40Ar-39Ar Geochronology and Tectonic Implications of the Blueschist from Northwestern Qiangtang, Northern Tibet, Western China

作     者：TANG Xianchun ZHANG Kaijun 

作者机构：Guangzhou Institute of GeochemistryChinese Academy of Sciences Graduate University of Chinese Academy of Sciences Research Institute of Petroleum Exploration and DevelopmentEast China CompanySINOPEC Asian Tectonics Research GroupDepartment of Earth SciencesNanjing University 

出 版 物：《Acta Geologica Sinica(English Edition)》 (地质学报（英文版）)

年 卷 期：2012年第86卷第6期

页      面：1471-1478页

核心收录：

学科分类：070902[理学-地球化学] 0709[理学-地质学] 070901[理学-矿物学、岩石学、矿床学] 07[理学] 

主　　题：blueschist high-pressure metamorphism 40Ar-39Ar geochronology Qiangtang Tibet 

摘      要：Blueschist exposed in the northwestern Qiangtang terrane, northern Tibet, western China （84 30＇ E, 34024＇ N）, provides new constraints on the tectonic evolution of Qiangtang as well as northern Tibet. The blueschist represented by lawsonite- and glaucophane-bearing assemblages equilibrated at 375-400 C and 11 kbar. 4Ar-39Ar analysis on mineral separate from one blueschist sample yielded a well-defined plateau age of 242 Ma. Geochemical studies show the blueschist is metamorphosed within-plate basalts. The high pressure-low temperature blueschist indicates a Triassic event of lithosphere subduction, and clearly represents an extension of the central Qiangtang metamorphic belt, and defines an in situ suture between eastern and western Qiangtang.