Evaluating Atmospheric Oxygen Levels During the Great Oxidation Event

评估大氧化事件期间的大气氧气水平

• 批准号: 1349258
• 负责人: Lee Kump
• 金额: $ 22.82万
• 依托单位: Pennsylvania State Univ University Park
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2014
• 资助国家: 美国
• 起止时间: 2014-03-01 至 2017-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1349258&HistoricalAwards=false
• 关键词: Evaluating; Atmospheric; Oxygen; Levels; During

The establishment of an oxygen-rich atmosphere had a profound influence on the course of biological evolution, paving the way for the advent of eukaryotic cells and ultimately enabling the evolution of large animals, including humans. These conditions did not always exist: a substantial body of geologic evidence indicates that the atmosphere and oceans were free of oxygen during early part of Earth's history, prior to 2.4 billion years ago, but the subsequent history of the oxygenation is poorly resolved.This study addresses a key interval just after the first appearance of oxygen, from about 2.2 to 2.0 billion years ago, a time when tantalizing geologic evidence suggests that oxygen levels may have risen to levels that even exceeded modern levels before falling to lower levels that persisted for another billion and a half years before rising again to levels high enough to support the evolution of animals. Cores recently drilled in Fennoscandian rocks (with NSF funding) display features that appear to reflect extreme oxidation by groundwaters that permeated an ancient volcanic landscape. These cores will be scrutinized using a variety of microscopic and geochemical techniques to test the hypothesis that they were exposed to highly oxygen charged waters, themselves the consequence of an "overshoot" of atmospheric oxygen during the Great Oxidation Event.Participating in this project will be a Ph.D. student, an undergraduate working on a senior thesis, and a summer research intern participating in our ongoing program promoting earth sciences research to undergraduates from minority-serving institutions. This collaborative group will partner with their colleagues at the University of Wisconsin and in Europe in their exploration of the FAR-DEEP cores and the nature of environmental change in Earth's distant past.

富氧大气的建立对生物进化进程产生了深远的影响，为真核细胞的出现铺平了道路，并最终使包括人类在内的大型动物得以进化。这些条件并不总是存在的：大量的地质证据表明，在地球历史的早期，即24亿年前，大气和海洋是无氧的，但后来的氧合历史却没有得到很好的解决。这项研究解决了氧气首次出现后的一个关键时期，即大约22亿到20亿年前，在这个时期，诱人的地质证据表明，氧气含量可能已经上升到甚至超过现代水平的水平，然后下降到更低的水平，这种水平持续了15亿年，然后再次上升到足以支持动物进化的水平。最近在芬诺斯坎迪亚岩石中钻探的岩心（由美国国家科学基金会资助）显示出一些特征，这些特征似乎反映了渗透到古代火山景观中的地下水的极端氧化。这些岩心将通过各种显微镜和地球化学技术进行仔细检查，以验证它们暴露于高氧水的假设，而高氧水本身就是大氧化事件期间大气氧气“过量”的结果。参与该项目的将是一名博士生、一名正在撰写高级论文的本科生，以及一名参加我们正在进行的促进少数民族院校本科生地球科学研究项目的暑期研究实习生。这个合作小组将与他们在威斯康辛大学和欧洲的同事合作，共同探索远深地核和地球遥远过去环境变化的本质。