U.S.-China Cooperative Research: Geochemistry and Origin of Archean Granulities in Northeastern China

中国拥有地球上暴露的古代岩石的很大一部分，这些岩石大多不为西方地质学家所知。新墨西哥矿业与技术研究所Kent C. Condie博士和北京大学钱湘林博士在早期地壳研究中提出的这一建议，将通过对太古宙高品位表壳岩和伴生侵入岩的野外和地球化学研究，对东北葛虎窑地区的地体进行特征描述。该麻粒岩带包含所有太古宙高品位地体的典型表壳岩性，广泛分布有可能是火成岩成因的长英质和基性麻粒岩。其平行的绿岩带和高品位带为研究这两个太古宙组合的构造和成分关系提供了难得的机会。由于其丰富的基性麻粒岩可能反映出比印度南部和其他地方暴露的太古宙地壳更深的部分，因此更准确地估计下太古宙地壳的组成应该是可能的，从而揭示大陆是如何形成的。研究人员将绘制关键暴露图，完成变质岩和变质沉积岩的主要元素和微量元素分析，进行岩浆起源和来源的地球化学研究，进行构造和变质研究。德国和法国的合作者将研究地热测量、气压测量、Nd和Pb各向同性，并进行U - Pb锆石定年。本项目由美国国家科学基金会和中国国家自然科学基金共同资助。

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.