailaoshan micro-block may yield significant information on the Tethyan tectonic evolution of the Ailaoshan tectonic belt. This study reports new LA-ICP-MS zircon U-Pb geochronology and Hf isotope data of four granitoids from the Ailaoshan high-grade metamorphic belt. Zircon grains from the Yinjie granitoid do not have inherited cores and yield a weighted mean U-Pb age of 247.1 ± 2.0 Ma. The zircon ɛ Hf(t) values range from 7.8 to 12.1, and Hf model ages from 775 to 546 Ma, indicating that the granitoid was derived from juvenile crust. The rims of zircons from the Majie and Yuanjiang granitoids yield weighted mean U-Pb ages of 239.5 ± 1.8 and 237.9 ± 2.6 Ma, respectively, whereas the cores yield ages of 1608-352 Ma. The ɛ Hf(t) values of zircon rims range from -20.4 to -5.3, yielding Hf model ages from 2557 to 1606 Ma and suggesting that the source magma of the Majie and Yuanjiang granitoids was derived from ancient crust. An additional granitoid located near the Majie Village yields a zircon U-Pb age of 241.2 ± 1.0 Ma. Based on our geochronological and geochemical data, combined with geological observations, we propose that the Ailaoshan micro-block was derived from the western margin of the Yangtze block, and is comparable to the Zhongzan and Nam Co micro-blocks. The presence of late Permian mafic rocks with rift-related geochemical characteristics within the Ailaoshan micro-block, together with granitoids derived

  4. Diagenetic overprint on negative δ13C excursions across the Permian/Triassic boundary: A case study from Meishan section, China

    Science.gov (United States)

    Li, Rong

    2016-04-01

    The Permian-Triassic carbonate succession that formed during the biggest mass extinction event in geological history has long been studied to examine the biomass extinction patterns and mechanisms. Such studies have shown that the stable inorganic carbon isotope displays a worldwide significant negative shift in the Permian/Triassic transitional period, which has generally been attributed to a synchronistic shift in δ13C in the global carbon cycle. The assertion, however, is based on the assumption that the δ13C signals recorded in the carbonate succession are primary in origin. In this study, the diagenetic features of Beds 24 to 62 from Meishan Section, China, which is the Global Stratotype Section and Point (GSSP) of the Permian-Triassic boundary, are examined to determine the negative shift in δ13Ccarb across the Permian-Triassic mass extinction (PTME) is diagenetic in origin or not. Bed 24, the topmost unit of Changhsing Formation, is formed of skeletal packstones. Beds 25 to 62, belonging to Yinkeng Formation, are formed of either claystones, or mudstones and/or calcareous mudstones with dolomite being present. Petrographic data indicate that zoned dolomite crystals are widespread in early Triassic beds. Geochemical data including stable isotopic composition, minor and trace elements, and rare-earth elements indicate that the dolomite and coexisting calcite are formed in different depositional/diagenetic environment. The dramatically negative δ13C excursions of calcite in Beds 26 and 28 are related to meteoric diagenesis, while the negative δ13C excursions of calcite in dolomite-bearing beds are ascribed to enriched 12C resulted from dolomitization mediated by sulfate reducing bacterial (SRB) in burial process. The results show that the δ13C signals recorded in the global stratotype section that spans the PTB is not primary in origin. The synchronistic negative shift in δ13C signals across the PTME are partly contributed by diagenesis.

  5. Delayed recovery of non-marine tetrapods after the end-Permian mass extinction tracks global carbon cycle.

    Science.gov (United States)

    Irmis, Randall B; Whiteside, Jessica H

    2012-04-07

    During the end-Permian mass extinction, marine ecosystems suffered a major drop in diversity, which was maintained throughout the Early Triassic until delayed recovery during the Middle Triassic. This depressed diversity in the Early Triassic correlates with multiple major perturbations to the global carbon cycle, interpreted as either intrinsic ecosystem or external palaeoenvironmental effects. In contrast, the terrestrial record of extinction and recovery is less clear; the effects and magnitude of the end-Permian extinction on non-marine vertebrates are particularly controversial. We use specimen-level data from southern Africa and Russia to investigate the palaeodiversity dynamics of non-marine tetrapods across the Permo-Triassic boundary by analysing sample-standardized generic richness, evenness and relative abundance. In addition, we investigate the potential effects of sampling, geological and taxonomic biases on these data. Our analyses demonstrate that non-marine tetrapods were severely affected by the end-Permian mass extinction, and that these assemblages did not begin to recover until the Middle Triassic. These data are congruent with those from land plants and marine invertebrates. Furthermore, they are consistent with the idea that unstable low-diversity post-extinction ecosystems were subject to boom-bust cycles, reflected in multiple Early Triassic perturbations of the carbon cycle.

  6. Carbon isotope composition of the Lower Triassic marine carbonates, Lower Yangtze Region, South China

    Institute of Scientific and Technical Information of China (English)

    ZUO; Jingxun; TONG; Jinnan; QIU; Haiou; ZHAO; Laishi

    2006-01-01

    Studies on three Lower Triassic sections located on the shallow water platform, the deep water slope and in the deep water basin in the Lower Yangtze Region, South China, show the similar trend of carbon isotope evolution. Biostratigraphic correlations among the Lower Triassic sections on the basis of standard conodont zones indicate that three negative shifts occurred in the Griesbachian, the Smithian and the late Spathian stages respectively, and one distinctly positive shift occurred in the early Spathian stage. Trend of carbon isotope evolution of the Lower Triassic reflects some significant changes in the global carbon cycle. Moreover, δ13C background values are intensively controlled by palaeogeographic environment. In general, δ13C values from deep-water slope carbonates are lighter than those from carbonate platform and heavier than those from deep-water basin carbonates. The positive carbon isotope excursion may be induced by a significant amount of organic carbon burial in marine sediments and increase in primary productivity. The large negative carbon isotope excursions during the Early Triassic in Lower Yangtze Region are interpreted to relate to volcano eruptions based on tuffaceous claystone interlayers observed near the Permian-Triassic boundary, the Induan- Olenekian boundary and the Lower Triassic-Middle Triassic boundary.

  7. The Cluster Mass Function from Early SDSS Data: Cosmological Implications

    OpenAIRE

    Bahcall, Neta A.; Dong, Feng; Bode, Paul; Kim, Rita; Annis, James; Mckay, Timothy A.; Hansen, Sarah; Gunn, James; Ostriker, Jeremiah P.; Postman, Marc; Nichol, Robert C.; Goto, Tomotsugu; Brinkmann, Jon; Knapp, Gillian R.; Lamb, Don O.

    2002-01-01

    The mass function of clusters of galaxies is determined from 400 deg^2 of early commissioning imaging data of the Sloan Digital Sky Survey; ~300 clusters in the redshift range z = 0.1 - 0.2 are used. Clusters are selected using two independent selection methods: a Matched Filter and a red-sequence color magnitude technique. The two methods yield consistent results. The cluster mass function is compared with large-scale cosmological simulations. We find a best-fit cluster normalization relatio...

  8. Mass Extinction and Evolution of Sedimentary Microfacies Across the Permian-Triassic Boundary in Chongyang, Hubei Province%湖北崇阳二叠纪—三叠纪之交生物灭绝和沉积微相演化

    Institute of Scientific and Technical Information of China (English)

    单厚香; 王永标; 何磊; 余黎雪

    2012-01-01

    Chongyang was located on shallow carbonate platform during the Permian-Triassic transition, where the end-Permian global event of biotic crisis was highly marked both on fossil record and sedimentary facies. Before the end-Permian mass extinction, abundant and diverse species, such as fusulinds, calcareous alga, calcisponges, echinoderms, lived in a normal shallow marine environment. However, microgas-tropods, ostracods and abundant calcified cyanobacteria replaced these Permian species after the big crisis. A thickness of 25 cm laminated microbialites sharply overlaps on Permian packstone in Chongyang, and next are 6. 4 m thrombolites and 2. 3 m dome microbialites. Different types of microbialites have different sedimentary structures and biological compositions. Oolitic limestones began to deposit after the termination of microbialites. Three sedimentary facies are concluded according to the five sedimentary microfacies above, which are open platform facies, tidal-flat facies and platform edge shallow facies. The mass extinction and change of sedimentary facies in Chongyang section typically stand for the interaction between creatures and environment on shallow carbonate platform across the Permian-Triassic boundary. Hence, this study offers new information for studying the end-Permian global event.%二叠纪—三叠纪之交,湖北崇阳地区处于浅水碳酸盐岩台地环境.二叠纪末的全球事件在该剖面的沉积微相和生物演化上均留下了清楚的记录.二叠纪末生物大灭绝之前,崇阳地区为典型的正常浅海台地环境,生物种类多样,数量丰富,主要生物化石有钙藻、有孔虫、腕足、棘皮类和海绵等.生物大灭绝之后,钙藻、(筳)类、棘皮类、海绵、绝大部分有孔虫开始消失,取而代之的是个体微小的腹足、介形虫和大量的蓝细菌化石.大灭绝界线之上,首先出现的是25 cm厚的纹层状的微生物岩,含较丰富的种类单调的有孔虫化石.之后

  9. A new archosauriform (Reptilia: Diapsida from the Manda beds (Middle Triassic of southwestern Tanzania.

    Directory of Open Access Journals (Sweden)

    Sterling J Nesbitt

    Full Text Available BACKGROUND: Archosauria and their closest relatives, the non-archosaurian archosauriforms, diversified in the Early and Middle Triassic, soon after the end-Permian extinction. This diversification is poorly documented in most Lower and Middle Triassic rock sequences because fossils of early groups of archosauriforms are relatively rare compared to those of other amniotes. The early Middle Triassic (? late Anisian Manda beds of southwestern Tanzania form an exception, with early archosaur skeletons being relatively common and preserved as articulated or associated specimens. The Manda archosaur assemblage is exceptionally diverse for the Middle Triassic. However, to date, no non-archosaurian archosauriforms have been reported from these rocks. METHODOLOGY/PRINCIPAL FINDINGS: Here, we name a new taxon, Asperoris mnyama gen. et sp. nov., from the Manda beds and thoroughly describe the only known specimen. The specimen consists of a well-preserved partial skull including tooth-bearing elements (premaxilla, maxilla, the nasal, partial skull roof, and several incomplete elements. All skull elements are covered in an autapomorphic highly rugose sculpturing. A unique combination of character states indicates that A. mnyama lies just outside Archosauria as a stem archosaur within Archosauriformes, but more precise relationships of A. mnyama relative to other early archosauriform clades (e.g., Erythrosuchidae cannot be determined currently. CONCLUSIONS/SIGNIFICANCE: Asperoris mnyama is the first confirmed non-archosaurian archosauriform from the Manda beds and increases the morphological and taxonomic diversity of early archosauriforms known from the Middle Triassic. The direct association of A. mnyama with species referable to Archosauria demonstrates that non-archosaurian archosauriforms were present during the rise and early diversification of Archosauria. Non-archosaurian archosauriforms and archosaurs co-occur in fossil reptile assemblages across

  10. EARLY TRIASSIC SPORE-POLLEN ASSEMBLAGES FROM THE HONGSHUICHUAN GROUP OF CENTRAL-WESTERN QINGHAI%青海省中西部洪水川群孢粉组合及其时代

    Institute of Scientific and Technical Information of China (English)

    欧阳舒; 冀六祥; 罗伟

    2011-01-01

    The Hongshuichuan Group typically crops out in the Maduo and Dulan counties of central Qing-hai, consisting mainly of volcano-elastics and limestones with thick basal conglomerates, it is dated as Early Triassic based on faunal evidence (e. g. from cephalopods). However, the group actually extends far to the western area of the province and includes two sets of strata,lithologically represented mainly by dark grey muddy siltstones and dark grey sandy shales, previously assigned respectively to the Permian and Jurassic. The present paper deals with abundant and diverse fossil spores and pollen recovered for the first time from these two sets of stratigraphic units, represented by two sections (Fig. 1) in a depopulated area far West of the Geermu City, located at ca. 36. 00-36. 40°NX 93. 00°-93. 4°E, to the North of the Deep-Big Fracture-F3. The assemblages are all characterized by the constant presence of Calamospora, Li-matulasporites, Lundbladispora, Aratrisporites, Taeniaesporites ( = Lunatisporites) and Tuber-monocolpites ( = Sulcusicystis), etc.. They totally about 106 species (forms) in 89 genera of spores and pollen, including 9 new species; and 15 species in 15 genera of acritarchs, including 3 new species. All are listed and mostly of them illustrated here. As a whole the assemblages contain an average contents of 43. 98% cryptogam spores, 45. 81% gymnospermous pollen and 10. 04% acritarchs.Two assemblages have been distinguished, the Calamospora (8. 4%) - Limatulasporites (14. 36%) -Taeniaesporites (17. 70%) - Micrhystridium (2.30%) Assemblage from the lower part (the so called "Lower Lithoformation") of the Hongshuichuan Group; and the Limatulasporites (6.8%) -Taeniaesporites (11.0%) - Tubermonocolpites (1.70%) - Baltisphaeridium (1. 80%) Assemblage from the upper part ("the Upper Lithoformation"). Both assemblages are similar in appearance, especially at generic level, and indicate an Early Triassic age.The lower assemblage is dated as Induan because

  11. Integration of molecules and new fossils supports a Triassic origin for Lepidosauria (lizards, snakes, and tuatara)

    Science.gov (United States)

    2013-01-01

    Background Lepidosauria (lizards, snakes, tuatara) is a globally distributed and ecologically important group of over 9,000 reptile species. The earliest fossil records are currently restricted to the Late Triassic and often dated to 227 million years ago (Mya). As these early records include taxa that are relatively derived in their morphology (e.g. Brachyrhinodon), an earlier unknown history of Lepidosauria is implied. However, molecular age estimates for Lepidosauria have been problematic; dates for the most recent common ancestor of all lepidosaurs range between approximately 226 and 289 Mya whereas estimates for crown-group Squamata (lizards and snakes) vary more dramatically: 179 to 294 Mya. This uncertainty restricts inferences regarding the patterns of diversification and evolution of Lepidosauria as a whole. Results Here we report on a rhynchocephalian fossil from the Middle Triassic of Germany (Vellberg) that represents the oldest known record of a lepidosaur from anywhere in the world. Reliably dated to 238–240 Mya, this material is about 12 million years older than previously known lepidosaur records and is older than some but not all molecular clock estimates for the origin of lepidosaurs. Using RAG1 sequence data from 76 extant taxa and the new fossil specimens two of several calibrations, we estimate that the most recent common ancestor of Lepidosauria lived at least 242 Mya (238–249.5), and crown-group Squamata originated around 193 Mya (176–213). Conclusion A Early/Middle Triassic date for the origin of Lepidosauria disagrees with previous estimates deep within the Permian and suggests the group evolved as part of the faunal recovery after the end-Permain mass extinction as the climate became more humid. Our origin time for crown-group Squamata coincides with shifts towards warmer climates and dramatic changes in fauna and flora. Most major subclades within Squamata originated in the Cretaceous postdating major continental fragmentation. The

  12. The carbon and sulfur cycles and atmospheric oxygen from middle Permian to middle Triassic

    Science.gov (United States)

    Berner, Robert A.

    2005-07-01

    The results of a theoretical isotope mass balance model are presented for the time dependence of burial and weathering-plus-degassing fluxes within the combined long-term carbon and sulfur cycles. Averaged data for oceanic δ 13C and δ 34S were entered for every million years from 270 to 240 Ma (middle Permian to middle Triassic) to study general trends across the Permian-Triassic boundary. Results show a drop in the rate of global organic matter burial during the late Permian and a predominance of low values during the early-to-middle Triassic. This overall decrease with time is ascribed mainly to epochs of conversion of high biomass forests to low biomass herbaceous vegetation resulting in a decrease in the production of terrestrially derived organic debris. Additional contributions to lessened terrestrial carbon burial were increased aridity and a drop in sea level during the late Permian which led to smaller areas of low-lying coastal wetlands suitable for coal and peat deposition. Mirroring the drop in organic matter deposition was an increase in the burial of sedimentary pyrite, and a dramatic increase in the calculated global mean ratio of pyrite-S to organic-C. High S/C values resulted from an increase of deposition in marine euxinic basins combined with a decrease in the burial of low-pyrite associated terrestrial organic matter. The prediction of increased oceanic anoxia during the late Permian and early Triassic agrees with independent studies of the composition of sedimentary rocks. Weathering plus burial fluxes for organic carbon and pyrite sulfur were used to calculate changes in atmospheric oxygen. The striking result is a continuous drop in O 2 concentration from ˜30% to ˜13% over a twenty million year period. This drop was brought about mainly by a decrease in the burial of terrestrially derived organic matter. but with a possible contribution from the weathering of older organic matter on land. It must have exerted a considerable influence on

  13. Integration of molecules and new fossils supports a Triassic origin for Lepidosauria (lizards, snakes, and tuatara).

    Science.gov (United States)

    Jones, Marc E H; Anderson, Cajsa Lisa; Hipsley, Christy A; Müller, Johannes; Evans, Susan E; Schoch, Rainer R

    2013-09-25

    Lepidosauria (lizards, snakes, tuatara) is a globally distributed and ecologically important group of over 9,000 reptile species. The earliest fossil records are currently restricted to the Late Triassic and often dated to 227 million years ago (Mya). As these early records include taxa that are relatively derived in their morphology (e.g. Brachyrhinodon), an earlier unknown history of Lepidosauria is implied. However, molecular age estimates for Lepidosauria have been problematic; dates for the most recent common ancestor of all lepidosaurs range between approximately 226 and 289 Mya whereas estimates for crown-group Squamata (lizards and snakes) vary more dramatically: 179 to 294 Mya. This uncertainty restricts inferences regarding the patterns of diversification and evolution of Lepidosauria as a whole. Here we report on a rhynchocephalian fossil from the Middle Triassic of Germany (Vellberg) that represents the oldest known record of a lepidosaur from anywhere in the world. Reliably dated to 238-240 Mya, this material is about 12 million years older than previously known lepidosaur records and is older than some but not all molecular clock estimates for the origin of lepidosaurs. Using RAG1 sequence data from 76 extant taxa and the new fossil specimens two of several calibrations, we estimate that the most recent common ancestor of Lepidosauria lived at least 242 Mya (238-249.5), and crown-group Squamata originated around 193 Mya (176-213). A Early/Middle Triassic date for the origin of Lepidosauria disagrees with previous estimates deep within the Permian and suggests the group evolved as part of the faunal recovery after the end-Permain mass extinction as the climate became more humid. Our origin time for crown-group Squamata coincides with shifts towards warmer climates and dramatic changes in fauna and flora. Most major subclades within Squamata originated in the Cretaceous postdating major continental fragmentation. The Vellberg fossil locality is expected

  14. Magnetostratigraphic correlations of Permian-Triassic marine-to-terrestrial sections from China

    Science.gov (United States)

    Glen, J.M.G.; Nomade, S.; Lyons, J.J.; Metcalfe, I.; Mundil, R.; Renne, P.R.

    2009-01-01

    We have studied three Permian-Triassic (PT) localities from China as part of a combined magnetostratigraphic, 40Ar/39Ar and U-Pb radioisotopic, and biostratigraphic study aimed at resolving the temporal relations between terrestrial and marine records across the Permo-Triassic boundary, as well as the rate of the biotic recovery in the Early Triassic. The studied sections from Shangsi (Sichuan Province), Langdai (Guihzou Province), and the Junggar basin (Xinjiang Province), span marine, paralic, and terrestrial PT environments, respectively. Each of these sections was logged in detail in order to place geochronologic, paleomagnetic, geochemical, conodont and palynologic samples within a common stratigraphic context. Here we present rock-magnetic, paleomagnetic and magnetostratigraphic results from the three localities. At Shangsi, northern Sichuan Province, we sampled three sections spanning Permo-Triassic marine carbonates. Magnetostratigraphic results from the three sections indicate that the composite section contains at least eight polarity chrons and that the PT boundary occurs within a normal polarity chron a short distance above the mass extinction level and a reversed-to-normal (R-N) polarity reversal. Furthermore, the onset of the Illawarra mixed interval lies below the sampled section indicating that the uppermost Permian Changhsingian and at least part of the Wuchiapingian stages postdate the end of the Kiaman Permo-Carboniferous Reversed Superchron. At Langdai, Guizhou Province, we studied magnetostratigraphy of PT paralic mudstone and carbonate sediments in two sections. The composite section spans an R-N polarity sequence. Section-mean directions pass a fold test at the 95% confidence level, and the section-mean poles are close to the mean PT pole for the South China block. Based on biostratigraphic constraints, the R-N transition recorded at Langdai is consistent with that at Shangsi and demonstrates that the PT boundary occurred within a normal

  15. Sodium storage in deep paleoweathering profiles beneath the Paleozoic-Triassic unconformity

    Science.gov (United States)

    Thiry, M.; Parcerisa, D.; Ricordel-Prognon, C.; Schmitt, J.-M.

    2009-04-01

    A major sodium accumulation has been recognized for long and by numerous authors in the Permo-Triassic salt deposits (Hay et al., 2006). Beside these basinal deposits, important masses of sodium were stored on the continents within deep palaeoweathering profiles in form of albite. Indeed, wide surfaces and huge volumes of granito-gneissic basements of the Hercynian massifs are albitized from North-Africa up to Scandinavia. These albitized rocks have usually been considered as related to tardi-magmatic metasomatic processes (Cathelineau 1986; Petersson and Eliasson 1997). Geometrical arrangement and dating of these alterations point out that these albitizations, or at least a part of them, developed under low temperature subsurface conditions in relation with the Triassic palaeosurface (Ricordel et al., 2007; Parcerisa et al., 2009). Petrology The albitized igneous rocks show a strong alteration with pseudomorphic replacement of the primary plagioclases into albite, replacement of primary biotite by chlorite and minor precipitation of neogenic minerals like albite, chlorite, apatite, haematite, calcite and titanite. Albitized rocks are characterized by their pink coloration due to the presence of minute haematite inclusions in the albite. The development and distribution of the albitization and related alterations above the unaltered basement occurs in three steps that define a vertical profile, up to 100-150 m depth. 1) In the lower part of the profile, albitization occurs within pink-colored patches in the unaltered rock, giving a pink-spotted aspect to the rock. 2) In the middle part of the profile, rocks have an overall pink coloration due to the albitization of the primary Ca-bearing igneous plagioclases. Usually, this facies develops in a pervasive manner, affecting the whole rock, but it may also be restricted to joints, giving a sharp-pink coloration to the fracture wall. 3) Finally, the top of the profile is defined by the same mineral paragenesis as in the

  16. Body mass index is reduced early in Parkinson's disease.

    Science.gov (United States)

    Cheshire, William P; Wszolek, Zbigniew K

    2005-01-01

    Mean body mass index (BMI) in 100 cases of idiopathic Parkinson's disease (PD) was found to be 9% reduced in comparison to that in patients with either essential tremor or no neurologic disease. A similar reduction in BMI was also discovered among the 24 cases of PD in whom retrospective BMI data were available from their presymptomatic years. These results suggest that alterations in nutrient intake or metabolism could reflect early changes in the central autonomic network preceding the emergence of classical extrapyramidal manifestations of PD.

  17. Anoxia/high temperature double whammy during the Permian-Triassic marine crisis and its aftermath.

    Science.gov (United States)

    Song, Haijun; Wignall, Paul B; Chu, Daoliang; Tong, Jinnan; Sun, Yadong; Song, Huyue; He, Weihong; Tian, Li

    2014-02-19

    The Permian-Triassic mass extinction was the most severe biotic crisis in the past 500 million years. Many hypotheses have been proposed to explain the crisis, but few account for the spectrum of extinction selectivity and subsequent recovery. Here we show that selective losses are best accounted for by a combination of lethally warm, shallow waters and anoxic deep waters that acted to severely restrict the habitable area to a narrow mid-water refuge zone. The relative tolerance of groups to this double whammy provides the first clear explanation for the selective extinction losses during this double-pulsed crisis and also the fitful recovery. Thus, high temperature intolerant shallow-water dwellers, such as corals, large foraminifers and radiolarians were eliminated first whilst high temperature tolerant ostracods thrived except in anoxic deeper-waters. In contrast, hypoxia tolerant but temperature intolerant small foraminifers were driven from shallow-waters but thrived on dysoxic slopes margins. Only those mollusc groups, which are tolerant of both hypoxia and high temperatures, were able to thrive in the immediate aftermath of the extinction. Limited Early Triassic benthic recovery was restricted to mid-water depths and coincided with intervals of cooling and deepening of water column anoxia that expanded the habitable mid-water refuge zone.

  18. Paleomagnetic study on the Triassic rocks from the Lhasa Terrane, Tibet, and its paleogeographic implications

    Science.gov (United States)

    Zhou, Yanan; Cheng, Xin; Yu, Lei; Yang, Xingfeng; Su, Hailun; Peng, Ximing; Xue, Yongkang; Li, Yangyang; Ye, Yakun; Zhang, Jin; Li, Yuyu; Wu, Hanning

    2016-05-01

    We present paleomagnetic results from the newly discovered Early-Middle and Late Triassic marine sediments of the Lhasa Terrane. Orientated samples were collected from 32 sites (330 samples) on the north side of the Dibu Co Lake (84.7°E, 30.9°N), Coqên County, in the western region of the Lhasa terrane. Rock magnetic data revealed that most of the samples were dominated by magnetite and/or pyrrhotite. The stepwise demagnetization curves illustrated three-components: a low temperature component (Component A) near the present-day field (PDF), a secondary remanent magnetization (Component B) that may be from the Cretaceous Period, and a high-temperature component (Component C). The Component C were isolated from the Early-Middle Triassic rocks in 8 sites (47 specimens) and from the Late Triassic rocks in 6 sites (37 specimens). The Component C of the Early-Middle Triassic rocks passed a reversal test (B class, 95% confidence level) and a fold test (99% confidence level), that of the Late Triassic rocks passed a fold test (95% confidence level). The corresponding paleopoles for the Early-Middle and Late Triassic periods of the Lhasa Terrane were at 18.9°N, 208.4°E with A95 = 3.9° and 19.6°N, 211.8°E with A95 = 10.7°, respectively. We suggest that the Lhasa Terrane maintained a relative stable latitude (16.5 ± 3.9°S and 18.4 ± 10.7°S) in the southern hemisphere during the Triassic Period before moving northwards and amalgamating with the main body of Eurasia. The Qiangtang and Lhasa terranes, which were located at the mid-low latitudes of the southern hemisphere, might have been isolated between Eurasia and Gondwanaland since the Early Triassic Period. The Meso-Tethys, potentially represented by the Bangong-Nujiang suture zone (BNS) between the Lhasa and Qiangtang terranes, opened up in the Early-Middle Triassic Period and expanded during the entire course of the Triassic Period.

  19. Feedback in low-mass galaxies in the early Universe.

    Science.gov (United States)

    Erb, Dawn K

    2015-07-09

    The formation, evolution and death of massive stars release large quantities of energy and momentum into the gas surrounding the sites of star formation. This process, generically termed 'feedback', inhibits further star formation either by removing gas from the galaxy, or by heating it to temperatures that are too high to form new stars. Observations reveal feedback in the form of galactic-scale outflows of gas in galaxies with high rates of star formation, especially in the early Universe. Feedback in faint, low-mass galaxies probably facilitated the escape of ionizing radiation from galaxies when the Universe was about 500 million years old, so that the hydrogen between galaxies changed from neutral to ionized-the last major phase transition in the Universe.

  20. Do early life factors influence body mass index in adolescents?

    Directory of Open Access Journals (Sweden)

    M.Z. Goldani

    Full Text Available The association between early life factors and body mass index (BMI in adulthood has been demonstrated in developed countries. The aim of the present study was to assess the influence of early life factors (birth weight, gestational age, maternal smoking, and social class on BMI in young adulthood with adjustment for adult socioeconomic position. A cohort study was carried out in 1978/79 with 6827 mother-child pairs from Ribeirão Preto city, located in the most developed economic area of the country. Biological, economic and social variables and newborn anthropometric measurements were obtained shortly after delivery. In 1996, 1189 males from this cohort, 34.3% of the original male population, were submitted to anthropometric measurements and were asked about their current schooling on the occasion of army recruitment. A multiple linear regression model was applied to determine variables associated with BMI. Mean BMI was 22.7 (95%CI = 22.5-23.0. After adjustment, BMI was 1.22 kg/m² higher among infants born with high birth weight (³4000 g, 1.21 kg/m² higher among individuals of low social class at birth and 0.69 kg/m² higher among individuals whose mothers smoked during pregnancy (P < 0.05. The association between social class at birth and BMI remained statistically significant (P < 0.05 even after adjustment for adult schooling. These findings suggest that early life social influences on BMI were more important and were not reversed by late socioeconomic position. Therefore, prevention of overweight and obesity should focus not only on changes in adult life styles but also on factors such as high birth weight.

  1. Permian-Triassic Wildfire Gap Responses to the Mass Extinction-An Example Study in the Meishan Section,Zhejiang Province%二叠纪-三叠纪野火间断事件对生物灭绝的响应--以浙江煤山剖面为例

    Institute of Scientific and Technical Information of China (English)

    沈文杰; 钟莉莉; 林杨挺; 孙永革; 张华; 杨志军; 周永章

    2014-01-01

    Great changes occurred in the earth’s surrounding environments during the Permian-Triassic (P-Tr)transition and resulted in the collapse of land and marine ecosystems.Thus,the most severe mass extinction in the earth’s history appeared across the P-Tr boundary.Wildfire,as a key ecosystem driver and climate change indicator,is seldom reported in the documents of the pre-Quaternary researches.In this study,a 521 ka record of wildfire during the P-Tr mass extinction was recurred through the black car-bon (BC)and combustion-derived polycyclic aromatic hydrocarbons (PAHs)records in the GSSP section of Meishan.There were frequent wildfires in the 163 ka of history just before the P-Tr mass extinction and the most intensive one occurred in the mass extinction event beds.No combustion records were found in the beds above mass extinction line and a wildfire gap (lasting 358 ka)was recognized in the Early Trias-sic.Wildfire gap may be not a local phenomenon,but a response of global climatic and environmental changes.Wildfire would vanish accompanied by the destruction of land vegetation and abrupt drop of at-mospheric oxygen.Therefore,Meishan P-Tr wildfire gap can be used as an indicator of the mass extinc-tion.%二叠纪末期地球气候环境发生重大变化,导致陆地和海洋生态系统崩溃,发生了地质历史上最大规模的生物灭绝事件。大火(亦称野火)作为陆地生态系统的关键影响因子,以及气候环境变化的重要指标,在第四纪以前的历史研究中很少有报道。剖析了煤山二叠纪-三叠纪界线521 ka黑碳和燃烧源多环芳烃的沉积记录,恢复了生物灭绝前后的大火历史。研究显示,生物灭绝前的163 ka内大火频繁,在生物灭绝时则发生了最大规模的大火事件;生物灭绝线以上早三叠世地层中未发现燃烧的记录,出现了大火事件间断(时间持续约358 ka)。对比全球多个剖面,这种大火间断事件可能不是局

  2. Stratigraphy, biostratigraphy and C-isotopes of the Permian-Triassic non-marine sequence at Dalongkou and Lucaogou, Xinjiang Province, China

    Science.gov (United States)

    Metcalfe, I.; Foster, C. B.; Afonin, S. A.; Nicoll, R. S.; Mundil, R.; Xiaofeng, Wang; Lucas, S. G.

    2009-11-01

    Measured lithostratigraphic sections of the classic Permian-Triassic non-marine transitional sequences covering the upper Quanzijie, Wutonggou, Guodikeng and lower Jiucaiyuan Formations at Dalongkou and Lucaogou, Xinjiang Province, China are presented. These measured sections form the framework and reference sections for a range of multi-disciplinary studies of the P-T transition in this large ancient lake basin, including palynostratigraphy, vertebrate biostratigraphy, chemostratigraphy and magnetostratigraphy. The 121 m thick Wutonggou Formation at Dalongkou includes 12 sandstone units ranging in thickness from 0.5 to 10.5 m that represent cyclical coarse terrigenous input to the lake basin during the Late Permian. The rhythmically-bedded, mudstone-dominated Guodikeng Formation is 197 m and 209 m thick on the north and south limbs of the Dalongkou anticline, respectively, and 129 m thick at Lucaogou. Based on limited palynological data, the Permian-Triassic boundary was previously placed approximately 50 m below the top of this formation at Dalongkou. This boundary does not coincide with any mappable lithologic unit, such as the basal sandstones of the overlying Jiucaiyuan Formation, assigned to the Early Triassic. The presence of multiple organic δ13C-isotope excursions, mutant pollen, and multiple algal and conchostracan blooms in this formation, together with Late Permian palynomorphs, suggests that the Guodikeng Formation records multiple climatic perturbation signals representing environmental stress during the late Permian mass extinction interval. The overlap between the vertebrates Dicynodon and Lystrosaurus in the upper part of this formation, and the occurrence of late Permian spores and the latest Permian to earliest Triassic megaspore Otynisporites eotriassicus is consistent with a latest Permian age for at least part of the Guodikeng Formation. Palynostratigrahic placement of the Permian-Triassic boundary in the Junggar Basin remains problematic

  3. Provincialization of terrestrial faunas following the end-Permian mass extinction.

    Science.gov (United States)

    Sidor, Christian A; Vilhena, Daril A; Angielczyk, Kenneth D; Huttenlocker, Adam K; Nesbitt, Sterling J; Peecook, Brandon R; Steyer, J Sébastien; Smith, Roger M H; Tsuji, Linda A

    2013-05-14

    In addition to their devastating effects on global biodiversity, mass extinctions have had a long-term influence on the history of life by eliminating dominant lineages that suppressed ecological change. Here, we test whether the end-Permian mass extinction (252.3 Ma) affected the distribution of tetrapod faunas within the southern hemisphere and apply quantitative methods to analyze four components of biogeographic structure: connectedness, clustering, range size, and endemism. For all four components, we detected increased provincialism between our Permian and Triassic datasets. In southern Pangea, a more homogeneous and broadly distributed fauna in the Late Permian (Wuchiapingian, ∼257 Ma) was replaced by a provincial and biogeographically fragmented fauna by Middle Triassic times (Anisian, ∼242 Ma). Importantly in the Triassic, lower latitude basins in Tanzania and Zambia included dinosaur predecessors and other archosaurs unknown elsewhere. The recognition of heterogeneous tetrapod communities in the Triassic implies that the end-Permian mass extinction afforded ecologically marginalized lineages the ecospace to diversify, and that biotic controls (i.e., evolutionary incumbency) were fundamentally reset. Archosaurs, which began diversifying in the Early Triassic, were likely beneficiaries of this ecological release and remained dominant for much of the later Mesozoic.

  4. Characteristics and origin of Early Triassic vermicular limestone in Chongqing area,China%重庆地区早三叠世蠕虫状灰岩特征及成因

    Institute of Scientific and Technical Information of China (English)

    程明; 时志强; 王湘君; 王艳艳; 金鑫; 段雄; 崔磊

    2014-01-01

    The vermicular limestone is one of the anachronistic limestone and widespread in the Lower Triassic Feixianguan Formation and Jialingjiang Formation in the Chongqing area.In terms of detailed field observation,sampling,thin-section identification,SEM,etc.for more than 10 sections,it is considered that the vermicular limestone consists of dark vermicuform bodies and light-coloured tint matrixes,among which the vermicuform bodies are in varied shapes.The main composition of the vermicuform bodies is calcite,whose content is above 95%.The matrix has more clay content,whose calcite unexpectedly reaches 85% ~ 90%.There are few metazoan fossils that can be found in vermicular limestone,but pyrite and algae are observed under the microscope.According to the shape,the vermicular limestone is divided into three types,that is,laminar-like limestone,spot-like limestone and messy-like vermicular limestone.The formation of the vermicular limestone is related to cyanobacteria or algae activities,and the storms play a very important role in the process of its formation.The disturbance of metazoans (e.g.brachiopods,gastropods and bivalves)will inhibit the development of the vermicular limestone,thus the genesises of the vermicular limestone are biological and mechanical.The formation of the vermicular limestone is owing to such extremely grim conditions of the Early Triassic Tethys Ocean such as the high seawater temperature,high content of CO2 ,low content of O2 ,stagnant anoxia environments and frequent storms,etc.%重庆地区早三叠世沉积中广泛发育一种“错时相”灰岩---蠕虫状灰岩。通过对重庆地区十余条典型剖面飞仙关组及嘉陵江组进行野外观察、采样及室内薄片鉴定、扫描电镜研究,认为蠕虫状灰岩由形似蠕虫的“蠕体”和浅色基质组成,其中蠕体形态多样,常呈条带状、粒状、不规则状发育于基质中,蠕体的主要成分为方解石(质量分数高达95%以上),基

  5. Early adolescent Body Mass Index and the constructed environment.

    Science.gov (United States)

    Jones, Randall M; Vaterlaus, J Mitchell

    2014-07-01

    Previous research has shown that macro-level environmental features such as access to walking trails and recreational facilities are correlated with adolescent weight. Additionally, a handful of studies have documented relationships between micro-level environmental features, such as the presence (or absence) of a television in the bedroom, and adolescent weight. In this exploratory study we focus exclusively on features of the micro-level environment by examining objects that are found within adolescent personal bedrooms in relation to the adolescent occupant's Body Mass Index score (BMI). Participants were 234 early adolescents (eighth graders and ninth graders) who lived with both biological parents and who had their own private bedroom. Discriminant analyses were used to identify the bedrooms belonging to adolescents with below and above average BMI using objects contained within the micro-level environment as discriminating variables. Bedrooms belonging to adolescents with above average BMI were more likely to contain objects associated with sedentary behavior (e.g., magazines, electronic games, dolls), whereas the bedrooms belonging to the average and below average BMI adolescents were more likely to contain objects that reflect past physical activity (e.g., trophies, souvenirs, pictures of places that they had visited). If causal connections between micro-environmental variables and adolescent BMI can be established in future longitudinal research, environmental manipulations may affect adolescent BMI. Copyright © 2014 The Foundation for Professionals in Services for Adolescents. Published by Elsevier Ltd. All rights reserved.

  6. Thermal evolution characteristics of Triassic coal in Chuxiong Basin and its geological significance

    Institute of Scientific and Technical Information of China (English)

    Wang Meng; Li Xiaoping; Dai Xuguang

    2016-01-01

    Chuxiong Basin in Yunnan is a typical Mesozoic foreland basin which is enriched in widely distributed Triassic coal resources with thick deposits and of important strategic significance. By applying vitrinite reflectance measurement, inclusion thermometry, fission track dating and EASY%Ro numerical simula-tion, the Triassic coal thermal evolution history of the Chuxiong Basin was analyzed, and the results were concluded. The vitrinite reflectance of Chuxiong Basin is higher in the west and south in general. Vertically, in the east, west, and north of the basin, the vitrinite reflectance increases with increasing depth, and in the northern part, exceptionally high values occur, and there is no significant regularity in the east. The formation of inclusions inside quartz veins in Chuxiong Basin Triassic coal are unrelated with magmatic hydrothermal fluid, and there are multi-phase inclusions formed in three or four sections of tectonic movements. The main heating period (apparent age) of the Triassic coal is concentrated in the late Cenozoic, during which the coal was subjected to repeated thermal disturbance, resulting in a mul-timodal distribution of the fission track data, which reveals mild burial features of the early stages of the Late Cenozoic. The Triassic coal of Chuxiong Basin has experienced two major temperature increasing processes, which occurred in the early-mid Yanshan and the early Himalayan, respectively. The first hydrocarbon generation period of coal organic matter occurred in the formation stage of the foreland basin, during which the south and west of the basin generated large amounts of hydrocarbon, but little was preserved. The second generation stage in the Early Himalayan had conditions suitable for high gas accumulation, especially in the western and southern regions. The upper Triassic coal is of moderate bur-ial depth and is less affected by the strike-slip effect. There are key areas of Chuxiong Basin oil and gas exploration, such as the

  7. Stratigraphical and palaeogeographical significance of the continental sedimentary transition across the Permian–Triassic boundary in Spain

    OpenAIRE

    2005-01-01

    The Permian–Triassic transition, a time of phenomenal palaeoenvironmental and palaeogeographical change, represents the largest episode of mass extinctions known to palaeontologists. This episode is, however, very poorly understood, and a lack of sediments and palaeontological data, particularly in the continental record, is a feature common to every basin. Despite compelling information on the continental Permian–Triassic boundary (PTB) emerging from recent efforts evaluating verteb...

  8. Triassic deep-marine sedimentation in the western Qinling and Songpan terrane

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Triassic and lower portion of Middle Triassic successions in the northern Songpan terrane is similar to that of the Dangchang-Diebu region of the western Qinling, as manifested by development of Lower-early Middle Triassic shallow-marine carbonate and a rapid shift to base-of-slope apron sediments since the Ladinian.

  9. Synchronous wildfire activity rise and mire deforestation at the triassic-jurassic boundary.

    Directory of Open Access Journals (Sweden)

    Henrik I Petersen

    Full Text Available The end-Triassic mass extinction event (∼201.4 million years ago caused major faunal and floral turnovers in both the marine and terrestrial realms. The biotic changes have been attributed to extreme greenhouse warming across the Triassic-Jurassic (T-J boundary caused by massive release of carbon dioxide and/or methane related to extensive volcanism in the Central Atlantic Magmatic Province (CAMP, resulting in a more humid climate with increased storminess and lightning activity. Lightning strikes are considered the primary source of wildfires, producing charcoal, microscopically recognized as inertinite macerals. The presence of polycyclic aromatic hydrocarbons (PAHs of pyrolytic origin and allochthonous charcoal in siliciclastic T-J boundary strata has suggested widespread wildfire activity at the time. We have investigated largely autochthonous coal and coaly beds across the T-J boundary in Sweden and Denmark. These beds consist of predominantly organic material from the in situ vegetation in the mires, and as the coaly beds represent a substantial period of time they are excellent environmental archives. We document a remarkable increase in inertinite content in the coal and coaly beds across the T-J boundary. We show estimated burning temperatures derived from inertinite reflectance measurements coupled with palynological data and conclude that pre-boundary late Rhaetian mire wildfires included high-temperature crown fires, whereas latest Rhaetian-Sinemurian mire wildfires were more frequent but dominated by lower temperature surface fires. Our results suggest a major change in the mire ecosystems across the T-J boundary from forested, conifer dominated mires to mires with a predominantly herbaceous and shrubby vegetation. Contrary to the overall regional vegetation for which onset of recovery commenced in the early Hettangian, the sensitive mire ecosystem remained affected during the Hettangian and did not start to recover until around

  10. Biofacies evolution in the Triassic platforms of the Dolomites, Italy

    Directory of Open Access Journals (Sweden)

    Franco Russo

    2005-10-01

    Full Text Available The Triassic of the Dolomites includes many carbonate platform generations, ranging in age from the Anisian to the Norian-Rhaetian. After the Permian-Triassic biological crisis, “reef” communities reappeared during the Anisian time. These buildups were generally characterized by a limited relief, lacking any primary skeletal framework and evidence of syndepositional cementation. The microfacies are dominated by micrites, mainly allochthonous or detrital in origin. The sparse biota are generally binder and buffler organisms, such as dasycladacean algae, sphinctozoans and briozoans.The second generation of carbonate buildups (late Anisian–early Ladinian, Sciliar Fm are dominated by syndepositional cements (e.g. Marmolada Platform. These cements represent the main component of margin and upper slope facies. They form more or less isolated or laterally linked bodies: the “evinosponges”. During the late Ladinian and Carnian p.p., the post-volcanic platforms developed (Cassian Dolomite. The microfacies of these platforms manly consist of micrites, cements and skeletons. The automicrites constitute more than 50% of the rock volume, the cements the 20%, and the skeletal organisms less than the 10%. The metazoan contribution is subordinated to that of skeletal cyanobacteria, like Cladogirvanella cipitensis and microproblematica, like Tubyphites. The primary marine cements provide evidence of a widespread early syndepositional lithification. Towards the top of Julian Substage (Carnian, at the base of the Heiligkreutz/Dürrenstein Formation (i.e. Alpe di Specie, small calcareous bioconstructions, interpreted as patch-reefs, show a much more “modern” faunal association. For the first time in the Triassic, a primary skeletal framework developed, largely formed by calcified demosponges and scleractinians. Corals were still subordinated to sponges. Taxonomic diversity increases greatly and the skeletal component exceeds the 50% of the rock volume

  11. Triassic rift-related sedimentary basins in northern Chile (24° 29°S)

    Science.gov (United States)

    Suarez, M.; Bell, C. M.

    1992-10-01

    Triassic rocks in northern Chile (latitude 24°-29°S) include marine and continental rift-related sedimentary deposits, associated with basaltic, andesitic, and silicic volcanic rocks. Five main successions include the deposits of two marine basins (Profeta and San Félix) separated by three continental basins (Cifuncho, La Ternera, and La Coipa). The marine strata include turbidites and debris flow deposits interpreted as coarse-grained fan-delta sediments. The continental sediments include lacustrine fan delta, open lake, braided river, alluvial fan, and sabkha deposits. The widespread fan-delta systems (both marine and lacustrine), together with abrupt lateral and vertical facies discontinuities and large-scale depositional cycles, are indicative of rift-controlled sedimentation. The associated magmatic activity indicates that this rifting was the product of subduction-related extension or strike-slip movement on the active plate margin. Triassic rifting was followed in Late Triassic to Early Jurassic times by widespread thermotectonic subsidence.

  12. The end-Triassic negative δ13C excursion : A lithologic test

    NARCIS (Netherlands)

    Bachan, Aviv; van de Schootbrugge, Bas; Payne, Jonathan L.

    2014-01-01

    The end-Triassic mass extinction is associated with a large negative carbon isotope excursion, which has been interpreted as reflecting the rapid injection of 13C depleted CO2 or methane associated with the emplacement of the Central Atlantic Magmatic Province. However, in a number of sections in ce

  13. A tale of two extinctions : converging end-Permian and end-Triassic scenarios

    NARCIS (Netherlands)

    van de Schootbrugge, Bas; Wignall, Paul B.

    2016-01-01

    The end-Permian (c. 252 Ma) and end-Triassic (c. 201 Ma) mass-extinction events are commonly linked to the emplacement of the large igneous provinces of the Siberia Traps and Central Atlantic Magmatic Province, respectively. Accordingly, scenarios for both extinctions are increasingly convergent and

  14. Astronomical age constraints and extinction mechanisms of the Late Triassic Carnian crisis

    NARCIS (Netherlands)

    Miller, C.S.; Peterse, F; Da Silva, A.-C.; Baranyi, V.; Reichart, G.J.; Kürschner, W.M.

