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

24亿年前，一个含氧大气层的建立，预示着在接下来的4亿年里，环境变化的进展，永久地改变了全球地球化学循环。从芬诺斯坎迪亚新获得的岩心提供了一个无与伦比的机会，建立一个更连续的事件年表，通过这个间隔。一个具有同位素和地球化学分析以及数值模拟专业知识的调查人员团队将通过取芯层段产生一套海洋和大气成分的环境代用指标，并在一组关于大气氧化速度和建立强氧化还原-还原反应的假设的背景下，通过数值模拟对其进行定量解释。这一建议的智力价值集中在重建地球历史这一关键时期全球环境变化序列的重要性上。当太古代特有的带状铁地层沉积停止时，大范围的，甚至可能是赤道的冰川作用发生了。在没有预期的大量有机质沉积证据的情况下，海相碳酸盐岩中13 C的长期富集是地球历史上第一次，也是规模最大、时间最长的，但奇怪的是，随着碳同位素组成恢复正常，大量有机质和海相磷块岩沉积下来。各种代用指标表明，氧化风化作用只是在生物圈逐渐变化的这段时间结束时才变得重要。来自南非的钻探岩心，加上在那里以及加拿大、美国、西澳大利亚和芬诺斯坎迪亚的实地研究，记录了这些事件，但记录不完整。芬诺斯堪的纳维亚的钻探岩心提供了填补这些空白的最佳机会，解决了这一时间间隔令人困惑的矛盾，并建立了基于Re-Os的精确年表，评估了大气和海洋的氧化还原演化克里思。大多数人对地下地质结构的复杂性知之甚少，也不知道地质学家如何利用地下地质作为地球历史的档案。为了改善这种情况，同时解决该项目的更广泛的影响目标，调查人员，连同他们的学生，博物馆和专业的外展工作人员将建立一个互动的博物馆展览。参观者将能够从三维显示的复杂地质结构中提取一定长度的岩芯，并从这些岩芯中重建该地区的地质历史。宾夕法尼亚州立大学地质墙上的3D显示器以及游客按下按钮产生的合成地震仪将有助于理解。该项目的其他更广泛的影响包括加强行业对富含有机物的沉积岩的Re-Os系统学领域的兴趣，以及一个真正的国际，跨学科，多研究者项目的学生和研究人员团队的参与。本科生研究助理将从不同的申请人中选拔到我们的机构？少数民族外联方案，例如，十大会议？暑期研究机会计划。

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.