Collaborative Research: Ocean Redox Evolution at the Dawn of Animal Life: An Integrated Geological and Geochemical Study of the Ediacaran Yangtze Platform in South China

合作研究：动物生命开始时的海洋氧化还原演化：华南埃迪卡拉纪扬子地台地质和地球化学综合研究摘要最近的研究表明，埃迪卡拉纪（约2000年）期间的主要氧化事件。635 Ma到542 Ma）引发了地球的第一次出现和演化？的最早的动物生活，但关键的评价所提出的联系是有限的，缺乏一个详细的文件的空间和时间的氧化还原变化的埃迪卡拉海洋和埃迪卡拉生物的反应，这种氧化还原变化。埃迪卡拉纪扬子地台的综合地质，地球化学和古生物学研究旨在提高我们对海洋氧化还原变化，地球化学异常和早期动物进化之间的相互作用的理解，在一个很少保存，丰富的沉积档案。本研究的目的是验证以下假设：（1）深海是缺氧/富氧的，直到约。551 Ma;（2）大洋溶解有机碳（DOC）储层的幕式氧化导致了地球化学异常的形成，包括异常的负碳同位素偏移;（3）埃迪卡拉纪生物的时空分布与海洋氧化还原条件相耦合。研究的目的是确定：（1）整个海盆的碳酸盐和有机碳同位素变化，以测试可能比现代海洋大得多的潜在的表层到深层海洋碳同位素梯度;（2）空间和时间的硫同位素变化，以测试整个海盆硫酸盐还原和硫还原的持续性和/或波动;（3）钼（Mo）浓度和钼同位素、铁（Fe）形态和铁同位素的时空变化，以确定长期氧化还原演化和与稳定同位素漂移相关的潜在氧化还原波动;（4）埃迪卡拉纪化石的时空产状及其与地球化学边界/异常的关系。研究的最终目标是整合古生物学和地球化学数据，以测试埃迪卡拉纪生物的氧化还原条件和空间/时间模式之间的耦合。预期的数据将为我们理解与地球历史上重大生物创新相关的环境力量提供重要信息。该项目将部分支持来自内华达州拉斯维加斯大学、弗吉尼亚理工学院、加州大学滨江分校和亚利桑那州州立大学的四名博士生。该项目开发了四个不同机构的研究人员之间的新合作，并为具有不同研究重点的学生之间的互动提供了广泛的培训机会。研究成果将与四所院校的课程相结合，并将提高四所院校本科生对研究项目的参与。该项目还将促进与中国和加拿大机构科学家的国际合作。

EAR 0745825COLLABORATIVE RESEARCH: Ocean Redox Evolution at the Dawn of Animal Life: An Integrated Geological and Geochemical Study of the Ediacaran Yangtze Platform in South ChinaABSTRACTRecent studies suggested that major oxidation events during the Ediacaran Period (ca. 635 Ma to 542 Ma) triggered the first appearance and evolution of the Earth?s earliest animal life, but critical evaluation of the proposed linkages is limited by the lack of a detailed documentation on spatial and temporal redox changes of Ediacaran oceans and the responses of Ediacaran organisms to such redox changes. An integrated geological, geochemical, and paleobiological study of the Ediacaran Yangtze platform is aimed at improving our understanding of the interplay between ocean redox changes, geochemical anomalies, and early animal evolution in a rarely preserved, fossiliferous sedimentary archive. The proposed research is designed to test the following hypotheses: (1) the deep ocean was anoxic/euxinic until ca. 551 Ma; (2) episodic oxidation of a large oceanic dissolved organic carbon (DOC) reservoir led to the formation of geochemical anomalies including unusually negative carbon isotope excursions; and (3) the spatial and temporal distribution of Ediacaran organisms was coupled with ocean redox conditions. Objectives of the research are to determine: (1) carbonate and organic carbon isotope variability across the basin to test a potential surface-to-deep ocean carbon isotope gradient that may have been much greater than in the modern ocean; (2) spatial and temporal sulfur isotope variability to test the persistence and/or fluctuation of sulfate reduction and sulfur disproportionation across the basin; (3) spatial and temporal changes of molybdenum (Mo) concentrations and Mo isotopes, iron (Fe) speciation and Fe isotopes to determine the secular redox evolution and potential redox fluctuation associated with stable isotope excursions; and (4) spatial and temporal occurrences of Ediacaran fossils and their relationships with geochemical boundaries/anomalies. The ultimate goal of the research is to integrate paleontological and geochemical data to test the coupling between redox conditions and spatial/temporal patterns of Ediacaran organisms. Anticipated data would provide important information for our understanding of the environmental forces related to a significant biological innovation in Earth history.The project will partially support four PhD students from University of Nevada Las Vegas, Virginia Polytechnic Institute, University of California at Riverside, and Arizona State University. The project develops new collaborations between researchers at four different institutions and provides a broad training opportunity for interactions among students with different research foci. Research results will be integrated with courses taught at four institutions and will enhance undergraduate involvement in the research project at four institutions. The project will also promote international collaborations with scientists from institutions in China and Canada.