    2017-01-01

    The geological record contains evidence for numerous pronounced perturbations in the global carboncycle, some of which are associated with mass extinction. In the Carnian (Late Triassic), evidence fromsedimentology and fossil pollen points to a significant change in climate, resulting in biotic

  15. Additive effects of acidification and mineralogy on calcium isotopes in Triassic/Jurassic boundary limestones

    NARCIS (Netherlands)

    Jost, Adam B.; Bachan, Aviv; van de Schootbrugge, Bas; Brown, Shaun T.; Depaolo, Donald J.; Payne, Jonathan L.

    The end-Triassic mass extinction coincided with a negative δ13C excursion, consistent with release of 13C-depleted CO2 from the Central Atlantic Magmatic Province. However, the amount of carbon released and its effects on ocean chemistry are poorly constrained. The coupled nature of the carbon and

  16. Alkane Biomarkers in Permian-Triassic Boundary Strata at Meishan Section, Changxing,Zhejiang Province

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    Meishan Section D in Changxing County, Zhejiang Province, China has been selected as the global stratotype of the Permian-Triassic boundary and various studies have been done at the boundary, but the gas chromatographic-mass spectrographic analysis of alkane biomarkers has not been investigated. This paper presents the results of a study of the biomarkers analyzed in a series of samples across the Permian-Triassic boundary at both Meishan Section A and Section D. The results show that the overall concentration of alkane biomarkers in the Permian-Triassic boundary strata is high in Bed 26 while it is low in Bed 27. A variety of biomarker parameters demonstrate that the main sources of organic matter in the sediment are algae and bacteria and that the depositional environment varied from weakly oxidizing to reducing during the studied interval.

  17. Absence of Suction Feeding Ichthyosaurs and Its Implications for Triassic Mesopelagic Paleoecology

    Science.gov (United States)

    Motani, Ryosuke; Ji, Cheng; Tomita, Taketeru; Kelley, Neil; Maxwell, Erin; Jiang, Da-yong; Sander, Paul Martin

    2013-01-01

    Mesozoic marine reptiles and modern marine mammals are often considered ecological analogs, but the extent of their similarity is largely unknown. Particularly important is the presence/absence of deep-diving suction feeders among Mesozoic marine reptiles because this would indicate the establishment of mesopelagic cephalopod and fish communities in the Mesozoic. A recent study suggested that diverse suction feeders, resembling the extant beaked whales, evolved among ichthyosaurs in the Triassic. However, this hypothesis has not been tested quantitatively. We examined four osteological features of jawed vertebrates that are closely linked to the mechanism of suction feeding, namely hyoid corpus ossification/calcification, hyobranchial apparatus robustness, mandibular bluntness, and mandibular pressure concentration index. Measurements were taken from 18 species of Triassic and Early Jurassic ichthyosaurs, including the presumed suction feeders. Statistical comparisons with extant sharks and marine mammals of known diets suggest that ichthyosaurian hyobranchial bones are significantly more slender than in suction-feeding sharks or cetaceans but similar to those of ram-feeding sharks. Most importantly, an ossified hyoid corpus to which hyoid retractor muscles attach is unknown in all but one ichthyosaur, whereas a strong integration of the ossified corpus and cornua of the hyobranchial apparatus has been identified in the literature as an important feature of suction feeders. Also, ichthyosaurian mandibles do not narrow rapidly to allow high suction pressure concentration within the oral cavity, unlike in beaked whales or sperm whales. In conclusion, it is most likely that Triassic and Early Jurassic ichthyosaurs were ‘ram-feeders’, without any beaked-whale-like suction feeder among them. When combined with the inferred inability for dim-light vision in relevant Triassic ichthyosaurs, the fossil record of ichthyosaurs does not suggest the establishment of modern

  18. Absence of suction feeding ichthyosaurs and its implications for triassic mesopelagic paleoecology.

    Science.gov (United States)

    Motani, Ryosuke; Ji, Cheng; Tomita, Taketeru; Kelley, Neil; Maxwell, Erin; Jiang, Da-yong; Sander, Paul Martin

    2013-01-01

    Mesozoic marine reptiles and modern marine mammals are often considered ecological analogs, but the extent of their similarity is largely unknown. Particularly important is the presence/absence of deep-diving suction feeders among Mesozoic marine reptiles because this would indicate the establishment of mesopelagic cephalopod and fish communities in the Mesozoic. A recent study suggested that diverse suction feeders, resembling the extant beaked whales, evolved among ichthyosaurs in the Triassic. However, this hypothesis has not been tested quantitatively. We examined four osteological features of jawed vertebrates that are closely linked to the mechanism of suction feeding, namely hyoid corpus ossification/calcification, hyobranchial apparatus robustness, mandibular bluntness, and mandibular pressure concentration index. Measurements were taken from 18 species of Triassic and Early Jurassic ichthyosaurs, including the presumed suction feeders. Statistical comparisons with extant sharks and marine mammals of known diets suggest that ichthyosaurian hyobranchial bones are significantly more slender than in suction-feeding sharks or cetaceans but similar to those of ram-feeding sharks. Most importantly, an ossified hyoid corpus to which hyoid retractor muscles attach is unknown in all but one ichthyosaur, whereas a strong integration of the ossified corpus and cornua of the hyobranchial apparatus has been identified in the literature as an important feature of suction feeders. Also, ichthyosaurian mandibles do not narrow rapidly to allow high suction pressure concentration within the oral cavity, unlike in beaked whales or sperm whales. In conclusion, it is most likely that Triassic and Early Jurassic ichthyosaurs were 'ram-feeders', without any beaked-whale-like suction feeder among them. When combined with the inferred inability for dim-light vision in relevant Triassic ichthyosaurs, the fossil record of ichthyosaurs does not suggest the establishment of modern

  19. Absence of suction feeding ichthyosaurs and its implications for triassic mesopelagic paleoecology.

    Directory of Open Access Journals (Sweden)

    Ryosuke Motani

    Full Text Available Mesozoic marine reptiles and modern marine mammals are often considered ecological analogs, but the extent of their similarity is largely unknown. Particularly important is the presence/absence of deep-diving suction feeders among Mesozoic marine reptiles because this would indicate the establishment of mesopelagic cephalopod and fish communities in the Mesozoic. A recent study suggested that diverse suction feeders, resembling the extant beaked whales, evolved among ichthyosaurs in the Triassic. However, this hypothesis has not been tested quantitatively. We examined four osteological features of jawed vertebrates that are closely linked to the mechanism of suction feeding, namely hyoid corpus ossification/calcification, hyobranchial apparatus robustness, mandibular bluntness, and mandibular pressure concentration index. Measurements were taken from 18 species of Triassic and Early Jurassic ichthyosaurs, including the presumed suction feeders. Statistical comparisons with extant sharks and marine mammals of known diets suggest that ichthyosaurian hyobranchial bones are significantly more slender than in suction-feeding sharks or cetaceans but similar to those of ram-feeding sharks. Most importantly, an ossified hyoid corpus to which hyoid retractor muscles attach is unknown in all but one ichthyosaur, whereas a strong integration of the ossified corpus and cornua of the hyobranchial apparatus has been identified in the literature as an important feature of suction feeders. Also, ichthyosaurian mandibles do not narrow rapidly to allow high suction pressure concentration within the oral cavity, unlike in beaked whales or sperm whales. In conclusion, it is most likely that Triassic and Early Jurassic ichthyosaurs were 'ram-feeders', without any beaked-whale-like suction feeder among them. When combined with the inferred inability for dim-light vision in relevant Triassic ichthyosaurs, the fossil record of ichthyosaurs does not suggest the

  20. 广西十万大山调查区晚三叠世至早侏罗世聚煤规律研究%Research on the coal accumulation regularity of Shiwandashan survey area in Guangxi during Late Triassic epoch to Early Jurassic

    Institute of Scientific and Technical Information of China (English)

    张新柱; 李居奎; 姚存伟

    2015-01-01

    Taking the Shiwandashan prospecting area during Late Triassic epoch to Early Ju-rassic as the research obj ect,the coal seam properties,main coal seam distribution,main coal-controlling factors and coal forming pattern were discussed on the basis of detail field geological investigation and laboratory analysis. The results showed that the main coal-bearing formation was Fulongao Formation of Upper Triassic,especially the upper fourth section,the coal-bearing property of Lower Triassic was very bad. The coal distribution scale was not large,most of the coal seams were carbon mudstone lamina,mudstone containing carbon or extremely thin coal seam except three layers of minable seams or local minable seams. The lateral distribution of coal seam was inhomogenous obviously,it concentrated mainly in mid-eastern region of investigation area which located between Shiwandashan forest park and Pinghehuai,and distributed discontinu-ously. The coal formation controlling factors were mainly sedimentary environment and paleoto-pography. The coal-forming environment was depression between alluvial fans.%以广西十万大山勘查区晚三叠世至早侏罗世为研究对象,在详细野外地质调查和实验室分析的基础上探讨研究区主要含煤层段的性质、主要煤层的分布、主要控煤因素及成煤模式。研究表明调查区主要含煤地层为上三叠统扶隆坳组,尤其是第四段上部,下侏罗统含煤性则极差。煤层分布规模不大,除了3层可采或局部可采煤层以外,绝大多数均为薄层炭质泥岩、含炭泥岩或煤线。煤层分布具有明显的不均一性,主要集中于调查区中东部十万大山森林公园与平和怀之间,并呈透镜体状不连续地展布。煤炭形成的控制因素主要为沉积环境和古地形。成煤环境主要为冲积扇扇间洼地。

  1. Recovery and diversification of marine communities following the late Permian mass extinction event in the western Palaeotethys

    Science.gov (United States)

    Foster, William J.; Sebe, Krisztina

    2017-08-01

    The recovery of benthic invertebrates following the late Permian mass extinction event is often described as occurring in the Middle Triassic associated with the return of Early Triassic Lazarus taxa, increased body sizes, platform margin metazoan reefs, and increased tiering. Most quantitative palaeoecological studies, however, are limited to the Early Triassic and the timing of the final phase of recovery is rarely quantified. Here, quantitative abundance data of benthic invertebrates were collected from the Middle Triassic (Anisian) succession of the Mecsek Mountains (Hungary), and analysed with univariate and multivariate statistics to investigate the timing of recovery following the late Permian mass extinction. These communities lived in a mixed siliciclastic-carbonate ramp setting on the western margin of the Palaeotethys Ocean. The new data presented here is combined with the previously studied Lower Triassic succession of the Aggtelek Karst (Hungary), which records deposition of comparable facies and in the same region of the Palaeotethys Ocean. The Middle Triassic benthic fauna can be characterised by three distinct ecological states. The first state is recorded in the Viganvár Limestone Formation representing mollusc-dominated communities restricted to above wave base, which are comparable to the lower and mid-Spathian Szin Marl Formation faunas. The second state is recorded in the Lapis Limestone Formation and records extensive bioturbation that is not limited to wave base and is comparable to the upper Spathian Szinpetri Limestone Formation. The third ecological state occurs in the Zuhánya Limestone Formation which was deposited in the Pelsonian Binodosus Zone, and has a more 'Palaeozoic' structure with sessile brachiopods dominating assemblages for the first time in the Mesozoic. The return of community-level characteristics to pre-extinction levels and the diversification of invertebrates suggests that the final stages of recovery and the radiation

  2. Mass Extinctions in Earth's History

    Science.gov (United States)

    Ward, P. D.

    2002-12-01

    Mass extinctions are short intervals of elevated species death. Possible causes of Earth's mass extinctions are both external (astronomical) and internal (tectonic and biotic changes from planetary mechanisms). Paleontologists have identified five "major" mass extinctions (>50 die-off in less than a million years) and more than 20 other minor events over the past 550 million years. Earlier major extinction events undoubtedly also occurred, but we have no fossil record; these were probably associated with, for example, the early heavy bombardment that cleared out the solar system, the advent of oxygen in the atmosphere, and various "snowball Earth" events. Mass extinctions are viewed as both destructive (species death ) and constructive, in that they allow evolutionary innovation in the wake of species disappearances. From an astrobiological perspective, mass extinctions must be considered as able both to reduce biodiversity and even potentially end life on any planet. Of the five major mass extinctions identified on Earth, only one (the Cretaceous/Tertiary event 65 million years ago that famously killed off the dinosaurs ) is unambiguously related to the impact of an asteroid or comet ( 10-km diameter). The Permian/Triassic (250 Myr ago) and Triassic/Jurassic (202 Myr ago) events are now the center of debate between those favoring impact and those suggesting large volume flooding by basaltic lavas. The final two events, Ordovician (440 Myr ago) and Devonian (370 Myr ago) have no accepted causal mechanisms.

  3. Large Igneous Province Volcanism, Ocean Anoxia and Marine Mass Extinction

    DEFF Research Database (Denmark)

    Ruhl, Micha; Bjerrum, Christian J.; Canfield, Donald

    2013-01-01

    -Triassic (~252 Ma) boundaries, which coincide with Central Atlantic Magmatic Province (CAMP) and Siberian Trap volcanism, respectively. The Triassic-Jurassic mass extinction is often contributed to carbon release driven ocean acidification while the Permian-Triassic mass extinction is suggested to be related...... to widespread ocean anoxia. We compare Permian-Triassic and Triassic-Jurassic ocean redox change along continental margins in different geographic regions (Permian-Triassic: Greenland, Svalbard, Iran; Triassic-Jurassic: UK, Austria) and discuss its role in marine mass extinction. Speciation of iron [(FeHR/ Fe...... extinctions however shows 2 phases of euxinia along continental margins, with an initial short peak at the onset of volcanism followed by a shift to ferruginous conditions, possibly due to a strongly diminished ocean sulphate reservoir because of massive initial pyrite burial. D34Spyrite suggests...

  4. The Inception of the Colorado Plateau Coring Project: Filling the Triassic Geochronologic Gap and Providing a Continuous Record of Continental Environmental Change in Western Equatorial Pangea

    Science.gov (United States)

    Geissman, J. W.; Olsen, P. E.; Kent, D. V.; Irmis, R. B.; Gehrels, G. E.; Mundil, R.; Parker, W.; Bachmann, G. H.; Kurschner, W. M.; Sha, J.

    2014-12-01

    The Triassic Period was punctuated by two of the largest Phanerozoic mass-extinctions and witnessed the evolution of elements of the modern biota and the advent of the age of dinosaurs. A rich archive of biotic and environmental changes on land for the early Mesozoic is on the Colorado Plateau, which despite over 100 years of study still remains poorly calibrated in time and poorly registered to other global records. Over 15 years ago, a diverse team of scientists began to develop the concept of a multi-phase, long term Colorado Plateau Coring Project (CPCP). Planning involved two major meetings (DOSECC/NSFICDP supported in Fall, 2007, St. George, UT; and International Continental Drilling Program (ICDP) supported in Spring, 2009, Albuquerque, NM). The National Park Service embraced the concept of Phase One drilling at Petrified Forest National Park (PFNP) in northern Arizona, which exposes one of the most famous and best studied successions of the continental Triassic on Earth, and the Phase One target was decided. Most drilling operation costs were secured from ICDP in Summer, 2010. In late 2013, following more recent NSF support, the research team, utilizing Ruen Drilling Inc., drilled a continuous ~530 m core (60o plunge) through the entire section of Triassic strata (Chinle and Moenkopi fms.) in the north end and a ~240 m core (75o plunge) in lower Chinle and all Moenkopi strata at the south end of the PFNP. Our continuous sampling will place this record in a reliable quantitative and exportable time scale, as a reference section in which magnetostratigraphic, geochronologic, environmental, and paleontologic data are registered to a common thickness scale with unambiguous superposition using pristine samples. The cores are being scanned at the High Resolution X-ray Computed Tomography Facility at UT Austin. They will be transported to the LacCore National Lacustrine Core Facility at U Minnesota, where they will be split, imaged, and scanned for several

  5. Trace Metals, Rare Earths, Carbon and Pb Isotopes as Proxies of Environmental Catastrophe at the Permian - Triassic Boundary in Spiti Himalayas, India

    Science.gov (United States)

    Ghosh, N.; Basu, A. R.; Garzione, C. N.; Ghatak, A.; Bhargava, O. N.; Shukla, U. K.; Ahluwalia, A. D.

    2015-12-01

    Himalayan sediments from Spiti Valley, India preserve geochemical signatures of the Permian - Triassic (P-Tr) mass extinction in the Neo-Tethys Ocean. We integrate new sedimentological and fossil record with high-resolution geochemical-isotopic data from Spiti that reveals an ecological catastrophe of global proportions. Trace elements of U, Th, Nb, Ta, Zr, Hf, the rare earths (REE) and carbon, oxygen and lead isotopes measured across the P-Tr boundary in Spiti are used as proxies for evaluating abrupt changes in this continental shelf environment. δ13Corg excursions of 2.4‰ and 3.1‰ in Atargu and Guling P-Tr sections in Spiti Valley are associated with an abrupt fall of biological productivity while δ13Ccarb and δ18Ocarb record of these sediments shows effects of diagenesis. Here, the P-Tr boundary is compositionally distinct from the underlying Late Permian gray shales, as a partly gypsiferous ferruginous layer that allows additional geochemical-isotopic investigation of sedimentary sources. Conspicuous Ce - Eu anomalies in the light REE-enriched Late Permian shales reflect the source composition of the adjacent Panjal Trap basalts of Kashmir. An abrupt change of this source to continental crust is revealed by Nb - Ta and Zr - Hf anomalies at the P-Tr ferruginous layer and continuing through the overlying Early Triassic carbonate rocks. Pb concentration and isotope ratios of 206Pb/204Pb, 207Pb/204Pb and 208Pb/204Pb identify changes in the sedimentary element flux, distinguishing the Late Permian shales from the distinct siliciclastic continental crustal signature in the Early Triassic carbonates. These geochemical-isotopic constraints on the sedimentary geochemistry of one of the most critical transitions in geological record establish the utility of multi-proxy datasets for paleoenvironmental reconstructions.

  6. Mass spectrometric determination of early and advanced glycation in biology.

    Science.gov (United States)

    Rabbani, Naila; Ashour, Amal; Thornalley, Paul J

    2016-08-01

    Protein glycation in biological systems occurs predominantly on lysine, arginine and N-terminal residues of proteins. Major quantitative glycation adducts are found at mean extents of modification of 1-5 mol percent of proteins. These are glucose-derived fructosamine on lysine and N-terminal residues of proteins, methylglyoxal-derived hydroimidazolone on arginine residues and N(ε)-carboxymethyl-lysine residues mainly formed by the oxidative degradation of fructosamine. Total glycation adducts of different types are quantified by stable isotopic dilution analysis liquid chromatography-tandem mass spectrometry (LC-MS/MS) in multiple reaction monitoring mode. Metabolism of glycated proteins is followed by LC-MS/MS of glycation free adducts as minor components of the amino acid metabolome. Glycated proteins and sites of modification within them - amino acid residues modified by the glycating agent moiety - are identified and quantified by label-free and stable isotope labelling with amino acids in cell culture (SILAC) high resolution mass spectrometry. Sites of glycation by glucose and methylglyoxal in selected proteins are listed. Key issues in applying proteomics techniques to analysis of glycated proteins are: (i) avoiding compromise of analysis by formation, loss and relocation of glycation adducts in pre-analytic processing; (ii) specificity of immunoaffinity enrichment procedures, (iii) maximizing protein sequence coverage in mass spectrometric analysis for detection of glycation sites, and (iv) development of bioinformatics tools for prediction of protein glycation sites. Protein glycation studies have important applications in biology, ageing and translational medicine - particularly on studies of obesity, diabetes, cardiovascular disease, renal failure, neurological disorders and cancer. Mass spectrometric analysis of glycated proteins has yet to find widespread use clinically. Future use in health screening, disease diagnosis and therapeutic monitoring, and

  7. CALCAREOUS NANNOFOSSILS AT THE TRIASSIC/JURASSIC BOUNDARY: STRATIGRAPHIC AND PALEOCEANOGRAPHIC CHARACTERIZATION

    Directory of Open Access Journals (Sweden)

    CINZIA BOTTINI

    2016-10-01

    Full Text Available In this work, calcareous nannofossils are identified for the first time in the uppermost Triassic sequence of the Lombardy Basin (Southern Calcareous Alps, Italy. Two zones are recognized, namely the NT2b (latest Triassic and the NJT1 (earliest Jurassic. Two species resulted to be good markers to constrain the TJB interval: Prinsiosphaera triassica and Schizosphaerella punctulata. Nannofossil data are calibrated with C isotopic chemostratigraphy obtained for carbonate and organic matter. Size reduction of P. triassica and a decline in the abundance of Triassic nannofossils are detected soon after the “precursor Carbon Isotope Excursion (CIE and culminated during the “initial negative CIE” characterized by lowest nannofossil abundances and small-sized P. triassica. The extinction of Triassic nannofossils occurred in distinctive steps within the “initial negative CIE”, while the Jurassic S. punctulata is first observed at the base of the “main negative CIE”. The latest Triassic nannofossil decline in abundance, size reduction and extinctions, represent a progressive deterioration associated to the Central Atlantic Magmatic Province (CAMP volcanism. Our findings are consistent with nannofossil changes at supraregional scale and indicate that the massive CAMP flood basalts were preceded by initial volcanic pulses. We speculate that a combination of climate change, fertilization and ocean acidification started to influence the calcification process prior to the “initial negative CIE”. Nannoplankton extinctions were not simultaneous and might imply limited capacity for adaptation in the early stages of evolutionary history. However, originations of new taxa soon after the disappearance of Triassic forms suggest the ability to rapidly overcame extreme stressing conditions.

  8. Molecular carbon isotope variations in core samples taken at the Permian-Triassic boundary layers in southern China

    Science.gov (United States)

    Wang, Ruiliang; Zhang, Shuichang; Brassell, Simon; Wang, Jiaxue; Lu, Zhengyuan; Ming, Qingzhong; Wang, Xiaomei; Bian, Lizeng

    2012-07-01

    Stable carbon isotope composition (δ13C) of carbonate sediments and the molecular (biomarker) characteristics of a continuous Permian-Triassic (PT) layer in southern China were studied to obtain geochemical signals of global change at the Permian-Triassic boundary (PTB). Carbonate carbon isotope values shifted toward positive before the end of the Permian period and then shifted negative above the PTB into the Triassic period. Molecular carbon isotope values of biomarkers followed the same trend at and below the PTB and remained negative in the Triassic layer. These biomarkers were acyclic isoprenoids, ranging from C15 to C40, steranes (C27 dominates) and terpenoids that were all significantly more abundant in samples from the Permian layer than those from the Triassic layer. The Triassic layer was distinguished by the dominance of higher molecular weight (waxy) n-alkanes. Stable carbon isotope values of individual components, including n-alkanes and acyclic isoprenoids such as phytane, isop-C25, and squalane, are depleted in δ13C by up to 8-10‰ in the Triassic samples as compared to the Permian. Measured molecular and isotopic variations of organic matter in the PT layers support the generally accepted view of Permian oceanic stagnation followed by a massive upwelling of toxic deep waters at the PTB. A series of large-scale (global) outgassing events may be associated with the carbon isotope shift we measured. This is also consistent with the lithological evidence we observed of white thin-clay layers in this region. Our findings, in context with a generally accepted stagnant Permian ocean, followed by massive upwelling of toxic deep waters might be the major causes of the largest global mass extinction event that occurred at the Permian-Triassic boundary.

  9. Uppermost Permian to Lower Triassic Conodont Zonation from Enshi area, western Hubei Province, South China

    Science.gov (United States)

    Lyu, Z.; Zhao, L.; Chen, Z. Q.; Ma, D.; Yan, P.; Zhan, P.

    2015-12-01

    The Permian-Triassic transition witnessed the largest biotic turnover of Earth life during the Phanerozoic history. Ecosystems in sea and on land have also experienced the most protected restoration following the end-Permian mass extinction. These biocrises were also associated with climatic and environmental extremes through the latest Permian to Middle Triassic. In order to uncover the links among these extreme events, we need to establish high-resolution biochronostratigraphy, which offers precise timescales for reconstructing event sequences and probing the possible causes. Of these, conodont biostratigraphy is an operational tool in enhancing stratigraphic resolution. Although their ancestors and phylogeny remain unclear, conodonts are a rapid evolutionary lineage and extremely abundant in the Triassic marine carbonate successions. Here, we present recent study results of the Lower Triassic conodont zonation from the Ganxi and Jianshi areas, western Hubei Province, South China, which were situated on a carbonate ramp at the southern northern margin of the Upper Yangtze Platform. Therein, the uppermost Permian to Lower Triassic successions are well exposed and yield abundant conodonts. A total of nine conodont zones was established: (1) Clarkina yini-Clarkina zhangi Zone, (2) Hindeodus changxingensis Zone, (3) Hindeodus parvus Zone, (4) Isarcicella staeschei Zone, (5) Clarkina planata Zone, (6) Neoclarkina discrete Zone, (7) Neospathodus dieneri Zone, (8) Novispathodus waageni Zone, and (9) Triassospathodus homeri Zone. The Ns. dieneri M1, Ns. dieneri M2 and Ns. dieneri M3 subzones have also been distinguished from the Ns. dieneri Zone. Both Nv. waageni eowaageni subzones and Nv. waageni waageni subzones are also recognizable from the Nv. waageni Zone. The first occurrence of H. parvus marks the Permian-Triassic boundary(PTB), while the first occurrence of Nv. waageni eowaageni defines the Induan-Olenekian boundary. These conodont zones correlate well with

  10. Geographic range did not confer resilience to extinction in terrestrial vertebrates at the end-Triassic crisis.

    Science.gov (United States)

    Dunhill, Alexander M; Wills, Matthew A

    2015-08-11

    Rates of extinction vary greatly through geological time, with losses particularly concentrated in mass extinctions. Species duration at other times varies greatly, but the reasons for this are unclear. Geographical range correlates with lineage duration amongst marine invertebrates, but it is less clear how far this generality extends to other groups in other habitats. It is also unclear whether a wide geographical distribution makes groups more likely to survive mass extinctions. Here we test for extinction selectivity amongst terrestrial vertebrates across the end-Triassic event. We demonstrate that terrestrial vertebrate clades with larger geographical ranges were more resilient to extinction than those with smaller ranges throughout the Triassic and Jurassic. However, this relationship weakened with increasing proximity to the end-Triassic mass extinction, breaking down altogether across the event itself. We demonstrate that these findings are not a function of sampling biases; a perennial issue in studies of this kind.

  11. Lithofacies, age, and geochemistry of the Otuk Formation (Triassic) in the Red Dog District, northwest Alaska

    Science.gov (United States)

    Dumoulin, Julie A.; Burruss, Robert A.; Blome, Charles D.

    2011-01-01

    A complete penetration of the Otuk Fm. in continuous drill core (DH 927) from the Red Dog District illuminates the facies, age, source rock potential, and isotope stratigraphy of this unit in northwest Alaska. The section, in the Wolverine Creek plate of the Endicott Mountains Allochthon, is ~82 m thick. It gradationally overlies undated gray siliceous mudstone of the Siksikpuk Fm. and underlies undated black organic-rich mudstone of the Kingak(?) Shale. Shale, chert, and limestone members of the Otuk are recognized in DH 927 but the Blankenship Member is absent. The lower (shale) member consists of 28 m of variegated, silty shale with up to 6.9 wt % TOC; thin limy layers near the base contain bivalve fragments (Claraia sp.?) consistent with an Early Triassic (Griesbachian-early Smithian) age. Gray radiolarian chert dominates the middle member (25 m thick) and yields radiolarians of Middle Triassic (Anisian, Ladinian) and Late Triassic (Carnian-Norian) ages; a distinctive, ~2.5-m-thick interval of black shale and calcareous radiolarite ~6 m below the top has 9.8 wt % TOC. The upper (limestone) member (29 m thick) is lime mudstone with monotid bivalves and late Norian radiolarians, overlain by gray chert that contains the first Rhaetian (latest Triassic) radiolarians recognized in the Otuk. Rare black shale interbeds have up to 3.4 wt % TOC. Regional correlations indicate that Otuk lithofacies vary with both structural and geographic position.

  12. Permo-Triassic paleogeographic, paleoclimatic and paleoceanographic evolutions in eastern Tethys and their coupling

    Institute of Scientific and Technical Information of China (English)

    YAN; Jiaxin

    2001-01-01

    [1]Yang, Z. Y., Wu. S. B., Yin, H. E et al., Permo-Triassic Events of South China (in Chinese), Beijing: Geological Publishing House, 1991, 1-180.[2]Jin Y. G., Wang, Y.. Wang, W. et al., Pattern of marine mass extinction near the Permian-Triassic boundary in South China,Science, 2000, 289(5478): 432-36.[3]Ziegler. A. M., Michael, L., Hulver. M. L. et al., Permian world topography and climate, in Late Glacial and Postglacial Environmental Changes——Quaternary, Carboniferous-Permian and Proterozoic (ed., Maitini, I. P.), New York: Oxford Univ. Press, 1997, 111-146.[4]Crowley, T. J., Pangea climate, In Pangea: Paleoclimate, Tectonics and Sedimentation during Accretion, Zenith and Breakup of a Supercontinent (ed., Klein, G. D.), Colorado: Geological Society of America Special Paper 288, 1994,25-39.[5]Parrish, J. T., Climate of the supercontinent Pangea, The Journal of Geology, 1993, 101:215-233.[6]Ziegler. A. M., Phytogeographic patterns and continental configurations during the Permian Period, in Palaeozoic Palaeogeography and Biogeography (eds, McKerrow, W. S., Scotese, C. R.), London: Geological Society Memoir 12, 1990,363-379.[7]Yan, J. X., Liu, B. P., Zhang, H. Q., Palaeogeographic implications of Carboniferous to Permian oolitic limestones in the Changning-Menglian belt of west Yunnan, Journal of Palaeogeography (in Chinese), 1999,1 (3): 13-18.[8]Yin, H. F., Peng, Y. Q., The Triassic of China and its interregional correlation, in Permian-Triassic Evolution of Tethys and Western Circum-Pacific (eds., Yin, H. F., Dickins, J. M., Shi, G. R. et al.), Amsterdam: Elsevier, 2000, 197-220.[9]Yan. J. X.,Permian-Triassic paleoclimatic of eastern Tethys and its paleogeographic implication, Earth Science (in Chinese), 1999, 24(1): 13-20.[10]Yan, J. X., Yin, H. F., Paleoclimatic constraints for Early Permian paleogeography of eastern Tethys, In Permian-Triassic Evolution of Tethys and Western Circum-Pacific (eds., Yin, H, F., Dickins

  13. Behavior of lophophorates during the end-Permian mass extinction and recovery

    Science.gov (United States)

    Powers, Catherine M.; Bottjer, David J.

    2009-11-01

    The end-Permian mass extinction devastated most marine communities and the recovery was a protracted event lasting several million years into the Early Triassic. Environmental and biological processes undoubtedly controlled patterns of recovery for marine invertebrates in the aftermath of the extinction, but are often difficult to single-out. The global diversity and distribution of marine lophophorates during the aftermath of the end-Permian mass extinction indicates that stenolaemate bryozoans, rhynchonelliform brachiopods, and lingulid brachiopods displayed distinct recovery patterns. Bryozoans were the most susceptible of the lophophorates, experiencing relatively high rates of extinction at the end of the Permian, and becoming restricted to the Boreal region during the Early Triassic. The recovery of bryozoans was also delayed until the Late Triassic and characterized by very low diversity and abundance. Following the final disappearance of Permian rhynchonelliform brachiopod survivors, Early Triassic rhynchonelliform brachiopod abundance remained suppressed despite a successful re-diversification and a global distribution, suggesting a decoupling between global taxonomic and ecological processes likely driven by lingering environmental stress. In contrast with bryozoans and rhynchonelliforms, lingulid brachiopods rebounded rapidly, colonizing shallow marine settings left vacant by the extinction. Lingulid dominance, characterized by low diversity but high numerical abundance, was short-lived and they were once again displaced back into marginal settings as environmental stress changed through the marine recovery. The presence in lingulid brachiopods of the respiratory pigment hemerythrin, known to increase the efficacy of oxygen storage and transport, when coupled with other morphological and physiological adaptations, may have given lingulids a survival advantage in environmentally stressed Early Triassic settings.

  14. Using ductoscopy to detect breast mass at an early stage.

    Science.gov (United States)

    Sparks, Carol A

    2002-11-01

    Using a new procedure termed fiberoptic ductoscopy, a surgeon can visualize a patient's breast mammary ducts directly with a 0.9-mm scope. Eighty-five percent of breast cancers are thought to originate in the epithelial lining of the mammary ducts. The hope is that this new technique will allow surgeons to detect breast cancer in high-risk patients before a mass is felt or seen via mammography.

  15. Two pulses of oceanic environmental disturbance during the Permian-Triassic boundary crisis

    Science.gov (United States)

    Shen, Jun; Feng, Qinglai; Algeo, Thomas J.; Li, Chao; Planavsky, Noah J.; Zhou, Lian; Zhang, Mingliang

    2016-06-01

    Pyrite morphology, iron speciation, and pyrite sulfur isotope data from the Xiakou section (Hubei Province, South China) were integrated to explore oceanic environmental variations through the Permian-Triassic transition and their possible relations to the largest mass extinction in Earth history. High ratios of highly-reactive iron to total iron (FeHR/FeT > 0.6) and pyrite iron to highly-reactive iron (FePy/FeHR > 0.7) together with a high abundance of small (mean diameter Permian (pre-extinction interval). High ratios of FeHR/FeT (mostly >0.6) along with lower values of FePy/FeHR (Permian to earliest Triassic (post-extinction interval). The largest fluctuations of these redox proxies are observed in the ∼1.0 m of strata directly overlying the first (latest Permian) extinction horizon, indicating unsettled marine environmental conditions marked by frequent perturbations during the ∼60-kyr interval immediately following the mass extinction. The two largest redox events at Xiakou coincided with deposition of volcanic ash layers that have been correlated with Beds 25 and 28 of the Meishan D section, each of which was associated with an extinction pulse (the first and second extinction horizons of latest Permian and earliest Triassic age, respectively). Thus, our observations document two pulses of oceanic environmental change during the Permian-Triassic transition, each associated with a faunal crisis and possibly triggered by contemporaneous volcanic activity.

  16. The oldest dinosaur? A Middle Triassic dinosauriform from Tanzania.

    Science.gov (United States)

    Nesbitt, Sterling J; Barrett, Paul M; Werning, Sarah; Sidor, Christian A; Charig, Alan J

    2013-02-23

    The rise of dinosaurs was a major event in vertebrate history, but the timing of the origin and early diversification of the group remain poorly constrained. Here, we describe Nyasasaurus parringtoni gen. et sp. nov., which is identified as either the earliest known member of, or the sister-taxon to, Dinosauria. Nyasasaurus possesses a unique combination of dinosaur character states and an elevated growth rate similar to that of definitive early dinosaurs. It demonstrates that the initial dinosaur radiation occurred over a longer timescale than previously thought (possibly 15 Myr earlier), and that dinosaurs and their immediate relatives are better understood as part of a larger Middle Triassic archosauriform radiation. The African provenance of Nyasasaurus supports a southern Pangaean origin for Dinosauria.

  17. Sequence stratigraphy of continental Triassic strata of Southernmost Brazil: a contribution to Southwestern Gondwana palaeogeography and palaeoclimate

    Science.gov (United States)

    Zerfass, Henrique; Lavina, Ernesto Luiz; Schultz, Cesar Leandro; Garcia, Antônio Jorge Vasconcellos; Faccini, Ubiratan Ferrucio; Chemale, Farid

    2003-09-01

    The continental Triassic succession of southernmost Brazil comprises two second-order depositional sequences—the Sanga do Cabral (Early Triassic) and the Santa Maria (Middle to Late Triassic) supersequences. The first one includes ephemeral, low-sinuosity fluvial deposits developed on a low gradient plain. Based on fossil tetrapods, especially procolophonids, an Upper Induan age is estimated for this sequence. Facies association of the Santa Maria Supersequence indicates low-sinuosity fluvial rivers, deltas and lakes. This supersequence can be further subdivided into three third-order sequences (age provided by palaeovertebrate biostratigraphic data) as follows: Santa Maria 1 (Ladinian), Santa Maria 2 (Carnian to Early Norian) and Santa Maria 3 (probably Raethian or Early Jurassic) sequences. The Gondwanides paroxysms I and II in the Sierra de la Ventana-Cape Fold Belt are directly related to the development of both supersequences. The source area of the Sanga do Cabral Supersequence was located to the south. It consisted of an uplifted peripheral bulge situated landward of the retro-foreland system, from where older sedimentary rocks were eroded. The source area of the Santa Maria Supersequence was also positioned southwards and related to the uplifted Sul-Rio-Grandense and Uruguayan shields. The Santa Maria Supersequence stratigraphic architecture is comparable to the Triassic rift basins of Western Argentina. Diagenesis, facies and palaeontology of the studied succession suggest a dominantly semiarid climate during the Triassic.

  18. Evolution and global correlation for strontium isotopic composition of marine Triassic from Huaying Mountains,eastern Sichuan,China

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    Strontium isotope stratigraphy (SIS) has progressively become an efficient chemostratigraphic tool in the research and correlation of global geological events, such as global sea level fluctuations, orogeny, and paleoclimatic and paleoenvironmental changes. In this paper, 87Sr/86Sr ratios of the Triassic marine carbonate rock samples from Huaying Mountains, eastern Sichuan are measured, and the corre-sponding Sr-isotopic curve is constructed, based on the fundamental principle of strontium isotope stratigraphy, analysis of rock fabric, luminescent intensity, chemical composition and representative evaluation for the coeval seawater information. The 87Sr/86Sr ratios show a rapid rise from 0.70721 near the Permian-Triassic transition to 0.70830 at the end of Early Triassic, and then they decline rapidly to 0.70787 in the early Middle Triassic. These data are generally coincident with 87Sr/86Sr ratios of coeval seawater from previous papers, and the curve is also similar to other previous curves. This indicates that the global geological events are the most important controlling factors to the strontium isotope evolution of the global seawater in the Early and Middle Triassic.

  19. Evolution and global correlation for strontium isotopic composition of marine Triassic from Huaying Mountains,eastern Sichuan, China

    Institute of Scientific and Technical Information of China (English)

    HU ZuoWei; HUANG SiJing; QING HaiRuo; WANG QingDong; WANG ChunMei; GAO XiaoYong

    2008-01-01

    Strontium isotope stratigraphy (SIS) has progressively become an efficient chemostratigraphic tool in the research and correlation of global geological events, such as global sea level fluctuations, orogeny,and paleoclimati~ and paleoenvironmental changes. In this paper, 87Sr/86Sr ratios of the Triassic marine carbonate rock samples from Huaying Mountains, eastern Sichuan are measured, and the corresponding Sr-isotopic curve is constructed, based on the fundamental principle of strontium isotope stratigraphy, analysis of rock fabric, luminescent intensity, chemical composition and representative evaluation for the coeval seawater information. The 87Sr/86Sr ratios show a rapid rise from 0.70721 near the Permian-Triassic transition to 0.70830 at the end of Early Triassic, and then they decline rapidly to 0.70787 in the early Middle Triassic. These data are generally coincident with 8rSr/86Sr ratios of coeval seawater from previous papers, and the curve is also similar to other previous curves. This indicates that the global geological events are the most important controlling factors to the strontium isotope evolution of the global seawater in the Early and Middle Triassic.

  20. Tethys- and Atlas-related deformations in the Triassic Basin, Algeria

    Energy Technology Data Exchange (ETDEWEB)

    Jackson, J.S.; Moore, S.R.; Quarles, A.I. [ARCO International Oil and Gas Company, Plano, TX (United States)

    1995-08-01

    Petroleum provinces of Algeria can be divided into Paleozoic and Mesozoic domains. Paleozoic basins are located on the Gondwanaland paleo-continent where the last significant tectonic episode is ascribed to the Late Paleozoic Hercynian Orogeny. Mesozoic basins are located on the south margin of the Neo-Tethyan seaway. These basins were subject to varying degrees of contractional deformation during the Cenozoic Atlas Orogeny. The Triassic Basin of Algeria is a Tethyan feature located above portions of the Paleozoic Oued M`ya and Ghadames Basins. Paleozoic strata are deeply truncated at the Hercynian Unconformity on a broad arch between the older basins. This is interpreted to reflect rift margin rebound during Carboniferous time. Continental Lower Triassic sediments were deposited in a series of northeast trending basins which opened as the Neo-Tethys basin propagated from east to west between Africa and Europe. Middle Triassic marine transgression from the east resulted in evaporate deposition persisting through the Early Jurassic. Passive margin subsidence associated with carbonate marine deposition continued through the Early Cretaceous. Several zones of coeval wrench deformation cross the Atlas and adjoining regions. In the Triassic Basin, inversion occurred before the end of the Early Cretaceous. This episode created discrete uplifts, where major hydrocarbon accumulations have been discovered, along northeast trending lineaments. During the Eocene, the main phase of the Atlas Orogeny produced low amplitude folding of Jurassic and Cretaceous sediments. The folds detach within the Triassic-Jurassic evaporate interval. Many of these folds have been tested without success, as the deeper reservoirs do not show structural closure.

  1. MIDDLE TRIASSIC AUTOCLASTIC DEPOSITS FROM SOUTHWESTERN BOSNIA AND HERZEGOVINA

    Directory of Open Access Journals (Sweden)

    Duje Smirčić

    2016-06-01

    Full Text Available Middle Triassic volcanic and volcaniclastic rocks have been recognized at several localities near Bosansko Grahovo, in southwestern part of Bosnia and Herzegovina in the External Dinarides. Peculiar types of autoclastic rocks were investigated. These are peperites and hyaloclastites. Regarding specific structures, mineral composition and micropetrographic characteristics it was possible to further differentiate hyaloclastites into in situ hyaloclastites and slightly resedimented hyaloclastites that represent genetic succession. All rock types occurred in a deep sea troughs that formed as a consequence of Middle Triassic extensional tectonic and rift related wrench faulting. In situ hyaloclastites and slightly resedimented hyaloclastites were formed due to quenching at the contact of lava effusions with sea water. Genesis of peperites is related to lava emplacement in unconsolidated water saturated lime mudstones that were deposited in deep sea basin. All investigated rock types represent first findings of autoclastic deposits in the External Dinarides. Biostratigraphic constraints achieved by means of conodont species Neogondolella excentrica, Paragondolella excelsa, Paragondolella trammeri and Gladigondolella tethydis indicate Late Anisian to Early Ladinian interval of the autoclastic deposits from Bosansko Grahovo.

  2. Early puberty and thoracic mass: presentation of a case

    OpenAIRE

    Laredo Reyna, María Nataly; Instituto Nacional de Salud del Niño. Lima, Perú. Médico pediatra; Falen Bogio, Juan Manuel; Facultad de Medicina, Universidad Nacional Federico Villareal. Lima, Perú. médico endocrinólogo; Lipa Chancolla, Roxana; Instituto Nacional de Salud del Niño. Lima, Perú. médico patólogo clínico; Núñez Almache, Oswaldo; Instituto Nacional de Salud del Niño. Lima, Perú. médico endocrinologo pediatra; Pinto, Paola; Instituto Nacional de Salud del Niño. Lima, Perú. Médico pediatra; Espinoza Robles, Oscar; Instituto Nacional de Salud del Niño. Lima, Perú. Médico pediatra; Chávez, Eliana; Instituto Nacional de Salud del Niño. Lima, Perú. Médico pediatra; Rojas Gabulli, María Isabel; Instituto Nacional de Salud del Niño. Lima, Perú. Facultad de Medicina, Universidad Nacional Federico Villareal. Lima, Perú. médico endocrinólogo; Del Aguila Villar, Carlos; Instituto Nacional de Salud del Niño. Lima, Perú. Facultad de Medicina, Universidad Nacional Federico Villareal. Lima, Perú. Médico pediatra

    2014-01-01

    A case is reported of a 7 year old patient with progressive dyspnea and genital development according to Marshall and Tanner criteria at the G2 VP3 stage. A mass of regular and well-defined borders was found in the chest, with calcifications and cystic areas of heterogeneous content. Basal measurements of FSH, LH and testosterone were <10 mIU/mL, 12.2 mIU/mL and 724 ng/dL, respectively. α-fetoprotein was 145.1 ng/mL. Excising the tumor improved respiratory symptoms, diminished hormone leve...

  3. Transgression regression event element geochemistry records of southwestern Fujian in Late Triassic-Middle Jurassic

    Institute of Scientific and Technical Information of China (English)

    许中杰; 程日辉; 张莉; 王嘹亮

    2013-01-01

    Southwest Fujian area has experienced a large-scale transgression regression cycle in Late Triassic-Middle Jurassic and the maximum transgression has taken place in Early Jurassic. The migration and enrichment of geochemical element in the continuous fine-grained sediments in the basin recorded the paleosalinity and the paleodepth. The changes of paleosalinity and paleodepth indicate the sea(lake) level relative change in every period of Late Triassic-Middle Jurassic in southwestern Fujian. The relative change curve of sea(lake) level in southwestern Fujian is established based on the m value(m=100×w(MgO)/w(Al2 O3)) and the ratios of w(B)/w(Ga), w(Sr)/w(Ba) and w(Ca)/w(Mg). The curve indicates that level I sea-level relative change in southwestern Fujian is composed of the transgression in Late Triassic-Early Jurassic and the regression in the late period of Early Jurassic-Middle Jurassic. The level III sea-level relative change is frequent, which is composed by the lake level descent lake level rise lake level descent of Wenbin Shan formation in Late Triassic, the regression transgression regression of Lishan formation in Early Jurassic and the lake level rise lake level descent-lake level rise lake level descent of Zhangping formation in Middle Jurassic. The transgression regression cycle in southwestern Fujian is significantly controlled by the sea-level change in the north of South China Sea. The relative change curve trends of the level I sea-level in the north of South China Sea and the one in southwestern Fujian are the same. The maximum transgressions both occur in Early Jurassic. The level III sea-level curve reflects the fluctuation of a transgression and two regressions in the early period of Early Jurassic.

