HR: 1400h
AN: B13B-09    [Abstracts]
TI: Possible Biofilms in Earth's Oldest Known Tidal Environment (> 3.7 Ga Isua Greenstone Belt, Greenland)
AU: * Noffke, N
EM: nnoffke@odu.edu
AF: Old Dominion University, Dept. of Ocean, Earth & Atmospheric Sciences, 4600 Elkhorn Avenue, Norfolk, VA 23529, United States
AU: Schiffbauer, J D
EM: jdschiff@vt.edu
AF: Virginia Tech, Department of Geosciences, Blacksburg, VA 24061, United States
AU: Hazen, R M
EM: rhazen@ciw.edu
AF: Carnegie Institution, Geophysical Laboratory, 5251 Broad Branch Road NW, Washington, DC 20015, United States
AU: Armstrong, J T
EM: jarmstrong@ciw.edu
AF: Carnegie Institution, Geophysical Laboratory, 5251 Broad Branch Road NW, Washington, DC 20015, United States
AU: Bower, D M
EM: dbower@ciw.edu
AF: Carnegie Institution, Geophysical Laboratory, 5251 Broad Branch Road NW, Washington, DC 20015, United States
AU: Simpson, C
EM: csimpson@odu.edu
AF: Old Dominion University, Dept. of Ocean, Earth & Atmospheric Sciences, 4600 Elkhorn Avenue, Norfolk, VA 23529, United States
AU: Swift, D J
EM: dswift@odu.edu
AF: Old Dominion University, Dept. of Ocean, Earth & Atmospheric Sciences, 4600 Elkhorn Avenue, Norfolk, VA 23529, United States
AB: Earth's earliest biosphere is known from carbon and sulfur isotopes in rocks of Eoarchean (3.85 to 3.6 Ga) ages. However, fossils or biogenic structures of this antiquity have not been found. We have identified a preserved sandy tidal flat from the > 3.7 Ga Isua Greenstone Belt (IGB), Greenland, in which quartzite and metapelite rocks define original tidal sedimentary beds. On several bedding planes, flat clasts are preserved that in geometry and dimension strikingly resemble pieces of biofilm ripped off from their parent benthic community. Such biofilms are common in similar shallow-marine environments that have been described in siliciclastic deposits of early Archean to Recent ages., The preserved clasts in the IGB have sulfur isotope signals of possible biogenic origin and suggest that by 3.7 Ga biofilms may have covered portions of the ancient seafloor. If so, the clasts are the oldest known fossils preserved in Earth history.
DE: 0424 Biosignatures and proxies
DE: 0442 Estuarine and nearshore processes (4235)
DE: 0459 Macro- and micropaleontology (3030, 4944)
DE: 9315 Arctic region (0718, 4207)
DE: 9623 Archean
SC: Biogeosciences [B]
MN: 2009 Joint Assembly