Geochemistry and Petrology of Archaean Supracrustal Rocks from West Greenland

地球早期地壳的演化将通过对西格陵兰岛的Isua和Malene表壳岩石的研究来研究。主要元素和微量元素的X射线荧光和仪器中子活化分析将与同位素研究的结果相结合，以便：(A)描述碎屑变沉积岩中地壳成分的多样性；(B)通过对变沉积化学成分进行多元混合计算，识别伊苏瓦岩古地壳成分的性质；(C)评估马来片麻岩的成因，认为它可能是古代大洋铁锈在高温海水作用下热液蚀变的产物；以及(D)确定变质沉积麻粒岩是否像许多变质为麻粒岩相的花岗质片麻岩那样出现元素亏损。矿物成分将通过电子探针分析确定，相关的地温计和地质压力计将用于精炼该地区的变质历史。将开展野外工作，以评估马来表壳岩石与花岗片麻岩的关系，并描述它们的地层和岩性变化。首席调查员是早期地球地球化学和岩石学方面的主要权威，并在格陵兰岛拥有丰富的野外经验。这次调查所需的设施在华盛顿大学是足够的。

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.