  4. The mass-discrepancy acceleration relation in early-type galaxies: extended mass profiles and the phantom menace to MOND

    CERN Document Server

    Janz, Joachim; Romanowsky, Aaron J; Ciotti, Luca; Alabi, Adebusola; Forbes, Duncan A

    2016-01-01

    The dark matter (DM) haloes around spiral galaxies appear to conspire with their baryonic content: empirically, significant amounts of DM are inferred only below a universal characteristic acceleration scale. Moreover, the discrepancy between the baryonic and dynamical mass, which is usually interpreted as the presence of DM, follows a very tight mass discrepancy acceleration (MDA) relation. Its universality, and its tightness in spiral galaxies, poses a challenge for the DM interpretation and was used to argue in favour of MOdified Newtonian Dynamics (MOND). Here, we test whether or not this applies to early-type galaxies. We use the dynamical models of fast-rotator early-type galaxies by Cappellari et al. based on ATLAS$^{3D}$ and SLUGGS data, which was the first homogenous study of this kind, reaching ~4 $R_e$, where DM begins to dominate the total mass budget. We find the early-type galaxies to follow a MDA relation similar to spiral galaxies, but systematically offset. Also, while the slopes of the mass ...

  5. Endurance training in early life results in long-term programming of heart mass in rats.

    Science.gov (United States)

    Wadley, Glenn D; Laker, Rhianna C; McConell, Glenn K; Wlodek, Mary E

    2016-02-01

    Being born small for gestational age increases the risk of developing adult cardiovascular and metabolic diseases. This study aimed to examine if early-life exercise could increase heart mass in the adult hearts from growth restricted rats. Bilateral uterine vessel ligation to induce uteroplacental insufficiency and fetal growth restriction in the offspring (Restricted) or sham surgery (Control) was performed on day 18 of gestation in WKY rats. A separate group of sham litters had litter size reduced to five pups at birth (Reduced litter), which restricted postnatal growth. Male offspring remained sedentary or underwent treadmill running from 5 to 9 weeks (early exercise) or 20 to 24 weeks of age (later exercise). Remarkably, in Control, Restricted, and Reduced litter groups, early exercise increased (P heart mass in adulthood. This was despite the animals being sedentary for ~4 months after exercise. Later exercise also increased adult absolute and relative heart mass (P early or later exercise. Phosphorylation of Akt Ser(473) in adulthood was increased in the early exercise groups but not the later exercise groups. Microarray gene analysis and validation by real-time PCR did not reveal any long-term effects of early exercise on the expression of any individual genes. In summary, early exercise programs the heart for increased mass into adulthood, perhaps by an upregulation of protein synthesis based on greater phosphorylation of Akt Ser(473).

  6. The succession of late Palaeozoic and Triassic plant assemblages of eastern China

    Science.gov (United States)

    Xingxue, Li; Xiuyuan, Wu

    This is a study dealing with the succession of the megafloras or plant assemblages of China's eastern part, ranging from the early Devonian to later Triassic. The plant assemblages in ascending order are as follows: 1. In the three floras formerly recognized for the early, middle and late Devonian, the latter two are here revised as the Protolepidodendron flora and the Leptophloeum-Archaeopteris flora, respectively. 2. Since the two-fold system of the Carboniferous has been currently accepted in China and the mid-Carboniferous boundary in NW China is drawn at the top of the Tsingyuan Formation (s.s.), the latest plant assemblage of the Lower Carboniferous is better named the Eleutherophyllum waldenburgense-Linopteris densissima-Pecopteris aspera Assemblage and its corresponding plant assemblage in SE China being tentatively named the Paripteris gigantea-Karinopteris acuta f. obtusa Assemblage. Moreover, recent studies on the Penchi flora of north China reveal that some typical Cathaysian elements, e.g. Lepidodendron posthumii, Tingia spp., occurred in the Penchi Formation, of which the plant assemblage is revised as the Paripteris gigantea-Linopteris neuropteroides-Conchophyllum richthofeni Assemblage, known probably as the first assemblage assigned to the early Cathaysian flora in east Asia. 3. The latest Permian (Tartarian) of north China is represented by the Ullmannia bronnii-Yuania magnifolia Assemblage based on recent studies of the flora of the Shihchienfeng (Sunjiagou) Formation. 4. Recent studies on the early Triassic flora in north China disclose that the flora may be named the Pleuromeia flora, which can be subdivided into the early Triassic Pl. jiaochengensis assemblage and the late early Triassic Pl. sternbergii Assemblage. In addition, problems about the correlation for some of the representative formations and their palaeophytogeographical regions are also discussed.

  7. Bone microstructure and the evolution of growth patterns in Permo-Triassic therocephalians (Amniota, Therapsida of South Africa

    Directory of Open Access Journals (Sweden)

    Adam K. Huttenlocker

    2014-04-01

    Full Text Available Therocephalians were a speciose clade of nonmammalian therapsids whose ecological diversity and survivorship of the end-Permian mass extinction offer the potential to investigate the evolution of growth patterns across the clade and their underlying influences on post-extinction body size reductions, or ‘Lilliput effects’. We present a phylogenetic survey of limb bone histology and growth patterns in therocephalians from the Middle Permian through Middle Triassic of the Karoo Basin, South Africa. Histologic sections were prepared from 80 limb bones representing 11 genera of therocephalians. Histologic indicators of skeletal growth, including cortical vascularity (%CV and mean primary osteon diameters (POD, were evaluated in a phylogenetic framework and assessed for correlations with other biologically significant variables (e.g., size and robusticity. Changes in %CV and POD correlated strongly with evolutionary changes in body size (i.e., smaller-bodied descendants tended to have lower %CV than their larger-bodied ancestors across the tree. Bone wall thickness tended to be high in early therocephalians and lower in the gracile-limbed baurioids, but showed no general correlation with cross-sectional area or degree of vascularity (and, thus, growth. Clade-level patterns, however, deviated from previously studied within-lineage patterns. For example, Moschorhinus, one of few therapsid genera to have survived the extinction boundary, demonstrated higher %CV in the Triassic than in the Permian despite its smaller size in the extinction aftermath. Results support a synergistic model of size reductions for Triassic therocephalians, influenced both by within-lineage heterochronic shifts in survivor taxa (as reported in Moschorhinus and the dicynodont Lystrosaurus and phylogenetically inferred survival of small-bodied taxa that had evolved short growth durations (e.g., baurioids. These findings mirror the multi-causal Lilliput patterns described in

  8. Bone microstructure and the evolution of growth patterns in Permo-Triassic therocephalians (Amniota, Therapsida) of South Africa.

    Science.gov (United States)

    Huttenlocker, Adam K; Botha-Brink, Jennifer

    2014-01-01

    Therocephalians were a speciose clade of nonmammalian therapsids whose ecological diversity and survivorship of the end-Permian mass extinction offer the potential to investigate the evolution of growth patterns across the clade and their underlying influences on post-extinction body size reductions, or 'Lilliput effects'. We present a phylogenetic survey of limb bone histology and growth patterns in therocephalians from the Middle Permian through Middle Triassic of the Karoo Basin, South Africa. Histologic sections were prepared from 80 limb bones representing 11 genera of therocephalians. Histologic indicators of skeletal growth, including cortical vascularity (%CV) and mean primary osteon diameters (POD), were evaluated in a phylogenetic framework and assessed for correlations with other biologically significant variables (e.g., size and robusticity). Changes in %CV and POD correlated strongly with evolutionary changes in body size (i.e., smaller-bodied descendants tended to have lower %CV than their larger-bodied ancestors across the tree). Bone wall thickness tended to be high in early therocephalians and lower in the gracile-limbed baurioids, but showed no general correlation with cross-sectional area or degree of vascularity (and, thus, growth). Clade-level patterns, however, deviated from previously studied within-lineage patterns. For example, Moschorhinus, one of few therapsid genera to have survived the extinction boundary, demonstrated higher %CV in the Triassic than in the Permian despite its smaller size in the extinction aftermath. Results support a synergistic model of size reductions for Triassic therocephalians, influenced both by within-lineage heterochronic shifts in survivor taxa (as reported in Moschorhinus and the dicynodont Lystrosaurus) and phylogenetically inferred survival of small-bodied taxa that had evolved short growth durations (e.g., baurioids). These findings mirror the multi-causal Lilliput patterns described in marine faunas, but

  9. Crinoids from Svalbard in the aftermath of the end−Permian mass extinction

    Directory of Open Access Journals (Sweden)

    Salamon Mariusz A.

    2015-09-01

    Full Text Available The end-Permian mass extinction constituted a major event in the history of crinoids. It led to the demise of the major Paleozoic crinoid groups including cladids, disparids, flexibles and camerates. It is widely accepted that a single lineage, derived from a late Paleozoic cladid ancestor (Ampelocrinidae, survived this mass extinction. Holocrinid crinoids (Holocrinus, Holocrinida along with recently described genus Baudicrinus (Encrinida, the only crinoid groups known from the Early Triassic, are considered the stem groups for the post-Paleozoic monophyletic subclass Articulata. Here, we report preliminary data on unexpectedly diverse crinoid faunas comprising at least four orders from the Lower Triassic (Induan and Olenekian of Svalbard, extending their stratigraphic ranges deeper into the early Mesozoic. These findings strongly imply that the recovery of crinoids in the aftermath of the end-Permian extinction began much earlier at higher palaeolatitudes than in the central Tethys.

  10. Characteristics of the Triassic Source Rocks of the Aitutu Formation in the (West Timor Basin

    Directory of Open Access Journals (Sweden)

    Asep Kurnia Permana

    2014-12-01

    Full Text Available DOI:10.17014/ijog.v1i3.192The Triassic rocks of the (West Timor Basin have been identified that was mainly deposited in the  marine environment. The fine grained clastics and carbonate  rocks of this Triassic marine  facies are considered to be the most promising source rocks potential in this basin. In this paper we present geochemical and petrographic data from outcrop samples of the Triassic carbonate Aitutu Formation, due to emphasized the organic maturation, kerogen type of the organic matter and the origin of the organic matter.  A representative of selected sample were subjected to the Rock-Eval Pyrolisis, vitrinite reflectance and thermal alteration index, bitumen extraction, were analyzed on the GC-MS. The samples were collected from marine deposit of the Triassic Sequence. The TOC values of the analyzed sample range between rich and rich organic richness (0.51% - 9.16%, wt.%, TOC, which consists mainly of type II and III kerogen and the organic matter consider to be predominantly oil/gas prone and gas prone potential. The thermal maturity assessed from Tmax, TAI, and vitrinite reflectance shows an immature to early peak mature stage of the organic matter. The GC-MS analyses of the biomarkers indicate mainly the organic matter derived from mixed source rocks facies containing alga debris and higher plant terrestrial origin.

  11. 西藏羌塘地体南部多龙增生杂岩早三叠世辉长岩的发现及其地质意义%The discovery of the Early Triassic gabbro rocks of the Duolong accretionary complexes in southern Qiangtang terrane of Tibet and its geological significance

    Institute of Scientific and Technical Information of China (English)

    段瑶瑶; 李亚林; 段志明

    2016-01-01

    The outcropped Late Triassic-Jurassic accretionary complexes are located along northern Bangong Co-Nujiang suture zone where a large subduction-type Duolong porphyry copper-gold ore concentration area is developed. Bulk-rock major and trace elements, Sr-Nd isotope and LA-ICP-MS zircon U-Pb data are reported for gabbro rocks sampled from the Duolong accretionary complexes. The 206Pb/238U age of zircon in the gabbro analyzed by LA-ICP-MS is 246.0±1.4Ma, which represents the crystallization age of the magma. Na, Mg, LREE and large ion lithophile elements (Ba, U, La and Sr) are concentrated whereas Ti, K and high-field strength elements (Nb and Ta) are deficient. These characteristics suggest that the geochemistry of the gabbro is similar to that of the island arc type basalt. The isotopic compositions of the Sr and Nd ( (87Sr/86Sr)i=0.707605~0.709778, (143Nd/144Nd)i=0.512515~0.512678, and TDM2=0.54~0.99Ga) suggest that gabbro is developed on the arc in an intraplate environment. It is considered that the end of early Triassic igneous activity probably resulted from the northward subduction of the Bangong Co-Nujiang Ocean crust which interacted with the lithospheric mantle material. The discovery and understand ing provide the northward subduction of the Bangong Co-Nujiang ocean crust in early Triassic with important evidence of magma tism.%西藏多龙矿集区是班公湖-怒江缝合带北缘在增生楔基础上发育的超大型岛弧斑岩铜金矿床。对多龙增生杂岩中的辉长岩进行了LA-ICP-MS锆石U-Pb定年及主量、微量元素分析和Sr-Nd同位素组成研究,获得了多龙增生杂岩中辉长岩的成岩时代。由LA-ICP-MS测得的辉长岩锆石206Pb/238U年龄为246.0±1.4Ma,代表了岩浆的结晶年龄。辉长岩以低钛、富钠、富镁、贫钾、富集轻稀土元素和大离子亲石元素(Ba、U、La、Sr)、亏损高场强元素Nb和Ta为特征,具有与岛弧玄武岩相似的主量和微量元素组成,相

  12. Permo-Triassic Events in the Eastern Tethys

    Science.gov (United States)

    Sweet, Walter C.; Zunyi, Yang; Dickins, J. M.; Hongfu, Yin

    2003-12-01

    Permian and Triassic rocks in the eastern Tethyan region form continuous marine sequences that record the waning phases of the Paleozoic and the early stages of the Mesozoic eras. This book describes and interprets these rocks, summarizing the distribution of major fossil groups in a way that will allow detailed comparison with strata of comparable age in the western Tethys and other parts of the world. The sixteen contributions by forty authors are the culmination of the five-year long International Geological Correlation Programme Project 203. The detailed information presented here is gathered from many areas in the eastern Tethyan region - from France to Australia - and will be of use in the evaluation of the major changes in the global marine biosphere known to have taken place at the end of the Paleozoic era. The stratigraphic record for this fascinating segment of Earth history is not widespread elsewhere in the world and is most continuous in the region covered by this book.

  13. Continental Ecosystem Instability During the Late Triassic Rise of Dinosaurs

    Science.gov (United States)

    Whiteside, J. H.; Dunlavey, M.; Lindström, S.; Irmis, R. B.; Kasprak, A. H.; Glasspool, I.; Nesbitt, S.; Smith, N.; Turner, A.

    2012-12-01

    Our assessment of the Earth system response to future global climate change requires the characterization of feedbacks that occur at temperatures significantly warmer than modern. Patterns derived from hothouse intervals in Earth's past can inform process-based models to better understand and predict such feedbacks. pCO2 values exceeded 1000 ppm during the Late Triassic (~235 million to 201.5 million years ago), one of the warmest - and one of the most climatically dynamic - intervals in Earth history. This long period of warmth saw rare and species-poor assemblages of early dinosaurs and their relatives at low-paleolatitudes. Here we present new records of palynology, charcoal, polycyclic aromatic hydrocarbon (PAH) biomarkers of regional wildfires, and the bulk carbon isotopic composition of organic matter (δ13Corg) from fluvial and overbank sediments of the Chinle Formation of the Chama Basin in north-central New Mexico from low paleolatitude Pangea. These data illuminate the climatic and ecological drivers of low dinosaur diversity. Our data suggest that strongly fluctuating but generally very hot and periodically arid environmental conditions prevailed at low paleolatitudes in the Late Triassic. Strong variations in δ13Corg and xerophytic palynomorph abundance are highly correlated, suggesting these proxies responded to fluctuating arid conditions with intermittent wildfires, some burning at temperatures reaching at least 680°C. The abundant, reliable food source required by an extensive, diverse community of large-bodied, herbivorous, fast-growing tachymetabolic dinosaurs did not develop until climatic changes in the Early Jurassic. Despite this, the basic structure of this pseudosuchian archosaur-dominated community remained stable over ~10-15 million years.

  14. A theropod tooth from the Late Triassic of southern Africa

    Indian Academy of Sciences (India)

    Sanghamitra Ray; Anusuya Chinsamy

    2002-06-01

    An isolated, large recurved and finely serrated tooth found associated with the prosauropod Euskelosaurus from the Late Triassic part of the Elliot Formation is described here. It is compared to the Triassic thecodonts and carnivorous dinosaurs and its possible affinity is discussed. The tooth possibly belongs to a basal theropod and shows some features similar to the allosauroids. This tooth is of significance, as dinosaur remains except for some footprints and trackways, are poorly known in the Late Triassic horizons of southern Africa.

  15. Mass-independent isotope effects in planetary atmospheres and the early solar system.

    Science.gov (United States)

    Thiemens, M H

    1999-01-15

    A class of isotope effects that alters isotope ratios on a mass-independent basis provides a tool for studying a wide range of processes in atmospheres of Earth and other planets as well as early processes in the solar nebula. The mechanism for the effect remains uncertain. Mass-independent isotopic compositions have been observed in O3, CO2, N2O, and CO in Earth's atmosphere and in carbonate from a martian meteorite, which suggests a role for mass-independent processes in the atmosphere of Mars. Observed mass-independent meteoritic oxygen and sulfur isotopic compositions may derive from chemical processes in the presolar nebula, and their distributions could provide insight into early solar system evolution.

  16. Geological significance of the lycopod megaspores from the early triassic Kayitou Formation of the Western Guizhou and Eastern Yunnan Region%黔西滇东早三叠世卡以头组石松类大孢子的地质意义

    Institute of Scientific and Technical Information of China (English)

    李慧; 喻建新; 黄其胜; 史骁; 黄程

    2014-01-01

    在黔西滇东地区海陆过渡相密德剖面早三叠世卡以头组发现了大量的大孢子印痕化石,通过光学显微镜和扫描电子显微镜的观察,对大孢子的形态进行了初步的研究,共分为9属16种(包括未定种),其中最丰富的是Trileites ,其次为Maexisporites , Triangulatisporites , Horstisporites , Aneuletes ,其余仅个别。这一研究丰富了该地区的生物化石种类和植物面貌,进一步验证了卡以头组的时代为早三叠世早期。%Abundant dispersed megaspore impression fossils were described from the Kayitou formation of the Mide Section of the marine-terrestrial transitional facies for the first time in the western Guizhou and eastern Yunnan Region. Sixteen species of nine genera were recognized under light-microscope and SEM. Trileites dominates this megaspore assemblage, while Maexisporites, Triangulatisporites, Horstisporites and Aneuletes are in a subordinate position, and the others are occasionally seen. New biostratigraphical evidence was obtained on the early triassic age of the Kayitou formation and the missing parts of lycopods species filled.

  17. Coring and High-Resolution Imaging of the Permian-Triassic Boundary in Deltadalen, Svalbard

    Science.gov (United States)

    Planke, Sverre

    2016-04-01

    The Permian-Triassic extinction was likely triggered by the voluminous igneous activity of the Siberian Traps. There are, however, limited information available about the effects of the Siberian Traps volcanism in Permian to Triassic sedimentary successions outside Siberia. We drilled two boreholes across the Permian-Triassic boundary (PTB) in Deltadalen, Svalbard, in August 2014, to better document the extinction event and environmental changes in the sedimentary succession in this region. Even though the PTB event is studied in several outcrops to varying degree if scrutiny on Svalbard, a scientific core is important for understanding the details of the PTB event, as outcrops may not permit studies at the appropriate levels of resolution, exposure or confidence. The Deltadalen site was chosen as an optimal drilling location after field work in the Isfjorden area in 2013 and early 2014. The almost 100 m deep holes were fully cored and penetrated the Triassic Vikinghøgda Formation (about 85 m recovered) and the Permian Kapp Starostin Formation (about 15 m). The main lithologies include Permian chert-rich green glauconitic sandstones and Triassic mudstones. A 10 m thick sedimentary reference outcrop section across the PTB was further logged and sampled in a nearby river valley. A comprehensive core analysis program is now underway. High-resolution XRF, MST and hyperspectral core scanning has been completed along the entire core surface, while high-resolution CT scanning has been carried out for whole core sections. The DD-1 core has subsequently been split, photographed, described, and sampled for geochemical, micropaleontological, petrological and magnetic analyses. Almost 10 bentonite layers have furthermore been sampled for volcanological and geochronological studies. Our goal is that the cores will become an important future reference section of the PTB in Svalbard and the high-Arctic, and help constrain the extent of the regional effects of explosive volcanism

  18. Evidence of Impact at the Permian/Triassic Boundary from Moessbauer Spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Verma, H. C.; Upadhyay, C. [Indian Institute of Technology, Department of Physics (India); Tripathi, R. P. [Jai Narain Vyas University, Department of Physics (India); Shukla, A. D.; Bhandari, N. [Physical Research Laboratory, Navrangpura (India)

    2002-06-15

    Sediment samples from Spiti valley, India, deposited about 250 Million years ago during the Permian-Triassic transition, have been analysed. {sup 57}Fe Moessbauer spectroscopic studies show that iron occurs mainly as nanoparticles of hematite and goethite with a broad size distribution. The results show a high degree of resemblance with the Cretaceous-Tertiary boundary (65 My) samples where an asteroidal impact is believed to have caused mass extinction.

  19. CONODONT BIOSTRATIGRAPHY AND LITHOSTRATIGRAPHY ACROSS THE PERMIAN-TRIASSIC BOUNDARY AT THE LUKAC SECTION IN WESTERN SLOVENIA

    Directory of Open Access Journals (Sweden)

    TEA KOLAR-JURKOVSEK

    2011-03-01

    Full Text Available Detailed conodont biostratigraphy and lithostratigraphy of the Late Permian and Early Triassic beds were studied at the LukaC section in western Slovenia. The analyzed section is composed of the Bellerophon Formation ("evaporite-dolomite member" and the newly introduced Lukaè Formation ("transitional beds", "streaky limestone member" and "carbonate-clastic beds member". The Permian-Triassic boundary interval is represented by "transitional beds" of carbonate facies deposited in shallow restricted marine conditions. The presence of H. parvus in sample L1 in the "transitional beds" marks the systemic boundary between Permian and Triassic. The studied interval is characterized by a diverse microfauna that contain conodonts, foraminifers, ostracods and gastropods. Six conodont zones have been recognized, in ascending order, the latest Changhsingian (uppermost Permian praeparvus Zone, and the Griesbachian (lowermost Triassic parvus, lobata, staeschei-isarcica, postparvus and anceps zones. This faunal succession represents the first known and the most complete conodont biozonation across the Permian-Triassic interval from the entire Dinaric region. The recognized conodont biozones can be correlated with the biozonation of the Southern Alps and of the GSSP Meishan D section. 

  20. Variable Low-Mass X-ray Binaries in Early-Type Galaxies

    CERN Document Server

    Sivakoff, Gregory R; Juett, Adrienne M; Sarazin, Craig L; Irwin, Jimmy A

    2007-01-01

    As the Chandra X-ray Observatory mission matures, increasing numbers of nearby galaxies are being observed multiple times, sampling the variability of extragalactic X-ray binaries on timescales extending from seconds to years. We present results on luminous low-mass X-ray binaries from several early-type galaxies. We show that instantaneous LMXB luminosity functions of early-type galaxies do not significantly change between observations; a relatively low fraction of sources are strongly variable on <~ 5 yr timescales. We discuss the implications that a relatively small number of transient LMXBs are being discovered in early-type galaxies.

  1. Thecamoebians (Testate Amoebae) Straddling the Permian-Triassic Boundary in the Guryul Ravine Section, India: Evolutionary and Palaeoecological Implications.

    Science.gov (United States)

    Singh, Vartika; Pandita, Sundeep K; Tewari, Rajni; van Hengstum, Peter J; Pillai, Suresh S K; Agnihotri, Deepa; Kumar, Kamlesh; Bhat, G D

    2015-01-01

    Exceptionally well-preserved organic remains of thecamoebians (testate amoebae) were preserved in marine sediments that straddle the greatest extinction event in the Phanerozoic: the Permian-Triassic Boundary. Outcrops from the Late Permian Zewan Formation and the Early Triassic Khunamuh Formation are represented by a complete sedimentary sequence at the Guryul Ravine Section in Kashmir, India, which is an archetypal Permian-Triassic boundary sequence. Previous biostratigraphic analysis provides chronological control for the section, and a perspective of faunal turnover in the brachiopods, ammonoids, bivalves, conodonts, gastropods and foraminifera. Thecamoebians were concentrated from bulk sediments using palynological procedures, which isolated the organic constituents of preserved thecamoebian tests. The recovered individuals demonstrate exceptional similarity to the modern thecamoebian families Centropyxidae, Arcellidae, Hyalospheniidae and Trigonopyxidae, however, the vast majority belong to the Centropyxidae. This study further confirms the morphologic stability of the thecamoebian lineages through the Phanerozoic, and most importantly, their apparent little response to an infamous biological crisis in Earth's history.

  2. Lower Triassic Inorganic Carbon Isotope Excursion in Chaohu, Anhui Province, China

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    This paper reports a Lower Triassic inorganic carbon isotope profile from the North Ping-dingshan Section in Chaohu, Anhui Province, China, which was situated in a deep part of the LowerYangtze carbonate ramp. The δ(13C) excursion shows two periods from the Permian-Triassic boundaryto the lower Spathian substage, corresponding to the ecosystem undergoing evolution and recovery afterthe end-Permian mass extinction and related events. The first period starts at the δ (13 C) depletioncaused by the mass extinction and evolves with a gradual δ(13C) increase resulting from the developmentof some disaster taxa during the Induan. The strong Smithian δ(13 C) depletion in the second periodmight be formed by the collapse of the disaster ecosystem and the biotic recovery occurred with the explo-sive increase of bioproductivity in the Spathian. Thus the δ(13C) excursion in the Lower Triassic expres-ses patterns of biotic evolution and recovery during the erratic ecosystem that followed the great end-Permian mass extinction.

  3. The Total Mass of the Early-Type Galaxy NGC 4649 (M60

    Directory of Open Access Journals (Sweden)

    Ćirković, M. M.

    2008-12-01

    Full Text Available In this paper the problem of the total mass and the total mass-to-light ratio of the early-type galaxy NGC~4649 (M60 is analyzed. Use is made of two independent techniques: the X-ray methodology which is based on the temperature of the X-ray halo of NGC~4649 and the tracer mass estimator (TME which uses globular clusters (GCs observed in this galaxy. The mass is calculated in Newtonian and MOdified Newtonian Dynamics (MOND approaches and it is found that inside 3 effective radii ($R_e$ there is no need for large amounts of dark matter. Beyond $3R_e$ the dark matter starts to play important dynamical role. The possible reasons for the discrepancy between the estimates of the total mass based on X-rays and TME in the outer regions of NGC~4649 are also discussed.

  4. Determinants of Growth, Adiposity and Bone Mass in Early Life : The Generation R Study

    NARCIS (Netherlands)

    D.H.M. Heppe (Denise)

    2016-01-01

    markdownabstractAbstract Environmental influences during fetal life and early infancy have been suggested to influence body composition throughout the life-course. Especially poor fetal nutrition and fetal growth restriction have been designated important risk factors for gaining high fat mass or

  5. Determinants of Growth, Adiposity and Bone Mass in Early Life : The Generation R Study

    NARCIS (Netherlands)

    D.H.M. Heppe (Denise)

    2016-01-01

    markdownabstractAbstract Environmental influences during fetal life and early infancy have been suggested to influence body composition throughout the life-course. Especially poor fetal nutrition and fetal growth restriction have been designated important risk factors for gaining high fat mass

  6. Triassic rift-raft tectonics in the German Southern North Sea; Flosstektonik in der Trias der Deutschen Suedlichen Nordsee

    Energy Technology Data Exchange (ETDEWEB)

    Thieme, B.; Rockenbauch, K. [BEB Erdgas und Erdoel GmbH, Hannover (Germany)

    2001-12-01

    This paper discusses extensional structures in the German Southern North Sea which were formed during Triassic rifting. Recent salt tectonic concepts and palinspastic methods provided the basis for structural interpretation. The results were compared with examples of the adjacent North Sea sectors and other raft provinces worldwide. Rifting in the German Southern North Sea began in Early Triassic times causing faulting and subsequent lateral movements and rotations of rigid Bunter blocks on the ductile Zechstein salinar substrate. This process, called >>raft-tectonics<<, exerted important controls on the further tectonic and sedimentary evolution during Triassic (and Early Jurassic) times. The structures created were formed by a complex interaction of basin extension, halokinesis and deposition of syn- and post-raft sediments. Variations in the controlling factors led to the different morphologies and styles observed. The German Southern North Sea did not undergo any inversion. As a consequence, the extensional rift-raft features remained without compressional overprint, allowing therefore a detailed interpretation of the deformation history. Main characteristics of the raft features in the German Southern North Sea are: raft structures represent an initial stage of development (extension and translation), rift-raft features within the Triassic interval are genetically related to basement extension (Triassic rifting), Triassic rifting was polyphase, rift-raft features are associated with reactive salt diapirs and/or syn- and post-rift depocenters, both of which developed syn-tectonically in the gaps created between the rafts, controlling factors on the morphologies observed are: moderate extension, low angle detachment (gentle regional dip and low strain rates), thick detachment layer (salt thickness of the Zechstein salinar), and lithology (sediment thickness and competence) of the raft- and post-raft Mesozoic sequences. Finally, the impact of raft tectonics on

  7. Late Triassic - Early Jurassic successions of the Atuel depocenter: sequence stratigraphy and tectonic controls Sucesiones del Triásico Tardío - Jurásico Temprano del depocentro Atuel: estratigrafía secuencial y controles tectónicos

    Directory of Open Access Journals (Sweden)

    Silvia Lanés

    2008-12-01

    Full Text Available Biostratigraphic correlations of the Late Triassic - Early Jurassic successions of the Atuel depocenter allowed determining the accommodation changes and the possible tectonic controls on sedimentation. The Rhaetian - late Early Sinemurian deposits contain facies of slope-type fan deltas, braided fluvial systems and low sinuosity rivers with alternate bars deposited during a synrift phase. The late Early Sinemurian - Toarcian series host facies of intermediate (Gilbert to shelf type fan deltas, braided and low sinuosity fluvial systems, wave-dominated estuaries, transgressive storm-dominated and turbidite-influenced marine shelves which record the sag phase. According to different criteria two stratigraphic schemes are proposed, the first one considering tectosedimentary units (TSU and the second one using "Exxon-like" sequences. In the first scheme the synrift TSU matches the actual Precuyo Mesosequence and the sag TSU is partly equivalent to the Cuyo Mesosequence, mainly keeping the current mesosequence scheme for the Neuquén basin but assigning the fandeltaic deposits to the Precuyo Mesosequence. The second sequence scheme considers the whole Late Triassic - Early Jurassic succession as a part of the Cuyo Mesosequence, where the synrift deposits composes the detached lowstand system tract (LST and most of the sag deposits makes the transgressive system tract (TST. The basal sequence boundary does not crop out, the flooding surface at the TST base and the maximum flooding surface at the TST top are respectively marked by the lowest estuarine levels and by black shales with suboxic-compatible bivalves (Bositra sp..La correlación bioestratigráfica de las sucesiones del Triásico Tardío - Jurásico Temprano del depocentro Atuel permitió determinar los cambios del espacio de acomodación y los posibles controles tectónicos de la sedimentación. La sección del Retiano - Sinemuriano Temprano tardío contiene facies de abanicos deltaicos de

  8. A NEW GENUS OF CYCADALEAN PLANTS FROM THE EARLY TRIASSIC OF WESTERN LIAONING, CHINA--MEDIOCYCAS GEN. NOV. AND ITS EVOLUTIONARY SIGNIFICANCE%辽宁西部早三叠世苏铁植物一新属--Mediocycas gen. nov.及其演化意义

    Institute of Scientific and Technical Information of China (English)

    李楠; 傅晓平; 张武; 郑少林; 曹雨

    2005-01-01

    报道苏铁植物大孢子叶化石一新属--中间苏铁属(Mediocycas gen. nov.).标本采集于辽宁省西部,喀左县杨树沟煤矿后山的早三叠世红砬组. 这些标本以前曾被处理为疑问化石 (Problematicum).因当时资料不足,所以没有确定属种名称.但鉴于这些化石在苏铁类早期起源与演化研究中具有重要意义,故对它们作了重新研究.文中除了以喀左中间苏铁(Mediocycas kazuoensis gen. et sp. nov.)为典型种进行描述以外,还对新属、种在苏铁类起源与演化方面的意义作了较为详细的讨论.%A new genus--Mediocycas gen. nov. of fossil cycad megasporophylls is proposed based on the specimens collected from Yangshugou village, Kazuo county, western Liaoning Province, China. The stratum of plant-bearing bed belongs to the Lower Triassic Hongla Formation. The specimens were previously considered as a problematical fossil due to the lack of material. These fossils, however, are of vital importance in understanding the early evolution of cycads, and therefore worthy of reinvestigation. In the present paper, description of the typical species Mediocycas kazuoensis gen. et sp. nov. was made, and its important significance in the origin and early evolution of the megasporophyll of cycads was discussed.

  9. Permian and Triassic microfloral assemblages from the Blue Nile Basin, central Ethiopia

    Science.gov (United States)

    Dawit, Enkurie L.

    2014-11-01

    Palynological investigation was carried out on surface samples from up to 400 m thick continental siliciclastic sediments, here referred to as “Fincha Sandstone”, in the Blue Nile Basin, central Ethiopia. One hundred sixty species were identified from 15 productive samples collected along a continuous road-cut exposure. Six informal palynological assemblage zones have been identified. These assemblage zones, in ascending order, are: “Central Ethiopian Permian Assemblage Zone - CEPAZ I”, earliest Permian (Asselian-Sakmarian); “CEPAZ II”, late Early Permian (Artinskian-Kungurian); CEPAZ III - Late Permian (Kazanian-Tatarian); “CETAZ IV”, Lower Triassic (Olenekian Induan); “CETAZ V”, Middle Triassic (Anisian Ladinian); “CETAZ VI”, Late Triassic (Carnian Norian). Tentative age ranges proposed herein are compared with faunally calibrated palynological zones in Gondwana. The overall composition and vertical distribution of miospores throughout the studied section reveals a wide variation both qualitatively and quantitatively. The high frequency of monosaccate pollen in CEPAZ I may reflect a Glossopterid-dominated upland flora in the earliest Permian. The succeeding zone is dominated by straite/taeniate disaccate pollen and polyplicates, suggesting a notable increase in diversity of glossopterids. The decline in the diversity of taeniate disaccate pollen and the concomitant rise in abundance of non-taeniate disaccates in CEPAZ III may suggest the decline in Glossopteris diversity, though no additional evidence is available to equate this change with End-Permian extinction. More diverse and dominant non-taeniate, disaccate, seed fern pollen assignable to FalcisporitesAlisporites in CETAZ IV may represent an earliest Triassic recovery flora. The introduction of new disaccate forms with thick, rigid sacci, such as Staurosaccites and Cuneatisporites, in CETAZ V and VI may indicate the emergence of new gymnospermous plants that might have favourably

  10. Late Triassic syn-exhumation magmatism in central Qiangtang, Tibet: Evidence from the Sangehu adakitic rocks

    Science.gov (United States)

    Liu, Han; Wang, Bao-di; Ma, Long; Gao, Rui; Chen, Li; Li, Xiao-bo; Wang, Li-quan

    2016-12-01

    The geodynamic setting of Late Triassic magmatic activity along the Longmu Co-Shuanghu suture zone (LSSZ) in central Qiangtang, Tibet is a matter of debate. This paper presents zircon LA-ICP-MS U-Pb ages, zircon Hf isotopic compositions, and whole-rock geochemical data for the Sangehu (SGH) granitic intrusion in central Qiangtang, and addresses the petrogenesis of Late Triassic magmatism, and the history of collision between the northern and southern Qiangtang terranes. The SGH pluton consists mainly of biotite adamellite with mafic microgranular enclaves (MMEs), and small amounts of K-feldspar granite. The biotite adamellite, MMEs, and K-feldspar granite give ages of 207.8 ± 3.0 Ma, 212.4 ± 31 Ma, and 211.6 ± 3.8 Ma, respectively. The MMEs show magmatic textures and acicular apatite, and are coeval with the host biotite adamellite, suggesting they were produced by magma mixing. All samples from the SGH pluton show high Sr and low Y contents, and positive Eu anomalies, similar to adakitic rocks. The high K2O contents and low Mg#, Cr, and Ni contents, and enriched Hf isotopic characteristics of the zircons indicate that these magmas were derived from the partial melting of thickened crust. However, the whole-rock geochemical data and zircon Hf isotopic compositions also reveal heterogeneity at the source. The combined magmatic and metamorphic records suggest that Triassic magmatic activity in central Qiangtang was closely related to the collision of the northern and southern Qiangtang terranes. The large-scale Late Triassic (225-200 Ma) magmatic event in central Qiangtang may have resulted from the breakoff of the Longmu Co-Shuanghu Tethys Ocean lithospheric slab in the early Late Triassic (236-230 Ma). The Late Triassic magmatic rocks, including adakitic rocks, are coeval with retrograde high-pressure (HP) to ultrahigh-pressure (UHP) metamorphic rocks in central Qiangtang, and show characteristics of syn-exhumation magmatism. The early adakitic rocks (>220 Ma

  11. Waste storage potential of Triassic basins in southeast United States

    Energy Technology Data Exchange (ETDEWEB)

    Weaver, C.E.

    1976-07-01

    Triassic basins, elongated deep basins filled with sediments, extend from Nova Scotia to Florida. The geology of the basins is discussed for each state. Their potential for liquid waste storage is assessed. Seismic risk is among the factors evaluated. It is recommended that the shallow Triassic Florence basin in northeast South Carolina be studied. 10 fig. (DLC)

  12. The luminosity and stellar mass Fundamental Plane of early-type galaxies

    CERN Document Server

    Hyde, J B

    2008-01-01

    From a sample of ~50000 early-type galaxies from the SDSS, we measured the traditional Fundamental Plane in four bands. We then replaced luminosity with stellar mass, and measured the "stellar mass" FP. The FP steepens slightly as one moves from shorter to longer wavelengths: the orthogonal fit has slope 1.40 in g and 1.47 in z. The FP is thinner at longer wavelengths: scatter is 0.062 dex in g, 0.054 dex in z. The scatter is larger at small galaxy sizes/masses; at large masses measurement errors account for essentially all of the observed scatter. The FP steepens further when luminosity is replaced with stellar mass, to slope ~ 1.6. The intrinsic scatter also reduces further, to 0.048 dex. Since color and stellar mass-to-light ratio are closely related, this explains why color can be thought of as the fourth FP parameter. However, the slope of the stellar mass FP remains shallower than the value of 2 associated with the virial theorem. This is because the ratio of dynamical to stellar mass increases at large...

  13. Triassic-Jurassic organic carbon isotope stratigraphy of key sections in the western Tethys realm (Austria)

    Science.gov (United States)

    Ruhl, Micha; Kürschner, Wolfram M.; Krystyn, Leopold

    2009-05-01

    The late Triassic period is recognized as one of the five major mass extinctions in the fossil record. All these important intervals in earth history are associated with excursions in C-isotope records thought to have been caused by perturbations in the global carbon cycle. The nature and causes of C-isotopic events across the Triassic-Jurassic (T-J) transition however, are poorly understood. We present several new high resolution organic C-isotope records from the Eiberg Basin, Austria, including the proposed Global boundary Stratotype Section and Point (GSSP) for the base of the Jurassic. The Triassic-Jurassic boundary interval in these records is characterized by the initial and main negative organic carbon isotope excursions (CIE) of up to 8‰. The initial and main CIEs are biostratigraphically constrained by first and last occurrences of boundary defining macro- and microfossils (e.g. ammonites). High resolution C-isotope records appear to be an excellent correlation proxy for this period in the Eiberg Basin. Pyrolysis analysis demonstrates increased Hydrogen Index (HI) values for organic matter coinciding with the initial CIE. Terrestrial organic matter influx and mass occurrences of green algae remains may have influenced the C-isotope composition of the sedimentary organic matter. This may have contributed to the extreme amplitude of the initial CIE in the Eiberg Basin.

  14. Ascent of dinosaurs linked to an iridium anomaly at the Triassic-Jurassic boundary.

    Science.gov (United States)

    Olsen, P E; Kent, D V; Sues, H-D; Koeberl, C; Huber, H; Montanari, A; Rainforth, E C; Fowell, S J; Szajna, M J; Hartline, B W

    2002-05-17

    Analysis of tetrapod footprints and skeletal material from more than 70 localities in eastern North America shows that large theropod dinosaurs appeared less than 10,000 years after the Triassic-Jurassic boundary and less than 30,000 years after the last Triassic taxa, synchronous with a terrestrial mass extinction. This extraordinary turnover is associated with an iridium anomaly (up to 285 parts per trillion, with an average maximum of 141 parts per trillion) and a fern spore spike, suggesting that a bolide impact was the cause. Eastern North American dinosaurian diversity reached a stable maximum less than 100,000 years after the boundary, marking the establishment of dinosaur-dominated communities that prevailed for the next 135 million years.

  15. Trouble Upstairs: Reconstructing Permian-Triassic Climate during Siberian Traps Magmatism

    Science.gov (United States)

    Black, B. A.; Neely, R. R., III; Lamarque, J. F.; Elkins-Tanton, L. T.; Mills, M. J.

    2014-12-01

    The eruption of large igneous provinces can transfer significant masses of volatiles from Earth's interior to the atmosphere. What are the consequences of this degassing for habitability and extinction? In this presentation, we consider this question in the context of Siberian Traps magmatism, which has been shown to overlap within geochronologic uncertainty with catastrophic deterioration of Permian-Triassic marine and terrestrial ecosystems. To investigate the impacts of endogenic gases on climate, atmospheric chemistry, and ocean circulation, we conducted a series of numerical experiments with a comprehensive global model for the Permian-Triassic. Our simulations predict the intensity and distribution of acid rain and ozone depletion, with implications for terrestrial biota. We further explore feedbacks between sulfur emissions, transient cooling, and shifts in ocean circulation. We suggest that Siberian Traps magmatism may have triggered several distinct kill mechanisms in the oceans and on land, contributing to a complex combined pattern of environmental stress and latest Permian ecological failure.

  16. Association between body mass index percentile trajectories in infancy and adiposity in childhood and early adulthood.

    Science.gov (United States)

    Kwon, Soyang; Janz, Kathleen F; Letuchy, Elena M; Burns, Trudy L; Levy, Steven M

    2017-01-01

    To identify distinct body mass index (BMI) percentile trajectories during early childhood and examine adiposity levels in childhood and early adulthood according to the BMI percentile trajectories. Iowa Fluoride Study cohort parents (n = 1,093) reported their child's anthropometric data on average six times between ages 0 and 23 months. A subset of the cohort underwent DXA scans at approximately age 8 years (n = 495) and again at approximately age 19 years (n = 314). Group-based trajectory analysis was conducted to identify distinct BMI percentile trajectories from ages 0 to 23 months. Sex-specific age-adjusted linear regression analyses were conducted to compare fat mass index in childhood and early adulthood among subgroups that follow the distinct BMI percentile patterns. Four BMI percentile patterns were identified: consistently low (group 1: 9.8%), increase in the second year (group 2: 33.7%), increase in the first year (group 3: 23.9%), and consistently high (group 4: 32.6%). Compared with group 2 females, groups 3 and 4 females had higher fat mass index in childhood and early adulthood (P BMI percentile in the first year of life, as opposed to a steep increase in the second year of life, may have higher body fat later in life, but this was not found in males. © 2016 The Obesity Society.

  17. THE PERMIAN -TRIASSIC BOUNDARY, DEAD SEA, JORDAN: TRANSITIONAL ALLUVIAL TO MARINE DEPOSITIONAL SEQUENCES AND BIOSTRATIGRAPHY

    Directory of Open Access Journals (Sweden)

    JOHN H. POWELL

    2016-10-01

    Full Text Available The Permian to Triassic transition in Jordan is characterised by a sequence boundary underlain by red-bed, alluvial lithofacies deposited in a humid-tropical climate by low-sinuosity rivers, and overlain by shallow marine siliciclastics with thin carbonates. The low-gradient alluvial floodplain was repeatedly subjected to the development of ferralitic and pisolitic paleosols on the interfluves. In contrast, dysaerobic environments in the fluvial channels and abandoned lakes resulted in the preservation of a prolific flora of macro-plants and palynomorphs that indicate a probable range from Mid- to Late Permian age, though the abundant presence of the distinctive pollen Pretricolpipollenites bharadwajii  indicates the youngest part of that range.  Above the sequence boundary, reddened shallow-marine beds characterised by ripple cross-laminated, siltstones/sandstone with desiccation cracks and sparse surface burrows mark the initial Triassic marine transgression in the region (Arabian Plate Tr 10. These are followed by two thin limestone (packstone beds with shallow scours and bivalve shell lags, that have yielded a low diversity assemblage of conodonts (e.g. Hadrodontina aequabilis and foraminifera (“Cornuspira” mahajeri that are interpreted as euryhaline  taxa characterising the early Induan (Early Triassic. Thus the absence of body fossils and vertical infaunal burrows in the lowest marine beds may reflect low-diversity ecosystems following the Permian-Triassic extinction event, or be a result of stressed shallow marine environments. A gradational upward increase in grey, green and yellow siltstones beds accompanied by a concomitant increase in bioturbation (and infaunal vertical burrows and thin-shelled bivalves about 15 m above the boundary indicates colonisation of the substrate under more normal shallow marine conditions perhaps indicating recovery phase following the extinction event.

  18. The Origin and Early Radiation of Archosauriforms: Integrating the Skeletal and Footprint Record.

    Science.gov (United States)

    Bernardi, Massimo; Klein, Hendrik; Petti, Fabio Massimo; Ezcurra, Martín D

    2015-01-01

    We present a holistic approach to the study of early archosauriform evolution by integrating body and track records. The ichnological record supports a Late Permian-Early Triassic radiation of archosauriforms not well documented by skeletal material, and new footprints from the Upper Permian of the southern Alps (Italy) provide evidence for a diversity not yet sampled by body fossils. The integrative study of body fossil and footprint data supports the hypothesis that archosauriforms had already undergone substantial taxonomic diversification by the Late Permian and that by the Early Triassic archosauromorphs attained a broad geographical distribution over most parts of Pangea. Analysis of body size, as deduced from track size, suggests that archosauriform average body size did not change significantly from the Late Permian to the Early Triassic. A survey of facies yielding both skeletal and track record indicate an ecological preference for inland fluvial (lacustrine) environments for early archosauromorphs. Finally, although more data is needed, Late Permian chirotheriid imprints suggest a shift from sprawling to erect posture in archosauriforms before the end-Permian mass extinction event. We highlight the importance of approaching palaeobiological questions by using all available sources of data, specifically through integrating the body and track fossil record.

