The Paleocene Metamorphism of the Southeastern Margin of Lhasa Terrane and Its Tectonic Significance
详细信息
- 责任者：Lin Yanhao (Faculty of Earth Sciences ; China University of Geosicences ; Wuhan 430074 ; China) ; Zhang Zeming
- 刊名：Acta Petrologica Sinica
- 出版年：2013
- 卷期：29(6)
- 关键词：片麻岩 ; gneisses ; 铀—铅计时 ; U-Pb dating ; 变质作用 ; metamorphism ; 西藏 ; Tibet
- 页码：p.1962-1976
- 图表：illus., 3 tables, 71 refs.
- 分类号：0802
- issnNo：ISSN1000-0569
- isbnNo：CN11-1922/P
摘要
The Nyingchi Complex is located in the southeastern margin of Lhasa terrane,Tibetan Plateau. Its petrology and geochronology are reported in this paper. The studied samples consist of orthogneiss and paragneiss,which were metamorphosed under a medium-pressure amphibolite-facies condition. Petrogeochemistry studies show that the protoliths of orthogneisses have the characteristic of calc-alkaline island-arc volcanic rocks. Detrital zircons from the paragneiss are typical of magmatic origin,which give a206 Pb /238 U age range of 3012～522Ma. The overgrowth rims of thedetrital zircons yielded metamorphic ages of～51Ma. For the orthogneisses,magmatic cores and metamorphic rims of zircons from biotite gneiss and garnet-hornblende-biotite-plagioclase gneiss yield protolith ages of～67Ma and～58Ma,and metamorphic ages of～55Ma and～54Ma,respectively. The studied Nyingchi Complexdoes not represent Precambrian basement of the Lhasa terrane,but it is composed of Paleozoic sedimentary and Late Cretaceous to Early Cenozoic Gangdese igneous rocks. The ca. 55～50Ma medium-pressure amphibolite-facies metamorphisms of these supracrustal rock and intrusive rocks would be related to the crustal accretion and thickening resulted from the subduction of the Neo-Tethys.
© 2004-2018 中国地质图书馆版权所有 京ICP备05064691号 京公网安备11010802017129号 地址：北京市海淀区学院路29号 邮编：100083 电话：办公室：(+86 10)66554848；文献借阅、咨询服务、科技查新：66554700 |