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：动物生命初期的海洋氧化还原演化：华南埃迪卡拉纪扬子地台综合地质与地球化学研究

• 批准号: 0745605
• 负责人: Timothy Lyons
• 金额: $ 9.8万
• 依托单位: University of California-Riverside
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2008
• 资助国家: 美国
• 起止时间: 2008-08-01 至 2012-06-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0745605&HistoricalAwards=false
• 关键词: Collaborative; Research; Ocean; Redox; Evolution

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.

EAR 0745825合作研究：动物生命黎明时的海洋氧化还原演化：华南埃迪卡拉纪扬子地台的综合地质和地球化学研究摘要最近的研究表明，埃迪卡拉纪（约 635 Ma 至 542 Ma）期间的主要氧化事件引发了第一次氧化还原事件。地球上最早的动物生命的出现和进化，但对所提出的联系的严格评估由于缺乏关于埃迪卡拉海洋的空间和时间氧化还原变化以及埃迪卡拉生物对这种氧化还原变化的反应的详细记录。对埃迪卡拉纪扬子地台进行综合地质、地球化学和古生物学研究，旨在提高我们对罕见保存的含化石沉积档案中海洋氧化还原变化、地球化学异常和早期动物进化之间相互作用的理解。拟议的研究旨在检验以下假设：（1）深海直到大约 10 年前一直处于缺氧/缺氧状态。第551章（2）大型海洋溶解有机碳（DOC）储层的间歇性氧化导致地球化学异常的形成，包括异常负碳同位素偏移； (3)埃迪卡拉生物的时空分布与海洋氧化还原条件有关。研究的目标是确定：（1）整个盆地的碳酸盐和有机碳同位素变异性，以测试潜在的地表到深海碳同位素梯度，该梯度可能比现代海洋大得多； (2) 硫同位素的时空变异性，以测试整个流域硫酸盐还原和硫歧化的持续性和/或波动； (3) 钼 (Mo) 浓度和 Mo 同位素、铁 (Fe) 形态和 Fe 同位素的时空变化，以确定与稳定同位素偏移相关的长期氧化还原演化和潜在氧化还原波动； (4) 埃迪卡拉化石的时空分布及其与地球化学边界/异常的关系。该研究的最终目标是整合古生物学和地球化学数据，以测试氧化还原条件与埃迪卡拉生物的时空模式之间的耦合。预期数据将为我们了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大学拉斯维加斯分校、弗吉尼亚理工学院、加州大学河滨分校和亚利桑那州的四名博士生州立大学。该项目在四个不同机构的研究人员之间开展了新的合作，并为不同研究重点的学生之间的互动提供了广泛的培训机会。研究成果将与四个机构教授的课程相结合，并将加强本科生对四个机构研究项目的参与。该项目还将促进与中国和加拿大机构科学家的国际合作。