Oxidized micrometeorites suggest either high <i>p</i> CO <sub>2</sub> or low <i>p</i> N <sub>2</sub> during the Neoarchean
R. C. Payne, D. E. Brownlee, James F. Kasting
Abstract
Significance Paleosols (ancient soils) have been used to estimate CO 2 concentrations during the Archean Eon, 4.0 to 2.5 Ga. However, different paleosol studies disagree with each other and with climate model estimates for ancient CO 2 levels. Oxidized iron micrometeorites dated at 2.7 Ga represent a new CO 2 proxy with which to compare. These meteorites suggest that CO 2 constituted 25 to 50% of the atmosphere at that time. This is easiest to explain if the N 2 partial pressure was lower than today so that the atmospheric greenhouse effect was modest and the climate was cool, consistent with evidence for contemporaneous glaciation.
Topics & Concepts
Atmosphere (unit)ChemistryOxygenArcheanBar (unit)MethaneAnalytical Chemistry (journal)Environmental chemistryGeologyThermodynamicsGeochemistryPhysicsOrganic chemistryOceanographyPaleontology and Stratigraphy of FossilsGeochemistry and Elemental AnalysisGeology and Paleoclimatology Research