Two-way feedback between biology and deep Earth processes: AGU2012 P14A-07
Research output: Contribution to conference › Conference abstract for conference › Research
The presence of the metamorphic products of banded iron formation and black shale indicate that the Earth teemed with life by the time of the earliest preserved rocks, ca. 3.85 Ga. Iron and sulfur-based anoxygenic photosynthesis with full carbon cycles was present by this time. The pH of the ocean was ~8. The lack of older rock record cloaks pre-biotic evolution and the origin of life. Nascent and early life obtained energy from chemical disequilibria in rocks rather than sunlight. Appraising putative rock pre-biological environments is difficult in that life has modified the composition of the atmosphere, the hydrosphere, and sedimentary rocks. It has greatly affected the composition of crystalline crustal rocks and measurably modified the mantle. Conversely, hard crustal rocks and the mantle likely sequester a very ancient record of last resort. Theory provides additional insight. The Earth’s surface and interior cooled following the moon-forming impact. The oceans passed through conditions favored by thermophile organisms before becoming clement. Ocean pH was ~6 and bars of CO2 existed in the atmosphere. Subduction removed the CO2 into the mantle before the time of rock record. Serpentinite likely existed in land, tidal, and marine environments as it does today. Seafloor spreading and arc volcanism likely drove hydrothermal circulation. The late heavy bombardment occurred after ca. 4.1 Ga; low heat flow environments and hence habitable subsurface refugia existed. It is conceivable that one or a few ocean-boiling impacts left thermophile survivors in their wake. Overall, the molecular biology of extant life likely conserves features that relate to its earliest abodes.
Original language | English |
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Publication date | 2012 |
Number of pages | 1 |
Publication status | Published - 2012 |
Event | American Geophysical Union Fall Meeting - San Francisco, United States Duration: 3 Dec 2012 → 7 Dec 2012 |
Conference
Conference | American Geophysical Union Fall Meeting |
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Country | United States |
City | San Francisco |
Period | 03/12/2012 → 07/12/2012 |
- Faculty of Science - biogeochemical cycles, processes, and modeling, geochemical cycles, origin of life, early environment of Earth
Research areas
ID: 101697950