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

合作研究：泛古纪和特提斯二叠纪-三叠纪边界剖面的化学地层学分析：全球古海洋动力学评估EAR-0745574 Thomas Algeo，辛辛那提大学 XLeadEAR-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大学EAR-0745592 Timothy Lyons，加州大学河滨分校EAR-0745817 Arne Winguth 和 Harry Rowe，德克萨斯大学阿灵顿分校摘要地球历史上最大规模的二叠纪-三叠纪边界 (PTB) 大规模灭绝的原因和动态仍然不确定。 二叠纪晚期海洋和陆地环境的逐渐恶化以及三叠纪早期不适宜生存的条件持续存在表明内在因素很重要，但灭绝率峰值、突然的岩相变化以及与二叠纪末事件视界相关的地球化学异常是灾难性事件的证据（例如大规模火山喷发、火流星撞击和/或大规模海洋翻转）。 尽管对PTB进行了长期研究，但对海洋边界部分的综合、高分辨率化学地层研究却很少，这些研究可以解决与二叠纪-三叠纪深海缺氧的范围和强度、有毒深海海水上涌至浅海陆架和平台的模式、此类事件与海水碳酸盐饱和度同期变化和海洋生物群延迟恢复的关系、对灭绝后全球负面影响的控制等关键问题。 C 同位素变化，以及海洋和陆地领域 PTB 危机的相对时间和因果关系。 在本项目中，我们建议生成地球化学代理数据集，包括磁化率、元素浓度、TOC-TIC、?Ô13Ccarb-?Ô13Corg、S-Fe 形态、?Ô34Ssulfide-?Ô34Ssulfate、REE 和生物标记，涉及 8 个研究区域的总共 19 个剖面，其中包括前泛海洋 (Cache Creek) 四个区域的 8 个剖面。地体、加拿大西部沉积盆地和斯维德鲁普盆地、新西兰麦泰-怀帕帕地体）以及原特提斯洋四个区域（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 C 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相关性。 古海洋学模型将用于研究潜在强迫对二叠纪-三叠纪海洋化学和沉积通量的影响，并且与全球综合化学地层数据集进行比较将允许完善模型模拟。 该项目有可能产生有关二叠纪-三叠纪边界事件的重要新发现，以及有关同期化学海洋扰动的直接和最终控制的关键见解。 对与地球历史上最大规模的物种灭绝相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具有科学素养的公众的极大兴趣。 该项目的更广泛影响是多种多样的，包括项目成果的公共宣传和传播、本科生和研究生的指导、不同地球科学专业人士群体之间研究协同作用的发展，以及具有广泛科学意义的成果的潜力。 PI 致力于培养下一代科学家（他们总共指导了约 60 名研究生，所有人都积极参与指导和培训本科生），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项目）。 由 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.