期刊
EARTH AND PLANETARY SCIENCE LETTERS
卷 369, 期 -, 页码 284-293出版社
ELSEVIER
DOI: 10.1016/j.epsl.2013.03.031
关键词
Precambrian; rise of atmospheric oxygen; ocean; atmosphere; uranium in the ocean
资金
- NSERC
- NSF-EAR [EAR-0720362]
- NASA
- Astrobiology Institute
- Agouron Institute
- Russian Foundation for Basic Research
- AAPG
- NSF-EAR-PDF
- 973 Program
- Moe grant of China
- Directorate For Geosciences [0951998] Funding Source: National Science Foundation
- Directorate For Geosciences
- Division Of Earth Sciences [1144317] Funding Source: National Science Foundation
- Division Of Earth Sciences [0951998] Funding Source: National Science Foundation
The atmosphere-ocean system experienced a progressive change from anoxic to more oxidizing conditions through time. This oxidation is traditionally envisaged to have occurred as two stepwise increases in atmospheric oxygen at the beginning and end of the Proterozoic Eon. Here, we present a study of the redox-sensitive element, uranium, in organic-rich shales to track the history of Earth's surface oxidation at an unprecedented temporal resolution. Fluctuations in the degree of uranium enrichment in organic-rich shales suggest that the initial rise of atmospheric oxygen similar to 2.4 billion yr ago was followed by a decline to less oxidizing conditions during the mid-Proterozoic. This redox state persisted for almost 1 billion yr, ending with a second oxygenation event in the latest Neoproterozoic. The U record tracks major fluctuations in surface oxygen level and challenges conventional models that suggest the Earth underwent a unidirectional rise in atmospheric oxygen during the Precambrian. (C) 2013 Elsevier B.V. All rights reserved.
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