  19. The Origin and Early Radiation of Archosauriforms: Integrating the Skeletal and Footprint Record.

    Directory of Open Access Journals (Sweden)

    Massimo Bernardi

    Full Text Available We present a holistic approach to the study of early archosauriform evolution by integrating body and track records. The ichnological record supports a Late Permian-Early Triassic radiation of archosauriforms not well documented by skeletal material, and new footprints from the Upper Permian of the southern Alps (Italy provide evidence for a diversity not yet sampled by body fossils. The integrative study of body fossil and footprint data supports the hypothesis that archosauriforms had already undergone substantial taxonomic diversification by the Late Permian and that by the Early Triassic archosauromorphs attained a broad geographical distribution over most parts of Pangea. Analysis of body size, as deduced from track size, suggests that archosauriform average body size did not change significantly from the Late Permian to the Early Triassic. A survey of facies yielding both skeletal and track record indicate an ecological preference for inland fluvial (lacustrine environments for early archosauromorphs. Finally, although more data is needed, Late Permian chirotheriid imprints suggest a shift from sprawling to erect posture in archosauriforms before the end-Permian mass extinction event. We highlight the importance of approaching palaeobiological questions by using all available sources of data, specifically through integrating the body and track fossil record.

  20. Systematic Variation of Central Mass Density Slope in Early-Type Galaxies

    Science.gov (United States)

    Tortora, C.; La Barbera, F.; Napolitano, N. R.; Romanowsky, A. J.; Ferreras, I.; de Carvalho, R. R.

    We study the total density distribution in the central regions (≲ 1 effective radius, R e) of early-type galaxies (ETGs), using data from the SPIDER survey (La Barbera et al., MNRAS 408:1313, 2010). We model each galaxy with two components (dark matter halo + stars), exploring different assumptions for the dark matter (DM) halo profile, and leaving stellar mass-to-light (M ⋆/L) ratios as free fitting parameters to the data. For a Navarro et al. (ApJ 462:563, 1996) profile, the slope of the total mass profile is non-universal. For the most massive and largest ETGs, the profile is isothermal in the central regions (˜ Re/2), while for the low-mass and smallest systems, the profile is steeper than isothermal, with slopes similar to those for a constant-M/L profile. For a concentration-mass relation steeper than that expected from simulations, the correlation of density slope with mass tends to flatten. Our results clearly point to a "non-homology" in the total mass distribution of ETGs, which simulations of galaxy formation suggest may be related to a varying role of dissipation with galaxy mass.

  1. Systematic variations of central mass density slopes in early-type galaxies

    Science.gov (United States)

    Tortora, C.; La Barbera, F.; Napolitano, N. R.; Romanowsky, A. J.; Ferreras, I.; de Carvalho, R. R.

    2014-11-01

    We study the total density distribution in the central regions (≲1 effective radius, Re) of early-type galaxies (ETGs), using data from SPIDER and ATLAS3D. Our analysis extends the range of galaxy stellar mass (M⋆) probed by gravitational lensing, down to ˜ 1010 M⊙. We model each galaxy with two components (dark matter halo + stars), exploring different assumptions for the dark matter halo profile (i.e. NFW, NFW-contracted, and Burkert profiles), and leaving stellar mass-to-light (M⋆/L) ratios as free fitting parameters to the data. For all plausible halo models, the best-fitting M⋆/L, normalized to that for a Chabrier initial mass function, increases systematically with galaxy size and mass. For an NFW profile, the slope of the total mass profile is non-universal, independently of several ingredients in the modelling (e.g. halo contraction, anisotropy, and rotation velocity in ETGs). For the most massive (M⋆ ˜ 1011.5 M⊙) or largest (Re˜ 15 kpc) ETGs, the profile is isothermal in the central regions (˜ Re/2), while for the low-mass (M⋆ ˜ 1010.2 M⊙) or smallest (Re˜ 0.5 kpc) systems, the profile is steeper than isothermal, with slopes similar to those for a constant-M/L profile. For a steeper concentration-mass relation than that expected from simulations, the correlation of density slope with galaxy mass tends to flatten, while correlations with Re and velocity dispersions are more robust. Our results clearly point to a `non-homology' in the total mass distribution of ETGs, which simulations of galaxy formation suggest may be related to a varying role of dissipation with galaxy mass.

  2. Early Mycoplasma pneumoniae infection presenting as multiple pulmonary masses: an unusual presentation in a child

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Edward; Altes, Talissa; Anupindi, Sudha A. [The Children' s Hospital of Philadelphia, Department of Radiology, Philadelphia, PA (United States)

    2008-04-15

    Mycoplasma pneumoniae is a major cause of community-acquired pneumonia. Because most children are not imaged prior to onset of clinical symptoms, the appearance of early Mycoplasma infection has not been extensively studied. We present the case of an 11-year-old boy with large pulmonary masses incidentally detected during spine MRI evaluation for scoliosis. Eight days later, the patient developed acute respiratory symptoms, and the masses seen previously had evolved into a diffuse bronchiolitis. Diagnostic testing identified Mycoplasma pneumoniae as the likely etiology. We briefly review chest CT findings of infection by Mycoplasma and compare them to this unusual presentation of Mycoplasma pneumonia with subclinical imaging findings. (orig.)

  3. Permo-Triassic evolution of Gondwanan eastern Indonesia, and the final Mesozoic separation of SE Asia from Australia

    Science.gov (United States)

    Charlton, T. R.

    2001-08-01

    Continental fragments with Australian/Gondwanan stratigraphic affinities are widely distributed throughout the eastern Indonesia collision complex. Despite their structural isolation from one another as a consequence of Tertiary orogenesis, these fragments show a remarkably uniform pattern of Permo-Triassic tectonostratigraphy, ranging from a granitoid belt in the north, through a continental platform, to an intracontinental rift system in the south. Within the rift system complementary upper and lower plate rifted margins can be recognised in the northern and southern Banda Arcs, respectively. The northern granitoid belt was initiated in the mid-Carboniferous, whilst the intracontinental rift system began to develop in latest Carboniferous-earliest Permian times. Extension in the northern rift margin ceased in the mid-Carnian (early Late Triassic), contemporaneous with a marked decline in igneous activity in the granitoid belt to the north. The Sibumasu Terrane of mainland SE Asia probably originated on the Gondwanaland continental margin, adjacent to reconstructed eastern Indonesia, but rifted away during the Early Permian. Previous interpretations have seen this rifting as marking the final separation between Gondwanaland and continental terranes now forming SE Asia. Alternatively, it is suggested here that Gondwanan eastern Indonesia acted as an indirect continental connection between Sibumasu/Indochina and Australia during the Permian and Triassic. This continental isthmus permitted continuing limited floral and faunal interchange between Gondwanaland and SE Asia until a final separation in the Late Triassic. The mid-Carnian structural event in eastern Indonesia is interpreted as related to this separation.

  4. Soft-sediment deformation structures in cores from lacustrine slurry deposits of the Late Triassic Yanchang Fm. (central China

    Directory of Open Access Journals (Sweden)

    Yang Renchao

    2016-09-01

    Full Text Available The fine-grained autochthonous sedimentation in the deep part of a Late Triassic lake was frequently interrupted by gravity-induced mass flows. Some of these mass flows were so rich in water that they must have represented slurries. This can be deduced from the soft-sediment deformation structures that abound in cores from these lacustrine deposits which constitute the Yanchang Fm., which is present in the Ordos Basin (central China.

  5. Triassic-Jurassic pteridosperms of Australasia: speciation, diversity and decline

    Energy Technology Data Exchange (ETDEWEB)

    Pattemore, G. A.; Rigby, J. F.; Playford, G.

    2015-07-01

    Pteridosperms are preserved abundantly in the Gondwanan Triassic, with many species exhibiting consider- able morphological variation that has been attributed to a hybridization model of speciation. This is an improbable explanation given that hybridization is very rare in gymnosperms. Allopatric speciation resulting from geographic and climatic provincialism is a more likely explanation for the morphological diversity which is well represented in Anisian Norian (Middle and Upper Triassic) floras of Australasia and elsewhere in Gondwana. Most specimens are distributed among three families: Umkomasiaceae, Peltaspermaceae and Matatiellaceae. These families, together with other possibly pteridospermous genera, are reviewed herein. Diversity in these families apparently declined by the Rhaetian and they did not persist into the Gondwanan post-Triassic. Australasian post-Triassic strata contain remarkably different floral assemblages to those of the Triassic. No fructifications are clearly pteridospermous and no remains show any obvious relationship with pteridosperms of the Gondwanan Triassic. Caytonialean fructifications are not known in Australasian strata; however, associated foliage has been reported from the Eastern Gondwanan Upper Triassic through Middle Jurassic including Australia. Much fern-like foliage, claimed to be pteridospermous from the Lower Jurassic through Eocene of Eastern Gondwana, lacks supporting evidence of such affiliation. (Author)

  6. Systematic variation of central mass density slope in early-type galaxies

    CERN Document Server

    Tortora, C; Napolitano, N R; Romanowsky, A J; Ferreras, I; de Carvalho, R R

    2015-01-01

    We study the total density distribution in the central regions ($<\\, 1$ effective radius, $R_{\\rm e}$) of early-type galaxies (ETGs), using data from the SPIDER survey. We model each galaxy with two components (dark matter halo + stars), exploring different assumptions for the dark matter (DM) halo profile, and leaving stellar mass-to-light ($M_{\\rm \\star}/L$) ratios as free fitting parameters to the data. For a Navarro et al. (1996) profile, the slope of the total mass profile is non-universal. For the most massive and largest ETGs, the profile is isothermal in the central regions ($\\sim R_{\\rm e}/2$), while for the low-mass and smallest systems, the profile is steeper than isothermal, with slopes similar to those for a constant-M/L profile. For a concentration-mass relation steeper than that expected from simulations, the correlation of density slope with mass tends to flatten. Our results clearly point to a "non-homology" in the total mass distribution of ETGs, which simulations of galaxy formation sugg...

  7. Dark matter inside early-type galaxies as function of mass and redshift

    Science.gov (United States)

    Nigoche-Netro, A.; Ramos-Larios, G.; Lagos, P.; Ruelas-Mayorga, A.; de la Fuente, E.; Kemp, S. N.; Navarro, S. G.; Corral, L. J.; Hidalgo-Gámez, A. M.

    2016-10-01

    We study the behaviour of the dynamical and stellar mass inside the effective radius (re) of early-type galaxies (ETGs). We use several samples of ETGs - ranging from 19 000 to 98 000 objects - from the ninth data release of the Sloan Digital Sky Survey. We consider Newtonian dynamics, different light profiles and different initial mass functions (IMF) to calculate the dynamical and stellar mass. We assume that any difference between these two masses is due to dark matter and/or a non-universal IMF. The main results for galaxies in the redshift range 0.0024 dark matter or a non-universal IMF or a combination of both; (v) the amount of dark matter inside ETGs would be equal to or less than the difference between dynamical and stellar mass depending on the impact of the IMF on the stellar mass estimation; (vi) the previous results go in the same direction of some results of the Fundamental Plane (FP) found in the literature in the sense that they could be interpreted as an increase of dark matter along the FP and a dependence of the FP on redshift.

  8. Early efficacy of the ketogenic diet is not affected by initial body mass index percentile.

    Science.gov (United States)

    Shull, Shastin; Diaz-Medina, Gloria; Wong-Kisiel, Lily; Nickels, Katherine; Eckert, Susan; Wirrell, Elaine

    2014-05-01

    Predictors of the ketogenic diet's success in treating pediatric intractable epilepsy are not well understood. The aim of this study was to determine whether initial body mass index and weight percentile impact early efficacy of the traditional ketogenic diet in children initiating therapy for intractable epilepsy. This retrospective study included all children initiating the ketogenic diet at Mayo Clinic, Rochester from January 2001 to December 2010 who had body mass index (children ≥2 years of age) or weight percentile (those diet initiation and seizure frequency recorded at diet initiation and one month. Responders were defined as achieving a >50% seizure reduction from baseline. Our cohort consisted of 48 patients (20 male) with a median age of 3.1 years. There was no significant correlation between initial body mass index or weight percentile and seizure frequency reduction at one month (P = 0.72, r = 0.26 and P = 0.91, r = 0.03). There was no significant association between body mass index or weight percentile quartile and responder rates (P = 0.21 and P = 0.57). Children considered overweight or obese at diet initiation (body mass index or weight percentile ≥85) did not have lower responder rates than those with body mass index or weight percentiles ketogenic diet. Copyright © 2014 Elsevier Inc. All rights reserved.

  9. Self-Similar Models for the Mass Profiles of Early-type Lens Galaxies

    CERN Document Server

    Rusin, D; Keeton, C R

    2003-01-01

    We introduce a self-similar mass model for early-type galaxies, and constrain it using the aperture mass-radius relations determined from the geometries of 22 gravitational lenses. The model consists of two components: a concentrated component which traces the light distribution, and a more extended power-law component (rho propto r^-n) which represents the dark matter. We find that lens galaxies have total mass profiles which are nearly isothermal, or slightly steeper, on the several-kiloparsec radial scale spanned by the lensed images. In the limit of a single-component, power-law radial profile, the model implies n=2.07+/-0.13, consistent with isothermal (n=2). Models in which mass traces light are excluded at >99 percent confidence. An n=1 cusp (such as the Navarro-Frenk-White profile) requires a projected dark matter mass fraction of f_cdm = 0.22+/-0.10 inside 2 effective radii. These are the best statistical constraints yet obtained on the mass profiles of lenses, and provide clear evidence for a small ...

  10. WASP-26b: A 1-Jupiter-mass planet around an early-G-type star

    CERN Document Server

    Smalley, B; Cameron, A Collier; Gillon, M; Hellier, C; Lister, T A; Maxted, P F L; Queloz, D; Triaud, A H M J; West, R G; Bentley, S J; Enoch, B; Pepe, F; Pollacco, D L; Segransan, D; Smith, A M S; Southworth, J; Udry, S; Wheatley, P J; Wood, P L; Bento, J

    2010-01-01

    We report the discovery of WASP-26b, a moderately over-sized Jupiter-mass exoplanet transiting its 11.3-magnitude early-G-type host star (1SWASP J001824.70-151602.3; TYC 5839-876-1) every 2.7566 days. A simultaneous fit to transit photometry and radial-velocity measurements yields a planetary mass of 1.02 +/- 0.03 M_Jup and radius of 1.32 +/- 0.08 R_Jup. The host star, WASP-26, has a mass of 1.12 +/- 0.03 M_sun and a radius of 1.34 +/- 0.06 R_sun and is in a visual double with a fainter K-type star. The two stars are at least a common-proper motion pair with a common distance of around 250 +/- 15 pc and an age of 6 +/- 2 Gy.

  11. New Data on the Clevosaurus (Sphenodontia: Clevosauridae) from the Upper Triassic of Southern Brazil

    Science.gov (United States)

    Hsiou, Annie Schmaltz; De França, Marco Aurélio Gallo; Ferigolo, Jorge

    2015-01-01

    The sphenodontian fossil record in South America is well known from Mesozoic and Paleogene deposits of Argentinean Patagonia, mainly represented by opisthodontians, or taxa closely related to the modern Sphenodon. In contrast, the Brazilian fossil record is restricted to the Caturrita Formation, Late Triassic of Rio Grande do Sul, represented by several specimens of Clevosauridae, including Clevosaurus brasiliensis Bonaparte and Sues, 2006. Traditionally, Clevosauridae includes several Late Triassic to Early Jurassic taxa, such as Polysphenodon, Brachyrhinodon, and Clevosaurus, the latter well-represented by several species. The detailed description of the specimen MCN-PV 2852 allowed the first systematic revision of most Clevosaurus species. Within Clevosauridae, Polysphenodon is the most basal taxon, and an IterPCR analysis revealed Brachrhynodon as a possible Clevosaurus; C. petilus, C. wangi, and C. mcgilli as possibly distinct taxonomic entities; and the South African Clevosaurus sp. is not closely related to C. brasiliensis. These data indicate the need of a deep phylogenetic review of Clevosauridae, in order to discover synapomorphic characters among the diversity of these Triassic/Jurassic sphenodontians. PMID:26355294

  12. Triassic magmatism and its relation to decratonization in the eastern North China Craton

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    Lithospheric removal and destruction of the North China Craton have been hotly discussed recently. It has been confirmed that the timing of a strong lithospheric removal took place in Late Mesozoic; however, little is known about when the lithospheric removal was initiated and how the Late Permian to Early Triassic deep subduction of Yangtze continental crust affected the cratonic destruction. This paper presents an overview on the temporal and spatial framework and geochemical characteristics of the Triassic intrusive rocks in the eastern North China Craton and use these data to trace their sources and petrogenetic processes, in order to constrain the tectonic setting in which they evolved. It is concluded that the destruction of the North China Craton was initiated in the Late Triassic and induced by delamination of the thickened continental crust by deep subduction of Yangtze continental crust and continent-continent collision. This suggests that the subduction of the continental crust and continent-continent collision are possibly interpreted as the inducement of Late Mesozoic decratonization of the North China Craton.

  13. Triassic magmatism and its relation to decratonization in the eastern North China Craton

    Institute of Scientific and Technical Information of China (English)

    YANG JinHui; WU FuYuan

    2009-01-01

    Lithospheric removal and destruction of the North China Craton have been hotly discussed recently.It has been confirmed that the timing of a strong lithospheric removal took place in Late Mesozoic;however,little is known about when the lithospheric removal was initiated and how the Late Permian to Early Triassic deep subduction of Yangtze continental crust affected the cratonic destruction.This paper presents an overview on the temporal and spatial framework and geochemical characteristics of the Triassic intrusive rocks in the eastern North China Craton and use these data to trace their sources and petrogenetic processes,in order to constrain the tectonic setting in which they evolved.It is concluded that the destruction of the North China Craton was initiated in the Late Triassic and induced by delamination of the thickened continental crust by deep subduction of Yangtze continental crust and continent-continent collision.This suggests that the subduction of the continental crust and continent-continent collision are possibly interpreted as the inducement of Late Mesozoic decratonization of the North China Craton.

  14. Floral changes across the Triassic/Jurassic boundary linked to flood basalt volcanism

    Science.gov (United States)

    van de Schootbrugge, B.; Quan, T. M.; Lindström, S.; Püttmann, W.; Heunisch, C.; Pross, J.; Fiebig, J.; Petschick, R.; Röhling, H.-G.; Richoz, S.; Rosenthal, Y.; Falkowski, P. G.

    2009-08-01

    One of the five largest mass extinctions of the past 600million years occurred at the boundary of the Triassic and Jurassic periods, 201.6million years ago. The loss of marine biodiversity at the time has been linked to extreme greenhouse warming, triggered by the release of carbon dioxide from flood basalt volcanism in the central Atlantic Ocean. In contrast, the biotic turnover in terrestrial ecosystems is not well understood, and cannot be readily reconciled with the effects of massive volcanism. Here we present pollen, spore and geochemical analyses across the Triassic/Jurassic boundary from three drill cores from Germany and Sweden. We show that gymnosperm forests in northwest Europe were transiently replaced by fern and fern-associated vegetation, a pioneer assemblage commonly found in disturbed ecosystems. The Triassic/Jurassic boundary is also marked by an enrichment of polycyclic aromatic hydrocarbons, which, in the absence of charcoal peaks, we interpret as an indication of incomplete combustion of organic matter by ascending flood basalt lava. We conclude that the terrestrial vegetation shift is so severe and wide ranging that it is unlikely to have been triggered by greenhouse warming alone. Instead, we suggest that the release of pollutants such as sulphur dioxide and toxic compounds such as the polycyclic aromatic hydrocarbons may have contributed to the extinction.

  15. A palaeoequatorial ornithischian and new constraints on early dinosaur diversification.

    Science.gov (United States)

    Barrett, Paul M; Butler, Richard J; Mundil, Roland; Scheyer, Torsten M; Irmis, Randall B; Sánchez-Villagra, Marcelo R

    2014-09-22

    Current characterizations of early dinosaur evolution are incomplete: existing palaeobiological and phylogenetic scenarios are based on a fossil record dominated by saurischians and the implications of the early ornithischian record are often overlooked. Moreover, the timings of deep phylogenetic divergences within Dinosauria are poorly constrained owing to the absence of a rigorous chronostratigraphical framework for key Late Triassic-Early Jurassic localities. A new dinosaur from the earliest Jurassic of the Venezuelan Andes is the first basal ornithischian recovered from terrestrial deposits directly associated with a precise radioisotopic date and the first-named dinosaur from northern South America. It expands the early palaeogeographical range of Ornithischia to palaeoequatorial regions, an area sometimes thought to be devoid of early dinosaur taxa, and offers insights into early dinosaur growth rates, the evolution of sociality and the rapid tempo of the global dinosaur radiation following the end-Triassic mass extinction, helping to underscore the importance of the ornithischian record in broad-scale discussions of early dinosaur history.

  16. Late Permian-earliest Triassic high-resolution organic carbon isotope and palynofacies records from Kap Stosch (East Greenland)

    Science.gov (United States)

    Sanson-Barrera, Anna; Hochuli, Peter A.; Bucher, Hugo; Schneebeli-Hermann, Elke; Weissert, Helmut; Adatte, Thierry; Bernasconi, Stefano M.

    2015-10-01

    During and after the end Permian mass extinction terrestrial and marine biota underwent major changes and reorganizations. The latest Permian and earliest Triassic is also characterized by major negative carbon isotope shifts reflecting fundamental changes in the carbon cycle. The present study documents a high-resolution bulk organic carbon isotope record and palynofacies analysis spanning the latest Permian-earliest Triassic of East Greenland. An almost 700 meter thick composite section from Kap Stosch allowed discriminating 6 chemostratigraphic intervals that provide the basis for the correlation with other coeval records across the world, and for the recognition of basin wide transgressive-regressive events documenting tectonic activity during the opening of the Greenland-Norway Basin. The identification of the main factors that influenced the organic carbon isotope signal during the earliest Triassic (Griesbachian to Dienerian) was possible due to the combination of bulk organic carbon isotope, palynofacies and Rock-Eval data. Two negative carbon isotopic shifts in the Kap Stosch record can be correlated with negative shifts recorded in coeval sections across the globe. A first negative shift precedes the base of the Triassic as defined by the first occurrence of the conodont Hindeodus parvus in the Meishan reference section, and the second one coincides with the suggested Griesbachian-Dienerian boundary. This new organic carbon isotope record from the extended Kap Stosch section from the Boreal Realm documents regional and global carbon cycle signals of the interval between the latest Palaeozoic and the onset of the Mesozoic.

  17. An ancestral turtle from the Late Triassic of southwestern China.

    Science.gov (United States)

    Li, Chun; Wu, Xiao-Chun; Rieppel, Olivier; Wang, Li-Ting; Zhao, Li-Jun

    2008-11-27

    The origin of the turtle body plan remains one of the great mysteries of reptile evolution. The anatomy of turtles is highly derived, which renders it difficult to establish the relationships of turtles with other groups of reptiles. The oldest known turtle, Proganochelys from the Late Triassic period of Germany, has a fully formed shell and offers no clue as to its origin. Here we describe a new 220-million-year-old turtle from China, somewhat older than Proganochelys, that documents an intermediate step in the evolution of the shell and associated structures. A ventral plastron is fully developed, but the dorsal carapace consists of neural plates only. The dorsal ribs are expanded, and osteoderms are absent. The new species shows that the plastron evolved before the carapace and that the first step of carapace formation is the ossification of the neural plates coupled with a broadening of the ribs. This corresponds to early embryonic stages of carapace formation in extant turtles, and shows that the turtle shell is not derived from a fusion of osteoderms. Phylogenetic analysis places the new species basal to all known turtles, fossil and extant. The marine deposits that yielded the fossils indicate that this primitive turtle inhabited marginal areas of the sea or river deltas.

  18. Recovery from the most profound mass extinction of all time.

    Science.gov (United States)

    Sahney, Sarda; Benton, Michael J

    2008-04-07

    The end-Permian mass extinction, 251 million years (Myr) ago, was the most devastating ecological event of all time, and it was exacerbated by two earlier events at the beginning and end of the Guadalupian, 270 and 260 Myr ago. Ecosystems were destroyed worldwide, communities were restructured and organisms were left struggling to recover. Disaster taxa, such as Lystrosaurus, insinuated themselves into almost every corner of the sparsely populated landscape in the earliest Triassic, and a quick taxonomic recovery apparently occurred on a global scale. However, close study of ecosystem evolution shows that true ecological recovery was slower. After the end-Guadalupian event, faunas began rebuilding complex trophic structures and refilling guilds, but were hit again by the end-Permian event. Taxonomic diversity at the alpha (community) level did not recover to pre-extinction levels; it reached only a low plateau after each pulse and continued low into the Late Triassic. Our data showed that though there was an initial rise in cosmopolitanism after the extinction pulses, large drops subsequently occurred and, counter-intuitively, a surprisingly low level of cosmopolitanism was sustained through the Early and Middle Triassic.

  19. Fullerenes and interplanetary dust at the Permian-Triassic boundary.

    Science.gov (United States)

    Poreda, Robert J; Becker, Luann

    2003-01-01

    We recently presented new evidence that an impact occurred approximately 250 million years ago at the Permian-Triassic boundary (PTB), triggering the most severe mass extinction in the history of life on Earth. We used a new extraterrestrial tracer, fullerene, a third carbon carrier of noble gases besides diamond and graphite. By exploiting the unique properties of this molecule to trap noble gases inside of its caged structure (helium, neon, argon), the origin of the fullerenes can be determined. Here, we present new evidence for fullerenes with extraterrestrial noble gases in the PTB at Graphite Peak, Antarctica, similar to PTB fullerenes from Meishan, China and Sasayama, Japan. In addition, we isolated a (3)He-rich magnetic carrier phase in three fractions from the Graphite Peak section. The noble gases in this magnetic fraction were similar to zero-age deep-sea interplanetary dust particles (IDPs) and some magnetic grains isolated from the Cretaceous-Tertiary boundary. The helium and neon isotopic compositions for both the bulk Graphite Peak sediments and an isolated magnetic fraction from the bulk material are consistent with solar-type gases measured in zero-age deep-sea sediments and point to a common source, namely, the flux of IDPs to the Earth's surface. In this instance, the IDP noble gas signature for the bulk sediment can be uniquely decoupled from fullerene, demonstrating that two separate tracers are present (direct flux of IDPs for (3)He vs. giant impact for fullerene).

  20. A large aberrant stem ichthyosauriform indicating early rise and demise of ichthyosauromorphs in the wake of the end-Permian extinction.

    Science.gov (United States)

    Jiang, Da-Yong; Motani, Ryosuke; Huang, Jian-Dong; Tintori, Andrea; Hu, Yuan-Chao; Rieppel, Olivier; Fraser, Nicholas C; Ji, Cheng; Kelley, Neil P; Fu, Wan-Lu; Zhang, Rong

    2016-05-23

    Contrary to the fast radiation of most metazoans after the end-Permian mass extinction, it is believed that early marine reptiles evolved slowly during the same time interval. However, emerging discoveries of Early Triassic marine reptiles are questioning this traditional view. Here we present an aberrant basal ichthyosauriform with a hitherto unknown body design that suggests a fast radiation of early marine reptiles. The new species is larger than coeval marine reptiles and has an extremely small head and a long tail without a fluke. Its heavily-built body bears flattened and overlapping gastral elements reminiscent of hupehsuchians. A phylogenetic analysis places the new species at the base of ichthyosauriforms, as the sister taxon of Cartorhynchus with which it shares a short snout with rostrally extended nasals. It now appears that ichthyosauriforms evolved rapidly within the first one million years of their evolution, in the Spathian (Early Triassic), and their true diversity has yet to be fully uncovered. Early ichthyosauromorphs quickly became extinct near the Early-Middle Triassic boundary, during the last large environmental perturbation after the end-Permian extinction involving redox fluctuations, sea level changes and volcanism. Marine reptile faunas shifted from ichthyosauromorph-dominated to sauropterygian-dominated composition after the perturbation.

  1. A Mass Spectrometric Analysis Method Based on PPCA and SVM for Early Detection of Ovarian Cancer.

    Science.gov (United States)

    Wu, Jiang; Ji, Yanju; Zhao, Ling; Ji, Mengying; Ye, Zhuang; Li, Suyi

    2016-01-01

    Background. Surfaced-enhanced laser desorption-ionization-time of flight mass spectrometry (SELDI-TOF-MS) technology plays an important role in the early diagnosis of ovarian cancer. However, the raw MS data is highly dimensional and redundant. Therefore, it is necessary to study rapid and accurate detection methods from the massive MS data. Methods. The clinical data set used in the experiments for early cancer detection consisted of 216 SELDI-TOF-MS samples. An MS analysis method based on probabilistic principal components analysis (PPCA) and support vector machine (SVM) was proposed and applied to the ovarian cancer early classification in the data set. Additionally, by the same data set, we also established a traditional PCA-SVM model. Finally we compared the two models in detection accuracy, specificity, and sensitivity. Results. Using independent training and testing experiments 10 times to evaluate the ovarian cancer detection models, the average prediction accuracy, sensitivity, and specificity of the PCA-SVM model were 83.34%, 82.70%, and 83.88%, respectively. In contrast, those of the PPCA-SVM model were 90.80%, 92.98%, and 88.97%, respectively. Conclusions. The PPCA-SVM model had better detection performance. And the model combined with the SELDI-TOF-MS technology had a prospect in early clinical detection and diagnosis of ovarian cancer.

  2. A Mass Spectrometric Analysis Method Based on PPCA and SVM for Early Detection of Ovarian Cancer

    Directory of Open Access Journals (Sweden)

    Jiang Wu

    2016-01-01

    Full Text Available Background. Surfaced-enhanced laser desorption-ionization-time of flight mass spectrometry (SELDI-TOF-MS technology plays an important role in the early diagnosis of ovarian cancer. However, the raw MS data is highly dimensional and redundant. Therefore, it is necessary to study rapid and accurate detection methods from the massive MS data. Methods. The clinical data set used in the experiments for early cancer detection consisted of 216 SELDI-TOF-MS samples. An MS analysis method based on probabilistic principal components analysis (PPCA and support vector machine (SVM was proposed and applied to the ovarian cancer early classification in the data set. Additionally, by the same data set, we also established a traditional PCA-SVM model. Finally we compared the two models in detection accuracy, specificity, and sensitivity. Results. Using independent training and testing experiments 10 times to evaluate the ovarian cancer detection models, the average prediction accuracy, sensitivity, and specificity of the PCA-SVM model were 83.34%, 82.70%, and 83.88%, respectively. In contrast, those of the PPCA-SVM model were 90.80%, 92.98%, and 88.97%, respectively. Conclusions. The PPCA-SVM model had better detection performance. And the model combined with the SELDI-TOF-MS technology had a prospect in early clinical detection and diagnosis of ovarian cancer.

  3. Back to the early Universe by a Monge-Ampere-Kantorovich mass transportation method

    CERN Document Server

    Frisch, U; Mohayaee, R; Sobolevski, A; Frisch, Uriel; Matarrese, Sabino; Mohayaee, Roya; Sobolevski, Andrei

    2002-01-01

    Reconstructing the minute density fluctuations in the early Universe that evolved into a highly clumpy matter distribution, as revealed by the present distribution of luminous matter, constitutes a major challenge of modern cosmology. A number of techniques have been devised in recent years which attempt to achieve this aim by using galaxy positions alone [8 refs.]. However, without knowledge of their velocities, this problem is not well-posed and its solution suffers frequently from lack of uniqueness. Here we make the hypothesis that the map from initial to present locations of mass elements is irrotational. Using recent mathematical work [Brenier], we then relate reconstruction to ``mass transportation'', a well-posed optimisation problem in engineering introduced by Monge in 1781. We propose a new powerful algorithm for unique reconstruction which, when tested against N-body simulations, gives excellent reconstruction down to scales of a few comoving megaparsecs and demonstrates the validity of our hypoth...

  4. Early developmental stages of Ascaris lumbricoides featured by high-resolution mass spectrometry.

    Science.gov (United States)

    Melo, Carlos Fernando Odir Rodrigues; Esteves, Cibele Zanardi; de Oliveira, Rosimeire Nunes; Guerreiro, Tatiane Melina; de Oliveira, Diogo Noin; Lima, Estela de Oliveira; Miné, Júlio César; Allegretti, Silmara Marques; Catharino, Rodrigo Ramos

    2016-11-01

    Ascaris lumbricoides is responsible for a highly disseminated helminth parasitic disease, ascariosis, a relevant parasitosis that responds for great financial burden on the public health system of developing countries. In this work, metabolic fingerprinting using high-resolution mass spectrometry (HRMS) was employed to identify marker molecules from A. lumbricoides in different development stages. We have identified nine biomarkers, such as pheromones and steroidal prohormones in early stages, among other molecules in late development stages, making up four molecules for fertilized eggs, four marker molecules for first larvae (L1) and one marker molecule for third larvae (L3). Therefore, our findings indicate that this approach is suitable for biochemical characterization of A. lumbricoides development stages. Moreover, the straightforward analytical method employed, with almost no sample preparation from a complex matrix (feces) using high-resolution mass spectrometry, suggests that it is possible to seek for an easier and faster way to study animal molding processes.

  5. Monitoring and prediction in Early Warning Systems (EWS) for rapid mass movements

    Science.gov (United States)

    Stähli, M.; Sättele, M.; Huggel, C.; McArdell, B. W.; Lehmann, P.; Van Herwijnen, A.; Berne, A.; Schleiss, M.; Ferrari, A.; Kos, A.; Or, D.; Springman, S. M.

    2014-11-01

    Rapid mass movements (RMM) pose a substantial risk to people and infrastructure. Reliable and cost-efficient measures have to be taken to reduce this risk. One of these measures includes establishing and advancing the State of Practice in the application of Early Warning Systems (EWS). EWS have been developed during the past decades and are rapidly increasing. In this document, we focus on the technical part of EWS, i.e. the prediction and timely recognition of imminent hazards, as well as on monitoring slopes at risk and released mass movements. Recent innovations in assessing spatial precipitation, as well as monitoring and modelling precursors, the triggering and deformation of RMM offer new opportunities for next-generation EWS. However, technical advancement can only be transferred into more reliable, operational EWS with an intense dialog between scientists, engineers and those in charge of warning. To this end, further experience with new comprehensive prototype systems jointly operated by scientists and practitioners will be essential.

  6. The early gaseous and stellar mass assembly of Milky Way-type galaxy haloes

    Science.gov (United States)

    Hensler, Gerhard

    2015-08-01

    In cosmological simulations of Cold Dark Matter (CDM) structure formation a vast number of subhalos is expected around massive galaxies like the Milky Way (MW). These DM subhalos are filled with baryons, gas that forms stars very early as observed from the stellar populations in the MW satellite galaxies. Satellite galaxies evolve in the tidal field of their mature galaxy and suffer accretion to the major galaxy and their partly disruption. By this, their mass loss is expected to feed the galaxy halo with stars and gas.From the Via Lactea II simulations we select a massive DM halo with its satellite system which evolves in the simulations to a present-day MW-type galaxy. We follow its evolution from redshift 4.5 to 2.5, i.e. over almost 2 billion years of the most interesting epoch of mass assembly. A high mass resolution allows for even low-mass satellites down to 10^5 Msun, but limits their distance range to the innermost 240 satellites of the system only. The applied chemo-dynamical method includes star formation, stellar energetic and chemical feedback, and gas physical processes.After the onset of the simulation our models demonstrate the action of tidal effects and satellite merging on the star-formation rate of the satellites, their gas loss by means of hot-gas expansion, of ram-pressure and tidal stripping, and the tidal extraction of stars, leading to the formation of the stellar and gaseous galactic halo. We also analyze the evolution of the satellites’ mass function, their baryonic and DM mass distributions, chemical abundances, their compactness, their present-day appearance, etc. with respect to observations and present-day correlations.

  7. Accelerating clinical insights: how to use accelerator mass spectrometry to make better early development decisions.

    Science.gov (United States)

    Seymour, Mark

    2010-12-01

    This paper is an overview of the applications of the technique of Accelerator Mass Spectrometry (AMS) in the biomedical drug development field. The work described here has been carried out at Xceleron (York, UK and Germantown, MD, USA), and it aims to apply AMS to provide better information about the human pharmacokinetic/metabolic behaviour of drugs or drug candidates as early as possible. It is hoped that the use of this technique will contribute to the delivery of better, more effective drugs onto the market sooner, which will be good news for all concerned.

  8. Mass-to-light ratios in early-type galaxies and the dark matter content

    CERN Document Server

    Capaccioli, M; Arnaboldi, M

    2002-01-01

    The distribution of the radial trends of the mass-to-light ratios (M/L) within an assorted sample of early-type galaxies is discussed. Three classes of galaxies are identified according to their M/L gradients. Two such classes are characterized by the presence or by the absence of a radial gradient of the dark-matter (DM) distribution. A third class contains objects which are likely undergoing interaction; they exhibit steep M/L gradients which are possibly the result of a wrong assumption on their equilibrium conditions. Finally, a possible correlation between DM content and morphological types is briefly discussed.

  9. Time variation of the electron mass in the early universe and the Barrow-Magueijo model

    CERN Document Server

    Scóccola, Claudia G; Landau, Susana J; Vucetich, Héctor

    2008-01-01

    We put limits on the time variation of the electron mass in the early universe using observational primordial abundances of D, He4 and Li7, recent data from the Cosmic Microwave Background and the 2dFGRS power spectrum. Furthermore, we use these constraints together with other astronomical and geophysical bounds from the late universe to test Barrow-Magueijo's model for the variation in m_e. From our analysis we obtain -0.615 < G\\omega/c^4 < -0.045 (3\\sigma interval) in disagreement with the result obtained in the original paper.

  10. U/Pb zircon geochronology and tempo of the end-permian mass extinction

    Science.gov (United States)

    Bowring; Erwin; Jin M W Martin YG; Davidek; Wang

    1998-05-15

    The mass extinction at the end of the Permian was the most profound in the history of life. Fundamental to understanding its cause is determining the tempo and duration of the extinction. Uranium/lead zircon data from Late Permian and Early Triassic rocks from south China place the Permian-Triassic boundary at 251.4 +/- 0.3 million years ago. Biostratigraphic controls from strata intercalated with ash beds below the boundary indicate that the Changhsingian pulse of the end-Permian extinction, corresponding to the disappearance of about 85 percent of marine species, lasted less than 1 million years. At Meishan, a negative excursion in delta13C at the boundary had a duration of 165,000 years or less, suggesting a catastrophic addition of light carbon.

  11. Permian Triassic palynofloral transition in Chintalapudi area, Godavari Graben, Andhra Pradesh, India

    Indian Academy of Sciences (India)

    Neerja Jha; M Basava Chary; Neha Aggarwal

    2012-10-01

    The entire 606 m-thick sedimentary sequence in borecore MCP-7 from Chintalapudi area, Chintalapudi sub-basin has been lithologically designated as Kamthi Formation. However, the palynological investigation revealed five distinct palynoassemblages, which essentially fall under two groups, one group (Palynoassemblage-I, II and III) having dominance of striate disaccates along with presence of some stratigraphically significant taxa, belongs to Late Permian (Raniganj) palynoflora, while the other group (Palynoassemblages IV and V) shows sharp decline in percentage of characteristic taxa of first group, i.e., striate disaccates, and consequent rise or dominance of taeniate and cingulate cavate spores, belongs to Early Triassic (Panchet) palynoflora. Palynoassemblage-I, II and III (Group I) are characterized by dominance of striate disaccates chiefly, Striatopodocarpites spp. and Faunipollenites spp. Along with presence of rare but stratigraphically significant taxa, viz., Gondisporites raniganjensis, Falcisporites nuthaliensis, Klausipollenites schaubergeri, Chordasporites sp., Striomonosaccites, ovatus, Crescentipollenites multistriatus, Verticipollenites debiles, Strotersporites crassiletus, Guttulapollenites hannonicus, G. gondwanensis, Hamiapollenites insolitus, Corisaccites alutus, Lunatisporites ovatus, Weylandites spp. and Vitreisporites pallidus. Palynoassemblage-I is distinguished by significant presence of Densipollenites spp. while Palynoassemblage-II shows significant presence of Crescentipollenites spp. and Palynoassemblage-III differs from the above two assemblages in having significant presence of Guttulapollenites hannonicus. Palynoassemblage-IV (Group II) is characterized by high percentage of taeniate disaccates chiefly Lunatisporites spp., while Palynoassemblage-V (Group II) is characterized by cingulate-cavate trilete spores chiefly, Lundbladispora spp. and Densoisporites spp. Striate disaccates show a sharp decline in these two assemblages. In

  12. A systematic variation of the stellar initial mass function in early-type galaxies

    CERN Document Server

    Cappellari, Michele; Alatalo, Katherine; Blitz, Leo; Bois, Maxime; Bournaud, Frederic; Bureau, M; Crocker, Alison F; Davies, Roger L; Davis, Timothy A; de Zeeuw, P T; Duc, Pierre-Alain; Emsellem, Eric; Khochfar, Sadegh; Krajnovic, Davor; Kuntschner, Harald; Lablanche, Pierre-Yves; Morganti, Raffaella; Naab, Thorsten; Oosterloo, Tom; Sarzi, Marc; Scott, Nicholas; Serra, Paolo; Weijmans, Anne-Marie; Young, Lisa M

    2012-01-01

    Much of our knowledge of galaxies comes from analysing the radiation emitted by their stars. It depends on the stellar initial mass function (IMF) describing the distribution of stellar masses when the population formed. Consequently knowledge of the IMF is critical to virtually every aspect of galaxy evolution. More than half a century after the first IMF determination, no consensus has emerged on whether it is universal in different galaxies. Previous studies indicated that the IMF and the dark matter fraction in galaxy centres cannot be both universal, but they could not break the degeneracy between the two effects. Only recently indications were found that massive elliptical galaxies may not have the same IMF as our Milky Way. Here we report unambiguous evidence for a strong systematic variation of the IMF in early-type galaxies as a function of their stellar mass-to-light ratio, producing differences up to a factor of three in mass. This was inferred from detailed dynamical models of the two-dimensional ...

  13. Systematic variations of central mass density slopes in early-type galaxies

    CERN Document Server

    Tortora, C; Napolitano, N R; Romanowsky, A J; Ferreras, I; de Carvalho, R R

    2014-01-01

    We study the total density distribution in the central regions (~ 1 effective radius, $R_e$) of early-type galaxies (ETGs), using data from SPIDER and $\\rm ATLAS^{3D}$. Our analysis extends the range of galaxy stellar mass ($M_{\\star}$) probed by gravitational lensing, down to ~ $10^{10}\\, \\rm M_{\\odot}$. We model each galaxy with two components (dark matter halo + stars), exploring different assumptions for the dark matter (DM) halo profile (i.e. NFW, NFW-contracted, and Burkert profiles), and leaving stellar mass-to-light ($M_{\\star}/L$) ratios as free fitting parameters to the data. For all plausible halo models, the best-fitting $M_{\\star}/L$, normalized to that for a Chabrier IMF, increases systematically with galaxy size and mass. For an NFW profile, the slope of the total mass profile is non-universal, independently of several ingredients in the modeling (e.g., halo contraction, anisotropy, and rotation velocity in ETGs). For the most massive ($M_{\\star}$ ~ $10^{11.5} \\, M_{\\odot}$) or largest ($R_{\\rm...

  14. Evidence for the rapid formation of low mass early-type galaxies in dense environments

    CERN Document Server

    Liu, Yiqing; Blakeslee, John; Côté, Patrick; Ferrarese, Laura; Jordán, Andrés; Puzia, Thomas H; Toloba, Elisa; Zhang, Hong-Xin

    2015-01-01

    We explore the environmental dependence of star formation timescales in low mass galaxies using the [$\\alpha$/Fe] abundance ratio as an evolutionary clock. We present integrated [$\\alpha$/Fe] measurements for 11 low mass ($M_\\star \\sim 10^9~M_\\odot$) early-type galaxies (ETGs) with a large range of cluster-centric distance in the Virgo Cluster. We find a gradient in [$\\alpha$/Fe], where the galaxies closest to the cluster center (the cD galaxy, M87) have the highest values. This trend is driven by galaxies within a projected radius of 0.4~Mpc (0.26 times the virial radius of Virgo~A), all of which have super-solar [$\\alpha$/Fe]. Galaxies in this mass range exhibit a large scatter in the [$\\alpha$/Fe]--$\\sigma$ diagram, and do not obviously lie on an extension of the relation defined by massive ETGs. In addition, we find a correlation between [$\\alpha$/Fe] and globular cluster specific frequency ($S_N$), suggesting that low-mass ETGs that formed their stars over a short period of time, were also efficient at f...

  15. The history of star formation and mass assembly in early-type galaxies

    CERN Document Server

    Clemens, M S; Nikolic, B; Rampazzo, R

    2008-01-01

    We define a volume limited sample of over 14,000 early-type galaxies (ETGs) selected from data release six of the Sloan Digital Sky Survey. The density of environment of each galaxy is robustly measured. By comparing narrow band spectral line indices with recent models of simple stellar populations (SSPs) we investigate trends in the star formation history as a function of galaxy mass (velocity dispersion), density of environment and galactic radius. We find that age, metallicity and alpha-enhancement all increase with galaxy mass and that field ETGs are younger than their cluster counterparts by ~2 Gyr. We find negative radial metallicity gradients for all masses and environments, and positive radial age gradients for ETGs with velocity dispersion over 180 km/s. Our results are qualitatively consistent with a relatively simple picture for ETG evolution in which the low-mass halos accreted by a proto-ETG contained not only gas but also a stellar population. This fossil population is preferentially found at la...

