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2006 Annual Science Report

University of Washington Reporting  |  JUL 2005 – JUN 2006

Building a Habitable Planet: The Geological Record

Project Summary

Research continued in the following 6 areas: late Archean — early Paleoproterozoic hydrocarbon biomarker molecules, Archean sulfur isotopes and sulfur cycling, metamorphism of early Archean biosignatures, nutrient availability (N, P) in Precambrian oceans, paleobarometry of the Archean atmosphere and diamond drilling of astrobiologically significant Archean and early Proterozoic sedimentary horizons in the Pilbara Craton of Australia. Field-work was conducted on early Archean supracrustal rocks of the Fortescue, Warrawoona and Coonterunah Groups in the Pilbara Craton, Australia and the Isua Supracrustal Belt, Greenland.

4 Institutions
3 Teams
0 Publications
0 Field Sites
Field Sites

Project Progress

Research continued in the following 6 areas: late Archean — early Paleoproterozoic hydrocarbon biomarker molecules, Archean sulfur isotopes and sulfur cycling, metamorphism of early Archean biosignatures, nutrient availability (N, P) in Precambrian oceans, paleobarometry of the Archean atmosphere and diamond drilling of astrobiologically significant Archean and early Proterozoic sedimentary horizons in the Pilbara Craton of Australia. Field-work was conducted on early Archean supracrustal rocks of the Fortescue, Warrawoona and Coonterunah Groups in the Pilbara Craton, Australia and the Isua Supracrustal Belt, Greenland. Principal outcomes were:

  • publication of the discovery of hydrocarbon biomarker molecules in early Paleoproterozoic fluid inclusions showing that ancient cyanobacterial and eukaryotic geolipids are not contaminants, that these organisms existed before the first of the “Snowball Earth” events and the rise in atmospheric oxygen, and that molecular fossils can survive for much longer under high temperature regimes than previously expected;
  • construction of a working computer box-model of the Archean sulfur biogeochemical cycle, which will lead to a better understanding of the role of sulfur in the regulation of redox states on the early Earth;
  • equipping the NAI Finnegan 253 IRMS mass-spectrometer for the analysis of sulfur isotopes;
  • analysis of carbon isotopes and total organic carbon contents of 2.6-2.4 billion year old sedimentary rocks from the NAI ADP drill-cores showing that mass-independent fractionations of sulfur isotopes are not correlated with either, ruling out the possibility that they are induced by organic diagenesis;
  • detailed mapping of 3.8 billion year old metasedimentary rocks from Isua, Greenland, showing that interpretations of a turbidite depositional environment are most consistent with field evidence;
  • collection and analysis of samples for Archean paleobarometry, indicating that atmospheric pressure was different to modern levels early in Earth’s history.