Collaborative Research: Environmental and Biogeochemical Reorganization during the Rise of Atmospheric Oxygen

合作研究：大气氧气上升过程中的环境和生物地球化学重组

• 批准号: 0820807
• 负责人: Nicolas Dauphas
• 金额: $ 3.5万
• 依托单位: University of Chicago
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2009
• 资助国家: 美国
• 起止时间: 2009-10-01 至 2010-09-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0820807&HistoricalAwards=false
• 关键词: Collaborative; Research; Environmental; Biogeochemical; Reorganization

The establishment of an oxygenated atmosphere 2.4 billion years ago was heralded by a progression of environmental changes over the next 400 million years that permanently transformed global biogeochemical cycling. Newly obtained drillcore from Fennoscandia provides an unparalleled opportunity to establish a more continuous chronology of events through this interval. A team of investigators with expertise in isotopic and geochemical analysis and numerical modeling will produce a suite of environmental proxies of oceanic and atmospheric composition through the cored interval and interpret them quantitatively through numerical modeling in the context of a set of hypotheses concerning the pace of atmospheric oxygenation and the establishment of a strongly redox-stratified global ocean.The intellectual merit of this proposal centers on the importance of reconstructing the sequence of global environmental change during this critical interval of Earth history. Widespread, perhaps even equatorial glaciation occurred as the deposition of banded iron formations, so characteristic of the Archean, ceased. A protracted interval of 13C enrichment in marine carbonates ensued, the first of its kind and the largest and longest in Earth history, without the expected evidence for abundant organic matter deposition.Paradoxically, as carbon isotopic compositions returned to normal, tremendous quantities of organic matter and marine phosphorites were deposited. Various proxies indicate that oxidative weathering only became important toward the end of this interval of progressive biospheric change. Drill core from South Africa, complemented by field studies there and in Canada, the United States, Western Australia and Fennoscandia, have documented these events but the records are incomplete. Fennoscandian drillcore presents the best opportunity yet to fill these gaps, address the perplexing paradoxes of this time interval, and, with the establishment of a precise chronology based on Re-Os, assess the tempo of redox evolution of the atmosphere and ocean.While there is general public interest in and curiosity about the subsurface, most people have little appreciation for the complexity of subsurface geologic structures and have no idea how geologists use the subsurface as an archive of the history of Earth. To improve this situation while addressing the broader impacts goals of the project, the investigators, together with their students, and museum and professional outreach staff will construct an interactive museum exhibit. The visitor will be able to extract lengths of rock core from a complex geologic structure displayed in three dimensions, and from these cores, reconstruct the geologic history of the area. Understanding will be aided by 3-D displays on the Penn State GeoWall, together with synthetic seismographs generated by the visitor at the push of a button. Additional broader impacts of this project include strengthening industry interests in the area of Re-Os systematics of organic-rich sedimentary rocks, and the involvement of a team of students and researchers in a truly international, interdisciplinary, multi-investigator project. Undergraduate research assistants will be drawn from diverse pools of applicants to our institutions? minority outreach program, e.g., the Big Ten Conference?s Summer Research Opportunities Program.

在接下来的4亿年中，环境变化的发展促进了24亿年前的氧化气氛，从而永久性地改变了全球生物地球化学循环。从Fennoscandia新获得的钻孔提供了无与伦比的机会，可以通过此间隔建立更连续的事件年代。一组具有同位素和地球化学分析和数值建模方面专业知识的研究人员团队将通过核心间隔产生一系列海洋和大气组成的环境代理，并通过数值建模在数值建模中以一组关于大气速度的假设进行数值模型来解释。氧合和建立强烈氧化还原分层的全球海洋。该提案的智力优点集中在地球历史的这一关键间隔内重建全球环境变化序列的重要性。广泛的，甚至可能是赤道冰川的，是因为带状的铁地层的沉积，即天古主义者的特征，停止了。随之而来的是海洋碳酸盐中13C富集的持久间隔，这是同类的第一个，也是地球历史上最大，最长的，没有预期的有机物质沉积的证据。并沉积了海洋磷酸盐。各种代理表明，氧化性风化仅在此进行性生物圈变化时间间隔的结束时才变得很重要。来自南非的钻芯，并在加拿大，美国，西澳大利亚州和芬诺斯坎迪亚的现场研究中得到了补充，已记录了这些事件，但记录并不完整。 Fennoscandian DrillCore提供了填补这些空白，解决此时间间隔的困惑悖论的最佳机会，并通过建立基于RE-OS的精确年表，评估大气和海洋的氧化还原演化的速度。对地下的一般公众兴趣和好奇心，大多数人对地下地质结构的复杂性几乎不明显，也不知道地质学家如何将地下用作地球历史的档案。为了改善这种情况，同时解决了该项目的更广泛影响，调查人员以及他们的学生以及博物馆和专业外展工作人员将建造一个互动的博物馆展览。访客将能够从三维中显示的复杂地质结构中提取岩石芯的长度，并从这些核心中重建该地区的地质历史。宾夕法尼亚州Geowall上的3D显示器将有助于理解，以及访客按按钮时访客生成的合成地震仪。该项目的其他更广泛的影响包括在有机丰富的沉积岩石系统中加强行业利益，以及一组学生和研究人员参与真正的国际跨学科，多元研究员项目。本科生的研究助理将从我们机构的各种申请人池中吸引？少数民族外展计划，例如十大会议的夏季研究机会计划。