期刊
SCIENCE ADVANCES
卷 6, 期 4, 页码 -出版社
AMER ASSOC ADVANCEMENT SCIENCE
DOI: 10.1126/sciadv.aay4644
关键词
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资金
- NASA Pathways Program
- University of Washington Astrobiology Program
- Virtual Planetary Laboratory at the University of Washington
- Simons Collaboration on the Origin of Life grant [51170]
- NASA Exobiology grant [NNX15AL23G]
- NASA Astrobiology Program [80NSSC18K0829]
- NASA [NNX15AL23G, 807041] Funding Source: Federal RePORTER
Earth's atmospheric composition during the Archean eon of 4 to 2.5 billion years ago has few constraints. However, the geochemistry of recently discovered iron-rich micrometeorites from 2.7 billion-year-old limestones could serve as a proxy for ancient gas concentrations. When micrometeorites entered the atmosphere, they melted and preserved a record of atmospheric interaction. We model the motion, evaporation, and kinetic oxidation by CO2 of micrometeorites entering a CO2-rich atmosphere. We consider a CO2-rich rather than an O-2-rich atmosphere, as considered previously, because this better represents likely atmospheric conditions in the anoxic Archean. Our model reproduces the observed oxidation state of micrometeorites at 2.7 Ga for an estimated atmospheric CO2 concentration of >70% by volume. Even if the early atmosphere was thinner than today, the elevated CO2 level indicated by our model result would help resolve how the Late Archean Earth remained warm when the young Sun was similar to 20% fainter.
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