Collaborative Research: The end Guadalupian (ca 260 Ma) biotic crisis: Research into timing, potential causes, and environmental proxies

该奖项是根据2009年美国复苏和再投资法案（公法111-5）资助的。【摘要】高分辨率地质年代学在检验大陆尺度、短期火山事件和环境危机之间的因果关系方面具有重要意义。本合作研究计划旨在揭示瓜德鲁普末期（约260 Ma）物种大灭绝的时间及其与中国西部峨眉山火山省的时间关系。地质年代学研究将辅以古环境研究（三角洲13c地层学）和生物地层学。目前已有的地质年代学和古环境数据表明两者之间存在因果关系，但由于限制峨眉山火山活动和灭绝事件的年龄数据不精确和不准确（有几个Ma的不确定性），并且delta13C研究仅限于少数地点的短剖面，因此缺乏足够的证据来自信地验证这一假设。因此，一些基本问题仍未得到解答。除了检验因果关系的假设外，pi还打算研究(1)灭绝事件在多大程度上在不同地区和环境之间具有跨时性(2)晚二叠纪生物恢复的速度(3)海洋化学中的极端值（如果存在）与火山活动脉冲以及恢复速度和模式的相关性。详细地说，pi将分析记录中国和澳大利亚瓜达鲁普期末事件的海洋和陆地剖面的火山灰层中的矿物（锆石，sanidine），应用锆石预处理，通过消除Pb损失的影响，大大提高了高分辨率TIMS U-Pb锆石数据的质量和可靠性。40Ar/39Ar定年法将被用作进一步的约束。除了沉积剖面外，他们还将对峨眉山火山产物进行U-Pb和40Ar/39Ar分析，分别应用于锆石、不良长岩和斜长石。通过将U-Pb和40Ar/39Ar地质年代学与化学和生物地层学相结合，将大大改善中至晚二叠世的时间尺度，并将更现实地评估生物危机及其后果的潜在原因。本文提出的研究对理解地球历史的一阶过程具有重要的基础意义。特别是对环境异常的理解已经成为地球科学和其他领域研究的主要焦点。pi将通过与加州大学古生物学博物馆及其公共推广计划合作，让更广泛的受众了解他们的发现。

This award is funded under the American Recovery and Reinvestment Act of 2009 (Public Law 111-5).Collaborative Research: The end Guadalupian (ca 260 Ma) biotic crisis: Research into timing, potential causes, and environmental proxiesRoland Mundil and Paul Renne: Berkeley Geochron LaboratoryJohathan Payne: Stanford UniversityEAR-0923669 and EAR-0923620ABSTRACTHigh-resolution geochronology is instrumental in testing proposed causal links between continental-scale, short-term volcanic events and environmental crises. This collaborative research proposal is aimed at unraveling the timing of the end-Guadalupian (ca 260 Ma) mass extinction and its temporal relation to the Emeishan volcanic province in W China. Geochronological research will be complemented with paleo-enviromental studies (delta13C stratigraphy) and biostratigraphy.Currently existing geochronological and paleo-environmental data suggest a causal link but are scarce and insufficient for testing this hypothesis with confidence, because age data constraining the Emeishan volcanism and the extinction event are imprecise and inaccurate (with several Ma uncertainties), and delta13C studies are restricted to short profiles from only a few sites. Therefore, fundamental questions remain unanswered. In addition to testing the hypothesis of a causal link PIs intend to study (1) to what extent the extinction event is diachronous among localities and environments (2) the rate of the biotic recovery in the Late Permian (3) the correlation of extrema in ocean chemistry (if present) with pulses of volcanism and with rates and modes of recovery.In detail, PIs will analyze minerals (zircon, sanidine) from ash-layers within marine and terrestrial sections recording the end-Guadalupian event in China and Australia, applying a zircon pre-treatment which is proven to dramatically improve the quality and reliability of high-resolution TIMS U-Pb zircon data by eliminating the effects of Pb loss. 40Ar/39Ar dating will be employed as a further constraint. In addition to the sedimentary sections they will target Emeishan volcanic products with both U-Pb and 40Ar/39Ar analyses applied to zircon and baddeleyite, and plagioclase, respectively.Through careful integration of U-Pb and 40Ar/39Ar geochronology with chemo- and biostratigraphy, the time scale of the Middle through Late Permian will be greatly improved and will lead to more realistic evaluation of potential causes for the biotic crisis and its aftermath.The research proposed herein is of fundamental importance to understanding first-order processes in Earth History. In particular the understanding of environmental anomalies has become a prime focus of research in Earth Sciences and other areas. PIs will make their findings accessible to a wider audience by collaborating with the University of California Museum of Paleontology and their public outreach program.