  16. Mass spectrometric detection of biomarkers for early assessment of intraamniotic fluid infection

    Directory of Open Access Journals (Sweden)

    Consuelo Cháfer-Pericás

    2015-12-01

    Full Text Available This data article contains information on glutathione sulfonamide (GSA structural confirmation and purity after synthesis, as well as mass spectrometry acquisition parameters for the determination of GSA and other biomarkers for the early assessment of intraamniotic fluid infection in amniotic fluid samples (Cháfer-Pericás et al., 2015 [1]. GSA standards were synthesized and structural confirmation was carried out employing time-of-flight mass spectrometry (TOF-MS; purity was assessed by high performance liquid chromatography (HPLC with UV detection. For optimization of the acquisition parameters of GSA and other biomarkers, individual analytical standard solution at a concentration of 1 µmol L−1 was injected into an Acquity – Xevo TQ liquid-chromatography coupled to tandem mass spectrometry (LC-MS/MS system from Waters (Milford, MA, USA operating in the positive electrospray (ESI+ mode. Mass spectrometric detection of 3-nitro-tyrosine (3NO2-Tyr, 3-chloro-tyrosine (3Cl-Tyr, 8-hydroxy-2′-deoxyguanosine (8OHdG, GSA and oxidized glutathione (GSSG was carried out by multiple reaction monitoring (MRM. Linear response curves were calculated for each analyte normalizing the signal with peak areas of internal standards.

  17. Puffing up early-type galaxies by baryonic mass loss: numerical experiments

    CERN Document Server

    Ragone-Figueroa, Cinthia

    2011-01-01

    We present numerical simulations of the effect of baryonic mass loss on the structure of a spheroidal stellar system, embedded in a dark matter halo. This process could be caused either by QSO/starburst driven galactic winds, promptly ejecting from Early Type Galaxies (ETGs) the residual gas (galactic winds), or by stellar mass returned to the ISM in the final stages of stellar evolution. We find that a conceivable loss of about 50% of the baryonic mass can produce a significant size increase, which could contribute to the claimed size evolution of ETGs since z about 2. However, most (all in the case of QSO driven winds) of the puffing up occurs when the stellar population are much younger than the estimated ages of compact high-z ETGs. We conclude that the putative expansion caused by galactic winds is still not observed, while that due to stellar evolution could contribute to, but not dominate, the evolution of the mass-size relationship of ETGs observed so far.

  18. Implications for the origin of early-type dwarf galaxies - the discovery of rotation in isolated, low-mass early-type galaxies

    Science.gov (United States)

    Janz, Joachim; Penny, Samantha J.; Graham, Alister W.; Forbes, Duncan A.; Davies, Roger L.

    2017-07-01

    We present the discovery of rotation in quenched, low-mass early-type galaxies that are isolated. This finding challenges the claim that (all) rotating dwarf early-type galaxies in clusters were once spiral galaxies that have since been harassed and transformed into early-type galaxies. Our search of the Sloan Digital Sky Survey data within the Local Volume (z half-light radius Re in the best cases, and beyond Re/2 for all. They reveal a variety of behaviours similar to those of a comparison sample of early-type dwarf galaxies in the Virgo cluster observed by Toloba et al. Both samples have similar frequencies of slow and fast rotators, as well as kinematically decoupled cores. This, and especially the finding of rotating quenched low-mass galaxies in isolation, reveals that the early-type dwarfs in galaxy clusters need not be harassed or tidally stirred spiral galaxies.

  19. Mass spectrometry-based serum proteome pattern analysis in molecular diagnostics of early stage breast cancer

    Directory of Open Access Journals (Sweden)

    Stobiecki Maciej

    2009-07-01

    Full Text Available Abstract Background Mass spectrometric analysis of the blood proteome is an emerging method of clinical proteomics. The approach exploiting multi-protein/peptide sets (fingerprints detected by mass spectrometry that reflect overall features of a specimen's proteome, termed proteome pattern analysis, have been already shown in several studies to have applicability in cancer diagnostics. We aimed to identify serum proteome patterns specific for early stage breast cancer patients using MALDI-ToF mass spectrometry. Methods Blood samples were collected before the start of therapy in a group of 92 patients diagnosed at stages I and II of the disease, and in a group of age-matched healthy controls (104 women. Serum specimens were purified and the low-molecular-weight proteome fraction was examined using MALDI-ToF mass spectrometry after removal of albumin and other high-molecular-weight serum proteins. Protein ions registered in a mass range between 2,000 and 10,000 Da were analyzed using a new bioinformatic tool created in our group, which included modeling spectra as a sum of Gaussian bell-shaped curves. Results We have identified features of serum proteome patterns that were significantly different between blood samples of healthy individuals and early stage breast cancer patients. The classifier built of three spectral components that differentiated controls and cancer patients had 83% sensitivity and 85% specificity. Spectral components (i.e., protein ions that were the most frequent in such classifiers had approximate m/z values of 2303, 2866 and 3579 Da (a biomarker built from these three components showed 88% sensitivity and 78% specificity. Of note, we did not find a significant correlation between features of serum proteome patterns and established prognostic or predictive factors like tumor size, nodal involvement, histopathological grade, estrogen and progesterone receptor expression. In addition, we observed a significantly (p = 0

  20. Evidence for prosauropod dinosaur gastroliths in the Bull Run Formation (Upper Triassic, Norian) of Virginia

    Science.gov (United States)

    Weems, R.E.; Culp, M.J.; Wings, O.

    2007-01-01

    Definitive criteria for distinguishing gastroliths from sedimentary clasts are lacking for many depositional settings, and many reported occurrences of gastroliths either cannot be verified or have been refuted. We discuss four occurrences of gastrolith-like stones (category 6 exoliths) not found within skeletal remains from the Upper Triassic Bull Run Formation of northern Virginia, USA. Despite their lack of obvious skeletal association, the most parsimonious explanation for several characteristics of these stones is their prolonged residence in the gastric mills of large animals. These characteristics include 1) typical gastrolith microscopic surface texture, 2) evidence of pervasive surface wear on many of these stones that has secondarily removed variable amounts of thick weathering rinds typically found on these stones, and 3) a width/length-ratio modal peak for these stones that is more strongly developed than in any population of fluvial or fanglomerate stones of any age found in this region. When taken together, these properties of the stones can be explained most parsimoniously by animal ingestion and gastric-mill abrasion. The size of these stones indicates the animals that swallowed them were large, and the best candidate is a prosauropod dinosaur, possibly an ancestor of the Early Jurassic gastrolith-producing prosauropod Massospondylus or Ammosaurus. Skeletal evidence for Upper Triassic prosauropods is lacking in the Newark Supergroup basins; footprints (Agrestipus hottoni and Eubrontes isp.) from the Bull Run Formation in the Culpeper basin previously ascribed to prosauropods are now known to be underprints (Brachychirotherium parvum) of an aetosaur and underprints (Kayentapus minor) of a ceratosaur. The absence of prosauropod skeletal remains or footprints in all but the uppermost (upper Rhaetian) Triassic rocks of the Newark Supergroup is puzzling because prosauropod remains are abundant elsewhere in the world in Upper Triassic (Carnian, Norian

  1. Chemo- and palyno-stratigraphy of the Permian-Triassic transition in the Boreal region

    Science.gov (United States)

    van Soelen, Els; Planke, Sverre; Svensen, Henrik; Twitchett, Richard; Polozov, Alexander; Kürschner, Wolfram

    2016-04-01

    Late Permian and early Triassic sediments from Boreal regions are studied using palynological and organic geochemical tools. We present preliminary results from two sites: a Norwegian site which is represented by a 100-m long borehole core and outcrops from Deltadalen on Spitsbergen, and a Russian site which is represented by outcrops and short cores collected near Norilsk in northern Siberia. The main goals of the project are to improve the stratigraphy and to study the environmental changes at high resolution. There is a growing scientific consensus that end Permian biotic crisis was linked to the Siberian Traps Large Igneous Province (LIP) event. However, direct evidence for a stratigraphic correlation of the marine and terrestrial extinction events, with the volcanic successions in the Siberian basin, is rather limited. The Permian-Triassic boundary successions in the Arctic are crucial for direct correlation eastwards to the Siberian Traps. The magnitude and timing of a carbon isotope excursion near the Permian-Triassic boundary is an important stratigraphical tool that may help to unravel the sequence of the events happening during this important period. Preliminary results from the Deltadalen core near the base of the Vikinghøgda Formation show shifts in δ13C from -24.5 to -32.7‰ in the interval expected to span the Permian/Triassic boundary. New Rock-Eval pyrolysis data will shed further light on the origin of the organic matter (e.g. marine versus terrestrial) and may help to understand how much of the δ13C signal can be explained by changes in organic matter source and how much may be attributed to a global change in the carbon isotope signature. Furthermore, compound specific isotope analysis will be done on terrestrial derived lipids (long chain n-alkanes) to reconstruct changes in atmospheric carbon isotopes. In addition to chemostratigraphy, the palynological record will be used for biostratigraphical studies at both Deltadalen and Norilsk

  2. Impact event at the Permian-Triassic boundary: evidence from extraterrestrial noble gases in fullerenes.

    Science.gov (United States)

    Becker, L; Poreda, R J; Hunt, A G; Bunch, T E; Rampino, M

    2001-02-23

    The Permian-Triassic boundary (PTB) event, which occurred about 251.4 million years ago, is marked by the most severe mass extinction in the geologic record. Recent studies of some PTB sites indicate that the extinctions occurred very abruptly, consistent with a catastrophic, possibly extraterrestrial, cause. Fullerenes (C60 to C200) from sediments at the PTB contain trapped helium and argon with isotope ratios similar to the planetary component of carbonaceous chondrites. These data imply that an impact event (asteroidal or cometary) accompanied the extinction, as was the case for the Cretaceous-Tertiary extinction event about 65 million years ago.

  3. Dietary energy density affects fat mass in early adolescence and is not modified by FTO variants.

    Directory of Open Access Journals (Sweden)

    Laura Johnson

    Full Text Available BACKGROUND: Dietary energy density (DED does not have a simple linear relationship to fat mass in children, which suggests that some children are more susceptible than others to the effects of DED. Children with the FTO (rs9939609 variant that increases the risk of obesity may have a higher susceptibility to the effects of DED because their internal appetite control system is compromised. We tested the relationship between DED and fat mass in early adolescence and its interaction with FTO variants. METHODS AND FINDINGS: We carried out a prospective analysis on 2,275 children enrolled in the Avon Longitudinal Study of Parents and Children (ALSPAC. Diet was assessed at age 10 y using 3-day diet diaries. DED (kJ/g was calculated excluding drinks. Children were genotyped for the FTO (rs9939609 variant. Fat mass was estimated at age 13 y using the Lunar Prodigy Dual-energy X-ray Absorptiometry scanner. There was no evidence of interaction between DED at age 10 y and the high risk A allele of the FTO gene in relation to fat mass at age 13 y (beta = 0.005, p = 0.51, suggesting that the FTO gene has no effect on the relation between DED at 10 y and fat mass at 13 y. When DED at 10 y and the A allele of FTO were in the same model they were independently related to fat mass at 13 y. Each A allele of FTO was associated with 0.35+/-0.13 kg more fat mass at 13 y and each 1 kJ/g DED at 10 y was associated with 0.16+/-0.06 kg more fat mass at age 13 y, after controlling for misreporting of energy intake, gender, puberty, overweight status at 10 y, maternal education, TV watching, and physical activity. CONCLUSIONS: This study reveals the multi-factorial origin of obesity and indicates that although FTO may put some children at greater risk of obesity, encouraging a low dietary energy density may be an effective strategy to help all children avoid excessive fat gain.

  4. Dietary energy density affects fat mass in early adolescence and is not modified by FTO variants.

    Science.gov (United States)

    Johnson, Laura; van Jaarsveld, Cornelia H M; Emmett, Pauline M; Rogers, Imogen S; Ness, Andy R; Hattersley, Andrew T; Timpson, Nicholas J; Smith, George Davey; Jebb, Susan A

    2009-01-01

    Dietary energy density (DED) does not have a simple linear relationship to fat mass in children, which suggests that some children are more susceptible than others to the effects of DED. Children with the FTO (rs9939609) variant that increases the risk of obesity may have a higher susceptibility to the effects of DED because their internal appetite control system is compromised. We tested the relationship between DED and fat mass in early adolescence and its interaction with FTO variants. We carried out a prospective analysis on 2,275 children enrolled in the Avon Longitudinal Study of Parents and Children (ALSPAC). Diet was assessed at age 10 y using 3-day diet diaries. DED (kJ/g) was calculated excluding drinks. Children were genotyped for the FTO (rs9939609) variant. Fat mass was estimated at age 13 y using the Lunar Prodigy Dual-energy X-ray Absorptiometry scanner. There was no evidence of interaction between DED at age 10 y and the high risk A allele of the FTO gene in relation to fat mass at age 13 y (beta = 0.005, p = 0.51), suggesting that the FTO gene has no effect on the relation between DED at 10 y and fat mass at 13 y. When DED at 10 y and the A allele of FTO were in the same model they were independently related to fat mass at 13 y. Each A allele of FTO was associated with 0.35+/-0.13 kg more fat mass at 13 y and each 1 kJ/g DED at 10 y was associated with 0.16+/-0.06 kg more fat mass at age 13 y, after controlling for misreporting of energy intake, gender, puberty, overweight status at 10 y, maternal education, TV watching, and physical activity. This study reveals the multi-factorial origin of obesity and indicates that although FTO may put some children at greater risk of obesity, encouraging a low dietary energy density may be an effective strategy to help all children avoid excessive fat gain.

  5. Systematic trends in total-mass profiles from dynamical models of early-type galaxies

    Science.gov (United States)

    Poci, Adriano; Cappellari, Michele; McDermid, Richard M.

    2017-01-01

    We study trends in the slope of the total mass profiles and dark matter fractions within the central half-light radius of 258 early-type galaxies, using data from the volume-limited ATLAS3D survey. We use three distinct sets of dynamical models, which vary in their assumptions and also allow for spatial variations in the stellar mass-to-light ratio, to test the robustness of our results. We confirm that the slopes of the total mass profiles are approximately isothermal, and investigate how the total-mass slope depends on various galactic properties. The most statistically-significant correlations we find are a function of either surface density, Σe, or velocity dispersion, σe. However there is evidence for a break in the latter relation, with a nearly universal logarithmic slope above log10[σe/(km s-1)] ˜ 2.1 and a steeper trend below this value. For the 142 galaxies above that critical σe value, the total mass-density logarithmic slopes have a mean value = -2.193 ± 0.016 (1σ error) with an observed rms scatter of only σ _{γ ^' }= 0.168 ± 0.015. Considering the observational errors, we estimate an intrinsic scatter of σ _{γ ^' }^intr ≈ 0.15. These values are broadly consistent with those found by strong lensing studies at similar radii and agree, within the tight errors, with values recently found at much larger radii via stellar dynamics or HI rotation curves (using significantly smaller samples than this work).

  6. Fluid Flow History in Lower Triassic Bulgo Sandstone, Central Sydney Basin, Australia

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    The fluid flow history during diagenesis of the Lower Triassic Bulgo sandstone has been investigated through integrated analyses of petrography, stable isotope and fluid inclusion. Combined application of these techniques was intended to constrain the temperature, timing, chemistry and source of pore fluids during diagenetic cementation events in the Lower Triassic Bulgo sandstone. The dlagenesis proceeded in two different flow regimes: early dynamic fluid flow regime and late slow static fluid flow regime. The former was characterized by a slight increase of δ(18O) of pore waters form estimated -15 × 10-3 to -14 × 10-3 with the temperature increasing from ~ 10 ℃ to ~ 75 ℃. During early diagenesis, early clays and pore filling carbonates precipitated from the pore waters. The late slow flow/static fluid regime was characterized by a rapid 18O-enrichment process. δ(18O) of pore waters increased from -14× 10-3 to -5× 10-3 with the temperature increasing from 75 ℃ to 110 ℃. During the late diagenesis, kaolin (generation Ⅲ ), quartz and illite crystallized. Oil migrated to the sandstones of the Bulgo sandstone during quartz cementation.

  7. The SLUGGS survey: revisiting the correlation between X-ray luminosity and total mass of massive early-type galaxies

    Science.gov (United States)

    Forbes, Duncan A.; Alabi, Adebusola; Romanowsky, Aaron J.; Kim, Dong-Woo; Brodie, Jean P.; Fabbiano, Giuseppina

    2017-01-01

    Here we utilize recent measures of galaxy total dynamical mass and X-ray gas luminosities (LX,Gas) for a sample of 29 massive early-type galaxies from the SLUGGS survey to probe LX, Gas-mass scaling relations. In particular, we investigate scalings with stellar mass, dynamical mass within 5 effective radii (Re) and total virial mass. We also compare these relations with predictions from Λ cold dark matter simulations. We find a strong linear relationship between LX, Gas and galaxy dynamical mass within 5Re, which is consistent with the recent cosmological simulations of Choi et al. that incorporate mechanical heating from AGN. We conclude that the gas surrounding massive early-type galaxies was shock-heated as it fell into collapsing dark matter haloes so that LX, Gas is primarily driven by the depth of a galaxy's potential well. Heating by an AGN plays an important secondary role in determining LX, Gas.

  8. Candidate autoantigens identified by mass spectrometry in early rheumatoid arthritis are chaperones and citrullinated glycolytic enzymes

    Science.gov (United States)

    Goëb, Vincent; Thomas-L'Otellier, Marlène; Daveau, Romain; Charlionet, Roland; Fardellone, Patrice; Le Loët, Xavier; Tron, François; Gilbert, Danièle; Vittecoq, Olivier

    2009-01-01

    Introduction The aim of our study was to identify new early rheumatoid arthritis (RA) autoantibodies. Methods Sera obtained from 110 early untreated RA patients (citrullination in each of these proteins was evaluated. FT-ICR mass spectrometry was used to verify experimentally the effect of citrullination upon the mass profile observed by MALDI-TOF analysis. Results The 110 1-DE patterns allowed detection of 10 recurrent immunoreactive bands of 33, 39, 43, 46, 51, 54, 58, 62, 67 and 70 kDa, which were further characterized by 2-DE and proteomic analysis. Six proteins were already described RA antigens: heterogeneous nuclear ribonucleoprotein A2/B1, aldolase, α-enolase, calreticulin, 60 kDa heat shock protein (HSP60) and BiP. Phosphoglycerate kinase 1 (PGK1), stress-induced phosphoprotein 1 and the far upstream element-binding proteins (FUSE-BP) 1 and 2 were identified as new antigens. Post-translational protein modifications were analyzed and potentially deiminated peptides were found on aldolase, α-enolase, PGK1, calreticulin, HSP60 and the FUSE-BPs. We compared the reactivity of RA sera with citrullinated and noncitrullinated α-enolase and FUSE-BP linear peptides, and showed that antigenicity of the FUSE-BP peptide was highly dependent on citrullination. Interestingly, the anti-cyclic citrullinated peptide antibody (anti-CCP2) status in RA serum at inclusion was not correlated to the reactivity directed against FUSE-BP citrullinated peptide. Conclusions Two categories of antigens, enzymes of the glycolytic family and molecular chaperones are also targeted by the early untreated RA autoantibody response. For some of them, and notably the FUSE-BPs, citrullination is involved in the immunological tolerance breakdown observed earlier in RA patients. Autoantibodies recognizing a citrullinated peptide from FUSE-BP may enhance the sensibility for RA of the currently available anti-CCP2 test. PMID:19284558

  9. The Krebs cycle and mitochondrial mass are early victims of endothelial dysfunction: proteomic approach.

    Science.gov (United States)

    Addabbo, Francesco; Ratliff, Brian; Park, Hyeong-Cheon; Kuo, Mei-Chuan; Ungvari, Zoltan; Csiszar, Anna; Ciszar, Anna; Krasnikov, Boris; Krasnikof, Boris; Sodhi, Komal; Zhang, Fung; Nasjletti, Alberto; Goligorsky, Michael S

    2009-01-01

    Endothelial cell dysfunction is associated with bioavailable nitric oxide deficiency and an excessive generation of reactive oxygen species. We modeled this condition by chronically inhibiting nitric oxide generation with subpressor doses of N(G)-monomethyl-L-arginine (L-NMMA) in C57B6 and Tie-2/green fluorescent protein mouse strains. L-NMMA-treated mice exhibited a slight reduction in vasorelaxation ability, as well as detectable abnormalities in soluble adhesion molecules (soluble intercellular adhesion molecule-1 and vascular cellular adhesion molecule-1, and matrix metalloproteinase 9), which represent surrogate indicators of endothelial dysfunction. Proteomic analysis of the isolated microvasculature using 2-dimensional gel electrophoresis and matrix-assisted laser desorption/ionization time-of-flight mass spectroscopy revealed abnormal expression of a cluster of mitochondrial enzymes, which was confirmed using immunodetection. Aconitase-2 and enoyl-CoA-hydratase-1 expression levels were decreased in L-NMMA-treated animals; this phenotype was absent in nitric oxide synthase-1 and -3 knockout mice. Depletion of aconitase-2 and enoyl-CoA-hydratase-1 resulted in the inhibition of the Krebs cycle and enhanced pyruvate shunting toward the glycolytic pathway. To assess mitochondrial mass in vivo, co-localization of green fluorescent protein and MitoTracker fluorescence was detected by intravital microscopy. Quantitative analysis of fluorescence intensity showed that L-NMMA-treated animals exhibited lower fluorescence of MitoTracker in microvascular endothelia as a result of reduced mitochondrial mass. These findings provide conclusive and unbiased evidence that mitochondriopathy represents an early manifestation of endothelial dysfunction, shifting cell metabolism toward "metabolic hypoxia" through the selective depletion of both aconitase-2 and enoyl-CoA-hydratase-1. These findings may contribute to an early preclinical diagnosis of endothelial dysfunction.

  10. Paleoclimate Reconstruction From the d13C Organic and d13C Carbonate Proxies in Triassic Paleosols and Sediments, Ischigualasto Basin Argentina

    Science.gov (United States)

    Moore, K. A.; Tabor, N. J.; Montañez, I. P.; Currie, B.; Shipman, T.

    2001-12-01

    Stable carbon isotopes of organic matter and paleosol carbonate from the Triassic Ischigualasto Formation, Argentina are used as a proxy of paleoatmospheric pCO2 and d13CO2. Carbon and Oxygen isotope values were determined for over 100 Triassic pedogenic carbonate nodules and associated organic matter. The d13C of carbonate ranges from -3.29 per mil to -10.56 per mil. The d13C of organic matter ranges from -21.07 per mil to -24.24 per mil. The Hydrogen and Oxygen indices and TOC values indicate that the best preserved organic matter samples yield the most negative d13C values. Reconstructed pCO2 levels were around 1000 ppm V in the early to mid- Triassic and increased to around 2000 ppm V later in the Triassic. This maximum is followed by a fall in pCO2 in the late Triassic. This previously undocumented rapid change in paleo-CO2 levels likely accompanied the evolution of mammal-like reptiles to true dinosaurs as well as rapid climate change.

  11. The Sensitivity of Harassment to Orbit: Mass Loss from Early-Type Dwarfs in Galaxy Clusters

    CERN Document Server

    Smith, Rory; Beasley, Michael A; Candlish, Graeme N; Gibson, Brad K; Puzia, Thomas H; Janz, Joachim; Knebe, Alexander; Aguerri, J Alfonso L; Lisker, Thorsten; Hensler, Gerhard; Fellhauer, Michael; Ferrarese, Laura; Yi, Sukyoung K

    2015-01-01

    We conduct a comprehensive numerical study of the orbital dependence of harassment on early-type dwarfs consisting of 168 different orbits within a realistic, Virgo-like cluster, varying in eccentricity and pericentre distance. We find harassment is only effective at stripping stars or truncating their stellar disks for orbits that enter deep into the cluster core. Comparing to the orbital distribution in cosmological simulations, we find that the majority of the orbits (more than three quarters) result in no stellar mass loss. We also study the effects on the radial profiles of the globular cluster systems of early-type dwarfs. We find these are significantly altered only if harassment is very strong. This suggests that perhaps most early-type dwarfs in clusters such as Virgo have not suffered any tidal stripping of stars or globular clusters due to harassment, as these components are safely embedded deep within their dark matter halo. We demonstrate that this result is actually consistent with an earlier st...

  12. Permo-Triassic vertebrate extinctions: A program

    Science.gov (United States)

    Olson, E. C.

    1988-01-01

    Since the time of the Authors' study on this subject, a great deal of new information has become available. Concepts of the nature of extinctions have changed materially. The Authors' conclusion that a catastrophic event was not responsible for the extinction of vertebrates has modified to the extent that hypotheses involving either the impact of a massive extra-terrestrial body or volcanism provide plausible but not currently fully testable hypotheses. Stated changes resulted in a rapid decrease in organic diversity, as the ratio of origins of taxa to extinctions shifted from strongly positive to negative, with momentary equilibrium being reached at about the Permo-Triassic boundary. The proximate causes of the changes in the terrestrial biota appear to lie in two primary factors: (1) strong climatic changes (global mean temperatures, temperature ranges, humidity) and (2) susceptibility of the dominant vertebrates (large dicynodonts) and the glossopteris flora to disruption of the equlibrium of the world ecosystem. The following proximate causes have been proposed: (1) rhythmic fluctuations in solar radiation, (2) tectonic events as Pangea assembled, altering land-ocean relationships, patterns of wind and water circulation and continental physiography, (3) volcanism, and (4) changes subsequent to impacts of one or more massive extra terrestrial objects, bodies or comets. These hypotheses are discussed.

  13. WASP-26b: a 1-Jupiter-mass planet around an early-G-type star

    Science.gov (United States)

    Smalley, B.; Anderson, D. R.; Collier Cameron, A.; Gillon, M.; Hellier, C.; Lister, T. A.; Maxted, P. F. L.; Queloz, D.; Triaud, A. H. M. J.; West, R. G.; Bentley, S. J.; Enoch, B.; Pepe, F.; Pollacco, D. L.; Segransan, D.; Smith, A. M. S.; Southworth, J.; Udry, S.; Wheatley, P. J.; Wood, P. L.; Bento, J.

    2010-09-01

    We report the discovery of WASP-26b, a moderately over-sized Jupiter-mass exoplanet transiting its 11.3-mag early-G-type host star (1SWASP J001824.70-151602.3; TYC 5839-876-1) every 2.7566 days. A simultaneous fit to transit photometry and radial-velocity measurements yields a planetary mass of 1.02 ± 0.03 MJup and radius of 1.32 ± 0.08 RJup. The host star, WASP-26, has a mass of 1.12 ± 0.03 M⊙ and a radius of 1.34 ± 0.06 R⊙ and is in a visual double with a fainter K-type star. The two stars are at least a common-proper motion pair with a common distance of around 250 ± 15 pc and an age of 6 ± 2 Gy. RV and photometric data are only available in electronic form at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/520/A56

  14. Methanol masers Reliable tracers of the early stages of high-mass star formation

    CERN Document Server

    Ellingsen, S P

    2006-01-01

    The GLIMPSE and MSX surveys have been used to examine the mid-infrared properties of a statistically complete sample of 6.7 GHz methanol masers. The GLIMPSE point sources associated with methanol masers are clearly distinguished from the majority, typically having extremely red mid-infrared colors, similar to those expected of low-mass class 0 young stellar objects. The intensity of the GLIMPSE sources associated with methanol masers is typically 4 magnitudes brighter at 8.0 micron than at 3.6 micron. Targeted searches towards GLIMPSE point sources with [3.6]-[4.5] > 1.3 and an 8.0 micron magnitude less than 10 will detect more than 80% of class II methanol masers. Many of the methanol masers are associated with sources within infrared dark clouds (IRDC) which are believed to mark regions where high-mass star formation is in its very early stages. The presence of class II methanol masers in a significant fraction of IRDC suggests that high-mass star formation is common in these regions. Different maser specie...

  15. Proposed new Lower Triassic stages in South China

    Institute of Scientific and Technical Information of China (English)

    TONG; Jinnan

    2001-01-01

    [1]Orchard, M., Executive notes from the Chair, Albertiana, 200l, 25: 3.[2]Yin Hongfu, Wu Shunbao, Du Yuansheng et al., South China defined as part of Tethyan sarchipelagic ocean system, Earth Science-Journal of China University of Geosciences (in Chinese with English abstract), 1999, 24(1): 1-12.[3]Tozer, E. T., The Trias and its ammonoids: the Evolution of a time scale, Geol. Surv. Canada, Miscellaneous Report, 1984,35: 1-171.[4]Gaetani, M., Report on the Meeting of the Subcommission, Albertiana, 1992, 10: 6-10.[5]Kozur, H., The problem of the Lower Triassic subdivision and some remarks to the position of the Permian-Triassic boundary, Jahrbuch fuer Geologie B. -A., 1993, 136(4): 795-797.[6]Chen Chuzhen, He Guoxiong, Chen Jinhua et al., Marine Triassic, Stratigraphical Studies in China (1979-1999) (in Chinese). Hefei: China University of Science and Technology Press, 2000, 241-259.[7]Zakharov. Y. D., Proposals on revision of the Siberian standard for the Lower Triassic and candidate stratotype section and point for the Induan-Olenekian boundary, A lbertiana, 1994, 14:44-51.[8]Yin Hongfu, Ding Meihua, Zhang Kexin et al., Dongwuan-Indosinian Ecostratigraphy of Yangtze Platform and its Margins (in Chinese with English summary), Beijing: Science Press, 1995, 1-338.[9]Tong Jinnan, Yang Yin, Advance in the Study of the Lower Triassic conodonts at Meishan Section, Changxing, Zhejiang Province. Chinese Science Bulletin, 1998, 43( 16): 1350-1353.[10]Tong Jinnan, Yin Hongfu, A study on the Griesbachian cyclostratigraphy of Meishan section, Changxing, Zhejiang Province. Journal of Stratigraphy (in Chinese with English abstract), 1999, 23(2): 130-135.[11]Sweet, W. C., Uppermost Permian and Lower Triassic conodonts of the Salt Range and Trans-Indus Ranges, West Pakistan. in Stratigraphic Boundary Problems: Permian and Triassic of West Pakistan (eds., Kummel, B., Teichert, C.), University of Kansas, Department of Geology Special

  16. The Triassic reworking of the Yunkai massif (South China): EMP monazite and U-Pb zircon geochronologic evidence

    Science.gov (United States)

    Chen, Cheng-Hong; Liu, Yung-Hsin; Lee, Chi-Yu; Sano, Yuji; Zhou, Han-Wen; Xiang, Hua; Takahata, Naoto

    2017-01-01

    Geohistory of the Yunkai massif in South China Block is important in understanding the geodynamics for the build-up of this block during the Phanerozoic orogenies. To investigate this massif, we conduct EMP monazite and U-Pb zircon geochronological determinations on mineral inclusions and separate for seventeen samples in four groups, representing metamorphic rocks from core domain, the Gaozhou Complex (amphibolite facies, NE-striking) and the Yunkai Group (greenschist facies, NW-striking) of this massif and adjacent undeformed granites. Some EMP monazite ages are consistent with the NanoSIMS results. Monazite inclusions, mostly with long axis parallel to the cleavage of platy and elongated hosts, give distinguishable age results for NW- and NE-trending deformations at 244-236 Ma and 236-233 Ma, respectively. They also yield ages of 233-230 Ma for core domain gneissic granites and 232-229 Ma for undefomed granites. Combining U-Pb zircon ages of the same group, 245 Ma and 230 Ma are suggested to constrain the time of two phases of deformation. Aside from ubiquity of Triassic ages in studied rocks, ages of detrital monazite in the meta-sandstone match the major U-Pb zircon age clusters of the metamorphic rock that are largely concentrated at Neoproterozoic (1.0-0.9 Ga) and Early Paleozoic (444-431 Ma). Based on these geochronological data, Triassic is interpreted as representing the time for recrystallization of these host minerals on the Early Paleozoic protolith, and the also popular Neoproterozoic age is probably inherited. With this context, Yunkai massif is regarded as a strongly reactivated Triassic metamorphic terrain on an Early Paleozoic basement which had incorporated sediments with Neoproterozoic provenances. Triassic tectonic evolution of the Yunkai massif is suggested to have been controlled by converging geodynamics of the South China and Indochina Blocks as well as mafic magma emplacement related to the Emeishan large igneous province (E-LIP).

  17. Middle Triassic pteridosperms (Pinophyta) of the Timan-Pechora basin

    Science.gov (United States)

    Kirichkova, A. I.; Esenina, A. V.

    2016-03-01

    The collection of fossil plants sampled by geologists from VNIGRI at the end of the 20th century from Triassic continental sections drilled by many wells and cropping out in several natural localities and stored at the Museum of Petroleum Geology and Paleontology of the same institute was critically revised. The use of the epidermal method for the study of plant remains with consideration of recent publications dedicated to continental sections of Central Europe made it possible to substantially broaden the taxonomic composition of the Triassic flora and first specify the composition of its pteridosperm representatives. Unlike the Triassic floras of Western Europe, the pteridosperms the Pechora region appeared to be relatively diverse. They number 37 species of 11 genera, which are confined to the upper part of the Triassic sequence: Anguran and Naryan-Mar formations and their analogs. The Middle Triassic, mainly, Ladinian, age of these formations is reliably substantiated both by paleontological (vertebrate and palynological) data and by results of the comparative analysis of the Anguran-Naryan-Mar taphofloras and coeval European type floras dated back to the Anisian-Ladinian by marine faunal remains. The stratigraphic significance of pteridospermous plant remains becomes undoubted for continental sections of the Timan-Pechora basin, while the genera Scytophyllum, Kalantarium, and Kirjamkenia may be considered with respect to their diversity and abundance as representing orthostratigraphic taxa.

  18. The Dynamic Response of Marine Life to Extreme Temperature and Low Oxygen Events Following the End-Permian Mass Extinction.

    Science.gov (United States)

    Pietsch, C.; Bottjer, D. J.

    2014-12-01

    The end-Permian mass extinction was the most devastating taxonomic and ecological crisis in the history of life on Earth. The recovery lasted 5 My making it the longest in geologic history, although the cause of the delay is still heavily debated. We find that additional environmental changes during the recovery interval reset the attempts that marine communities made toward ecological complexity, resulting in the overall appearance of a stagnant recovery. The extinction mechanisms during the end-Permian include extreme temperature change and low oxygen environments resulting from the volcanic emission of carbon dioxide and other toxic gasses to the atmosphere. The biotic response to ancient environmental change is a direct analog for the ecological impacts of modern anthropogenic climate change. We applied an ecological recovery rubric to benthic, sea floor dwelling, communities throughout the Early Triassic recovery in two major ocean basins. Newly collected bulk fossil data from the Moenkopi and Thaynes Formations from the Southwest US and the Werfen Formation in Italy were analyzed along with literature data. In Italy, directly following the extinction, low oxygen environments prevented an ecological rebound. Once low oxygen conditions receded, 600 kyr after the extinction, taxonomic diversity, fossil body size, and trace fossil complexity rebounded. A little more than 1 My into the Early Triassic, an extreme temperature event resulted in a reset of community complexity in both Italy and the Southwest US. The body size of gastropods and the repopulation of echinoderms were significantly inhibited as was trace fossil complexity. Low oxygen conditions that developed in the last ~2My of the Early Triassic limited diversity and body size in the Southwest United States. The stagnant recovery is re-interpreted as dynamic resets and rapid rebounds driven by environmental perturbations throughout the Early Triassic.

  19. Abrupt Changes at the Permian/Triassic Boundary: Tempo of Events from High-Resolution Cyclostratigraphy

    Science.gov (United States)

    Rampino, M. R.; Prokoph, A.; Adler, A. C.

    2000-01-01

    The Permian/Triassic (P/Tr) boundary (251.4 +/- 3 Myr) is marked by the most severe mass extinction in the geologic record. Recently, precise absolute dating has bracketed the marine extinctions and associated carbon-isotope anomaly within less than 1 Myr. We improve this resolution through high-resolution stratigraphy across the P/Tr boundary in the 331-m Gartnerkofel-1 core and nearby Reppwand outcrop section (Carnic Alps, Austria) utilizing FFT and wavelet timeseries analyses of cyclic components in down-hole core logs of density and natural gamma-ray intensity, and carbon-isotopic ratios of bulk samples. The wavelet analysis indicates continuity of deposition across the P/Tr boundary interval, and the timeseries analyses show evidence for persistent cycles in the ratio of approximately 40: 10: 4.7: 2.3 meters, correlated with Milankovitch-band orbital cycles of approximately 412: 100: 40: 20 kyr (eccentricity 1 and 2, obliquity, and precession), and giving a consistent average sedimentation rate of approximately 10 cm/1,000 yr. Milankovitch periods in delta C-13 and density in these shallow-water carbonates were most likely the result of climatically induced oscillations of sea level and climate, coupled with changes in ocean circulation and productivity, that affected sedimentation. Fluctuations in gamma radiation reflect varying input of clay minerals and the presence of shaly interbeds. Throughout the P/Tr boundary interval in the core, the 100,000-year eccentricity cycle seems to be dominant. Weaker obliquity and precession cycles are in line with the location of the Austrian section in the latest Permian, close to the Equator in the western bight of the Tethys, where obliquity and precessional effects on seasonal contrast might be subdued. Using the improved resolution provided by cycle analysis in the GK-1 core, we find that the dramatic change in the faunal record that marks the P/Tr boundary takes place over less than 6m, or less than 60,000 years. In

  20. Height, weight and body mass index in early adulthood and risk of schizophrenia

    DEFF Research Database (Denmark)

    Sørensen, Holger Jelling; Mortensen, E L; Reinisch, J M;

    2006-01-01

    individuals born between 1959 and 1961. In 1999, cases of schizophrenia were identified in the Danish Psychiatric Central Register, and the cases were compared with the cohort pool of controls with respect to height, weight, and BMI from draft records. The effect of low BMI was adjusted for parental social......OBJECTIVE: To illuminate the possible associations between height, weight, and body mass index (BMI) during early adulthood and the development of schizophrenia. METHOD: This prospective study is based on an all-male sample of 3210 individuals from the Copenhagen Perinatal Cohort, comprising...... status when the cohort members were 1 year old, birth weight, birth length, and maternal pre-pregnancy BMI. RESULTS: Forty-five cases of schizophrenia had a lower young adult mean body weight and BMI than controls. A significant inverse relationship between BMI and risk of later schizophrenia was found...

  1. A Tale of Two Timescales: Mixing, Mass Generation, and Phase Transitions in the Early Universe

    CERN Document Server

    Dienes, Keith R; Thomas, Brooks

    2015-01-01

    Light scalar fields such as axions and string moduli can play an important role in early-universe cosmology. However, many factors can significantly impact their late-time cosmological abundances. For example, in cases where the potentials for these fields are generated dynamically --- such as during cosmological mass-generating phase transitions --- the duration of the time interval required for these potentials to fully develop can have significant repercussions. Likewise, in scenarios with multiple scalars, mixing amongst the fields can also give rise to an effective timescale that modifies the resulting late-time abundances. Previous studies have focused on the effects of either the first or the second timescale in isolation. In this paper, by contrast, we examine the new features that arise from the interplay between these two timescales when both mixing and time-dependent phase transitions are introduced together. First, we find that the effects of these timescales can conspire to alter not only the tot...

  2. Height, weight and body mass index in early adulthood and risk of schizophrenia

    DEFF Research Database (Denmark)

    2006-01-01

    status when the cohort members were 1 year old, birth weight, birth length, and maternal pre-pregnancy BMI. RESULTS: Forty-five cases of schizophrenia had a lower young adult mean body weight and BMI than controls. A significant inverse relationship between BMI and risk of later schizophrenia was found....... No significant differences between cases and controls were observed with respect to adult height. CONCLUSION: Independent of several possible confounders, an inverse relationship between young adult BMI and risk of later development of schizophrenia was demonstrated in this all-male sample.......OBJECTIVE: To illuminate the possible associations between height, weight, and body mass index (BMI) during early adulthood and the development of schizophrenia. METHOD: This prospective study is based on an all-male sample of 3210 individuals from the Copenhagen Perinatal Cohort, comprising...

  3. Low body mass index is an important risk factor for low bone mass and increased bone loss in early postmenopausal women. Early Postmenopausal Intervention Cohort (EPIC) study group

    DEFF Research Database (Denmark)

    Ravn, Pernille; Cizza, G; Bjarnason, N H;

    1999-01-01

    Thinness (low percentage of body fat, low body mass index [BMI], or low body weight) was evaluated as a risk factor for low bone mineral density (BMD) or increased bone loss in a randomized trial of alendronate for prevention of osteoporosis in recently postmenopausal women with normal bone mass (n...... of fat mass parameters, prevention of postmenopausal osteoporosis can be equally achieved in thinner and heavier women....... (r = -0.12 to -0.15, p treatment effect of alendronate was dependent on these risk factors, the group treated with 5 mg of alendronate was included (n = 403). There were no associations between fat mass parameters and response to alendronate treatment, which...

  4. Late Permian to Triassic intraplate orogeny of the southern Tianshan and adjacent regions, NW China

    Directory of Open Access Journals (Sweden)

    Wei Ju

    2014-01-01

    Based on previous studies and recent geochronogical data, we suggest that the final collision between the Tarim Craton and the North Asian continent occurred during the late Carboniferous. Therefore, the Permian was a period of intracontinental environment in the southern Tianshan and adjacent regions. We propose that an earlier, small-scale intraplate orogenic stage occurred in late Permian to Triassic time, which was the first intraplate process in the South Tianshan Orogen and adjacent regions. The later large-scale and well-known Neogene to Quaternary intraplate orogeny was induced by the collision between the India subcontinent and the Eurasian plate. The paper presents a new evolutionary model for the South Tianshan Orogen and adjacent regions, which includes seven stages: (I late Ordovician–early Silurian opening of the South Tianshan Ocean; (II middle Silurian–middle Devonian subduction of the South Tianshan Ocean beneath an active margin of the North Asian continent; (III late Devonian–late Carboniferous closure of the South Tianshan Ocean and collision between the Kazakhstan-Yili and Tarim continental blocks; (IV early Permian post-collisional magmatism and rifting; (V late Permian–Triassic the first intraplate orogeny; (VI Jurassic–Palaeogene tectonic stagnation and (VII Neocene–Quaternary intraplate orogeny.

  5. Late Triassic tropical climate of Pangea: Carbon isotopic and other insights into the rise of dinosaurs

    Science.gov (United States)

    Whiteside, J. H.; Lindström, S.; Irmis, R. B.; Glasspool, I.; Schaller, M. F.; Dunlavey, M.; Nesbitt, S. J.; Smith, N. D.; Turner, A. H.

    2015-12-01

    The rarity and species-poor nature of early dinosaurs and their relatives at low paleolatitudes persisted for 30 million years after their origin and 10-15 million years after they became abundant and speciose at higher latitudes. New environmental reconstructions from stable carbon isotope ratios of preserved organic matter (δ13Corg), atmospheric pCO2 data based on the δ13C of soil carbonate, palynological, and wildfire data from charcoal from early dinosaur-bearing strata at low paleolatitudes in western North America show that variations in δ13Corg and palynomorph ecotypes are tightly correlated, displaying large and high-frequency excursions. These variations occurred within an environment characterized by elevated and increasing atmospheric pCO2, pervasive wildfires, and rapidly fluctuating extreme climatic conditions. Whereas pseudosuchian archosaur-dominated communities were able to persist in these same regions until the end-Triassic, the large-bodied, fast-growing tachymetabolic dinosaurian herbivores were not. We hypothesize that the greater resources required by the herbivores made it difficult from them to adapt to the unstable conditions at low paleolatitudes in the Late Triassic.

  6. Preheating of the early universe by radiation from high-mass X-ray binaries

    Science.gov (United States)

    Sazonov, S. Yu.; Khabibullin, I. I.

    2017-04-01

    Using a reliablymeasured intrinsic (i.e., corrected for absorption effects) present-day luminosity function of high-mass X-ray binaries (HMXBs) in the 0.25-2 keV energy band per unit star formation rate, we estimate the preheating of the early Universe by soft X-rays from such systems. We find that X-ray irradiation, mainly executed by ultraluminous and supersoft ultraluminous X-ray sources with luminosity L X > 1039 erg s-1, could significantly heat ( T > T CMB, where T CMB is the temperature of the cosmic microwave background) the intergalactic medium by z 10 if the specific X-ray emissivity of the young stellar population in the early Universe was an order of magnitude higher than at the present epoch (which is possible due to the low metallicity of the first galaxies) and the soft X-ray emission from HMXBs did not suffer strong absorption within their galaxies. This makes it possible to observe the 21 cm line of neutral hydrogen in emission from redshifts z < 10.

  7. Vertebrate biochronology of late Triassic red beds in New Mexico

    Energy Technology Data Exchange (ETDEWEB)

    Hunt, A.P. (Univ. of New Mexico, Albuquerque (USA))

    1989-09-01

    Four vertebrate biochrons can be recognized in Late Triassic strata of New Mexico: (A) Metoposaurus-Rutiodon-Desmatosuchus-Calyptosuchus-Placerias occurs in the Los Esteros member of the Santa Rosa formation near Lamy and is less well known from the lower Petrified Forest Member of the Chinle Formation near San Ysidro, at Mesa del Oro, near Fort Wingate, at Ojo Huelos, and in the Joyita hills. (B) Anaschisma-Belodon-Typothorax-Desmatosuchus-Paratypothorax occurs in the lower Bull Canyon formation in Bull Canyon and near Tucumcari, in the Trujillo Formation near Tucumcari, and possibly in the Travesser Formation of the Dry Cimarron valley, the Petrified Forest Member near Carthage, and the Garita Creek formation near Lamy and Conchas Lake. (C) Anaschisma-Belodon-Typothorax occurs in the upper Bull Canyon formation in Bull Canyon, in the upper Petrified Forest Member near San Ysidro, at Ghost Ranch, near Albuquerque (Correo Sandstone Bed), and possibly in the Sloan Canyon Formation of the Dry Cimarron valley. (D) Anaschisma-new phytosaur, cf. Typothorax-new sphenosuchian, occurs in the Redonda Formation near Tucumcari. The biochronologic ranges of significant vertebrate taxa within New Mexico follow: metoposaurs - Metoposaurus (A-B ), Anaschisma (B-D); phytosuars - Rutiodon (A), Belodon (B-C), new taxon (D); aetosaurs - Calyptosuchus (A), Desmatosuchus (A-B), Paratypothorax (B), Typothorax (B-D ); rauisuchians - Postosuchus (A-B), Chatterjeea (B-C); sphenosuchians - new taxon 1 (A), Hesperosuchus (B), new taxon 2 (D); dinosaurs - ornithischians (B), Coelophysis (C), other theropods (B-C); therapsids - Placerias (A), Pseudotriconodon (C). Biochron A may be Carnian in age, whereas biochrons B-D are probably early to middle ( ) Norian.

