Collaborative Research: Biogeochemistry of Neoproterozoic Snowball Earth and Its Aftermath in South China

合作研究：华南新元古代雪球地球的生物地球化学及其后果

• 批准号: 0720362
• 负责人: Gordon Love
• 金额: $ 25.46万
• 依托单位: University of California-Riverside
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2007
• 资助国家: 美国
• 起止时间: 2007-09-01 至 2010-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0720362&HistoricalAwards=false
• 关键词: Collaborative; Research; Biogeochemistry; Neoproterozoic; Snowball

The Neoproterozoic geological record contains evidence for extreme climatic change which may have profoundly influenced the course of biological evolution, particularly around the so-called Snowball Earth episodes of the Sturtian, Marinoan and Gaskiers glaciations. During the Neoproterozoic, body fossils and molecular biomarkers interpreted as being derived from multicellular animals have been reported although the radiation of basal animals is presently poorly constrained at sometime between the Sturtian and Marinoan glaciations. In this study, we aim to produce detailed temporal records of Neoproterozoic marine biogeochemistry from molecular biomarker analyses, organic and inorganic stable isotope records (including 13C, 2H and 34S) and from inorganic geochemical proxies of paleoredox for four sections in the Nanhua Basin in South China. This will allow us to investigate the effects of low-latitude Neoproterozoic glaciation on primary production, carbon cycling and redox structure applied to a shallow shelf-to-deep basinal paleoenvironmental transect. Given the scientific interest in fossilized animal fauna and other fossils from the Doushantuo Formation in South China, it may seem surprising that no detailed molecular biomarker records currently exist for the Neoproterozic in South China. This is undoubtedly due to the high thermal maturity of some sections and due to the inherent problems of discerning low concentrations of genuine Neoproterozic biomarker signals above a significant background of petroleum-derived contaminants. A scoping study has revealed that the thermal maturity of strata in our four sections in Nanhua Basin is not problematic for preserving detectable biomarker hydrocarbon signals. The originality and principal strength of the biomarker lipid work proposed here lies in obtaining kerogen-bound biomarker records which allow us to access a high proportion of the preserved biomarker record in Nanhua Basin essentially free from contamination effects. The PI's research has demonstrated the efficacy of a continuous flow catalytic hydropyrolysis (HyPy) technique for fragmenting kerogen and releasing covalently-bound biomarker constituents to essentially ground-truth all the biomarker lipid data obtained. We will address some fundamental questions regarding the biogeochemical history of the Neoproterozoic in South China: -Can we detect significant changes in marine redox structure in the immediate aftermath of the Sturtian and Marinon glaciations using our inorganic and biomarker proxies and, if so, is there strong evidence for concomitant fluctuations in source organism input? -Can we discern significantly different responses of shallow- versus deep-water settings to the aftermath of the glaciations in terms of their redox profiles and biota? -Can we detect specific steroid markers for basal animals (sponges) in the Nanhua Basin and, if so, when do these first appear relative to the Sturtian and Marinoan glaciations? Broader Impacts. The research will significantly improve our understanding of the extent to which the intense climatic shock of the Sturtian and Marinoan glaciations impacted on marine microbial communities by modifying nutrient cycling, dissolved oxygen availability and creating environmental niches in low latitude marine environments. In terms of providing educational opportunities, Love and Lyons will participate during each of the project years in the UCR Mentoring Summer Research Internship Program, whereby undergraduate students from ethnic groups historically underrepresented in the sciences (particularly the earth sciences) will receive hands-on experience in the two labs. Finally, our project will benefit greatly from collaboration with Professor Xuelei Chu (Institute of Geology and Geophysics, Chinese Academy of Sciences) and his research group, who have considerable experience of studying Neoproterozoic glacial strata in South China. Chu and colleagues will visit the Southern California biogeochemical community at Caltech and UCR during the course of the project to discuss findings and to promote long-term collaborative links.

新元古代的地质记录包含了极端气候变化的证据，这可能深刻影响了生物学进化的过程，尤其是在斯特拉特人，玛丽奴和加斯克斯冰川的所谓滚雪球事件周围。在新元古代，身体化石和分子生物标志物中，被解释为源自多细胞动物的分子生物标志物，尽管目前在Sturtian和Marinoan Glaciations之间的某个时候，基底动物的辐射在某个时候受到了限制。在这项研究中，我们的目标是从分子生物标志物分析，有机和无机稳定同位素记录（包括13c，2h和34s）以及来自Nanhua基础四个部分的Pealeoredox的无机地球化学代理中，从分子生物标志物分析，有机和无机稳定同位素记录（包括13c，2h和34s）中产生新元古代海洋生物地球化学的详细时间记录。这将使我们能够研究低纬度新元古代冰川对初级生产，碳循环和氧化还原结构的影响，该结构应用于浅层架头至深层的盆地古环境样带。鉴于中国南部杜斯汉图（Doushantuo）形成的化石动物动物动物和其他化石的科学兴趣，似乎令人惊讶的是，目前在中国南部没有详细的分子生物标志物记录。毫无疑问，这是由于某些部分的较高热成熟度，并且是由于辨别低浓度的真正的Neopererozic生物标志物信号的固有问题，高于石油衍生的污染物的重要背景。一项范围的研究表明，在我们在Nanhua盆地的四个部分中地层的热成熟度对于保留可检测的生物标志物烃信号并不是问题。此处提出的生物标志物脂质工作的独创性和主要强度在于获得结合动物体体结合的生物标志物记录，这使我们能够访问Nanhua盆地中保存的生物标志物记录的很大比例，这基本上没有污染效应。 PI的研究表明，连续流动催化水置（Hypy）技术对破裂的动构和释放共价结合的生物标志物成分对所有生物标志物脂质数据基本上实现。 We will address some fundamental questions regarding the biogeochemical history of the Neoproterozoic in South China: -Can we detect significant changes in marine redox structure in the immediate aftermath of the Sturtian and Marinon glaciations using our inorganic and biomarker proxies and, if so, is there strong evidence for concomitant fluctuations in source organism input? - 我们可以从氧化还原的概况和生物群中辨别浅水与深水环境的显着不同的反应？ - 我们可以检测到南部盆地中基底动物（海绵）的特定类固醇标记吗？更广泛的影响。这项研究将显着提高我们对斯特尔烷和大麻冰川的严重气候冲击的程度，从而通过修改营养循环，溶解的氧气可用性并在低纬度海洋环境中创造环境壁ni，从而影响了海洋微生物群落。在提供教育机会的方面，爱情和里昂人将在每个项目的年度参与UCR指导夏季研究实习计划，从而从历史上看不足的科学（尤其是地球科学）的本科生将在两个实验室中获得亲身体验。最后，我们的项目将从与Xuelei Chu教授（中国科学院地质与地球物理学研究所）及其研究小组合作中受益匪浅，他们在中国南部拥有研究新元古代冰古代地层的经验丰富。在项目过程中，Chu及其同事将访问Caltech和UCR的南加州生物地球化学社区，以讨论发现并促进长期合作联系。