Geochemistry and Petrology of Archaean Supracrustal Rocks from West Greenland

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The evolution of the Earth's early crust will be investigated through studies on the Isua and Malene supracrustal rocks from West Greenland. X-ray fluorescence and instrumental neutron activation analyses for major and trace elements will be integrated with results from isotopic studies in order to: (a) characterize the diversity of crustal components in clastic metasedimentary rocks; (b) identify the nature of ancient crustal components of the Isua rocks by carrying out multivariate mixing calculations on metasediment chemical compositions; (c) evaluate the origin of Malene gneisses as possible products of hydrothermal alteration of ancient oceanic rust by heated sea-water; and (d) determine whether metasedimentary granulite show element depletions, as found in many granitic gneisses metamorphosed to the granulite facies. Mineral compositions will be determined by electron microprobe analysis and relevant geothermometers and geobarometers will be used to refine the metamorphic history of this region. Field work will be carried out in order to evaluate the relationship of Malene Supracrustal rocks to granitic gneisses and characterize their stratigraphic and lithologic variations. The Principal Investigator is a leading authority on early Earth geochemistry and petrology, and has a great deal of field experience in Greenland. The facilities required for this investigation are adequate at Washington University.