LA-ICP-MS U-Pb Dating of Zircon from Granite-Gneiss in the Amdo Area, Northern Tibet, oft-com:office:smarttags" />
详细信息
- 责任者：Xie Chaoming (College of Earth Science ; Jilin University ; Changchun 130061 ; China) ; Li Cai
- 刊名：Geological Bulletin of China
- 出版年：2010
- 卷期：29(12)
- 关键词：花岗质片麻岩 ; granitic gneiss ; 铀—铅计时 ; U-Pb dating ; 西藏 ; Tibet
- 页码：p.1737-1744
- 图表：5 illus., 2 tables, 23 refs.
- 分类号：0801
- issnNo：ISSN1671-2552
- isbnNo：CN11-4648/P
摘要
Amdo gneiss which exposed in south of Amdo County about 30km, in the northern Tibet constitutes the major lithologic of Nierong Group on Nierong microcontinent. Nierong was a large micro-lens gripping Gangdise-Nyainqentanglha plate of northern Tibet and Qiangtang-Sanjiang composite plate in the Bangong Co-Nujiang River suture zone. The CL images of biotite-monzonite-gneiss zircons show distinct oscillatory zoning. Th/U ratios range from 0.63 to 1.04 with an average of 0.85. Gneiss zircons LA-ICP-MS U-Pb in situ isotopic age is 488.0±4.2 Ma. Dating results show that the Amdo gneiss protolith was emplaced in the Pan-African period, and verifies that Nierong microcontinent was effected by the late Pan-African thermal motion. This study provides an important chronological evidence for basement properties and tectonic evolution of the Nierong microcontinent.