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.

新元古代地质记录包含极端气候变化的证据，这些变化可能深刻地影响了生物进化的进程，特别是在斯图尔蒂安冰川、马里诺冰川和加斯基尔斯冰川的所谓“雪球地球”时期。在新元古代，尽管基础动物的辐射目前在斯图尔特冰川和马里诺冰川之间的某个时间受到很少的限制，但被解释为来自多细胞动物的身体化石和分子生物标志物已有报道。在本研究中，我们的目标是通过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）以及古氧化还原的无机地球化学代理，为南部南华盆地四个剖面提供新元古代海洋生物地球化学的详细时间记录。中国。这将使我们能够研究低纬度新元古代冰川作用对应用于浅陆架到深盆地古环境横断面的初级生产、碳循环和氧化还原结构的影响。鉴于对华南陡山沱组动物群化石和其他化石的科学兴趣，目前华南新元古代尚无详细的分子生物标志物记录似乎令人惊讶。这无疑是由于某些部分的高热成熟度以及由于在石油衍生污染物的显着背景之上识别低浓度的真正新元古代生物标志物信号的固有问题。范围界定研究表明，南华盆地四个剖面的地层热成熟度对于保存可检测的生物标志碳氢化合物信号来说不存在问题。这里提出的生物标志物脂质工作的原创性和主要优势在于获得干酪根结合的生物标志物记录，这使我们能够获得南华盆地保存的大部分生物标志物记录，基本上不受污染影响。 PI 的研究证明了连续流催化加氢热解 (HyPy) 技术在破碎干酪根和释放共价结合的生物标志物成分方面的功效，从而基本上真实地验证了所获得的所有生物标志物脂质数据。我们将解决有关华南新元古代生物地球化学历史的一些基本问题： -我们能否使用我们的无机和生物标志物代理检测斯图尔蒂安和马里农冰川之后海洋氧化还原结构的显着变化？源生物输入伴随波动的有力证据？ -我们能否从氧化还原曲线和生物群方面辨别浅水与深水环境对冰川作用后的显着不同反应？ -我们能否在南华盆地检测到基础动物（海绵）的特定类固醇标记，如果可以，这些标记何时首次出现与斯图尔蒂安冰川和马里诺冰川有关？更广泛的影响。该研究将通过改变营养循环、溶解氧可用性和在低纬度海洋环境中创造环境利基，显着提高我们对斯图尔蒂安冰川和马里诺冰川强烈气候冲击对海洋微生物群落影响程度的理解。在提供教育机会方面，洛夫和里昂将在每个项目年参加加州大学河滨分校指导暑期研究实习计划，来自历史上在科学领域（特别是地球科学）代表性不足的族裔群体的本科生将获得实践经验在两个实验室里。最后，我们的项目将受益于与中国科学院地质与地球物理研究所储学雷教授及其研究小组的合作，他们在研究华南新元古代冰川地层方面拥有丰富的经验。 Chu和同事将在项目期间访问加州理工学院和加州大学河滨分校的南加州生物地球化学界，讨论研究结果并促进长期合作联系。