COLLABORATIVE RESEARCH: Chemostratigraphic Analysis of Panthalassic and Tethyan Permian-Triassic Boundary Sections: Assessment of Global Paleoceanographic Dynamics

EAR-0745574 Thomas Algeo，辛辛那提大学EAR-0745393 Brooks B.Ellwood，路易斯安那州立大学EAR-0746189 Katherine Freeman，宾夕法尼亚州立大学EAR-0745592 Timothy Lyons，加州大学河滨分校EAR-0745817 Arne Wguth and Harry Rowe，德克萨斯大学，Arlington ABSTRACT地球历史上最大的二叠纪-三叠纪界线(PTB)大灭绝的原因和动力学仍不确定。晚二叠世海洋和陆地环境的逐渐恶化以及早三叠世不适宜居住条件的持续表明，内在因素是重要的，但与二叠纪末期相关的消失率峰值、突然的岩相变化和地球化学异常是灾难性事件(如大规模火山喷发、火流星撞击和/或大规模海洋倾覆)的证据。尽管对结核杆菌进行了很长时间的研究，但能够处理下列关键问题的海洋界线综合高分辨率化学地层学研究非常少：二叠纪-三叠纪深海缺氧的程度和强度、有毒深海水上涌至浅海陆架和平台的模式、这种事件与海水碳酸盐饱和度同期变化和海洋生物恢复延迟的关系、对灭绝后全球碳同位素负迁移的控制、以及海洋和陆地领域结核杆菌危机的相对时间和因果关系。在这个项目中，我们建议生成由磁化率、元素浓度、TOC-TIC、~(13)Ccarb-~(13)Corg、S-Fe形态、~(34)S-~(34)S-~(34)S硫酸盐、稀土元素和生物标志物组成的地球化学代理数据集，共8个研究区的19个剖面，包括前泛海4个区域(加拿大的Cach Creek地体、西部沉积盆地、Sverdrup盆地和新西兰的Maitai-Waipapa地体)的8个剖面和前特提斯洋4个区域(越南-中国、印度、伊朗和意大利)的11个剖面。牙形刺生物地层学与碳同位素和MS事件地层学相结合，将促进研究区域内和研究区域之间的对比。古海洋学模拟将用于研究潜在作用力对二叠纪-三叠纪海洋化学和沉积通量的影响，与全球整合的化学地层学数据集的比较将有助于改进模型模拟。该项目有可能产生关于二叠系-三叠系界线事件的重要新发现，以及关于同期化学海洋学扰动的最近和最终控制的关键见解。对与地球历史上最大规模的大灭绝有关的灾难性气候和环境变化的调查，应该引起地球科学界和受过科学教育的公众的极大兴趣。该项目的广泛影响是多种多样的，包括项目成果的公开宣传和传播、对本科生和研究生的指导、在不同的地球科学专业人员群体中发展研究协同作用，以及产生具有广泛科学意义的成果的潜力。私人投资机构致力于培养下一代科学家(他们共同指导了约60名研究生，所有人都积极参与建议和培训本科生)，推进公立学校的科学教育，并在这些未来的学者中实现更大的种族和性别多样性(Algeo和Ellwood都参与了招收少数族裔学生的计划)。通过NSF资助的项目数据集将通过Chronos和PaleoStrat提供给更大的科学界。

COLLABORATIVE RESEARCH: Chemostratigraphic Analysis of Panthalassic and Tethyan Permian-Triassic Boundary Sections: Assessment of Global Paleoceanographic DynamicsEAR-0745574 Thomas Algeo, University of Cincinnati¡XLeadEAR-0745393 Brooks B. Ellwood, Louisiana State UniversityEAR-0746189 Katherine Freeman, Pennsylvania State UniversityEAR-0745592 Timothy Lyons, University of California, RiversideEAR-0745817 Arne Winguth and Harry Rowe, University of Texas, ArlingtonABSTRACTThe causes and dynamics of the Permian-Triassic boundary (PTB) mass extinction, the largest in Earth history, remain uncertain. Gradual deterioration of marine and terrestrial environments during the Late Permian and persistence of inhospitable conditions through the Early Triassic suggest that intrinsic factors were important, but an extinction rate peak, abrupt lithofacies changes, and geochemical anomalies associated with the end-Permian event horizon are evidence of a catastrophic event (e.g., massive volcanic eruption, bolide impact, and/or large-scale oceanic overturn). Despite long study of the PTB, there are remarkably few integrated, high-resolution chemostratigraphic studies of marine boundary sections that can address critical questions related to the extent and intensity of Permo-Triassic deep-ocean anoxia, patterns of upwelling of toxic deep-ocean waters onto shallow-marine shelves and platforms, the relationship of such events to contemporaneous changes in seawater carbonate saturation and to the delayed recovery of marine biotas, controls on the post-extinction global negative C-isotope shift, and the relative timing and causal relationship of PTB crises in the marine and terrestrial realms. In this project, we propose to generate geochemical proxy datasets consisting of magnetic susceptibility, elemental concentrations, TOC-TIC, ?Ô13Ccarb-?Ô13Corg, S-Fe speciation, ?Ô34Ssulfide-?Ô34Ssulfate, REEs, and biomarkers for a total of 19 sections in eight study areas, including 8 sections in four areas of the former Panthalassic Ocean (the Cache Creek terrane, Western Sedimentary Basin, and Sverdrup Basin of Canada, and the Maitai-Waipapa terranes of New Zealand) and 11 sections in four areas of the former Tethys Ocean (Vietnam-China, India, Iran, and Italy). Conodont biostratigraphy combined with C-isotope and MS event stratigraphy will facilitate correlations within and between study areas. Paleoceanographic modeling will be used to investigate the effects of potential forcings on Permo-Triassic ocean chemistry and sedimentary fluxes, and comparisons with globally integrated chemostratigraphic datasets will allow refinement of model simulations. This project has the potential to yield important new findings regarding events at the Permian-Triassic boundary and key insights regarding proximate and ultimate controls on contemporaneous chemical oceanographic perturbations. Investigation of catastrophic climate and environmental change associated with the largest mass extinction in Earth history should be of considerable interest to both the Earth-science community and the scientifically literate public. The broader impacts of the project are varied and include public outreach and dissemination of project results, mentoring of undergraduate and graduate students, development of research synergies among a diverse group of geoscience professionals, and the potential for results of broad scientific significance. The PIs are committed to training the next generation of scientists (they have collectively supervised ~60 graduate students, and all are actively engaged in advising and training undergraduate students), to advancing science education in the public schools, and to achieving greater ethnic and gender diversity among these future scholars (Algeo and Ellwood are both involved in programs to recruit minority students). Project datasets funded through NSF will be made available to the larger scientific community through CHRONOS and PaleoStrat.