Rethinking the Paleoproterozoic Great Oxidation Event: A Biological Perspective

摘要: Competing geophysical/geochemical hypotheses for how Earth's surface became oxygenated - organic carbon burial, hydrogen escape to space, and changes in the redox state of volcanic gases are examined a more biologically-based hypothesis is offered response. It argued that burial minor importance accumulation oxygen mainly anoxic world where aerobic respiration not globally significant. Thus, Great Oxidation Event (GOE) ~ 2.4 Gyr ago, an increasing flux O2 due its production by expanding population cyanobacteria parameterized as primary source O2. Various factors would have constrained cyanobacterial proliferation during most Archean therefore long delay between appearance oxygenation atmosphere be expected. Destruction via CH4 oxidation was major sink Archean, GOE explained significant extent large decline methanogen corresponding which, turn, caused primarily partial ocean. The partially these waters also made it possible methanotroph become established. This further contributed reduction consumption diffusing upwards from deeper depths water column well any still being produced upper layer. lowered at about same time metamorphic gas sinks declined. As increased triggered burst continent formation 2.7-2.4 ago flipped permanently oxygenated.