COLLABORATIVE RESEARCH: Presaging Paleoproterozoic Global Chnage: Geobiology of the Late Archean Eon

合作研究：预示古元古代全球变化：太古代晚期的地球生物学

• 批准号: 0417716
• 负责人: Andrew Knoll
• 金额: $ 5万
• 依托单位: Harvard University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2004
• 资助国家: 美国
• 起止时间: 2004-09-01 至 2006-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0417716&HistoricalAwards=false
• 关键词: COLLABORATIVE; RESEARCH; Presaging; Paleoproterozoic; Global

Project will integrate geological, paleobiological and geochemical examination of a freshly-collected Archean sediment drill-core that will be obtained in the summer of 2004. This continuous core, ~ 1000 m in length, will sample the last ~ 250 million years of Archean stratigraphy in the Hamersley Basin of the Pilbara Craton, Western Australia. Sampled lithologies will include basalt, carbonate, chert and several kerogenous pyritic shale units.This proposal is possible because of an unprecedented opportunity for collaboration with the Astrobiology Drilling Program (ADP) of the NASA Astrobiology Institute. The ADP will fund acquisition of this core. The NSF funds will be used for initial characterization of core materials to include a detailed study of paleoecology and paleoenvironment in kerogenous sediments. Importantly, core recovery will be over-seen by PI Buick and is geared specifically toward the proposed research.Intellectual Merit: The general motivation of the proposed research is to characterize the nature of life and its environment in the late Archean, shortly before the rise of atmospheric oxygen. Many workers are examining the timing of this redox transition and its relationship to contemporaneous climatic oscillations that may include global ice ages. The team's interest, somewhat different but complementary, is to understand how the Archean biosphere set the stage for this singular environmental transformation. Specifically, a major goal of this project is to characterize the relative importance of different types of microbes in late Archean marine environments and, through lithofacies relationships, to study the envi-ronmental controls on their distributions. This goal will be achieved through integrated examination of hydrocarbon molecular biomarkers, redox indicators and biogeochemical cycling in kerogenous sediments.Clean drilling methods, immediate sampling and prompt analysis will allow us to unambiguously deter-mine if taxonomically diagnostic sterane and triterpenoid hydrocarbons are indigenous to these rocks. These compounds are abundant in existing, poorly-preserved Hamersley Basin drill core and, if not contaminants, constitute the earliest biomarkers of eukaryotes and cyanobacteria. Further, analysis of the new core should permit us to examine the relative abundances and isotopic compositions of such compounds in an environmental context, yielding information about ecological relationships. Additional goals are to characterize the status of major biogeochemical cycles in the late Archean and generate a robust baseline for future investigations by conducting sedimentological and biogeochemical reconnaissance of the entire core. Collectively, this work will test the hypothesis that oxygen-generating cyanobacteria and aerobic microorganisms were present in Archean ecosystems and that the environmental imprints of these me-tabolisms remained muted for hundreds of millions of years after their origins.Broader Impact: There are three areas of broader impact. First, ~ 6 graduate students will participate in an unusually integrative and multi-disciplinary research project spanning six major research universities. While each will be rooted in a single aspect of the program, these students will have substantive opportunities to bridge across subdisciplines and institutions. Second, because the planned drill core will ultimately be openly available in accordance with the ADP charter, this work will provide a lithological and chemostratigraphic framework of benefit to the wider research community. Third, it is hoped that this NSF-NASA collaboration will provide a positive precedent for future efforts by other investigators that might ultimately evolve into a broader inter-agency "Deep Time Drilling Program".

该项目将对将于 2004 年夏季获得的新收集的太古代沉积物钻芯进行地质、古生物学和地球化学检查。这个长约 1000 m 的连续岩心将对西澳大利亚皮尔巴拉克拉通哈默斯利盆地过去约 2.5 亿年的太古代地层进行采样。取样的岩性将包括玄武岩、碳酸盐、燧石和几个干酪质黄铁矿页岩单元。由于与 NASA 天体生物学研究所的天体生物学钻探计划 (ADP) 合作的前所未有的机会，该提案得以实现。 ADP 将资助收购该核心。美国国家科学基金会的资金将用于对岩心材料进行初步表征，包括对干酪质沉积物中古生态和古环境的详细研究。重要的是，核心回收将由 PI 别克监督，并专门针对拟议的研究。 智力优点：拟议研究的总体动机是描述太古代晚期（大气中氧气上升之前不久）的生命本质及其环境。许多工作人员正在研究这种氧化还原转变的时间及其与同期气候振荡（可能包括全球冰河时代）的关系。该团队的兴趣有些不同但互补，是了解太古宙生物圈如何为这种奇异的环境转变奠定基础。具体来说，该项目的一个主要目标是表征晚太古代海洋环境中不同类型微生物的相对重要性，并通过岩相关系研究环境对其分布的控制。这一目标将通过对干酪质沉积物中碳氢化合物分子生物标志物、氧化还原指标和生物地球化学循环的综合检查来实现。清洁钻探方法、即时采样和及时分析将使我们能够明确地确定分类学上诊断的甾烷和三萜类碳氢化合物是否是这些岩石的固有成分。这些化合物在现有的、保存不良的哈默斯利盆地钻芯中含量丰富，即使不是污染物，也构成了真核生物和蓝细菌最早的生物标志物。此外，对新核心的分析应该允许我们检查环境背景下此类化合物的相对丰度和同位素组成，从而产生有关生态关系的信息。其他目标是描述太古代晚期主要生物地球化学循环的状态，并通过对整个岩心进行沉积学和生物地球化学勘察，为未来的研究提供可靠的基线。总的来说，这项工作将检验以下假设：太古宙生态系统中存在产氧蓝藻和需氧微生物，并且这些代谢的环境印记在其起源后数亿年中仍然保持沉默。 更广泛的影响：有三个领域具有更广泛的影响。首先，约 6 名研究生将参与一项横跨六所主要研究型大学的异常综合性、多学科的研究项目。虽然每个人都将扎根于该计划的一个方面，但这些学生将有大量机会跨越子学科和机构。其次，由于计划中的钻探岩心最终将根据 ADP 章程公开提供，因此这项工作将为更广泛的研究界提供有益的岩性和化学地层学框架。第三，希望 NSF-NASA 的合作将为其他研究人员未来的努力提供一个积极的先例，这些研究可能最终发展成为更广泛的机构间“深时钻探计划”。