  8. A Low Mass for Mars from Jupiter's Early Gas-Driven Migration

    Science.gov (United States)

    Walsh, Kevin J.; Morbidelli, Alessandro; Raymond, Sean N.; O'Brien, David P.; Mandell, Avi M.

    2011-01-01

    Jupiter and Saturn formed in a few million years from a gas-dominated protoplanetary disk, and were susceptible to gas-driven migration of their orbits on timescales of only approximately 100,000 years. Hydrodynamic simulations show that these giant planets can undergo a two-stage, inward-then-outward, migration. The terrestrial planets finished accreting much later and their characteristics, including Mars' small mass, are best reproduced by starting from a planetesimal disk with an outer edge at about one astronomical unit from the Sun (1 AU is the Earth-Sun distance). Here we report simulations of the early Solar System that show how the inward migration of Jupiter to 1.5 AU, and its subsequent outward migration, lead to a planetesimal disk truncated at 1 AU; the terrestrial planets then form from this disk over the next 30-50 million years, with an Earth/Mars mass ratio consistent with observations. Scattering by Jupiter initially empties but then repopulates the asteroid belt, with inner-belt bodies originating between 1 and 3 AU and outer-belt bodies originating between and beyond the giant planets. This explains the significant compositional differences across the asteroid belt. The key aspect missing from previous models of terrestrial planet formation is the substantial radial migration of the giant planets, which suggests that their behaviour is more similar to that inferred for extrasolar planets than previously thought.

  9. Inventorying the stellar initial mass function of early-type galaxies

    CERN Document Server

    Tortora, Crescenzo; Napolitano, Nicola R

    2012-01-01

    Given a flurry of recent claims for systematic variations in the stellar initial mass function (IMF), we carry out a novel inventory of the observational evidence using different approaches. This includes literature results, as well as our own new findings from combined stellar-populations synthesis (SPS) and Jeans dynamical analyses of data on ~4500 early-type galaxies from the SPIDER project. We focus on the mass-to-light ratio mismatch relative to the Milky Way IMF, delta_IMF, correlated against the central stellar velocity dispersion, sigma_*. For the SPIDER sample, we find a strong correlation between delta_IMF and sigma_*, independently of assumptions on the dark matter (DM) profile. The overall normalization of delta_IMF, and the detailed DM profile, are less certain, but the data are consistent with standard cold-DM halos, and a central DM fraction that is roughly constant with sigma_*. For a variety of related studies in the literature, using SPS, dynamics, and gravitational lensing, similar results ...

  10. Early stages of insulin fibrillogenesis examined with ion mobility mass spectrometry and molecular modelling.

    Science.gov (United States)

    Cole, Harriet; Porrini, Massimiliano; Morris, Ryan; Smith, Tom; Kalapothakis, Jason; Weidt, Stefan; Mackay, C Logan; MacPhee, Cait E; Barran, Perdita E

    2015-10-21

    A prevalent type of protein misfolding causes the formation of β-sheet-rich structures known as amyloid fibrils. Research into the mechanisms of fibril formation has implications for both disease prevention and nanoscale templating technologies. This investigation into the aggregation of insulin utilises ion mobility mass spectrometry coupled with molecular modelling to identify and characterise oligomers formed during the 'lag' phase that precedes fibril growth. High resolution mass spectrometry and collision induced dissociation is used to unequivocally assign species as m/z coincident multimers or confomers, providing a robust analytical approach that supports the use of molecular dynamics to atomistically resolve the observed oligomers. We show that insulin oligomerises to form species In where 2 ≤ n ≤ 12 and within this set of oligomers we delineate over 60 distinct conformations, the most dominant of which are compact species. Modelling trained with experimental data suggests that the dominant compact dimers are enriched in β-sheet secondary structure and dominated by hydrophobic interactions, and provides a linear relationship between Rg and collision cross section. This approach provides detailed insight to the early stages of assembly of this much studied amyloidogenic protein, and can be used to inform models of nucleation and growth.

  11. AN INVENTORY OF THE STELLAR INITIAL MASS FUNCTION IN EARLY-TYPE GALAXIES

    Energy Technology Data Exchange (ETDEWEB)

    Tortora, C. [Institut fuer Theoretische Physik, Universitaet Zuerich, Winterthurerstrasse 190, CH-8057 Zuerich (Switzerland); Romanowsky, A. J. [University of California Observatories, 1156 High Street, Santa Cruz, CA 95064 (United States); Napolitano, N. R., E-mail: ctortora@physik.uzh.ch [INAF-Osservatorio Astronomico di Capodimonte, Salita Moiariello 16, I-80131 Napoli (Italy)

    2013-03-01

    Given a flurry of recent claims for systematic variations in the stellar initial mass function (IMF), we carry out the first inventory of the observational evidence using different approaches. This includes literature results, as well as our own new findings from combined stellar population synthesis (SPS) and Jeans dynamical analyses of data on {approx}4500 early-type galaxies (ETGs) from the SPIDER project. We focus on the mass-to-light ratio mismatch relative to the Milky Way IMF, {delta}{sub IMF}, correlated against the central stellar velocity dispersion, {sigma}{sub *}. We find a strong correlation between {delta}{sub IMF} and {sigma}{sub *}, for a wide set of dark matter (DM) model profiles. These results are robust if a uniform halo response to baryons is adopted across the sample. The overall normalization of {delta}{sub IMF} and the detailed DM profile are less certain, but the data are consistent with standard cold DM halos and a central DM fraction that is roughly constant with {sigma}{sub *}. For a variety of related studies in the literature, using SPS, dynamics, and gravitational lensing, similar results are found. Studies based solely on spectroscopic line diagnostics agree on a Salpeter-like IMF at high {sigma}{sub *} but differ at low {sigma}{sub *}. Overall, we find that multiple independent lines of evidence appear to be converging on a systematic variation in the IMF, such that high-{sigma}{sub *} ETGs have an excess of low-mass stars relative to spirals and low-{sigma}{sub *} ETGs. Robust verification of super-Salpeter IMFs in the highest-{sigma}{sub *} galaxies will require additional scrutiny of scatter and systematic uncertainties. The implications for the distribution of DM are still inconclusive.

  12. An Inventory of the Stellar Initial Mass Function in Early-type Galaxies

    Science.gov (United States)

    Tortora, C.; Romanowsky, A. J.; Napolitano, N. R.

    2013-03-01

    Given a flurry of recent claims for systematic variations in the stellar initial mass function (IMF), we carry out the first inventory of the observational evidence using different approaches. This includes literature results, as well as our own new findings from combined stellar population synthesis (SPS) and Jeans dynamical analyses of data on ~4500 early-type galaxies (ETGs) from the SPIDER project. We focus on the mass-to-light ratio mismatch relative to the Milky Way IMF, δIMF, correlated against the central stellar velocity dispersion, σsstarf. We find a strong correlation between δIMF and σsstarf, for a wide set of dark matter (DM) model profiles. These results are robust if a uniform halo response to baryons is adopted across the sample. The overall normalization of δIMF and the detailed DM profile are less certain, but the data are consistent with standard cold DM halos and a central DM fraction that is roughly constant with σsstarf. For a variety of related studies in the literature, using SPS, dynamics, and gravitational lensing, similar results are found. Studies based solely on spectroscopic line diagnostics agree on a Salpeter-like IMF at high σsstarf but differ at low σsstarf. Overall, we find that multiple independent lines of evidence appear to be converging on a systematic variation in the IMF, such that high-σsstarf ETGs have an excess of low-mass stars relative to spirals and low-σsstarf ETGs. Robust verification of super-Salpeter IMFs in the highest-σsstarf galaxies will require additional scrutiny of scatter and systematic uncertainties. The implications for the distribution of DM are still inconclusive.

  13. Giant Induan oolite: A case study from the Lower Triassic Daye Formation in the western Hubei Province, South China

    Directory of Open Access Journals (Sweden)

    Mingxiang Mei

    2012-11-01

    Full Text Available Most Phanerozoic oolites are marked by ooids with a diameter less than 2 mm. Observations on a Neoproterozoic oolite have resulted in a change of concept. The term “pisolite” that traditionally referred to oolites with a grain size of more than 2 mm, is now restricted to those coated carbonate grains formed by meteoritic freshwater diagenesis; oolites with a grain size of more than 2 mm are now defined as “giant”. Particular unusual giant oolites within a set of oolitic-bank limestones with thicknesses of more than 40 m in the top part of the Lower Triassic (Induan Daye (Ruiping Formation at the Lichuan section in the western part of Hubei Province in South China, represent an important sedimentological phenomenon in both the specific geological period and the geological setting that is related to the end-Permian biological mass extinction. Like the giant oolites of the Neoproterozoic that represent deposits where oolites formed in a vast low-angle carbonate ramp at that special geological period, the Triassic Daye Formation at the study section are significant because they provide a comparative example to help understand the evolving carbonate world reflected by oolites, the origin of which is still uncertain, and they give insight into the sedimentation pattern of the desolate sea floor, which resulted from the mass extinction at the turn of the Permian into the Triassic.

  14. An accurately delineated Permian-Triassic Boundary in continental successions

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    The Permian-Triassic Boundary Stratigraphic Set (PTBST), characteristic of the GSSP section of Meishan and widespread in marine Permian-Triassic Boundary (PTB) sequences of South China, is used to trace and recognize the PTB in a continental sequence at Chahe (Beds 66f―68c). Diversified Permian plant fossils extended to the PTBST, and a few relicts survived above that level. Sporomorphs are dominated by fern spores of Permian nature below the PTBST, above which they are replaced by gymnosperm pollen of Triassic aspect. In the nearby Zhejue Section, the continental PTBST is characterized by the fungal 'spike' recorded in many places throughout the world. The boundary claybeds (66f and 68a,c) of the PTBST are composed of mixed illite-montmorillonite layers analogous with those at Meishan. They contain volcanogenic minerals such as β quartz and zircon. U/Pb dating of the upper claybed gives ages of 247.5 and 252.6 Ma for Beds 68a and 68c respectively, averaging 250 Ma. In contrast to the situation in Xinjiang and South Africa, the sediment sequence of the Permian-Triassic transition in the Chahe section (Beds 56―80) become finer upward. Shallowing and coarsening upward is not, therefore, characteristic of the Permian-Triassic transition everywhere. The occurrence of relicts of the Gigantopteris Flora in the Kayitou Fm. indicates that, unlike most marine biota, relicts of this paleophytic flora survived into the earliest Triassic. It is concluded that Bed 67 at Chahe corresponds to Bed 27 at Meishan, and that the PTB should be put within the 60-cm-thick Bed 67b④, now put at its base tentatively. This is the most accurate correlation of the PTB in continental facies with that in the marine GSSP.

  15. Age and General Characteristics of the Calimicrobialite near the Permian-Triassic Boundary in Chongyang, Hubei Province

    Institute of Scientific and Technical Information of China (English)

    Yang Hao; Zhang Suxin; Jiang Haishui; Wang Yongbiao

    2006-01-01

    The calimicrobialites of Chongyang (崇阳), Hubei (湖北) Province, occur above the mass extinction line in the Late Permian reef facies. Below the boundary are the sponge reef limestone, crinoid bialites are generally composed of mid-coarse grains and microlite calcite with a structure of "graniphyic fabric" and stromatolite. The fossils discovered in the calimicrobialites include globular cyanobacteria,ostracods, micro-gastropods, bivalves, fish teeth and some micro-problematical fossils. Conodont fossils of Hindeodus parvus, H. typicalis and H. latidentatus were also found in the calimicrobialites. According to the conodonts, the calimicrobialites spanned the latest Permian and earliest Triassic in the Chongyang Section. The upper part above the first occurrence of Hindeodus parvus should be attributed to the earliest Triassic, and the lower part to the Changhsingian. The sedimentary structure, fossil composition and conodont zonation of the Chongyang calimicrobialites can be well correlated with the calimicrobialites found in other areas of South China.

  16. A multistratigraphic approach to pinpoint the Permian-Triassic boundary in continental deposits: The Zechstein-Lower Buntsandstein transition in Germany

    Science.gov (United States)

    Scholze, Frank; Wang, Xu; Kirscher, Uwe; Kraft, Johannes; Schneider, Jörg W.; Götz, Annette E.; Joachimski, Michael M.; Bachtadse, Valerian

    2017-05-01

    The Central European Basin is very suitable for high-resolution multistratigraphy of Late Permian to Early Triassic continental deposits. Here the well exposed continuous transition of the lithostratigraphic Zechstein and Buntsandstein Groups of Central Germany was studied for isotope-chemostratigraphy (δ13Corg, δ13Ccarb, δ18Ocarb), major and trace element geochemistry, magnetostratigraphy, palynology, and conchostracan biostratigraphy. The analysed material was obtained from both classical key sections (abandoned Nelben clay pit, Caaschwitz quarries, Thale railway cut, abandoned Heinebach clay pit) and a recent drill core section (Caaschwitz 6/2012) spanning the Permian-Triassic boundary. The Zechstein-Buntsandstein transition of Central Germany consists of a complex sedimentary facies comprising sabkha, playa lake, aeolian, and fluvial deposits of predominantly red-coloured siliciclastics and intercalations of lacustrine oolitic limestones. The new data on δ13Corg range from - 28.7 to - 21.7 ‰ showing multiple excursions. Most prominent negative shifts correlate with intercalations of oolites and grey-coloured clayey siltstones, while higher δ13Corg values correspond to an onset of palaeosol overprint. The δ13Ccarb values range from - 9.7 to - 1.3 ‰ with largest variations recorded in dolomitic nodules from the Zechstein Group. In contrast to sedimentary facies shifts across the Zechstein-Buntsandstein boundary, major element values used as a proxy (CIA, CIA*, CIA-K) for weathering conditions indicate climatic stability. Trace element data used for a geochemical characterization of the Late Permian to Early Triassic transition in Central Germany indicate a decrease in Rb contents at the Zechstein-Buntsandstein boundary. New palynological data obtained from the Caaschwitz quarry section reveal occurrences of Late Permian palynomorphs in the Lower Fulda Formation, while Early Triassic elements were recorded in the upper part of the Upper Fulda Formation

  17. Biodiversity and Sequence of the Middle Triassic Panxian Marine Reptile Fauna,Guizhou Province,China

    Institute of Scientific and Technical Information of China (English)

    JIANG Dayong; Ryosuke MOTANI; HAO Weicheng; Olivier RIEPPEL; SUN Yuanlin; Andrea TINTORI; SUN Zuoyu; Lars SCHMITZ

    2009-01-01

    The Middle Triassic Panxian fauna is a physical marker and representative record of the rapid recovery of the Triassic marine ecosystem following the Early Triassic stagnant stage after the end-Permian nlass extinction.Ten marine reptile taxa have been found from the 1.82-2.10 m-thick fossiliferous level in the Upper Member of the Guanling Formation,which can be subdivided into three marine reptile beds through the analysis on the stratigraphic distributions of fossil reptiles.The Lower Reptile Bed yields the sauropterygians Placodus inexpectatus Jiang et al.,2008 and Lariosaurus hongguoensis Jiang et al.,2006,the ichthyopterygians Xinminosaurus catactes Jiang et al.,2008 and Phalarodon cf.Phalarodon fraasi Merriam,1910,associated with Mixosaurus panxmnensis Jiang et al.,2006,representing a stage of predominance of durophagous taxa.In this bed,the large complete skeletons may reach up to 2.3 m in length,and lithofacies and chemostratigraphic analyses indicate a relatively deep carbonate platform with an oxic water environment near the bottom,as well as a rising sea level.The Middle Reptile Bed yields the sauropterygian Nothosaurus yangjuanensis Jiang et al.,2006 and the archosaur Qianosuchus mixtus Li et al.,2006,associated with Mixosaurus panxmnensisJiang et al..2006.The fossils in this bed are characterized by its pincering dentition and Iarge overall body size,with the largest possibly exceeding 3 m in length.This bed might represent a time of deepest basin with relatively anoxic condition near the bottom.The Upper Reptile Bed yields the sauropterygians Wumengosaurus delicatomandibularis Jiang et al.,2008,Keichousaurus sp.,the protorosaur Dinocephalosaurus orientalis Li,2003,and the iehthyopterygian Mixosaurus panxlanensis Jiang et al.,2006.In this bed,reptilian taxa characterized by suction feeding appeared,and most are less than 1 m long.This bed corresponds to a period of decreasing water depth.

  18. A Review on the Global Stratotype Section and Point of the Permian-Triassic Boundary

    Institute of Scientific and Technical Information of China (English)

    YIN Hongfu; TONG Jinnan; ZHANG Kexin

    2005-01-01

    This paper provides a synthetic review of researches on Meishan Section D, the Global Stratotype Section and Point of the Permian-Triassic Boundary (PTB). The history of research, geographic and geological setting of the section are briefly introduced. Changhsingian to "Griesbachian" conodont and ammonoid zonations, the most perfect Permo-Triassic zonations over the world, are presented, with a short discussion on the age of Otoceras. The Changhsingian to "Griesbachian" strata are subdivided into three 3rd order sequences, and the sedimentary structure of each sequence is indicated. The paper presents a correlation of the Changhsingian to "Griesbachian"magnetostratigraphy of the Meishan section with the general scale, and informed the negation of a short magnetic reversal at the PTB suggested by Zhu and Liu (1999). Recent developments of chemostratigraphy of δ13C and δ34S are introduced, especially the discovery of more than one negative δ 13C excursions across the PTB. Two important molecular researches reveal the profound changes at the base of eco-system, the microbial catastrophy, and the euxinic conditions in the photic zone during the Permian-Triassic superanoxic event. The paper reports the changes in dating the age of PTB since 2001. According to recent achievements, the age of volcanogenic claybed 25, 14 cm below the PTB, is now set at 252.4±0.3 Ma. A discussion on the eventostratigraphy concludes that, although there is a major event episode at beds 25-26, the events across the PTB at Meishan are multi-episodic and commenced prior to the Event Beds 25-26,thus the possibility that the mass extinction was mainly induced by an exterrestrial impact is largely excluded.

  19. Palaeo-equatorial temperatures and carbon-cycle evolution at the Triassic- Jurassic boundary: A stable isotope perspective from shallow-water carbonates from the UAE

    Science.gov (United States)

    Honig, M. R.; John, C. M.

    2013-12-01

    The Triassic-Jurassic boundary was marked by global changes including carbon-cycle perturbations and the opening of the Atlantic Ocean. These changes were accompanied by one of the major extinction events of the Phanerozoic. The carbon-cycle perturbations have been recorded in carbon isotope curves from bulk carbonates, organic carbon and fossil wood in several Tethyan locations and have been used for chemostratigraphic purposes. Here we present data from shallow-marine carbonates deposited on a homoclinal Middle Eastern carbonate ramp (United Arab Emirates). Our site was located at the equator throughout the Late Triassic and the Early Jurassic, and this study provides the first constraints of environmental changes at the low-latitudes for the Triassic-Jurassic boundary. Shallow-marine carbonate depositional systems are extremely sensitive to palaeoenvironmental changes and their usefulness for chemostratigraphy is being debated. However, the palaeogeographic location of the studied carbonate ramp gives us a unique insight into a tropical carbonate factory at a time of severe global change. Stable isotope measurements (carbon and oxygen) are being carried out on micrite, ooids and shell material along the Triassic-Jurassic boundary. The stable isotope results on micrite show a prominent negative shift in carbon isotope values of approximately 2 ‰ just below the inferred position of the Triassic-Jurassic boundary. A similar isotopic trend is also observed across the Tethys but with a range of amplitudes (from ~2 ‰ to ~4 ‰). These results seem to indicate that the neritic carbonates from our studied section can be used for chemostratigraphic purposes, and the amplitudes of the carbon isotope shifts provide critical constraints on the magnitude of carbon-cycle perturbations at low latitudes across the Triassic-Jurassic boundary. Seawater temperatures across the Triassic-Jurassic boundary will be constrained using the clumped isotope palaeo-thermometer applied

  20. Depositional environment, ichnological features and oxygenation of Permian to earliest Triassic marine sediments in central Spitsbergen, Svalbard

    Directory of Open Access Journals (Sweden)

    Alfred Uchman

    2016-05-01

    Full Text Available Late Early Permian–lowermost Triassic carbonate, siliceous (spiculites and clastic marine sediments in the Marmierfjellet area (Isfjorden, central Spitsbergen contain a relatively diverse and abundant trace fossil assemblage providing important information about the depositional processes. The Vøringen Member (Late Artinskian–Kungurian of the Kapp Starostin Formation (Late Artinskian–? Changhsingian contains trace fossils (Nereites, Phycosiphon, Zoophycos and Arenicolites—common in tempestites typical of the proximal–archetypal Cruziana ichnofacies, which indicates lower shoreface. Nereites, Phycosiphon and Zoophycos, accompanied by other rare trace fossils, characterize the Svenskegga and Hovtinden members of the Kapp Starostin Formation. They are interpreted as the distal Cruziana ichnofacies, possibly transitional to the Zoophycos ichnofacies typical of the lower offshore zone. However, the sporadic occurrences of Arenicolites and Macaronichnus can point to episodic shallowing to upper offshore–lower shoreface. The lowest part of the Triassic Vikinghøgda Formation (Induan–Olenekian contains a very low-diverse ichnoassemblage composed of a few simple and branched forms ascribed to the impoverished Cruziana ichnofacies (lower to upper offshore environment, which is attributed to the early recovery stage after the Permian–Triassic extinction. The trace fossils and loss of primary sedimentary structures caused by intense bioturbation throughout most of the section point to generally oxygenated pore waters on the sea floor. However, some horizons, especially laminated black shales, display reduced or no bioturbational activity. These horizons also show high V/(V+Ni ratios, which indicate oxygen-depleted sediments with periods of anoxic conditions. A remarkable black shale unit deposited under anoxic and sulphidic conditions occurs at the Permian–Triassic transition.

  1. Recognising ocean acidification in deep time: An evaluation of the evidence for acidification across the Triassic-Jurassic boundary

    Science.gov (United States)

    Greene, Sarah E.; Martindale, Rowan C.; Ritterbush, Kathleen A.; Bottjer, David J.; Corsetti, Frank A.; Berelson, William M.

    2012-06-01

    While demonstrating ocean acidification in the modern is relatively straightforward (measure increase in atmospheric CO2 and corresponding ocean chemistry change), identifying palaeo-ocean acidification is problematic. The crux of this problem is that the rock record is a constructive archive while ocean acidification is essentially a destructive (and/or inhibitory) phenomenon. This is exacerbated in deep time without the benefit of a deep ocean record. Here, we discuss the feasibility of, and potential criteria for, identifying an acidification event in deep time. Furthermore, we investigate the evidence for ocean acidification during the Triassic-Jurassic (T-J) boundary interval, an excellent test case because 1) it occurs in deep time, beyond the reach of deep sea drilling coverage; 2) a potential trigger for acidification is known; and 3) it is associated with one of the 'Big Five' mass extinctions which disproportionately affected modern-style invertebrates. Three main criteria suggest that acidification may have occurred across the T-J transition. 1) The eruption of the Central Atlantic Magmatic Province (CAMP) and the associated massive and rapid release of CO2 coincident with the end-Triassic mass extinction provide a suitable trigger for an acidification event (full carbonate undersaturation in the surface ocean is possible but improbable). 2) Tentative evidence for a global paucity of carbonate across the end-Triassic mass extinction versus the adjacent stratigraphy is consistent with a predicted sedimentary response to acidification. 3) The end-Triassic mass extinction was particularly selective against acid-sensitive organisms (more so than perhaps any other extinction event) and temporarily eliminated coral reefs. Therefore multiple lines of evidence are consistent with a T-J ocean acidification event within our current resolution to recognise such events in deep time. The conclusion that the end-Triassic extinction was influenced by acidification

  2. Siberian Origins of Neoproterozoic to Upper Triassic Rocks of Arctic Alaska

    Science.gov (United States)

    Clough, J. G.; Blodgett, R. B.

    2007-12-01

    Evidence for a connection of the Arctic Alaska plate (including Chukotka) with Siberia from Cambrian until Late Triassic time can be made on the basis of paleobiogeography. Arctic Alaska contains a number of biogeographically distinctive megafossils for select time intervals, notably the Middle Cambrian, Early and Late Ordovician, Early and Middle Devonian, Mississippian, and Late Triassic. Middle Cambrian trilobites are strictly Siberian in affinity, but also show close affinities with coeval trilobites from the Farewell terrane of SW Alaska. Late Ordovician brachiopods, gastropods, trilobites, and ostracodes are known from the Shublik Mountains, NE Brooks Range and York Mountains of the Seward Peninsula. Affinities are likewise primarily with Siberia (sharing the primarily Siberian pentameroid brachiopod genera Tcherskidium and Eoconchidium and the strictly Siberian trilobite genus Monorakos), but also with the Farewell terrane. Late Early Devonian and Middle Devonian brachiopods and calcareous green algae from Arctic Alaska are similarly allied with Siberia and the Farewell and Alexander terranes of southern Alaska. Early Mississippian faunas from the lower part of the Lisburne Group and underlying Endicott Group contain relatively widespread fauna, including taxa recognized both in North America and Eurasia, consistent with the relatively cosmopolitan paleobiogeographic conditions of this interval. However, Late Mississippian brachiopod fauna from the upper part of the Lisburne Group contain many brachiopods of strictly Eurasian affinities, notably the gigantoproductids, which are unknown in cratonic North America, but widespread across Eurasia and even North Africa. Late Mississippian lycopods from this terrane have previously been noted as demonstrating strong Angaran affinities. Permian faunas of Arctic Alaska show strong affinities as well with the Siberian Arctic, virtually lacking any fusilinids and reefal buildups, which in contradistinction are commonly

  3. Permian–Triassic palynostratigraphy in Mailaram area, Godavari Graben, Andhra Pradesh, India

    Indian Academy of Sciences (India)

    Neerja Jha; Neha Aggarwal

    2012-10-01

    Palynological investigations of five borecores, viz., GAM-3, GAM-6, GAM-7, GAM-8 and GAM-10 from Mailaram area have suggested the occurrence of complete Lower Gondwana succession in Mailaram area. Total nine palynozones have been identified on the basis of dominance, sub-dominance and appearance of various palynotaxa. These palynozones belong to Talchir, Upper Karharbari and Barakar (Early Permian), Raniganj (Late Permian) and Panchet (Early Triassic) palynofloras of Indian Gondwana. The oldest Palynozone-1 demonstrated in borecore GAM-6 (331.4–500 m) and borecore GAM-10 (505.66–581.55 m), is characterized by the dominance of Parasaccites and sub-dominance of Plicatipollenites belongs to Talchir Palynoflora; Palynozone-2 identified in borecore GAM-7 (667–749 m) and borecore GAM-8 (89.75 m) is characterized by the dominance of Parasaccites and sub-dominance of Scheuringipollenites which belongs to Upper Karharbari Palynoflora. Palynozone-3, identified in borecore GAM-6 (149.7–240.05 m) and borecore GAM-8 (84.95 m), is characterized by the dominance of Scheuringipollenites akin to Scheuringipollenites zone of Barakar palynoflora; Palynozone-4, recorded in borecores GAM-3 (294–437.98 m), GAM-7 (453–640.5 m) and GAM-8 (35.35 m) is characterized by the dominance of Faunipollenites and sub-dominance of Striatopodocarpites along with certain stratigraphically significant taxa, viz., Weylandites, Guttulapollenites, Corisaccites, Aurangapollenites and Osmundacidites. Palynozone-5, demarcated in borecore GAM-3 (144.86–221.3 m) and borecore GAM-10 (35.35 m), is distinguished by the dominance of striate disaccates along with at least 30% pollen assigned to Striasulcites; Palynozone-6, identified in borecore GAM-3 (35.1–73.08 m) and borecore GAM-7 (231–423 m), is characterized by the dominance of striate disaccates along with 20–30% of Densipollenites; Palynozone-7, recorded in borecore GAM-7 (206 m), is distinguished by the dominance of Crescentipollenites

  4. Multivariate analyses reveal a new assemblage of diverse and small archosauriforms (Reptilia, Diapsida) from the Upper Triassic of India

    Science.gov (United States)

    Shafi Bhat, Mohd; Ray, Sanghamitra; Mohan Datta, Pradipendra

    2017-04-01

    of the teeth collected from the Tiki Formation are similar to that of other known Late Triassic archosauriforms such as Protecovasaurus, Revueltosaurus, Pekinosaurus and Crosbysaurus Although more analyses are required for precise taxonomic identification, the current study highlights a large array of Late Triassic archosauriforms from India, which so far remained unknown. References: Hammer, O., Harper, D.A.T. 2006. Paleontological data analysis. Blackwell Publishing, Ltd., Malden, USA. Heckert, A.B. 2004. Late Triassic microvertebrates from the Upper Triassic Chinle Group (Otischalkian-Adamanian: Carnian), southwestern U.S.A.: New Mexico Museum of Natural History and Science Bulletin 27:1-170. Irmis, R.B., Parker, W.G., Nesbitt, S.J., Liu, J. 2007. Early ornithischian dinosaurs: the Triassic record. Historical Biology 19: 3-22.

  5. The First Mass Function and Rise of Carbon in the Early Universe

    Science.gov (United States)

    Rasmussen, Kaitlin; Beers, Timothy C.; Placco, Vinicius M.; Yoon, Jinmi

    2017-01-01

    We investigate the impact of the First Mass Function (FMF) of stars on the distribution of stellar carbon abundances in the early Universe. We propose a picture that includes primary carbon production by the massive first-generation stars, recorded in the atmospheres of CEMP-no stars (which show no over-abundances of neutron-capture elements), and secondary carbon production by subsequent generations of AGB stars, recorded in the subset of mass-transfer binaries now observed as CEMP-$s$ stars (which exhibit strong over-abundances of neutron-capture elements).Recently, CEMP-no stars have been found to comprise separable populations within this category, distinguished by their light-element and iron-peak element abundances (Yoon et al. 2016, Placco et al. 2016). The existence of these populations can also be used to indirectly infer information about the FMF. Additionally, we investigate the contrasting behavior of CEMP stars with their more metal-rich counterparts, focusing on their kinematics, spatial distribution, and elemental abundances, in order to constrain the chemical-enrichment history of the Galaxy, from the earliest stars to the present.References:Placco, V.~M., et al. (2016), ApJ, in press (arXiv:1609.02134)Yoon, J., et al. (2016), ApJ, in press (arXiv:1607.06336)This work received partial support from PHY 14-30152; Physics FrontierCenter/JINA Center for the Evolution of the Elements (JINA-CEE), awardedby the US National Science Foundation.

  6. The Atlas3D project - XX. Mass-size and Mass-sigma projections of the Virial Plane of early-type galaxies: variation of morphology, kinematics, mass-to-light ratio and stellar initial mass function

    CERN Document Server

    Cappellari, Michele; Alatalo, Katherine; Blitz, Leo; Bois, Maxime; Bournaud, Frederic; Bureau, M; Crocker, Alison F; Davies, Roger L; Davis, Timothy A; de Zeeuw, P T; Duc, Pierre-Alain; Khochfar, Sadegh; Krajnovic, Davor; Kuntschner, Harald; Morganti, Raffaella; Naab, Thorsten; Oosterloo, Tom; Sarzi, Marc; Scott, Nicholas; Serra, Paolo; Weijmans, Anne-Marie; Young, Lisa M

    2013-01-01

    In the companion Paper XIX we derive accurate total (M/L)_JAM within a sphere of radius r=Re, as well as stellar (M/L)_stars for the volume-limited Atlas3D sample of 260 early-type galaxies. Here we study the two projections (M_JAM,sigma_e) and (M_JAM,R_e^max) of the thin Virial Plane (VP)(M_JAM,sigma_e,R_e^max) which describes the distribution of the galaxy population. The distribution of galaxy properties on both projections of the VP is characterized by (i) a boundary in the galaxy distribution, described by two power-laws, joined by a break at a characteristic mass M_JAM ~ 3*10^10 Msun, which corresponds to the minimum Re and maximum stellar density, and (ii) a characteristic mass M_JAM ~ 2*10^11 Msun which separates a population dominated by fast rotator with disks at lower masses, from one dominated by quite round slow rotators at larger masses. The distribution of ETGs properties on the two projections of the VP tends to be constant along lines of constant sigma_e, and forms a continuous and parallel s...

  7. Paleomagnetism of Permian and Triassic rock, central Chilean Andes

    Science.gov (United States)

    Forsythe, Randall D.; Kent, Dennis V.; Mpodozis, Constantino; Davidson, John

    The first paleomagnetic data from Permian and Triassic formations west of the Andean divide are presented. Four formations of Permian or Triassic age in the central Chilean Andes have been investigated: two are located in the coastal ranges, and two are in the main cordillera. Of the formations in the main cordillera (Pastos Blancos and Matahuaico formations), only the Pastos Blancos Formation has yielded characteristic directions. While a fold test is absent, magnetizations are most likely secondary and yield pre-tilt corrected concordant inclinations, but yield declinations discordant 30° clockwise in comparison to the South American apparent polar wander path. Both formations from the coastal ranges (Cifuncho and Pichidangui formations) yielded stable directions. Postfolding magnetizations in the Cifuncho Formation also show declinations discordant 30° clockwise and concordant inclinations. The Pichidangui Formation has two stable components: one of postfolding age is concordant to apparent polar wander path data, and one of probable prefolding (Late Triassic) age is concordant in declination, but discordant in inclination. Further work is needed to better define the prefolding magnetizations in the Pichidangui Formation, but at present these preliminary results are the first paleomagnetic signs of displaced terranes along the Pacific margin of Chile. If correct, the results suggest that the Pichidangui Formation was some 15° of latitude farther south during the Late Triassic and had likely moved northward to its present latitudinal position with respect to cratonic South America by Middle to Late Jurassic.

  8. Terrestrial Permian - Triassic boundary sections in South China

    Science.gov (United States)

    Bercovici, Antoine; Vajda, Vivi

    2016-08-01

    The Permian-Triassic boundary interval in China comprises a significant record of faunal and floral changes during this important extinction event. Here we discuss the details of palynomorph preservation at the classical Western Guizhou and Eastern Yunnan sections in an effort to expand the stratigraphy and paleontology from these earlier studies.

  9. Carbon and oxygen isotope variations of the Middle-Late Triassic Al Aziziyah Formation, northwest Libya

    Science.gov (United States)

    Moustafa, Mohamed S. H.; Pope, Michael C.; Grossman, Ethan L.; Mriheel, Ibrahim Y.

    2016-06-01

    This study presents the δ13C and δ18O records from whole rock samples of the Middle-Late Triassic (Ladinian-Carnian) Al Aziziyah Formation that were deposited on a gently sloping carbonate ramp within the Jifarah Basin of Northwest Libya. The Al Aziziyah Formation consists of gray limestone, dolomite, and dolomitic limestone interbedded with shale. The Ghryan Dome and Kaf Bates sections were sampled and analyzed for carbon and oxygen isotope chemostratigraphy to integrate high-resolution carbon isotope data with an outcrop-based stratigraphy, to provide better age control of the Al Aziziyah Formation. This study also discusses the relation between the facies architecture of the Al Aziziyah Formation and the carbon isotope values. Seven stages of relative sea level rise and fall within the Ghryan Dome were identified based on facies stacking patterns, field observations and carbon stable isotopes. The Al Aziziyah Formation δ13C chemostratigraphic curve can be partially correlated with the Triassic global δ13C curve. This correlation indicates that the Al Aziziyah Formation was deposited during the Ladinian and early Carnian. No straight-forward relationship is seen between δ13C and relative sea level probably because local influences complicated systematic environmental and diagenetic isotopic effects associated with sea level change.

  10. Body Size Evolution in Conodonts from the Cambrian through the Triassic

    Science.gov (United States)

    Schaal, E. K.; Morgan, D. J.; Payne, J.

    2013-12-01

    The size of an organism exercises tremendous control over its physiology, life history, and ecology, yet the factors that influence body size evolution remain poorly understood. One major limitation is the lack of appropriate datasets spanning long intervals of evolutionary time. Here, we document size trends in conodonts (tooth-like microfossils from marine chordates) because they evolved rapidly and are known to change size during intervals of environmental change. By measuring photographs from the Catalogue of Conodonts (Ziegler 1982), we compiled a database of conodont P1 element measurements for 575 species and subspecies from the Cambrian through Triassic periods. Because tooth size correlates with body size in conodont animals and their extant relatives, conodont element length can serve as a proxy for the size of the conodont animal. We find that mean and maximum size across species increased during the early Paleozoic, peaked during the Devonian-Mississippian, and then generally decreased until conodonts went extinct at the end of the Triassic. We used regression analyses to compare conodont mean size trends to potential environmental predictors, such as changing atmospheric pO2, atmospheric pCO2, and sea level. Conodont size exhibited poor correlation with these environmental factors, suggesting that conodont evolution may have been more strongly influenced by other environmental covariates or ecological variables such as predation and competition.

  11. Functional diversity of marine ecosystems after the Late Permian mass extinction event

    Science.gov (United States)

    Foster, William J.; Twitchett, Richard J.

    2014-03-01

    The Late Permian mass extinction event about 252 million years ago was the most severe biotic crisis of the past 500 million years and occurred during an episode of global warming. The loss of around two-thirds of marine genera is thought to have had substantial ecological effects, but the overall impacts on the functioning of marine ecosystems and the pattern of marine recovery are uncertain. Here we analyse the fossil occurrences of all known benthic marine invertebrate genera from the Permian and Triassic periods, and assign each to a functional group based on their inferred lifestyle. We show that despite the selective extinction of 62-74% of these genera, all but one functional group persisted through the crisis, indicating that there was no significant loss of functional diversity at the global scale. In addition, only one new mode of life originated in the extinction aftermath. We suggest that Early Triassic marine ecosystems were not as ecologically depauperate as widely assumed. Functional diversity was, however, reduced in particular regions and habitats, such as tropical reefs; at these smaller scales, recovery varied spatially and temporally, probably driven by migration of surviving groups. We find that marine ecosystems did not return to their pre-extinction state, and by the Middle Triassic greater functional evenness is recorded, resulting from the radiation of previously subordinate groups such as motile, epifaunal grazers.

  12. Terrestrial events across the Permian Triassic boundary along the Yunnan Guizhou border, SW China

    Science.gov (United States)

    Jianxin, Yu; Yuanqiao, Peng; Suxin, Zhang; Fengqing, Yang; Quanming, Zhao; Qisheng, Huang

    2007-01-01

    The border area between western Guizhou and eastern Yunnan Provinces in SW China is an ideal place to undertake research considering the terrestrial-ecological system evolution across the Permian-Triassic boundary (PTB). The study of plant and palynomorph fossils, clay minerals, inorganic geochemistry and sedimentary facies in this area enable us to interpret the events occurring at that time. The extinction pattern of the flora interpreted from megafloral and palynomorph data is demonstrated by a sudden decline of species numbers at the PTB after a long-term of gradual changes, followed by a delayed extinction in the basal Triassic. The two boundary claybeds (Beds 66 and 68 in the Chahe Section, beds 47 and 49 in the Zhejue Section) are considered to be volcanogenic. The inorganic geochemical anomalies occurred between Beds 63 and 69, Chahe Section and Beds 45 and 50, Zhejue Section. Sedimentary facies changed from channels of braided rivers, into flood plains of braided rivers, then to shallow lakes, reflecting a gradual transgression by lakes across the area. Our conclusions are that the mass extinction across the PTB in western Guizhou and eastern Yunnan was probably caused by the Siberian basaltic eruption episode and the siliceous volcanism in South China. These lithospheric events represented by volcanisms heralded a series of climatic and environmental events, giving rise to a catastrophe for the biosphere.

  13. Chemostratigraphic reconstruction of biofacies: Molecular evidence linking cyst-forming dinoflagellates with pre-Triassic ancestors

    Science.gov (United States)

    Moldowan, J. Michael; Dahl, Jeremy; Jacobson, Stephen R.; Huizinga, Bradley J.; Fago, Frederick J.; Shetty, Rupa; Watt, David S.; Peters, Kenneth E.

    1996-02-01

    New data from numerous detailed mass-spectrometric studies have detected triaromatic dinosteroids in Precambrian to Cenozoic rock samples. Triaromatic dinosteroids are organic geochemicals derived from dinosterols, compounds known in modern organisms to be the nearly exclusive widely occurring products of dinoflagellates. We observed the ubiquitous occurrence of these dinosteroids in 49 Late Triassic through Cretaceous marine source rocks and the absence of them in 13 Permian-Carboniferous source rocks synergistic with the dinoflagellate cyst record. However, finding dinosteroids in lower Paleozoic and Precambrian strata presents challenging results for molecular paleontologists, evolutionary biologists, palynologists, and especially for those concerned with the food web at various times of biological crisis. Other than the few species known as parasites and symbionts, many other dinoflagellate species are important as primary producers. The presence of Precambrian to Devonian triaromatic dinosteroids gives chemostratigraphic evidence of dinoflagellates (or other organisms with similar chemosynthetic capabilities) in rocks significantly older than the oldest undisputed dinoflagellate fossils (dinoflagellate cysts from the Middle Triassic, ˜ 240 Ma), and older than the putative Silurian ˜ 420 Ma) dinocyst,Arpylorus antiquus (Calandra) Sargent, from Tunisia. This systematic chemostratigraphic approach can shed light not only on lineages of dinoflagellates and their precursors, but potentially on many other lineages, especially bacteria, algae, plants, and possibly some metazoans.

  14. Carbon isotope excursions across the Permian-Triassic boundary in the Meishan section, Zhejiang Province, China

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    Both gradual and sharp decrease in organic and carbonate carbon isotope values were detected across the Permian-Triassic boundary in the Meishan section, Changxing, Zhejiang Province, China. The gradual decrease in organic carbon isotope values started at the bottom of Bed 23, coinciding with the strong oscillations of total organic carbon (TOC) contents, indicates increasing fluxes from carbonate to organic carbon reservoir during this interval. A 2.3‰ sharp drop of inorganic carbon isotope values occurred at the uppermost part of Bed 24e. A 3.7‰ sharp drop of organic carbon isotope values occurred in Bed 26. The dramatic drop of inorganic carbon isotope value of 8‰ reported previously is not confirmed from the unweathered carbonate samples in Bed 27. The large-scale fluctuation of organic carbon isotope values in the Yinkeng Formation reflects different extent of mixing of marine and terrestrial organic matters. The gradual depletion and subsequent sharp drop of carbon isotopes near the Permian-Triassic boundary might indicate complex causes of the end-Permian mass extinction.

  15. Stellar age versus mass of early-type galaxies in the Virgo Cluster

    CERN Document Server

    Lisker, Thorsten

    2008-01-01

    The flux excess of elliptical galaxies in the far-ultraviolet can be reproduced by population synthesis models when accounting for the population of old hot helium-burning subdwarf stars. This has been achieved by Han and coworkers through a quantitative model of binary stellar evolution. Here, we compare the resulting evolutionary population synthesis model to the GALEX far-near ultraviolet colors (FUV-NUV) of Virgo cluster early-type galaxies that were published by Boselli and coworkers. FUV-NUV is reddest at about the dividing luminosity of dwarf and giant galaxies, and becomes increasingly blue for both brighter and fainter luminosities. This behavior can be easily explained by the binary model with a continuous sequence of longer duration and later truncation of star formation at lower galaxy masses. Thus, in contrast to previous conclusions, the GALEX data do not require a dichotomy between the stellar population properties of dwarfs and giants. Their apparently opposite behavior in FUV-NUV occurs natur...

  16. Thecamoebians (Testate Amoebae Straddling the Permian-Triassic Boundary in the Guryul Ravine Section, India: Evolutionary and Palaeoecological Implications.

    Directory of Open Access Journals (Sweden)

    Vartika Singh

    Full Text Available Exceptionally well-preserved organic remains of thecamoebians (testate amoebae were preserved in marine sediments that straddle the greatest extinction event in the Phanerozoic: the Permian-Triassic Boundary. Outcrops from the Late Permian Zewan Formation and the Early Triassic Khunamuh Formation are represented by a complete sedimentary sequence at the Guryul Ravine Section in Kashmir, India, which is an archetypal Permian-Triassic boundary sequence. Previous biostratigraphic analysis provides chronological control for the section, and a perspective of faunal turnover in the brachiopods, ammonoids, bivalves, conodonts, gastropods and foraminifera. Thecamoebians were concentrated from bulk sediments using palynological procedures, which isolated the organic constituents of preserved thecamoebian tests. The recovered individuals demonstrate exceptional similarity to the modern thecamoebian families Centropyxidae, Arcellidae, Hyalospheniidae and Trigonopyxidae, however, the vast majority belong to the Centropyxidae. This study further confirms the morphologic stability of the thecamoebian lineages through the Phanerozoic, and most importantly, their apparent little response to an infamous biological crisis in Earth's history.

  17. DYNAMICAL VERSUS STELLAR MASSES IN COMPACT EARLY-TYPE GALAXIES: FURTHER EVIDENCE FOR SYSTEMATIC VARIATION IN THE STELLAR INITIAL MASS FUNCTION

    Energy Technology Data Exchange (ETDEWEB)

    Conroy, Charlie [Department of Astronomy and Astrophysics, University of California, Santa Cruz, CA 95064 (United States); Dutton, Aaron A. [Max Planck Institute for Astronomy, Königstuhl 17, D-69117 Heidelberg (Germany); Graves, Genevieve J. [Department of Astrophysical Sciences, Princeton University, Princeton, NJ 08544 (United States); Mendel, J. Trevor [Max-Planck-Institute for Extraterrestrial Physics, Giessenbachstrasse, D-85748 Garching (Germany); Van Dokkum, Pieter G. [Department of Astrophysical Sciences, Yale University, New Haven, CT 06511 (United States)

    2013-10-20

    Several independent lines of evidence suggest that the stellar initial mass function (IMF) in early-type galaxies becomes increasingly 'bottom-heavy' with increasing galaxy mass and/or velocity dispersion, σ. Here we consider evidence for IMF variation in a sample of relatively compact early-type galaxies drawn from the Sloan Digital Sky Survey. These galaxies are of sufficiently high stellar density that a dark halo likely makes a minor contribution to the total dynamical mass, M {sub dyn}, within one effective radius. We fit our detailed stellar population synthesis models to the stacked absorption line spectra of these galaxies in bins of σ and find evidence from IMF-sensitive spectral features for a bottom-heavy IMF at high σ. We also apply simple 'mass-follows-light' dynamical models to the same data and find that M {sub dyn} is significantly higher than what would be expected if these galaxies were stellar dominated and had a universal Milky Way IMF. Adopting M {sub dyn} ≈ M {sub *} therefore implies that the IMF is 'heavier' at high σ. Most importantly, the quantitative amount of inferred IMF variation is very similar between the two techniques, agreeing to within ∼< 0.1 dex in mass. The agreement between two independent techniques, when applied to the same data, provides compelling evidence for systematic variation in the IMF as a function of early-type galaxy velocity dispersion. Any alternative explanations must reproduce both the results from dynamical and stellar population-based techniques.

