Direct dating of Archean microbial ichnofossils
- Neil R. Banerjee*1,
- Antonio Simonetti2,
- Harald Furnes3,
- Karlis Muehlenbachs4,
- Hubert Staudigel5,
- Larry Heaman6 and
- Martin J. Van Kranendonk7
- 1Department of Earth Sciences, University of Western Ontario, London, Ontario N6A 5B7, Canada
- 2Department of Earth and Atmospheric Sciences, University of Alberta, Edmonton, Alberta T6G 2E3, Canada
- 3Centre for Geobiology and Department of Earth Science, University of Bergen, Allegaten 41, 5007 Bergen, Norway
- 4Department of Earth and Atmospheric Sciences, University of Alberta, Edmonton, Alberta T6G 2E3, Canada
- 5Scripps Institution of Oceanography, University of California, La Jolla, California 92093-0225, USA
- 6Department of Earth and Atmospheric Sciences, University of Alberta, Edmonton, Alberta T6G 2E3, Canada
- 7Geological Survey of Western Australia, 100 Plain Street, East Perth, Western Australia 6004, Australia
Abstract
Well-preserved Archean pillow lavas from the ca. 3.35 Ga Euro Basalt of the Pilbara Craton, Western Australia, contain micron-sized tubular structures mineralized by titanite (CaTiSiO4) with residual organic carbon preserved along their margins. Direct U-Pb dating of titanite in the tubular structures demonstrates an Archean age. These tubular microstructures are identical to microbial ichnofossils in modern basalts, ophiolites, and greenstone belts, and are interpreted as a biogenic signature in these ancient rocks. Microbial colonization of basaltic glass thus appears to have been part of a deep subsurface biosphere established early in Earth's history.
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- Accepted 24 January 2007.
- Received 10 December 2006.
- Revision received 22 January 2007.
- Geological Society of America
