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

作　　者：TANG Xianchun ZHANG Kaijun 

机构地区：[1]Guangzhou Institute of Geochemistry,Chinese Academy of Sciences [2]Graduate University of Chinese Academy of Sciences [3]Research Institute of Petroleum Exploration and Development,East China Company,SINOPEC [4]Asian Tectonics Research Group,Department of Earth Sciences,Nanjing University

出　　处：《Acta Geologica Sinica(English Edition)》2012年第6期1471-1478,共8页地质学报（英文版）

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.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.

关 键 词：BLUESCHIST high-pressure metamorphism 40Ar-39Ar geochronology QIANGTANG Tibet 

分 类 号：P588.344[天文地球—岩石学] P597.3[天文地球—地质学]