  18. Evidence for Dark Matter Contraction and a Salpeter Initial Mass Function in a Massive Early-type Galaxy

    NARCIS (Netherlands)

    Sonnenfeld, A.; Treu, T.; Gavazzi, R.; Marshall, P. J.; Auger, M. W.; Suyu, S. H.; Koopmans, L. V. E.; Bolton, A. S.

    2012-01-01

    Stars and dark matter account for most of the mass of early-type galaxies, but uncertainties in the stellar population and the dark matter profile make it challenging to distinguish between the two components. Nevertheless, precise observations of stellar and dark matter are extremely valuable for t

  19. The Longitudinal Relation Between Accumulation of Adverse Life Events and Body Mass Index From Early Adolescence to Young Adulthood

    NARCIS (Netherlands)

    Elsenburg, Leonie K.; Smidt, Nynke; Liefbroer, Aart C.

    2017-01-01

    Objective: Stressors, such as adverse life events, can cause weight changes through behavioral and biological mechanisms. Whether the accumulation of adverse life events is related to body mass index (BMI) across multiple time points from early adolescence to young adulthood has not been investigate

  20. Jet mass reconstruction with the ATLAS Detector in early Run 2 data

    CERN Document Server

    The ATLAS collaboration

    2016-01-01

    This note presents the details of the ATLAS jet mass reconstruction for groomed large-radius jets. The jet mass scale calibrations are determined from Monte Carlo simulation. An alternative jet mass definition that incorporates tracking information called the track-assisted jet mass is introduced and its performance is compared to the traditional calorimeter-based jet mass definition. Events enriched in boosted $W$, $Z$ boson and top quark jets are used to directly compare the jet mass scale and jet mass resolution between data and simulation. This in-situ technique is also extended to constrain the jet energy scale and resolution.

  1. Lower mass normalization of the stellar initial mass function for dense massive early-type galaxies at z ~ 1.4

    CERN Document Server

    Gargiulo, A; Longhetti, M; Tamburri, S; Lonoce, I; Ciocca, F

    2014-01-01

    This paper aims at understanding if the normalization of the stellar initial mass function (IMF) of massive early-type galaxies (ETGs) varies with cosmic time and/or with mean stellar mass density Sigma (M*/2\\pi Re^2). For this purpose we have collected a sample of 18 dense (Sigma>2500 M_sun/pc^2) ETGs at 1.2 = 1.4 follow the same IMF-sigma_e trend of typical local ETGs, but with a lower mass-normalization. Nonetheless, once the IMF-sigma_e trend we have found for high-z dense ETGs is compared with that of local ETGs with similar Sigma and sigma_e, they turn out to be consistent. The similarity between the IMF-sigma_e trends of dense high-z and low-z ETGs over 9 Gyr of evolution and their lower mass-normalization with respect to the mean value of local ETGs suggest that, independently on formation redshift, the physical conditions characterizing the formation of a dense spheroid lead to a mass spectrum of new formed stars with an higher ratio of high- to low-mass stars with respect to the IMF of normal local ...

  2. Tectonic Fractures in Tight Gas Sandstones of the Upper Triassic Xujiahe Formation in the Western Sichuan Basin,China

    Institute of Scientific and Technical Information of China (English)

    ZENG Lianbo; LI Yuegang

    2010-01-01

    The western Sichuan Basin,which is located at the front of the Longmen Mountains in the west of Sichuan Province,China,is a foreland basin formed in the Late Triassic.The Upper Triassic Xujiahe Formation is a tight gas sandstone reservoir with low porosity and ultra-low permeability,whose gas accumulation and production are controlled by well-developed fracture zones.There are mainly three types of fractures developed in the Upper Triassic tight gas sandstones,namely tectonic fractures,diagenetic fractures and overpressure-related fractures,of which high-angle tectonic fractures are the most important.The tectonic fractures can be classified into four sets,i.e.,N-S-,NE-,E-W-and NW-striking fractures.In addition,there are a number of approximately horizontal shear fractures in some of the medium-grained sandstones and grit stones nearby the thrusts or slip layers.Tectonic fractures were mainly formed at the end of the Triassic,the end of the Cretaceous and the end of the Neogene-Early Pleistocene.The development degree of tectonic fractures was controlled by lithology,thickness,structure,stress and fluid pressure.Overpressure makes not only the rock shear strength decrease,but also the stress state change from compression to tension.Thus,tensional fractures can be formed in fold-thrust belts.Tectonic fractures are mainly developed along the NE-and N-S-striking structural belts,and are the important storage space and the principal flow channels in the tight gas sandstone.The porosity of fractures here is 28.4% of the gross reservoir porosity,and the permeability of fractures being two or three grades higher than that of the matrix pores.Four sets of high-angle tectonic fractures and horizontal shear fractures formed a good network system and controlled the distribution and production of gas in the tight sandstones.

  3. The SLUGGS Survey: revisiting the correlation between X-ray luminosity and total mass of massive early-type galaxies

    CERN Document Server

    Forbes, Duncan A; Romanowsky, Aaron J; Kim, Dong-Woo; Brodie, Jean P; Fabbiano, Giuseppina

    2016-01-01

    Here we utilise recent measures of galaxy total dynamical mass and X-ray gas luminosities (L$_{X,Gas}$) for a sample of 29 massive early-type galaxies from the SLUGGS survey to probe L$_{X,Gas}$--mass scaling relations. In particular, we investigate scalings with stellar mass, dynamical mass within 5 effective radii (R$_e$) and total virial mass. We also compare these relations with predictions from $\\Lambda$CDM simulations. We find a strong linear relationship between L$_{X,Gas}$ and galaxy dynamical mass within 5 R$_e$, which is consistent with the recent cosmological simulations of Choi et al. that incorporate mechanical heating from AGN. We conclude that the gas surrounding massive early-type galaxies was shock heated as it fell into collapsing dark matter halos so that L$_{X,Gas}$ is primarily driven by the depth of a galaxy's potential well. Heating by an AGN plays an important secondary role in determining L$_{X,Gas}$.

  4. The Low Mass of Mars: First Evidence of Early Gas-Driven Migration by Jupiter

    Science.gov (United States)

    Walsh, K. J.; Morbidelli, A.; Raymond, S. N.; O'Brien, D. P.; Mandell, A. M.

    2010-12-01

    Numerical simulations of planetary accretion have succeeded in matching most of the physical and orbital properties of the terrestrial planets with one glaring exception: they categorically form Mars analogs that are roughly an order of magnitude too massive (Raymond et al. 2009). The initial conditions that best reproduce the mass of Mars require that the inner planetesimal disk had an outer edge at 1 Astronomical Unit (AU) (Hansen 2009). To date, no mechanism has been shown to create this edge and remain compatible with the current-day solar system, in particular the existence of the asteroid belt. Here we show that a substantial gas-driven radial migration of the giant planets is the needed mechanism. Hydrodynamical simulations show that the evolution of Jupiter and Saturn in a gas-disk generically leads to a two-stage, inward-then-outward, migration where the extent of each stage of migration depends on a priori unconstrained disk parameters (Masset & Snellgrove 2001, Morbidelli et al. 2007, Pierens & Nelson 2008). We demonstrate with numerical simulations that, if Jupiter migrated inwards to 1.5 AU before migrating out towards its current location, its gravitational influence would truncate the inner planetesimal disk at 1 AU. The resulting disk naturally reproduces all the terrestrial planets including Mars. During the giant planets' migration, the asteroid belt is emptied and later re-populated from two distinct parent populations. This provides the first dynamical explanation for the current dichotomy of physical properties of the main asteroid belt, with anhydrous asteroids (S-type) in the inner part and primitive asteroids (C-type) in the outer part (Gradie & Tedesco 1982). Our model links the origin of the inner solar system -- explaining the mass of Mars and the properties of the asteroid belt -- to a realistic evolution of the giant planets. Thus Mars and the asteroid belt provide the first evidence for an early solar system evolution characterized by

  5. Basin geodynamics and sequence stratigraphy of Upper Triassic to Lower Jurassic deposits of Southern Tunisia

    Science.gov (United States)

    Carpentier, Cédric; Hadouth, Suhail; Bouaziz, Samir; Lathuilière, Bernard; Rubino, Jean-Loup

    2016-05-01

    Aims of this paper are to propose a geodynamic and sequential framework for the late Triassic and early Jurassic of and south Tunisia and to evidence the impact of local tectonics on the stratigraphic architecture. Facies of the Upper Triassic to Lower Jurassic of Southern Tunisia have been interpreted in terms of depositional environments. A sequential framework and correlation schemes are proposed for outcrops and subsurface transects. Nineteen middle frequency sequences inserted in three and a half low frequency transgression/regression cycles were evidenced. Despite some datation uncertainties and the unknown durations of Lower Jurassic cycles, middle frequency sequences appear to be controlled by eustasy. In contrast the tectonics acted as an important control on low frequency cycles. The Carnian flooding was certainly favored by the last stages of a rifting episode which started during the Permian. The regression accompanied by the formation of stacked angular unconformities and the deposition of lowstand deposits during the late Carnian and Norian occured during the uplift and tilting of the northern basin margins. The transpressional activity of the Jeffara fault system generated the uplift of the Tebaga of Medenine high from the late Carnian and led to the Rhaetian regional angular Sidi Stout Unconformity. Facies analysis and well-log correlations permitted to evidence that Rhaetian to Lower Jurassic Messaoudi dolomites correspond to brecciated dolomites present on the Sidi Stout unconformity in the North Dahar area. The Early-cimmerian compressional event is a possible origin for the global uplift of the northern African margin and Western Europe during the late Carnian and the Norian. During the Rhaetian and the early Jurassic a new episode of normal faulting occured during the third low frequency flooding. This tectonosedimentary evolution ranges within the general geodynamic framework of the north Gondwana margin controlled by the opening of both

  6. Post-Triassic thermal history of the Tazhong Uplift Zone in the Tarim Basin, Northwest China: Evidence from apatite fission-track thermochronology

    Directory of Open Access Journals (Sweden)

    Caifu Xiang

    2013-11-01

    Full Text Available The Tarim Basin is a representative example of the basins developed in the northwest China that are characterized by multiple stages of heating and cooling. In order to better understand its complex thermal history, apatite fission track (AFT thermochronology was applied to borehole samples from the Tazhong Uplift Zone (TUZ. Twelve sedimentary samples of Silurian to Triassic depositional ages were analyzed from depths coinciding with the apatite partial annealing zone (∼60–120 °C. The AFT ages, ranging from 132 ± 7 Ma (from a Triassic sample to 25 ± 2 Ma (from a Carboniferous sample, are clearly younger than their depositional ages and demonstrate a total resetting of the AFT thermometer after deposition. The AFT ages vary among different tectonic belts and decrease from the No. Ten Faulted Zone (133–105 Ma in the northwest, the Central Horst Zone in the middle (108–37 Ma, to the East Buried Hill Zone in the south (51–25 Ma. Given the low magnitude of post-Triassic burial heating evidenced by low vitrinite reflectance values (Ro < 0.7%, the total resetting of the AFT system is speculated to result from the hot fluid flow along the faults. Thermal effects along the faults are well documented by younger AFT ages and unimodal single grain age distributions in the vicinity of the faults. Permian–early Triassic basaltic volcanism may be responsible for the early Triassic total annealing of those samples lacking connectivity with the fault. The above arguments are supported by thermal modeling results.

  7. Geodynamic evolution of early Mesozoic sedimentary basins in eastern Australia

    Science.gov (United States)

    Rosenbaum, G.; Babaahmadi, A.; Esterle, J.

    2014-12-01

    Eastern Australia is covered by a series of continental sedimentary basins deposited during the Triassic and Jurassic, but the geodynamic context of these basins is not fully understood. Using gridded aeromagnetic data, seismic reflection data, geological maps, digital elevation models, and field observations, we conducted a structural synthesis aimed at characterizing major structures and deformation style in the Triassic-Jurassic sedimentary basins of eastern Australia. Our results show evidence for four alternating episodes of rifting and contractional events during the Triassic. Two major episodes of rifting, characterized by syn-sedimentary steep normal faults and bimodal volcanism, resulted in the development of the Early-Middle Triassic Esk-Nymboida Rift System and the early Late Triassic Ipswich Basin. Faults in the Esk-Nymboida Rift System have been controlled by a pre-existing oroclinal structure. Each phase of rifting was followed by a contractional event, which produced folds, reverse faults and unconformities in the basins. Since the latest Late Triassic, thermal subsidence led to the deposition of continental sediments in the Clarence-Moreton Basin, which continued until the Early Cretaceous. We suggest that the geodynamic control on the alternating episodes of rifting and contraction during the Triassic in eastern Australia was ultimately related to plate boundary migration and switches between trench retreat and advance.

  8. Early Childhood Caries and Body Mass Index in Young Children from Low Income Families

    Directory of Open Access Journals (Sweden)

    Maria Goretti Queiroz

    2013-03-01

    Full Text Available The relationship between early childhood caries (ECC and obesity is controversial. This cross-sectional survey investigated this association in children from low-income families in Goiania, Goias, Brazil and considered the role of several social determinants. A questionnaire examining the characteristics of the children and their families was administered to the primary caregiver during home visits. In addition, children (approximately 6 years of age had their height, weight, and tooth condition assessed. The primary ECC outcome was categorized as one of the following: caries experience (decayed, missing, filled tooth: “dmft” index > 0, active ECC (decayed teeth > 0, or active severe ECC (decayed teeth ≥ 6. Descriptive, bivariate and logistic regression analyses were conducted. The participants in the current study consisted of 269 caregiver-child dyads, 88.5% of whom were included in the Family Health Program. Caregivers were mostly mothers (67.7%, were 35.3 ± 10.0 years old on average and had 9.8 ± 3.1 years of formal education. The mean family income was 2.3 ± 1.5 times greater than the Brazilian minimum wage. On average, the children in the current study were 68.7 ± 3.8 months old. Of these, 51.7% were boys, 23.4% were overweight or obese, 45.0% had active ECC, and 17.1% had severe ECC. The average body mass index (BMI of the children was 15.9 ± 2.2, and their dmft index was 2.5 ± 3.2. BMI was not associated with any of the three categories of dental caries (p > 0.05. In contrast, higher family incomes were significantly associated with the lack of caries experience in children (OR 1.22, 95%CI 1.01–1.50, but the mother’s level of education was not significantly associated with ECC.

  9. THE VLA VIEW OF THE HL TAU DISK: DISK MASS, GRAIN EVOLUTION, AND EARLY PLANET FORMATION

    Energy Technology Data Exchange (ETDEWEB)

    Carrasco-González, Carlos; Rodríguez, Luis F.; Galván-Madrid, Roberto [Instituto de Radioastronomía y Astrofísica UNAM, Apartado Postal 3-72 (Xangari), 58089 Morelia, Michoacán, México (Mexico); Henning, Thomas; Linz, Hendrik; Birnstiel, Til; Boekel, Roy van; Klahr, Hubert [Max-Planck-Institut für Astronomie Heidelberg, Königstuhl 17, D-69117 Heidelberg (Germany); Chandler, Claire J.; Pérez, Laura [National Radio Astronomy Observatory, P.O. Box O, 1003 Lopezville Road, Socorro, NM 87801-0387 (United States); Anglada, Guillem; Macias, Enrique; Osorio, Mayra [Instituto de Astrofísica de Andalucía (CSIC), Apartado 3004, E-18080 Granada (Spain); Flock, Mario [Jet Propulsion Laboratory, California Institute of Technology, 4800 Oak Grove Drive, Pasadena, CA 91109 (United States); Menten, Karl [Jansky Fellow of the National Radio Astronomy Observatory (United States); Testi, Leonardo [European Southern Observatory, Karl-Schwarzschild-Str. 2, D-85748 Garching bei München (Germany); Torrelles, José M. [Institut de Ciències de l’Espai (CSIC-IEEC) and Institut de Ciències del Cosmos (UB-IEEC), Martí i Franquès 1, E-08028 Barcelona (Spain); Zhu, Zhaohuan, E-mail: c.carrasco@crya.unam.mx, E-mail: l.rodriguez@crya.unam.mx, E-mail: r.galvan@crya.unam.mx, E-mail: henning@mpia.de, E-mail: linz@mpia.de [Department of Astrophysical Sciences, Princeton University, Princeton, NJ 08544 (United States)

    2016-04-10

    The first long-baseline ALMA campaign resolved the disk around the young star HL Tau into a number of axisymmetric bright and dark rings. Despite the very young age of HL Tau, these structures have been interpreted as signatures for the presence of (proto)planets. The ALMA images triggered numerous theoretical studies based on disk–planet interactions, magnetically driven disk structures, and grain evolution. Of special interest are the inner parts of disks, where terrestrial planets are expected to form. However, the emission from these regions in HL Tau turned out to be optically thick at all ALMA wavelengths, preventing the derivation of surface density profiles and grain-size distributions. Here, we present the most sensitive images of HL Tau obtained to date with the Karl G. Jansky Very Large Array at 7.0 mm wavelength with a spatial resolution comparable to the ALMA images. At this long wavelength, the dust emission from HL Tau is optically thin, allowing a comprehensive study of the inner disk. We obtain a total disk dust mass of (1–3) × 10{sup −3} M {sub ⊙}, depending on the assumed opacity and disk temperature. Our optically thin data also indicate fast grain growth, fragmentation, and formation of dense clumps in the inner densest parts of the disk. Our results suggest that the HL Tau disk may be actually in a very early stage of planetary formation, with planets not already formed in the gaps but in the process of future formation in the bright rings.

  10. Maternal prepregnancy body mass index and gestational weight gain on offspring overweight in early infancy.

    Directory of Open Access Journals (Sweden)

    Nan Li

    Full Text Available OBJECTIVE: The aim of the present study was to evaluate the association of maternal prepregnancy body mass index (BMI and gestational weight gain (GWG with anthropometry in the offspring from birth to 12 months old in Tianjin, China. METHODS: Between 2009 and 2011, health care records of 38,539 pregnant women had been collected, and their children had been measured body weight and length at birth, 3, 6, 9 and 12 months of age. The independent and joint associations of pre-pregnancy BMI and GWG based on the Institute of Medicine (IOM guidelines with anthropometry in the offspring were examined using General Linear Model and Logistic Regression. RESULTS: Prepregnancy BMI and maternal GWG were positively associated with Z-scores for birth weight-for-gestational age, birth length-for-gestational age, and birth weight-for-length. Infants born to mothers with excessive GWG had the greatest changes in Z-scores for weight-for-age from birth to Month 3, and from Month 6 to Month 12, and the greatest changes in Z-scores for length-for-age from birth to months 3 and 12 compared with infants born to mothers with adequate GWG. Excessive GWG was associated with an increased risk of offspring overweight or obesity at 12 months old in all BMI categories except underweight. CONCLUSIONS: Maternal prepregnancy overweight/obesity and excessive GWG were associated with greater weight gain and length gain of offspring in early infancy. Excessive GWG was associated with increased infancy overweight and obesity risk.

  11. Early childhood caries and body mass index in young children from low income families.

    Science.gov (United States)

    Costa, Luciane Rezende; Daher, Anelise; Queiroz, Maria Goretti

    2013-03-05

    The relationship between early childhood caries (ECC) and obesity is controversial. This cross-sectional survey investigated this association in children from low-income families in Goiania, Goias, Brazil and considered the role of several social determinants. A questionnaire examining the characteristics of the children and their families was administered to the primary caregiver during home visits. In addition, children (approximately 6 years of age) had their height, weight, and tooth condition assessed. The primary ECC outcome was categorized as one of the following: caries experience (decayed, missing, filled tooth: "dmft" index > 0), active ECC (decayed teeth > 0), or active severe ECC (decayed teeth ≥ 6). Descriptive, bivariate and logistic regression analyses were conducted. The participants in the current study consisted of 269 caregiver-child dyads, 88.5% of whom were included in the Family Health Program. Caregivers were mostly mothers (67.7%), were 35.3 ± 10.0 years old on average and had 9.8 ± 3.1 years of formal education. The mean family income was 2.3 ± 1.5 times greater than the Brazilian minimum wage. On average, the children in the current study were 68.7 ± 3.8 months old. Of these, 51.7% were boys, 23.4% were overweight or obese, 45.0% had active ECC, and 17.1% had severe ECC. The average body mass index (BMI) of the children was 15.9 ± 2.2, and their dmft index was 2.5 ± 3.2. BMI was not associated with any of the three categories of dental caries (p > 0.05). In contrast, higher family incomes were significantly associated with the lack of caries experience in children (OR 1.22, 95%CI 1.01-1.50), but the mother's level of education was not significantly associated with ECC.

  12. Early spontaneous regression of a hypothalamic/chiasmatic mass in neurofibromatosis type 1: MR findings

    Energy Technology Data Exchange (ETDEWEB)

    Zuccoli, G.; Ferrozzi, F.; Bassi, P. [Department of Radiology, University of Parma, V. Gramsci, 14, I-43100 Parma (Italy); Sigorini, M.; Virdis, R. [Department of Paediatrics, University of Parma, V. Gramsci, 14, I-43100 Parma (Italy); Bellomi, M. [Division of Radiology, European Institute of Oncology, Milan (Italy)

    2000-07-01

    A patient with neurofibromatosis type 1 was found to have an enhancing mass in the hypothalamus and in the anterior optic pathway. A 3-month MR study showed a reduction in the size and enhancement of the mass. At a 9-month MR follow-up the mass disappeared and ceased to enhance. This report shows the unusual behaviour of a hypothalamic/chiasmatic mass confirming that in such asymptomatic cases the conservative management can be considered the treatment of choice. (orig.)

  13. A new stem-neopterygian fish from the Middle Triassic of China shows the earliest over-water gliding strategy of the vertebrates

    Science.gov (United States)

    Xu, Guang-Hui; Zhao, Li-Jun; Gao, Ke-Qin; Wu, Fei-Xiang

    2013-01-01

    Flying fishes are extraordinary aquatic vertebrates capable of gliding great distances over water by exploiting their enlarged pectoral fins and asymmetrical caudal fin. Some 50 species of extant flying fishes are classified in the Exocoetidae (Neopterygii: Teleostei), which have a fossil record no older than the Eocene. The Thoracopteridae is the only pre-Cenozoic group of non-teleosts that shows an array of features associated with the capability of over-water gliding. Until recently, however, the fossil record of the Thoracopteridae has been limited to the Upper Triassic of Austria and Italy. Here, we report the discovery of exceptionally well-preserved fossils of a new thoracopterid flying fish from the Middle Triassic of China, which represents the earliest evidence of an over-water gliding strategy in vertebrates. The results of a phylogenetic analysis resolve the Thoracopteridae as a stem-group of the Neopterygii that is more crown-ward than the Peltopleuriformes, yet more basal than the Luganoiiformes. As the first record of the Thoracopteride in Asia, this new discovery extends the geographical distribution of this group from the western to eastern rim of the Palaeotethys Ocean, providing new evidence to support the Triassic biological exchanges between Europe and southern China. Additionally, the Middle Triassic date of the new thoracopterid supports the hypothesis that the re-establishment of marine ecosystems after end-Permian mass extinction is more rapid than previously thought. PMID:23118437

  14. Sandstone provenance and U-Pb ages of detrital zircons from Permian-Triassic forearc sediments within the Sukhothai Arc, northern Thailand: Record of volcanic-arc evolution in response to Paleo-Tethys subduction

    Science.gov (United States)

    Hara, Hidetoshi; Kunii, Miyuki; Miyake, Yoshihiro; Hisada, Ken-ichiro; Kamata, Yoshihito; Ueno, Katsumi; Kon, Yoshiaki; Kurihara, Toshiyuki; Ueda, Hayato; Assavapatchara, San; Treerotchananon, Anuwat; Charoentitirat, Thasinee; Charusiri, Punya

    2017-09-01

    Provenance analysis and U-Pb dating of detrital zircons in Permian-Triassic forearc sediments from the Sukhothai Arc in northern Thailand clarify the evolution of a missing arc system associated with Paleo-Tethys subduction. The turbidite-dominant formations within the forearc sediments include the Permian Ngao Group (Kiu Lom, Pha Huat, and Huai Thak formations), the Early to earliest Late Triassic Lampang Group (Phra That and Hong Hoi formations), and the Late Triassic Song Group (Pha Daeng and Wang Chin formations). The sandstones are quartzose in the Pha Huat, Huai Thak, and Wang Chin formations, and lithic wacke in the Kiu Lom, Phra That, Hong Hoi and Pha Daeng formations. The quartzose sandstones contain abundant quartz, felsic volcanic and plutonic fragments, whereas the lithic sandstones contain mainly basaltic to felsic volcanic fragments. The youngest single-grain (YSG) zircon U-Pb age generally approximates the depositional age in the study area, but in the case of the limestone-dominant Pha Huat Formation the YSG age is clearly older. On the other hand, the youngest cluster U-Pb age (YC1σ) represents the peak of igneous activity in the source area. Geological evidence, geochemical signatures, and the YC1σ ages of the sandstones have allowed us to reconstruct the Sukhothai arc evolution. The initial Sukhothai Arc (Late Carboniferous-Early Permian) developed as a continental island arc. Subsequently, there was general magmatic quiescence with minor I-type granitic activity during the Middle to early Late Permian. In the latest Permian to early Late Triassic, the Sukhothai Arc developed in tandem with Early to Middle Triassic I-type granitic activity, Middle to Late Triassic volcanism, evolution of an accretionary complex, and an abundant supply of sediments from the volcanic rocks to the trench through a forearc basin. Subsequently, the Sukhothai Arc became quiescent as the Paleo-Tethys closed after the Late Triassic. In addition, parts of sediments of

  15. Evidence for Triassic sinistral shear along the Altyn Tagh fault, northern Tibet (China)

    Science.gov (United States)

    Li, H.; Yang, J.; Wu, C.; Xu, Z.; Tapponnier, P.; Arnaud, N.

    2005-12-01

    The strike-slip faults of north Tibet accommodate part of the Cenozoic convergence between India and Asia. Along the Xorkol basin west-north of Qaidam, the active traces of the Altyn Tagh fault follow narrow belts of granitic and amphibolitic mylonites. The deformation recorded in those mylonites is sinistral strike-slip. Three types of zircon may be sorted out from the mylonites: anatectic (magmatic), long columnar zircons, magmatic columnar zircons, and residual, metamorphic, sub-rounded zircon. Three groups of U-Pb ages measured by ion microprobe (SHRIMP) on single zircon were obtained: 530-550Ma for the columnar, magmatic zircon, 460-510Ma for the sub-rounded, residual metamorphic zircon, and 235-245Ma for the long-columnar anatectic (magmatic) zircon. The latter type of zircon is well oriented with the crystal long axis parallel to the stretching lineation. Mineral inclusions in the oriented zircons are also parallel to the stretching lineation, which coincides with the direction of maximum tectonic stress in the process of the strike-slip. Raman spectrum study indicates that the inclusion minerals show the melting phase feature, and cathodoluminescence images show that this type of zircon has a relatively homogeneous internal structure. Therefore, the long columnar zircons resulted from rapid oriented growth in a partial melting regime in the ductile shear process. It not only denotes the direction of shear strain in the strike-slip shear, but the growth age (crystallization age) of this type of zircon denotes the age of strike-slip shear. 40Ar/39Ar ages of directionaly grown hornblendes and biotite in the same samples are 220-230Ma and 190-200Ma, respectively. This suggest syntectonic anatexis and cooling occurred during strike-slip shear along the Altyn Tagh fault in Triassic time (to Early Jurassic). The Triassic shear may be related to oblique collision between the Bayan Har and the Kunlun- Qaidam blocks. 120Ma (Arnaud, et al., 2003) and 90Ma (Liu, et al

  16. Merger-driven evolution of the effective stellar initial mass function of massive early-type galaxies

    Science.gov (United States)

    Sonnenfeld, Alessandro; Nipoti, Carlo; Treu, Tommaso

    2017-02-01

    The stellar initial mass function (IMF) of early-type galaxies is the combination of the IMF of the stellar population formed in situ and that of accreted stellar populations. Using as an observable the effective IMF αIMF, defined as the ratio between the true stellar mass of a galaxy and the stellar mass inferred assuming a Salpeter IMF, we present a theoretical model for its evolution as a result of dry mergers. We use a simple dry-merger evolution model, based on cosmological N-body simulations, together with empirically motivated prescriptions for the IMF to make predictions on how the effective IMF of massive early-type galaxies changes from z = 2 to z = 0. We find that the IMF normalization of individual galaxies becomes lighter with time. At fixed velocity dispersion, αIMF is predicted to be constant with redshift. Current dynamical constraints on the evolution of the IMF are in slight tension with this prediction, even though systematic uncertainties, including the effect of radial gradients in the IMF, prevent a conclusive statement. The correlation of αIMF with stellar mass becomes shallower with time, while the correlation between αIMF and velocity dispersion is mostly preserved by dry mergers. We also find that dry mergers can mix the dependence of the IMF on stellar mass and velocity dispersion, making it challenging to infer, from z = 0 observations of global galactic properties, what is the quantity that is originally coupled with the IMF.

  17. 安徽巢湖平顶山西坡剖面下三叠统殷坑组沉积及地球化学特征%Sedimentary and Geochemical Characteristics of the Early Triassic Yinkeng Formantion at West Pingdingshan Section in Chaohu,Anhui Province

    Institute of Scientific and Technical Information of China (English)

    林春明; 张霞; 于进; 李达; 张妮

    2015-01-01

    In this paper,we discussed the sedimentary and diagenetic environments of the Early Triassic Yinkeng Formation at the west Pingdingshan section,Chaohu,Anhui Province,based on the detailed analyses of sedimentary sequence,mineral composition,sedimentary texture and structure,chemical components,as well as carbon and oxygen isotopes of the carbonates.The results indicate that the Yinkeng Formation contains four sedimentary facies,including the shallow open platform,upper slope,lower slope,and deep basin from bottom up,with the water depth and sea level deepening and rising,respectively.Nodular limestones,which are composed of nodules and matrix,are common in this formation.The nodule is gray or gray white micritic calcite while the matrix occurs predominantly of yellow,brown-yellow,and yellow-gray calcareous mudstones.Three types of nodular limestones,namely the banded nodular limestone, discontinuous nodular limestone,and random nodular limestone,are regularly distributed in the section, which may reflect original sedimentary environment from upper slope, lower slope to deep basin, respectively,with dissolution gradually increasing,and following diagenetic intensity.In addition,theδ1 3 C values of the carbonate in the Yinkeng Formation range from - 5.97‰ to - 1.17‰,displaying an obvious positive excursion with the magnitude up to 4.80‰,which may result from the biotic recovery, burial of organic matters,sea-level rising,and environmental changing.%本文在对安徽巢湖平顶山西坡剖面下三叠统殷坑组解剖的基础上,着重对其内部赋存的碳酸盐岩的矿物组成、结构构造、化学成分及碳氧同位素特征等方面做了系统研究,探讨了其沉积环境和成岩环境,以及与海平面变化的关系等。研究表明,下三叠统殷坑组是在海水不断变深的背景下沉积的,经历了较浅水开阔台地、较深水的上斜坡和下斜坡,最后到深水盆地的4个演化过程。瘤状灰岩在殷

  18. The SLUGGS Survey: The mass distribution in early-type galaxies within five effective radii and beyond

    CERN Document Server

    Alabi, Adebusola B; Romanowsky, Aaron J; Brodie, Jean P; Strader, Jay; Janz, Joachim; Pota, Vincenzo; Pastorello, Nicola; Usher, Christopher; Spitler, Lee R; Foster, Caroline; Jennings, Zachary G; Villaume, Alexa; Kartha, Sreeja

    2016-01-01

    We study mass distributions within and beyond 5~effective radii ($R_{\\rm e}$) in 23 early-type galaxies from the SLUGGS survey, using their globular cluster (GC) kinematic data. The data are obtained with Keck/DEIMOS spectrograph, and consist of line-of-sight velocities for ~$3500$ GCs, measured with a high precision of ~15 $\\rm km\\ s^{-1}$ per GC and extending out to $~13 R_{\\rm e}$. We obtain the mass distribution in each galaxy using the tracer mass estimator of Watkins et al. and account for kinematic substructures, rotation of the GC systems and galaxy flattening in our mass estimates. The observed scatter between our mass estimates and results from the literature is less than 0.2 dex. The dark matter fraction within $5R_{\\rm e}$ ($f_{\\rm DM}$) increases from ~$0.6$ to ~$0.8$ for low- and high-mass galaxies, respectively, with some intermediate-mass galaxies ($M_*{\\sim}10^{11}M_\\odot$) having low $f_{\\rm DM}\\sim0.3$, which appears at odds with predictions from simple galaxy models. We show that these res...

  19. BRACHIOPODS FROM THE UPPER TRIASSIC REEF HABITATS OF THE NORTHERN CALCAREOUS ALPS (DACHSTEIN LIMESTONE, HOCHSCHWAB, AUSTRIA

    Directory of Open Access Journals (Sweden)

    MILOS SIBLÍK

    2005-11-01

    Full Text Available Upper Triassic brachiopods from 2 localities in the reef Dachstein Limestone of the SE Hochschwab massif in Styria, Austria are systematically described and illustrated. About 900 variably preserved specimens belong to 28 species, representing thus the most diverse brachiopod fauna known from the North Alpine Dachstein Limestone. This indicates that brachiopods were common inhabitants of reef habitats during the Alpine Norian. Oxycolpella, Sinucosta and Aulacothyropsis are dominant. Seven brachiopod species are known from the Kössen Formation (Rhaetian. Adygella biplicata (Dagys and Ladinian Hungarispira loretzi (Bittner are the newcomers in the Nordalpine Dachstein Limestone. In addition to brachiopods, only some fragments of bivalves were found. Conodonts of the species Epigondolella triangularis (Budurov 1972 indicate the Early Norian age.

  20. Osteohistology of hyperodapedontine rhynchosaurs from the Upper Triassic of Southern Brazil

    Directory of Open Access Journals (Sweden)

    Fábio Hiratsuka Veiga

    2015-12-01

    Full Text Available The first osteohistological study focused exclusively on rhynchosaurs (non-archosauriform archosauromorphs, based on the hyperodapedontines Teyumbaita sulcognathus and Hyperodapedon sp., from the Upper Triassic of Southern Brazil, indicates a relatively rapid growth rate in early ontogeny shown by the fibrolamellar complex, with a change to slow intermittent growth during late ontogeny represented by parallel-fibred bone with several growth marks. Contrary to previous studies, which described a typical non-archosaur reptilian bone tissue pattern for rhynchosaurs, with growth marks extending across the entire cortex, we demonstrate that, in both studied taxa, the initial growth rate was faster in comparison to the later. This suggests that the ability of rapid growth at high rates was already present in basal non-archosauriform archosauromorphs.

  1. Fossil fungi with suggested affinities to the Endogonaceae from the Middle Triassic of Antarctica.

    Science.gov (United States)

    Krings, Michael; Taylor, Thomas N; Dotzler, Nora; Persichini, Gianna

    2012-01-01

    Documented fossil evidence of zygomycetous fungi is rare. A conspicuous fungal fossil, Jimwhitea circumtecta gen. et sp. nov., occurs in permineralized peat from the Middle Triassic of Antarctica. The fossil is interpreted as a mantled zygosporangium that buds from a macrogametangium subtended by a sac-like macrosuspensor. The macrogametangium is united at its tip with a microgametangium which is subtended by a micro-suspensor. This configuration is strikingly similar to the zygosporangium-gametangia complexes seen in certain modern Endogonaceae. Co-occurring with J. circumtecta are isolated propagules closely resembling the zygosporangium of J. circumtecta and a portion of a sporocarp containing zygosporangia embedded in a gleba. Several of the sporangia are borne on ovoid or elongate structures, which we interpret as gametangia. These fossils offer an exceptionally detailed view of the morphology and reproductive biology of early Mesozoic zygomycetes.

  2. Conodont zonation of Lower Triassic strata in Slovenia

    Directory of Open Access Journals (Sweden)

    Tea Kolar-Jurkovšek

    2015-12-01

    Full Text Available The paper presents the results of a conodont study carried out in the Triassic strata in the area of the Slovenian part of the Southern Alps, External Dinarides and the Transition region between the External and Internal Dinarides. The following conodont zones have been distinguished: Hindeodus praeparvus Z., H. parvus Z., Isarcicella lobata Z., I. staeschei – I. isarcica Z., H. postparvus Z., Hadrodontina aequabilis Z., Ha. anceps Z., Eurygnathodus costatus Z., Neospathodus planus Z., N. robustus Z., Platyvillosus corniger Z., Pl. regularis Z., Pachycladina obliqua Z., Foliella gardenae Z., Triassospathodus hungaricus Z., T. symmetricus Z., N. robustispinus - T. homeri Z. and T. triangularis Z. The introduced conodont zonation spans from the Induan, including the Permian-Triassic boundary interval to the late Olenekian and is valid for the shallow shelf environments of western Tethys.

  3. Bivalve reefs from the Upper Triassic of Iran

    Directory of Open Access Journals (Sweden)

    Franz T. Fürsich

    2005-10-01

    Full Text Available In the Upper Triassic Nayband Formation of east-central Iran, bivalves repeatedly form small patch reefson a mid to outer mixed carbonate-siliciclastic ramp in close stratigraphic neighbourhood to coral and coralspongereefs. In contrast to other Triassic-Jurassic bivalve-dominated patch reefs, the bivalve reefs of theNayband Formation are characterized by a comparatively high diversity of framebuilding taxa. These includetaxa from three different families, i.e., the ostreids Umbostrea emamii, U. iranica and U.? aff. parasiticum, the prospondylids Newaagia stocklini and Persia monstrosa, and the plicatulids Eoplicatula parvadehensis and Pseudoplacunopsis asymmetrica. The bivalve reef constructors may have had a competitive advantage over coral and calcareous sponges in environments characterized by a higher degree of turbidity and/or higher nutrient contents.

  4. Ophiuroids discovered in the middle triassic hypersaline environment.

    Directory of Open Access Journals (Sweden)

    Mariusz A Salamon

    Full Text Available Echinoderms have long been considered to be one of the animal phyla that is strictly marine. However, there is growing evidence that some recent species may live in either brackish or hypersaline environments. Surprisingly, discoveries of fossil echinoderms in non-(openmarine paleoenvironments are lacking. In Wojkowice Quarry (Southern Poland, sediments of lowermost part of the Middle Triassic are exposed. In limestone layer with cellular structures and pseudomorphs after gypsum, two dense accumulations of articulated ophiuroids (Aspiduriella similis (Eck were documented. The sediments with ophiuroids were formed in environment of increased salinity waters as suggested by paleontological, sedimentological, petrographical and geochemical data. Discovery of Triassic hypersaline ophiuroids invalidates the paleontological assumption that fossil echinoderms are indicators of fully marine conditions. Thus caution needs to be taken when using fossil echinoderms in paleoenvironmental reconstructions.

  5. A new Triassic sponge from the Antimonio terrane, Sonora, Mexico

    Science.gov (United States)

    Senowbari-Daryan, Baba; Stanley, George D.; Gonzalez-Leon, Carlos

    2001-10-01

    A new Upper Triassic (Norian) chambered sponge, Fanthalamia glomerata n. sp., from the Antimonio Formation (Antimonio terrane) of northwestern Sonora, Mexico, is described. Recrystallized limestone containing the new sponge, together with other marine invertebrates, is interpreted to represent tropical, shallow-water carbonate settings characterized by local biostromal and biohermal buildups. The new species increases understanding of the ancient depositional environment and paleobiogeography of the Antimonio Formation.

  6. NEW TRIASSIC ASTEROIDEA (ECHINODERMATA SPECIMENS AND THEIR EVOLUTIONARY SIGNIFICANCE

    Directory of Open Access Journals (Sweden)

    DANIEL B. BLAKE

    2017-04-01

    Full Text Available The Paleozoic-Mesozoic transition saw the disappearance of asteroid stem groups and the ascent of the crown group, but late Paleozoic and Triassic asteroids are rare and transition events are poorly documented. Three new Middle and Late Triassic specimens augment existing data; included are a specimen of Trichasteropsis weissmanni from Germany, a specimen of Trichasteropsis? sp. indet. from Italy, and a possible member of the extant Poraniidae from Slovenia. Presence of a small ossicle at the interbrachial midline and adjacent to the marginal series of the new T. weissmanni specimen is consistent with similar expressions not only of other trichasteropsids but also occurrence of two interbrachial ossicles in Paleozoic, stem-group asterozoans; presence is in turn consistent with a hypothesis of derivation of the axillary/odontophore coupling from two ossicles rather than direct derivation of the crown-group odontophore from a single stem-group axillary. Morphology of Trichasteropsis? sp. indet., including, for example, the evenly-tapering arms are reminiscent of those of diverse crown-group asteroids whereas the enlarged distal arms of T. weissmanni are unique, the morphology of T? sp. indet. thereby potentially indicative of a plesiomorphic, stemward positioning within the Trichasteropsiidae. The range of the Poraniidae is tentatively extended to the Carnian. Similarities shared by the Poraniidae and the Trichasteropsiidae suggest stemward positioning within crown-group diversification; however, known Triassic fossils do not appear closely related to extant taxa identified in recent molecular studies as basal within the crown-group. A temperate climate is suggested as preferred by the Triassic asteroids rather than a tropical, warmer one.

  7. Guanling Biota: A Marker of Triassic Biotic Recovery from the end-Permian Extinction in the Ancient Guizhou Sea

    Institute of Scientific and Technical Information of China (English)

    JIANG Dayong; Ryosuke MOTANI; LI Chun; HAO Weicheng; SUN Yuanlin; SUN Zuoyu; Lars SCHMITZ

    2005-01-01

    After a slow recovery from the end-Permian extinction during the Early Triassic and rapid radiation in the Middle Triassic, evolution of organisms reached a new peak phase in the Late Triassic. The Guanling Biota from the Wayao Member (conodont Paragondolella polygnathiformis Zone), Falang Formation, Xinpu, Guanling County, Guizhou Province, southwestern China corresponds to this peak that marks the full recovery from the end-Permian extinction of marine ecosystems. The biota is of high diversity, containing well preserved and completely articulated skeletons of vertebrates comprising marine reptiles, fishes, and invertebrates including crinoids, ammonites, bivalves, and other fossils,and is one of the best examples of marine ecosystem records in life history. The fossil marine reptiles and crinoids are most significant in this biota, especially the marine reptiles, which provide an important link between the Triassic Pacific and Tethys, and between Triassic basal forms and the Jurassic-Cretaceous marine top predators. The most remarkable fossils are the large completely articulated ichthyosaur skeletons up to and more than 10 m, and the first recorded thalattosaurs and placodonts in China. Following our review, of the 17 named reptilian taxa the eight listed here are considered to be valid: three ichthyosaurs (Qianichthyosaurus zhoui Li, 1999; Guizhouichthyosaurus tangae Cao and Luo in Yin et al.,2000, Guanlingsaurus liangae Yin in Yin et al., 2000), three thalattosaurs (Anshunsaurus huangguoshuensis Liu, 1999,Xinpusaurus suni Yin in Yin et al., 2000, Xinpusaurus kohi Jiang et al., 2004), and two placodonts (Sinocyamodus xinpuensis Li, 2000, Psephochelys polyosteoderma Li and Rieppel, 2002). Mixosaurus guanlingensis Cao in Yin et al.,2000 might be a junior synonym of Qianichthyosaurus zhoui Li, 1999, and Cymbospondylus asiaticus Li and You, 2002and Panjiangsaurus epicharis Chen and Cheng, 2003 might be junior synonyms of Guizhouichthyosaurus tangae Cao and Luo in

  8. Early laparoscopic management of appendicular mass in children: Still a taboo, or time for a change in surgical philosophy?

    Science.gov (United States)

    Agrawal, Vikesh; Acharya, Himanshu; Chanchlani, Roshan; Sharma, Dhananjaya

    2016-01-01

    INTRODUCTION: Early appendicectomy has been found to be a safe and better alternative for management of appendicular mass in various studies in adults, while very few studies report such advantages in the paediatric population. We conducted this study to assess the safety, efficacy and need of early laparoscopic appendicectomy (ELA) in child patients with appendicular mass. MATERIALS AND METHODS: All patients with appendicular mass who underwent ELA at our institute between September 2011 and August 2014 were retrospectively reviewed. Appendicular mass was defined as a right iliac fossa mass in a case of acute appendicitis, diagnosed by clinical, laboratory and radiological evaluation, and palpation under anaesthesia, the patient being subjected to laparoscopic treatment. RESULTS: Forty-eight (48) patients were confirmed to have appendicular mass intraoperatively and were included in the analysis. There were 30 males and 18 females, with ages ranging 7-13 years (mean 9 years). In the present study, appendicular complications included appendicular abscess (62.5%), gangrenous appendicitis (25%), sloughed-out appendix (8.33%) and appendicular perforation (4.16%). The average operative time was 72 min (range 45-93 min). One case (1.92%) required conversion to open procedure due to failure of identification of the appendicular base of a sloughed-out appendix. Post-operative complications were found in 4 (7.69%) patients, of whom 3 (5.76%) had minor wound infection at the umbilical port site and 1 (1.92%) had post-operative pelvic abscess, which was managed with percutaneous aspiration. DISCUSSION: ELA avoids misdiagnosis, treats complicated appendicitis at its outset, and avoids complications and/or failure of non-operative treatment of a potentially lethal, diseased appendix. This approach is associated with minimal complications in experienced hands and is a safe and feasible option in children with appendicular mass. PMID:27073299

  9. Geochemical significance of the relative enrichment of pristane and the negative excursion of δ13CPr across the Permian-Triassic Boundary at Meishan, China

    Institute of Scientific and Technical Information of China (English)

    WANG Chunjiang; LIU Yimei; LIU Hongxiu; ZHU Lei; SHI Quan

    2005-01-01

    Changes in the distribution of isoprenoid hydrocarbons and in δ13Ckero or δ13CPr across the section from the Changxing Formation to the lower Yinkeng Formation at Meishan (the GSSP of PTB) are studied, in which a relative enrichment of pristane and a sharp shift in both δ13Ckero and δ13Cmole near the boundary are revealed. A possible mechanism for the abnormal accumulation of pristane near PTB is suggested: Lipids in some marine animals and their metabolites, rich in pristane, can be preserved and accumulate in some suitable depositing facies under certain special conditions, such as the catastrophic death of animals and/or developing of an anoxic water column, and thus the pristane enrichment occurs in the sediment. The occurrences of isoprenoid enrichment and high Pr/Ph ratios have been found in other typical marine anoxic sediments accompanied by mass extinction in various extent during the most important geological periods, such as Late Ordovician, end of Devonian, Early Jurassic and Late Cretaceous. These occurrences support to a certain extent the above mechanism that interprets the genesis of a high Pr/Ph ratio in some typical marine anoxic sediments. The synchronous sharp negative shifts in δ13Cmole, δ13Ckero and δ13Ccarb from Beds 24 to 26 of the Meishan profile indicate that a sudden and strong variation of carbon source in the atmosphere-ocean system occurred during the quick but equable evolution from the end-Permian to Early Triassic, and the coupling between the pristane enrichment and negative shift in δ13Ckero and δ13CPr may well indicate the importance of the release of methane hydrates and marine anoxia in the end-Permian mass extinction.

