China contains a substantial fraction of the earth's exposures of ancient rocks, mostly unknown to Western geologists. This proposal in early crustal studies between Dr. Kent C. Condie of the New Mexico Institute of Mining and Technology and Dr. Qian Xianglin of Beijing University will characterize terranes of the Gehuyao area of Northeast China by a collaborative field and geochemical study of Archean high grade supracrustal rocks and associated intrusive rocks. This granulite belt contains excellent exposures of all supracrustal lithologies typical of Archean high grade terranes, with widespread felsic and mafic granulites of probable igneous origin. Its parallel greenstone and high grade belts offer an unusual opportunity to study the structural and compositional relationship of these two Archean associations. Because its abundant mafic granulites probably reflect a deeper section of Archean crust than is exposed in southern India and elsewhere, a more accurate estimate of the composition of the lower Archean crust should be possible, shedding light on how the continents formed. The researchers will map critical exposures, complete major and trace element analysis of both metaigneous and metasedimentary rocks, perform geochemical studies of magma origin and source, conduct structural and metamorphic studies. German and French collaborators will study geothermometry geobarometry and Nd and Pb isotropes, and do U Pb zircon dating. This project is jointly sponsored by NSF and the Chinese National Natural Science Foundation.
