2002 Annual Science Report

University of Washington Reporting  |  JUL 2001 – JUN 2002

Building a Habitable Planet: The Geological Record

Project Summary

Research was conducted on Archean U-Pb geochronology, basalt trace-element geochemistry, hydrocarbon biomarker geochemistry, sulfur isotopic fractionation, microfossil recognition, and Paleoproterozoic hydrocarbon preservation in fluid inclusions.

4 Institutions
3 Teams
0 Publications
0 Field Sites
Field Sites

Project Progress

Research was conducted on Archean U-Pb geochronology, basalt trace-element geochemistry, hydrocarbon biomarker geochemistry, sulfur isotopic fractionation, microfossil recognition, and Paleoproterozoic hydrocarbon preservation in fluid inclusions. Principal outcomes were:

  • determination of a precise age for the Sulphur Springs hydrothermal base-metal deposit at 3235 Ga, thus dating the oldest known oil and bitumen, constraining the oldest known fossilized subsurface microbiota and establishing the existence of thermophile organisms very early in Earth's history;
  • documentation of Paleoproterozoic oil-methane-carbon dioxide-water fluid inclusions from Elliott Lake, thus demonstrating the survival of complex hydrocarbon molecules for billions of years under closed-system and high-pressure conditions and establishing a base line for preservation of such biosignatures on other planets;
  • resolution of a controversy about the presence of widespread continental crust in the early Archean based on basalt geochemical evidence for crustal contamination, thus showing that Earth's surface differentiated early in its history and hence providing a source of refractory elements such as phosphorus;
  • completion of a major study of hydrocarbon biomarker molecules in late Archean sediments from the Hamersley Basin, showing that cyanobacterial and eukaryotic lipids are present in rocks half a billion years before body fossils of these groups appear in the geologic record and that molecular fossils can survive for much longer under high thermal regimes than previously expected.