  10. Osmium isotope evidence for a large Late Triassic impact event

    Science.gov (United States)

    Sato, Honami; Onoue, Tetsuji; Nozaki, Tatsuo; Suzuki, Katsuhiko

    2013-01-01

    Anomalously high platinum group element concentrations have previously been reported for Upper Triassic deep-sea sediments, which are interpreted to be derived from an extraterrestrial impact event. Here we report the osmium (Os) isotope fingerprint of an extraterrestrial impact from Upper Triassic chert successions in Japan. Os isotope data exhibit a marked negative excursion from an initial Os isotope ratio (187Os/188Osi) of ∼0.477 to unradiogenic values of ∼0.126 in a platinum group element-enriched claystone layer, indicating the input of meteorite-derived Os into the sediments. The timing of the Os isotope excursion coincides with both elevated Os concentrations and low Re/Os ratios. The magnitude of this negative Os isotope excursion is comparable to those found at Cretaceous–Paleogene boundary sites. These geochemical lines of evidence demonstrate that a large impactor (3.3–7.8 km in diameter) produced a global decrease in seawater 187Os/188Os ratios in the Late Triassic. PMID:24036603

  11. Groundwater table fluctuations recorded in zonation of microbial siderites from end-Triassic strata

    Science.gov (United States)

    Weibel, R.; Lindström, S.; Pedersen, G. K.; Johansson, L.; Dybkjær, K.; Whitehouse, M. J.; Boyce, A. J.; Leng, M. J.

    2016-08-01

    In a terrestrial Triassic-Jurassic boundary succession of southern Sweden, perfectly zoned sphaerosiderites are restricted to a specific sandy interval deposited during the end-Triassic event. Underlying and overlying this sand interval there are several other types of siderite micromorphologies, i.e. poorly zoned sphaerosiderite, spheroidal (ellipsoid) siderite, spherical siderite and rhombohedral siderite. Siderite overgrowths occur mainly as rhombohedral crystals on perfectly zoned sphaerosiderite and as radiating fibrous crystals on spheroidal siderite. Concretionary sparry, microspar and/or micritic siderite cement postdate all of these micromorphologies. The carbon isotope composition of the siderite measured by conventional mass spectrometry shows the characteristic broad span of data, probably as a result of multiple stages of microbial activity. SIMS (secondary ion mass spectrometry) revealed generally higher δ13C values for the concretionary cement than the perfectly zoned sphaerosiderite, spheroidal siderite and their overgrowths, which marks a change in the carbon source during burial. All the various siderite morphologies have almost identical oxygen isotope values reflecting the palaeo-groundwater composition. A pedogenic/freshwater origin is supported by the trace element compositions of varying Fe:Mn ratios and low Mg contents. Fluctuating groundwater is the most likely explanation for uniform repeated siderite zones of varying Fe:Mn ratios reflecting alternating physiochemical conditions and hostility to microbial life/activity. Bacterially mediated siderite precipitation likely incorporated Mn and other metal ions during conditions that are not favourable for the bacteria and continued with Fe-rich siderite precipitation as the physico-chemical conditions changed into optimal conditions again, reflecting the response to groundwater fluctuations.

  12. Effect of body mass index on the survival of patients with early-stage small cell lung cancer after surgery

    OpenAIRE

    Kolesnik, A. P.

    2013-01-01

    Lung cancer is an important medico-social problem. It is connected with high level of incidence and mortality of lung cancer. Nowadays we know that obesity has significant influence on cancer development, including lung cancer. Multivariate analysis confirmed that histological type of tumour, kind of operation and body mass index (BMI) influence on prognosis in patients with early stages of mall cell lung cancer. So, now we can use BMI along with other significant prognostic criteria for dete...

  13. The mafic, ultramafic and metamorphic xenoliths in triassic evaporite complexes, North West Algeria

    Energy Technology Data Exchange (ETDEWEB)

    Midoun, M.; Seddiki, A.

    2016-10-01

    In northwestern Algeria, triassic evaporate bodies contain varied xenoliths extracted from the lower crust and upper mantle and are interpreted as evidence of crustal thinning at the beginning of the Triassic period. Similar materials are known to occur in the internal areas of the western Mediterranean chains, which allow us to propose the existence of a wide area of crustal thinning during the Triassic along the future Tethyan axis. (Author)

  14. The SLUGGS survey: the mass distribution in early-type galaxies within five effective radii and beyond

    Science.gov (United States)

    Alabi, Adebusola B.; Forbes, Duncan A.; Romanowsky, Aaron J.; Brodie, Jean P.; Strader, Jay; Janz, Joachim; Pota, Vincenzo; Pastorello, Nicola; Usher, Christopher; Spitler, Lee R.; Foster, Caroline; Jennings, Zachary G.; Villaume, Alexa; Kartha, Sreeja

    2016-08-01

    We study mass distributions within and beyond 5 effective radii (Re) in 23 early-type galaxies from the SAGES Legacy Unifying Globulars and Galaxies Survey, using their globular cluster (GC) kinematic data. The data are obtained with Keck/DEep Imaging Multi-Object Spectrograph, and consist of line-of-sight velocities for ˜3500 GCs, measured with a high precision of ˜15 km s-1 per GC and extending out to ˜13 Re. We obtain the mass distribution in each galaxy using the tracer mass estimator of Watkins et al. and account for kinematic substructures, rotation of the GC systems and galaxy flattening in our mass estimates. The observed scatter between our mass estimates and results from the literature is less than 0.2 dex. The dark matter fraction within 5 Re (fDM) increases from ˜0.6 to ˜0.8 for low- and high-mass galaxies, respectively, with some intermediate-mass galaxies (M* ˜ 1011 M⊙) having low fDM ˜ 0.3, which appears at odds with predictions from simple galaxy models. We show that these results are independent of the adopted orbital anisotropy, stellar mass-to-light (M/L) ratio, and the assumed slope of the gravitational potential. However, the low fDM in the ˜1011 M⊙ galaxies agrees with the cosmological simulations of Wu et al. where the pristine dark matter distribution has been modified by baryons during the galaxy assembly process. We find hints that these M* ˜ 1011 M⊙ galaxies with low fDM have very diffuse dark matter haloes, implying that they assembled late. Beyond 5 Re, the M/L gradients are steeper in the more massive galaxies and shallower in both low and intermediate mass galaxies.

  15. Early peroxisome proliferator-activated receptor gamma regulated genes involved in expansion of pancreatic beta cell mass

    Directory of Open Access Journals (Sweden)

    Vivas Yurena

    2011-12-01

    Full Text Available Abstract Background The progression towards type 2 diabetes depends on the allostatic response of pancreatic beta cells to synthesise and secrete enough insulin to compensate for insulin resistance. The endocrine pancreas is a plastic tissue able to expand or regress in response to the requirements imposed by physiological and pathophysiological states associated to insulin resistance such as pregnancy, obesity or ageing, but the mechanisms mediating beta cell mass expansion in these scenarios are not well defined. We have recently shown that ob/ob mice with genetic ablation of PPARγ2, a mouse model known as the POKO mouse failed to expand its beta cell mass. This phenotype contrasted with the appropriate expansion of the beta cell mass observed in their obese littermate ob/ob mice. Thus, comparison of these models islets particularly at early ages could provide some new insights on early PPARγ dependent transcriptional responses involved in the process of beta cell mass expansion Results Here we have investigated PPARγ dependent transcriptional responses occurring during the early stages of beta cell adaptation to insulin resistance in wild type, ob/ob, PPARγ2 KO and POKO mice. We have identified genes known to regulate both the rate of proliferation and the survival signals of beta cells. Moreover we have also identified new pathways induced in ob/ob islets that remained unchanged in POKO islets, suggesting an important role for PPARγ in maintenance/activation of mechanisms essential for the continued function of the beta cell. Conclusions Our data suggest that the expansion of beta cell mass observed in ob/ob islets is associated with the activation of an immune response that fails to occur in POKO islets. We have also indentified other PPARγ dependent differentially regulated pathways including cholesterol biosynthesis, apoptosis through TGF-β signaling and decreased oxidative phosphorylation.

  16. Early

    Directory of Open Access Journals (Sweden)

    Kamel Abd Elaziz Mohamed

    2014-04-01

    Conclusion: Early PDT is recommended for patients who require prolonged tracheal intubation in the ICU as outcomes like the duration of mechanical ventilation length of ICU stay and hospital stay were significantly shorter in early tracheostomy.

  17. The importance of seed mass for early regeneration in tropical forest: a review

    NARCIS (Netherlands)

    Rose, S.A.; Poorter, L.

    2003-01-01

    Seed mass is an important component of the shade tolerance of rain forest tree species. Using a metaanalysis this article evaluates till what extent seed mass affects the survival, initial size, and growth of seedlings in light environments that are typical of forest gaps and understory

  18. Subthalamic Nucleus Deep Brain Stimulation in Early Stage Parkinson's Disease Is Not Associated with Increased Body Mass Index.

    Science.gov (United States)

    Millan, Sarah H; Hacker, Mallory L; Turchan, Maxim; Molinari, Anna L; Currie, Amanda D; Charles, David

    2017-01-01

    Previous studies suggest that deep brain stimulation of the subthalamic nucleus (STN-DBS) for Parkinson's disease (PD) leads to weight gain. This study analyzes changes in body mass index (BMI) in 29 subjects from a prospective, single-blind trial of DBS in early stage PD (age 50-75, Hoehn & Yahr stage II off medication, treated with antiparkinsonian medications for ≥6 months but 0.05). BMI change over two years was not different between the groups (p = 0.62, ODT = -0.89; DBS+ODT = -0.17). This study suggests that STN-DBS is not associated with weight gain in subjects with early stage PD. This finding will be tested in an upcoming FDA-approved phase III multicenter, randomized, double-blind, placebo-controlled, pivotal clinical trial evaluating DBS in early stage PD (ClinicalTrials.gov identifier NCT00282152).

  19. High prepregnant body mass index is associated with early termination of full and any breastfeeding in Danish women

    DEFF Research Database (Denmark)

    Baker, Jennifer Lyn; Michaelsen, Kim F; Sørensen, Thorkild I A;

    2007-01-01

    maternal obesity, was modified by gestational weight gain, and still existed when there was greater social support for breastfeeding. DESIGN: Study participants (37 459 women) were drawn from the Danish National Birth Cohort. The association of prepregnant BMI and gestational weight gain......BACKGROUND: An association between high prepregnant body mass index (BMI) and early termination of breastfeeding has been observed, but this finding may have depended on the sociocultural context. OBJECTIVE: The objective was to determine whether this association was stronger with increasing...... with the termination of full or any breastfeeding by 1, 16, or 20 wk postpartum was assessed with logistic regression analyses, and the risk of early termination of full and any breastfeeding during the first 18 mo postpartum was assessed with Poisson regression analyses. RESULTS: The risk of early termination of any...

  20. Computed tomography in palaeontology - case studies from Triassic to Cretaceous ammonites

    Science.gov (United States)

    Lukeneder, A.; Lukeneder, S.; Gusenbauer, C.

    2012-04-01

    Case studies on computed tomography on ammonites, ammonite mass-occurrences and trace fossils, deposited during the Upper Triassic (approx. 225 mya) of Turkey and during the Lower Cretaceous of Italy (approx. 130 mya), are presented. X-ray computed tomography is known in palaeontology as providing data for 3D visualization and geometrical modelling techniques. Computed tomography down to a few microns (or even below) of spatial resolution are increasingly employed for geoscientific investigations, using an equally variable range of processing techniques and software packages. Additionally internal structures are visualized without destruction of fossils, as computed tomography is a non-destructive method. Experimental The scans were made at the Upper Austria University of Applied Science in Wels with a dual source industrial 3D computed tomography device (RayScan 250 E), equipped with a 225 kV microfocus and a 450 kV minifocus X-ray tube as well as a 2048x2048 pixel flat panel detector (cone beam reconstruction). The spatial resolution (down to 5 μm) is determined by the size of each volumetric pixel (voxel) of the data set. For each fossil part the optimal voxel size and tube voltage were set according to the specimen dimensions. Case study 1: Triassic ammonites from Turkey (FWF Project P22109-B17) A case study in computed tomography on the ammonite genus Orthoceltites is presented. The latter studies are essential for palaeontology and systematic investigations. Ammonite shells and filled phragmocones (secondary calcite) from the Orthoceltites beds possess the same mass-density as the matrix in which the ammonite specimens are embedded. The almost identical mass-density of the embedding matrix (about 2.8 g/cm3), the ammonite shell (secondary calcite, about 2.6-2.8 g/cm3) and the infilled matrix (about 2.8 g/cm3) avoids their visualization. It is therefore not possible to visualize the ammonites by computed tomography. In few cases ammonite shells, body chambers

  1. AN EMPIRICAL CONNECTION BETWEEN THE ULTRAVIOLET COLOR OF EARLY-TYPE GALAXIES AND THE STELLAR INITIAL MASS FUNCTION

    Energy Technology Data Exchange (ETDEWEB)

    Zaritsky, Dennis [Steward Observatory, University of Arizona, 933 North Cherry Avenue, Tucson, AZ 85721 (United States); Gil de Paz, Armando; Bouquin, Alexandre Y. K., E-mail: dennis.zaritsky@gmail.com [Departamento de Astrofísica y CC. de la Atmósfera, Facultad de CC. Físicas, Universidad Complutense de Madrid, Avda. de la Complutense s/n, Madrid E-28040 (Spain)

    2014-01-01

    Using new UV magnitudes for a sample of early-type galaxies (ETGs) with published stellar mass-to-light ratios, Y{sub *}, we find a correlation between UV color and Y{sub *} that is tighter than those previously identified between Y{sub *} and either the central stellar velocity dispersion, metallicity, or alpha enhancement. The sense of the correlation is that galaxies with larger Y{sub *} are bluer in the UV. We conjecture that differences in the lower mass end of the stellar initial mass function (IMF) are related to the nature of the extreme horizontal branch populations that are generally responsible for the UV flux in ETGs. If so, then UV color can be used to identify ETGs with particular IMF properties and to estimate Y{sub *}.

  2. SDSS-IV MaNGA: Variation of the Stellar Initial Mass Function in Spiral and Early-type Galaxies

    Science.gov (United States)

    Li, Hongyu; Ge, Junqiang; Mao, Shude; Cappellari, Michele; Long, R. J.; Li, Ran; Emsellem, Eric; Dutton, Aaron A.; Li, Cheng; Bundy, Kevin; Thomas, Daniel; Drory, Niv; Lopes, Alexandre Roman

    2017-04-01

    We perform Jeans anisotropic modeling (JAM) on elliptical and spiral galaxies from the MaNGA DR13 sample. By comparing the stellar mass-to-light ratios estimated from stellar population synthesis and from JAM, we find a systematic variation of the initial mass function (IMF) similar to that in the earlier {{ATLAS}}3{{D}} results. Early-type galaxies (elliptical and lenticular) with lower velocity dispersions within one effective radius are consistent with a Chabrier-like IMF, while galaxies with higher velocity dispersions are consistent with a more bottom-heavy IMF such as the Salpeter IMF. Spiral galaxies have similar systematic IMF variations, but with slightly different slopes and larger scatters, due to the uncertainties caused by the higher gas fractions and extinctions for these galaxies. Furthermore, we examine the effects of stellar mass-to-light ratio gradients on our JAM modeling, and we find that the trends become stronger after considering the gradients.

  3. High-sensitivity Mass Spectrometry for Probing Gene Translation in Single Embryonic Cells in the Early Frog (Xenopus Embryo

    Directory of Open Access Journals (Sweden)

    Camille Lombard-Banek

    2016-10-01

    Full Text Available Direct measurement of protein expression with single-cell resolution promises to deepen the understanding of basic molecular processes during normal and impaired development. High-resolution mass spectrometry provides detailed coverage of the proteomic composition of large numbers of cells. Here we discuss recent mass spectrometry developments based on single-cell capillary electrophoresis that extend discovery proteomics to sufficient sensitivity to enable the measurement of proteins in single cells. The single-cell mass spectrometry system is used to detect a large number of proteins in single embryonic cells in blastomeres in the 16-cell embryo of the South African clawed frog (Xenopus laevis that give rise to distinct tissue types. Single-cell measurements of protein expression provide complementary information on gene transcription during early development of the vertebrate embryo, raising a potential to understand how differential gene expression coordinates normal cell heterogeneity during development.

  4. Plant diversity does not buffer drought effects on early-stage litter mass loss rates and microbial properties.

    Science.gov (United States)

    Vogel, Anja; Eisenhauer, Nico; Weigelt, Alexandra; Scherer-Lorenzen, Michael

    2013-09-01

    Human activities are decreasing biodiversity and changing the climate worldwide. Both global change drivers have been shown to affect ecosystem functioning, but they may also act in concert in a non-additive way. We studied early-stage litter mass loss rates and soil microbial properties (basal respiration and microbial biomass) during the summer season in response to plant species richness and summer drought in a large grassland biodiversity experiment, the Jena Experiment, Germany. In line with our expectations, decreasing plant diversity and summer drought decreased litter mass loss rates and soil microbial properties. In contrast to our hypotheses, however, this was only true for mass loss of standard litter (wheat straw) used in all plots, and not for plant community-specific litter mass loss. We found no interactive effects between global change drivers, that is, drought reduced litter mass loss rates and soil microbial properties irrespective of plant diversity. High mass loss rates of plant community-specific litter and low responsiveness to drought relative to the standard litter indicate that soil microbial communities were adapted to decomposing community-specific plant litter material including lower susceptibility to dry conditions during summer months. Moreover, higher microbial enzymatic diversity at high plant diversity may have caused elevated mass loss of standard litter. Our results indicate that plant diversity loss and summer drought independently impede soil processes. However, soil decomposer communities may be highly adapted to decomposing plant community-specific litter material, even in situations of environmental stress. Results of standard litter mass loss moreover suggest that decomposer communities under diverse plant communities are able to cope with a greater variety of plant inputs possibly making them less responsive to biotic changes.

  5. KMOS3D: Dynamical Constraints on the Mass Budget in Early Star-forming Disks

    Science.gov (United States)

    Wuyts, Stijn; Förster Schreiber, Natascha M.; Wisnioski, Emily; Genzel, Reinhard; Burkert, Andreas; Bandara, Kaushala; Beifiori, Alessandra; Belli, Sirio; Bender, Ralf; Brammer, Gabriel B.; Chan, Jeffrey; Davies, Ric; Fossati, Matteo; Galametz, Audrey; Kulkarni, Sandesh K.; Lang, Philipp; Lutz, Dieter; Mendel, J. Trevor; Momcheva, Ivelina G.; Naab, Thorsten; Nelson, Erica J.; Saglia, Roberto P.; Seitz, Stella; Tacconi, Linda J.; Tadaki, Ken-ichi; Übler, Hannah; van Dokkum, Pieter G.; Wilman, David J.; Wuyts, Eva

    2016-11-01

    We exploit deep integral-field spectroscopic observations with KMOS/Very Large Telescope of 240 star-forming disks at 0.6\\lt z\\lt 2.6 to dynamically constrain their mass budget. Our sample consists of massive (≳ {10}9.8 {M}⊙ ) galaxies with sizes {R}e≳ 2 {kpc}. By contrasting the observed velocity and dispersion profiles with dynamical models, we find that on average the stellar content contributes {32}-7+8 % of the total dynamical mass, with a significant spread among galaxies (68th percentile range {f}{star}˜ 18 % {--}62 % ). Including molecular gas as inferred from CO- and dust-based scaling relations, the estimated baryonic mass adds up to {56}-12+17 % of the total for the typical galaxy in our sample, reaching ˜ 90 % at z\\gt 2. We conclude that baryons make up most of the mass within the disk regions of high-redshift star-forming disk galaxies, with typical disks at z\\gt 2 being strongly baryon-dominated within R e . Substantial object-to-object variations in both stellar and baryonic mass fractions are observed among the galaxies in our sample, larger than what can be accounted for by the formal uncertainties in their respective measurements. In both cases, the mass fractions correlate most strongly with measures of surface density. High-{{{Σ }}}{star} galaxies feature stellar mass fractions closer to unity, and systems with high inferred gas or baryonic surface densities leave less room for additional mass components other than stars and molecular gas. Our findings can be interpreted as more extended disks probing further (and more compact disks probing less far) into the dark matter halos that host them. Based on observations collected at the European Organisation for Astronomical Research in the Southern Hemisphere under ESO programs 092.A-0091, 093.A-0079, 094.A-0217, 095.A-0047, and 096.A-0025.

  6. New primitive ichthyosaurian (Reptilia,Diapsida) from the Middle Triassic of Panxian,Guizhou,southwestern China and its position in the Triassic biotic recovery

    Institute of Scientific and Technical Information of China (English)

    Dayong Jianga; Ryosuke Motani; Weicheng Hao; Lars Schmitz; Olivier Rieppel; Yuanlin Sun; Zuoyu Sun

    2008-01-01

    A new primitive ichthyopterygian Xinminosaurus catactes gen.et.sp.nov,is erected based on a complete skeleton from the Middle Triassic Upper Member of the Guanling Formation at Panxian,Guizhou,southwestern China.It has a suite of uniquely derived characters in its dentition,ulna,carpals and tarsals.It is similar to primitive ichthyopterygians in retaining elongated limb bones.The new taxon and a diversity of marine reptiles in Panxian Fauna are the physical markers of the Middle Triassic Biotic radiation.Detailed studies of this fauna will supply essential knowledge on the diversity,migration and paleobiogeographic affinity of Middle Triassic ichthyopterygians.

  7. Spatially resolved variations of the IMF mass normalisation in early-type galaxies as probed by molecular gas kinematics

    CERN Document Server

    Davis, Timothy A

    2016-01-01

    We here present the first spatially-resolved study of the IMF in external galaxies derived using a dynamical tracer of the mass-to-light ratio. We use the kinematics of relaxed molecular gas discs in seven early-type galaxies (ETGs) selected from the ATLAS3D survey to dynamically determine mass-to-light ratio (M/L) gradients. These M/L gradients are not very strong in the inner parts of these objects, and galaxies that do show variations are those with the highest specific star formation rates. Stellar population parameters derived from star formation histories are then used in order to estimate the stellar initial mass function function (IMF) mismatch parameter, and shed light on its variation within ETGs. Some of our target objects require a light IMF, otherwise their stellar population masses would be greater than their dynamical masses. In contrast, other systems seem to require heavier IMFs to explain their gas kinematics. Our analysis again confirms that IMF variation seems to be occurring within massiv...

  8. A novel compact mass detection platform for the open access (OA) environment in drug discovery and early development.

    Science.gov (United States)

    Gao, Junling; Ceglia, Scott S; Jones, Michael D; Simeone, Jennifer; Antwerp, John Van; Zhang, Li-Kang; Ross, Charles W; Helmy, Roy

    2016-04-15

    A new 'compact mass detector' co-developed with an instrument manufacturer (Waters Corporation) as an interface for liquid chromatography (LC), specifically Ultra-high performance LC(®) (UPLC(®) or UHPLC) analysis was evaluated as a potential new Open Access (OA) LC-MS platform in the Drug Discovery and Early Development space. This new compact mass detector based platform was envisioned to provide increased reliability and speed while exhibiting significant cost, noise, and footprint reductions. The new detector was evaluated in batch mode (typically 1-3 samples per run) to monitor reactions and check purity, as well as in High Throughput Screening (HTS) mode to run 24, 48, and 96 well plates. The latter workflows focused on screening catalysis conditions, process optimization, and library work. The objective of this investigation was to assess the performance, reliability, and flexibility of the compact mass detector in the OA setting for a variety of applications. The compact mass detector results were compared to those obtained by current OA LC-MS systems, and the capabilities and benefits of the compact mass detector in the open access setting for chemists in the drug discovery and development space are demonstrated.

  9. zCOSMOS 10k-bright spectroscopic sample: exploring mass and environment dependence in early-type galaxies

    CERN Document Server

    Moresco, M; Cimatti, A; Zamorani, G; Mignoli, M; Di Cesare, S; Bolzonella, M; Zucca, E; Lilly, S; Kovac, K; Scodeggio, M; Cassata, P; Tasca, L; Vergani, D; Halliday, C; Carollo, M; Contini, T; Kneib, J -P; Le Fèvre, O; Mainieri, V; Renzini, A; Bardelli, S; Bongiorno, A; Caputi, K; Coppa, G; Cucciati, O; de la Torre, S; de Ravel, L; Franzetti, P; Garilli, B; Iovino, A; Kampczyk, P; Knobel, C; Lamareille, F; Le Borgne, J F; Le Brun, V; Maier, C; Pello, R; Peng, Y; Montero, E Perez; Ricciardelli, E; Silverman, J D; Tanaka, M; Tresse, L; Abbas, U; Bottini, D; Cappi, A; Guzzo, L; Koekemoer, A M; Leauthaud, A; Maccagni, D; Marinoni, C; McCracken, H J; Memeo, P; Meneux, B; Nair, P; Oesch, P; Porciani, C; Scaramella, R; Scarlata, C; Scoville, N

    2010-01-01

    We present the analysis of the U-V rest-frame color distribution and some spectral features as a function of mass and environment for two sample of early-type galaxies up to z=1 extracted from the zCOSMOS spectroscopic survey. The first sample ("red galaxies") is defined with a photometric classification, while the second ("ETGs") by combining morphological, photometric, and spectroscopic properties to obtain a more reliable sample. We find that the color distribution of red galaxies is not strongly dependent on environment for all mass bins, with galaxies in overdense regions redder than galaxies in underdense regions with a difference of 0.027\\pm0.008 mag. The dependence on mass is far more significant, with average colors of massive galaxies redder by 0.093\\pm0.007 mag than low-mass galaxies throughout the entire redshift range. We study the color-mass relation, finding a mean slope 0.12\\pm0.005, while the color-environment relation is flatter, with a slope always smaller than 0.04. The spectral analysis t...

  10. Geochronology, geochemistry and tectonic implications of Late Triassic granites in the Mongolian Altai Mountains

    Science.gov (United States)

    Dash, Batulzii; Boldbaatar, Enkhjargal; Zorigtkhuu, Oyun-Erdene; Yin, An

    2016-03-01

    Although the closure of the Paleo-Asian Ocean in western China and western Mongolia occurred in the Late Carboniferous and Early Permian, widespread intra-continental magmatism continued to occur across this region from the Late Permian to the end of the Triassic. In this study we document field relationships and geochemical characterization of a Late Triassic felsic intrusive complex in the western Mongolian Altai. The plutonic complex occurs as sills, dikes, and small stocks and its composition varies from biotite granite, two-mica granite, to leucogranite. Structurally, the plutonic complex occurs in the hanging wall of a segment of the regionally extensively (>1500 km long) Irtysh-Ertix-Bulgan thrust zone. As the plutonic bodies both cut and are deformed by the shear fabrics in this regional thrust shear zone, the duration of felsic magmatism and regional thrusting was temporally overlapping. This suggests that magmatism was coeval with crustal thickening. Major- and trace-element data and isotopic analysis of granitoid samples from our study area indicate that the felsic intrusions were derived from partial melting of meta-sediments, with the biotite and two-mica granite generated through vapor-absent melting and the leucogranite from flux melting. Although the Mongolian Altai intrusions were clearly originated from anatexis, coeval granite in the Chinese Altai directly west of our study area in the hanging wall of the Irtysh-Ertix-Bulgan thrust was derived in part from mantle melting. To reconcile these observations, we propose a Himalayan-style intracontinental-subduction model that predicts two geologic settings for the occurrence of felsic magmatism: (1) along the intracontinental thrust zone where granite was entirely generated by anatexis and (2) in the hanging wall of the intracontinental thrust where convective removal and/or continental subduction induced mantle melting.

  11. Late Permian to Triassic intraplate orogeny of the southern Tianshan and adjacent regions, NW China

    Institute of Scientific and Technical Information of China (English)

    Wei Ju; Guiting Hou

    2014-01-01

    The South Tianshan Orogen and adjacent regions of Central Asia are located in the southwestern part of the Central Asian Orogenic Belt. The formation of South Tianshan Orogen was a diachronous, scissors-like process, which took place during the Palaeozoic, and its western segment was accepted as a site of the final collision between the Tarim Craton and the North Asian continent, which occurred in the late Palaeozoic. However, the post-collisional tectonic evolution of the South Tianshan Orogen and adjacent regions remains debatable. Based on previous studies and recent geochronogical data, we suggest that the final collision between the Tarim Craton and the North Asian continent occurred during the late Carboniferous. Therefore, the Permian was a period of intracontinental environment in the southern Tianshan and adjacent regions. We propose that an earlier, small-scale intraplate orogenic stage occurred in late Permian to Triassic time, which was the first intraplate process in the South Tianshan Orogen and adjacent regions. The later large-scale and well-known Neogene to Quaternary intraplate orogeny was induced by the collision between the India subcontinent and the Eurasian plate. The paper presents a new evolutionary model for the South Tianshan Orogen and adjacent regions, which includes seven stages: (I) late Ordovicianeearly Silurian opening of the South Tianshan Ocean;(II) middle Silurianemiddle Devonian subduction of the South Tianshan Ocean beneath an active margin of the North Asian continent; (III) late Devonianelate Carboniferous closure of the South Tianshan Ocean and collision between the Kazakhstan-Yili and Tarim continental blocks;(IV) early Permian post-collisional magmatism and rifting;(V) late PermianeTriassic the first intraplate orogeny;(VI) JurassicePalaeogene tectonic stagnation and (VII) NeoceneeQuaternary intraplate orogeny.

  12. LATE TRIASSIC (LATE NORIAN-RHAETIAN RADIOLARIANS FROM THE ANTALYA NAPPES, CENTRAL TAURIDES, SOUTHERN TURKEY

    Directory of Open Access Journals (Sweden)

    UGUR KAGAN TEKIN

    2002-11-01

    Full Text Available The Hocaköy section measured from the Alakirçay Nappe (middle nappe of the Antalya Nappes contain rich radiolarian fauna ranging from late Norian (Late Triassic to middle-late Cenomanian (mid Cretaceous. At the basal part of the section, the Late Triassic (late Norian-Rhaetian Gökdere Formation is characterized by gray to beige cherty limestone at the base and pinkish red chert- gray to beige limestone alternation at the top, with moderately to well-preserved radiolarians in the red chert beds. The overlying Jurassic - Middle Cretaceous Hocaköy Radiolarite is mainly represented by chert-mudstone alternations with some limestone interlayers. Radiolarians of the Gökdere Formation can be well correlated with that of the fauna from the Mino Terrane, central Japan and the fauna from the Queen Charlotte Islands, British Columbia, Canada. Four radiolarian zones from central Japan are recognized in the fauna obtained from Gökdere Formation such as “Praemesosaturnalis multidentatus Lowest Occurrence Zone (TR8A” (late Norian, “Praemesosaturnalis pseudokahleri Lowest Occurrence Zone (TR8B” (late Norian, ? “ Skirt F lowest Occurrence Zone (TR8C” (late Norian-Rhaetian and partly “Haeckelicyrtium breviora Taxon Range Zone (TR8D” (Rhaetian. In comparison with the Queen Charlotte fauna, the two zones “Betraccium deweveri Zone” (late Norian and “Proparvicingula moniliformis Zone” (early Rhaetian are also encountered in the Gökdere Formation. Radiolarians of the uppermost part of the Gökdere Formation indicate that “Globolaxtorum tozeri Zone” defined in Queen Charlotte Islands corresponding to the late Rhaetian, is not present in the section. Five new taxa, Capnuchosphaera okayi, Bistarkum rhaeticum, Praemesosaturnalis heilongjiangensis aksekiensis, P. nobleae, Veghicyclia sanfilippoae were determined within the late Norian-Rhaetian radiolarian fauna of the Gökdere Formation in Hocaköy section.   

  13. Microfacies Analyses and Carbon Isotope Studies on Lower Triassic Microbialites from Armenia

    Science.gov (United States)

    Friesenbichler, Evelyn; Baud, Aymon; Krystyn, Leopold; Sahakyan, Lilit; Richoz, Sylvain

    2016-04-01

    After the end-Permian mass extinction the upper Paleozoic skeletal carbonate factory was abruptly replaced by a non-skeletal carbonate factory and Permian-Triassic boundary microbialites (PTBMs) were flourishing. These PTBMs were abundant in low-latitude shallow-marine carbonate shelves in central Tethyan continents and were present during at least four events in the Lower Triassic. The investigated PTBMs from three different sites in southern Armenia were formed in a distal open marine setting on a pelagic carbonate ramp. They grew during two microbial growth phases in Griesbachian times, whereas the microbialites from the first microbial growth phase co-occur with calcium carbonate crystal fans (CCFs). The microbes formed predominantly thrombolites that vary in size between 5 cm to 1.5 m. The biggest thrombolite has a cone-shaped build-up geometry and an asymmetrical growth, which indicates the influence of a steady bottom current. It consists of numerous thrombolite domes with a top head diameter of up to 8 m width and a total height of up to 12 m. The microbialites are surrounded by a bioclastic wackestone that mainly contains ostracods, foraminifers, microgastropods, thin-shelled bivalves and sponges. Carbon isotope studies were performed on both the microbialites and the surrounding sediment. A comparison between the δ13C values of the microbialites and the surrounding sediment revealed that there is little difference (<0.4‰) between these values in the microbialites that formed during the second microbial growth phase. In contrast, the microbialites and CCFs from the first microbial growth phase show differences in the δ13C values of up to 2.3‰ , which could be due to microbial activity.

  14. The osteology of the basal archosauromorph Tasmaniosaurus triassicus from the Lower Triassic of Tasmania, Australia.

    Directory of Open Access Journals (Sweden)

    Martín D Ezcurra

    Full Text Available Proterosuchidae are the most taxonomically diverse archosauromorph reptiles sampled in the immediate aftermath of the Permo-Triassic mass extinction and represent the earliest radiation of Archosauriformes (archosaurs and closely related species. Proterosuchids are potentially represented by approximately 15 nominal species collected from South Africa, China, Russia, Australia and India, but the taxonomic content of the group is currently in a state of flux because of the poor anatomic and systematic information available for several of its putative members. Here, the putative proterosuchid Tasmaniosaurus triassicus from the Lower Triassic of Hobart, Tasmania (Australia, is redescribed. The holotype and currently only known specimen includes cranial and postcranial remains and the revision of this material sheds new light on the anatomy of the animal, including new data on the cranial endocast. Several bones are re-identified or reinterpreted, contrasting with the descriptions of previous authors. The new information provided here shows that Tasmaniosaurus closely resembles the South African proterosuchid Proterosuchus, but it differed in the presence of, for example, a slightly downturned premaxilla, a shorter anterior process of maxilla, and a diamond-shaped anterior end of interclavicle. Previous claims for the presence of gut contents in the holotype of Tasmaniosaurus are considered ambiguous. The description of the cranial endocast of Tasmaniosaurus provides for the first time information about the anatomy of this region in proterosuchids. The cranial endocast preserves possibly part of the vomero-nasal ( = Jacobson's system laterally to the olfactory bulbs. Previous claims of the absence of the vomero-nasal organs in archosaurs, which is suggested by the extant phylogenetic bracket, are questioned because its absence in both clades of extant archosaurs seems to be directly related with the independent acquisition of a non-ground living

  15. The osteology of the basal archosauromorph Tasmaniosaurus triassicus from the Lower Triassic of Tasmania, Australia.

    Science.gov (United States)

    Ezcurra, Martín D

    2014-01-01

    Proterosuchidae are the most taxonomically diverse archosauromorph reptiles sampled in the immediate aftermath of the Permo-Triassic mass extinction and represent the earliest radiation of Archosauriformes (archosaurs and closely related species). Proterosuchids are potentially represented by approximately 15 nominal species collected from South Africa, China, Russia, Australia and India, but the taxonomic content of the group is currently in a state of flux because of the poor anatomic and systematic information available for several of its putative members. Here, the putative proterosuchid Tasmaniosaurus triassicus from the Lower Triassic of Hobart, Tasmania (Australia), is redescribed. The holotype and currently only known specimen includes cranial and postcranial remains and the revision of this material sheds new light on the anatomy of the animal, including new data on the cranial endocast. Several bones are re-identified or reinterpreted, contrasting with the descriptions of previous authors. The new information provided here shows that Tasmaniosaurus closely resembles the South African proterosuchid Proterosuchus, but it differed in the presence of, for example, a slightly downturned premaxilla, a shorter anterior process of maxilla, and a diamond-shaped anterior end of interclavicle. Previous claims for the presence of gut contents in the holotype of Tasmaniosaurus are considered ambiguous. The description of the cranial endocast of Tasmaniosaurus provides for the first time information about the anatomy of this region in proterosuchids. The cranial endocast preserves possibly part of the vomero-nasal ( = Jacobson's) system laterally to the olfactory bulbs. Previous claims of the absence of the vomero-nasal organs in archosaurs, which is suggested by the extant phylogenetic bracket, are questioned because its absence in both clades of extant archosaurs seems to be directly related with the independent acquisition of a non-ground living mode of life.

  16. Development of lower Triassic wrinkle structures: implications for the search for life on other planets.

    Science.gov (United States)

    Mata, Scott A; Bottjer, David J

    2009-11-01

    Wrinkle structures are microbially mediated sedimentary structures that are a common feature of Proterozoic and earliest Phanerozoic siliciclastic seafloors on Earth and occur only rarely in post-Cambrian strata. These macroscopic microbially induced sedimentary structures are readily identifiable at the outcrop scale, and their recognition on other planetary bodies by landed missions may suggest the presence of past microbial life. Wrinkle structures of the Lower Triassic (Spathian) Virgin Limestone Member of the Moenkopi Formation in the western United States record an occurrence of widespread microbialite formation in the wake of the end-Permian mass extinction, the largest biotic crisis of the Phanerozoic. Wrinkle structures occur on proximal sandy tempestites deposited within the offshore transition. Storm layers appear to have been rapidly colonized by microbial mats and were subsequently buried by mud during fair-weather conditions. Wrinkle structures exhibit flat-topped crests and sinuous troughs, with associated mica grains oriented parallel to bedding, suggestive of trapping and binding activity. Although Lower Triassic wrinkle structures postdate the widespread occurrence of these features during the Proterozoic and Cambrian, they exhibit many of the same characteristics and environmental trends, which suggests a conservation of microbial formational and preservational processes in subtidal siliciclastic settings on Earth from the Precambrian into the Phanerozoic. In the search for extraterrestrial life, it may be these conservative characteristics that prove to be the most useful and robust for recognizing microbial features on other planetary bodies, and may add to an ever-growing foundation of knowledge for directing future explorations aimed at seeking out macroscopic microbial signatures.

  17. Merger-driven evolution of the effective stellar initial mass function of massive early-type galaxies

    CERN Document Server

    Sonnenfeld, Alessandro; Treu, Tommaso

    2016-01-01

    The stellar initial mass function (IMF) of early-type galaxies is the combination of the IMF of the stellar population formed in-situ and that of accreted stellar populations. Using as an observable the effective IMF $\\alpha_{IMF}$, defined as the ratio between the true stellar mass of a galaxy and the stellar mass inferred assuming a Salpeter IMF, we present a theoretical model for its evolution as a result of dry mergers. We use a simple dry merger evolution model, based on cosmological $N$-body simulations, together with empirically motivated prescriptions for the IMF to make predictions for how the effective IMF of massive early-type galaxies changes from $z=2$ to $z=0$. We find that the IMF normalization of individual galaxies becomes lighter with time. At fixed velocity dispersion, $\\alpha_{IMF}$ is predicted to be constant with redshift. Current constraints on the evolution of the IMF are in slight tension with this prediction, even though systematic uncertainties prevent a conclusive statement. The co...

  18. The characteristic black hole mass resulting from direct collapse in the early Universe

    Science.gov (United States)

    Latif, M. A.; Schleicher, D. R. G.; Schmidt, W.; Niemeyer, J. C.

    2013-12-01

    Black holes of a billion solar masses are observed in the infant Universe a few hundred million years after the big bang. The direct collapse of protogalactic gas clouds in primordial haloes with Tvir ≥ 104 K provides the most promising way to assemble massive black holes. In this study, we aim to determine the characteristic mass scale of seed black holes and the time evolution of the accretion rates resulting from the direct collapse model. We explore the formation of supermassive black holes via cosmological large eddy simulations (LES) by employing sink particles and following their evolution for 20 000 yr after the formation of the first sink. As the resulting protostars were shown to have cool atmospheres in the presence of strong accretion, we assume here that UV feedback is negligible during this calculation. We confirm this result in a comparison run without sinks. Our findings show that black hole seeds with characteristic mass of 105 M⊙ are formed in the presence of strong Lyman-Werner flux which leads to an isothermal collapse. The characteristic mass is about two times higher in LES compared to the implicit large eddy simulations. The accretion rates increase with time and reach a maximum value of 10 M⊙ yr-1 after 104 yr. Our results show that the direct collapse model is clearly feasible as it provides the expected mass of the seed black holes.

  19. KMOS^3D: Dynamical constraints on the mass budget in early star-forming disks

    CERN Document Server

    Wuyts, S; Wisnioski, E; Genzel, R; Burkert, A; Bandara, K; Beifiori, A; Belli, S; Bender, R; Brammer, G B; Chan, J; Davies, R; Fossati, M; Galametz, A; Kulkarni, S K; Lang, P; Lutz, D; Mendel, J T; Momcheva, I G; Naab, T; Nelson, E J; Saglia, R P; Seitz, S; Tacconi, L J; Tadaki, K; Übler, H; van Dokkum, P G; Wilman, D J; Wuyts, E

    2016-01-01

    We exploit deep integral-field spectroscopic observations with KMOS/VLT of 240 star-forming disks at 0.6 2 being strongly baryon-dominated within $R_e$. Substantial object-to-object variations in both stellar and baryonic mass fractions are observed among the galaxies in our sample, larger than what can be accounted for by the formal uncertainties in their respective measurements. In both cases, the mass fractions correlate most strongly with measures of surface density. High $\\Sigma_{star}$ galaxies feature stellar mass fractions closer to unity, and systems with high inferred gas or baryonic surface densities leave less room for additional mass components other than stars and molecular gas. Our findings can be interpreted as more extended disks probing further (and more compact disks probing less far) into the dark matter halos that host them. However, a non-negligible tail of the derived baryonic mass fraction distribution reaching into the unphysical $f_{bar} > 1$ regime may in addition hint at more effi...

  20. Breeding Young as a Survival Strategy during Earth’s Greatest Mass Extinction

    Science.gov (United States)

    Botha-Brink, Jennifer; Codron, Daryl; Huttenlocker, Adam K.; Angielczyk, Kenneth D.; Ruta, Marcello

    2016-04-01

    Studies of the effects of mass extinctions on ancient ecosystems have focused on changes in taxic diversity, morphological disparity, abundance, behaviour and resource availability as key determinants of group survival. Crucially, the contribution of life history traits to survival during terrestrial mass extinctions has not been investigated, despite the critical role of such traits for population viability. We use bone microstructure and body size data to investigate the palaeoecological implications of changes in life history strategies in the therapsid forerunners of mammals before and after the Permo-Triassic Mass Extinction (PTME), the most catastrophic crisis in Phanerozoic history. Our results are consistent with truncated development, shortened life expectancies, elevated mortality rates and higher extinction risks amongst post-extinction species. Various simulations of ecological dynamics indicate that an earlier onset of reproduction leading to shortened generation times could explain the persistence of therapsids in the unpredictable, resource-limited Early Triassic environments, and help explain observed body size distributions of some disaster taxa (e.g., Lystrosaurus). Our study accounts for differential survival in mammal ancestors after the PTME and provides a methodological framework for quantifying survival strategies in other vertebrates during major biotic crises.

  1. Breeding Young as a Survival Strategy during Earth’s Greatest Mass Extinction

    Science.gov (United States)

    Botha-Brink, Jennifer; Codron, Daryl; Huttenlocker, Adam K.; Angielczyk, Kenneth D.; Ruta, Marcello

    2016-01-01

    Studies of the effects of mass extinctions on ancient ecosystems have focused on changes in taxic diversity, morphological disparity, abundance, behaviour and resource availability as key determinants of group survival. Crucially, the contribution of life history traits to survival during terrestrial mass extinctions has not been investigated, despite the critical role of such traits for population viability. We use bone microstructure and body size data to investigate the palaeoecological implications of changes in life history strategies in the therapsid forerunners of mammals before and after the Permo-Triassic Mass Extinction (PTME), the most catastrophic crisis in Phanerozoic history. Our results are consistent with truncated development, shortened life expectancies, elevated mortality rates and higher extinction risks amongst post-extinction species. Various simulations of ecological dynamics indicate that an earlier onset of reproduction leading to shortened generation times could explain the persistence of therapsids in the unpredictable, resource-limited Early Triassic environments, and help explain observed body size distributions of some disaster taxa (e.g., Lystrosaurus). Our study accounts for differential survival in mammal ancestors after the PTME and provides a methodological framework for quantifying survival strategies in other vertebrates during major biotic crises. PMID:27044713