地质通报2012，Vol.31Issue(10)：1576-1587,12.
祁连造山带东端张家川地区长宁驿中元古代花岗质片麻岩LA-ICP-MS锆石U-Pb年龄及其构造意义
LA-ICP-MS zircon U-Pb dating of the Mesoproterozoic granitic gneisses at Changningyi of Zhangjiachuan area on the eastern edge of the Qilian Orogenic belt
摘要
Abstract
The newly identified Mesoproterozoic granitic gneisses are located in Paleoproterozic Longshan Group at the eastern end of Qilian Orogenic belt. In order to accurately determine the formation age of granitic gneisses from Changningyi, the authors carried out single grain zircon micro area U-Pb isotope dating by means of Laser Ablation Inductively Coupled Plasma Mass Spectrometry. The Th/U ratios of zircons from granitic gneisses are between 0.50 and 2.09, and CL images show that the internal zircon has developed typical oscillatory girdle structure of magma growth, which belongs to the product of magma crystallization. And the original rock crystallization age of granitic gneiss is 1765Ma±57Ma, suggesting that granite rock was produced in early Mesoproterozoic period, and was probably formed in an post-orogenic environment, under which North China Block was experiencing the Lüliang movement. In addition, from the captured inherited magma zircon, the authors obtained the inherited ages of 1.95Ga and 2.20Ga. In combination with regional geological data and on the basis of a comprehensive study and analysis, the authors found that Qilian block remained a southwestern part of North China Block in Mesoproterozoic, for they had the same crystalline basement and structural properties. Besides, they both experienced the post orogenic stage and intracontinental stretch cracking stage after Lüliang movement. So they were probably closely related to the polymerization and cracking of Columbia supercontinent.关键词
花岗质片麻岩/祁连造山带东端/LA-ICP-MS锆石U-Pb年龄/华北板块Key words
granitic gneisses/ eastern end of the Qilian orogenic belt/ LA- ICP-MS zircon U-Pb dating/ North China Block分类
天文与地球科学引用本文复制引用
王银川,陈有炘,裴先治,李佐臣,李瑞保,裴磊,魏方辉,刘成军,高景民,吴树宽..祁连造山带东端张家川地区长宁驿中元古代花岗质片麻岩LA-ICP-MS锆石U-Pb年龄及其构造意义[J].地质通报,2012,31(10):1576-1587,12.基金项目
国家自然科学基金项目《西秦岭北缘变形构造解析及其祁连-秦岭构造交接关系研究》(批准号:40972136)、中央高校基本科研业务费专项资金项目《中央造山带(中西段)关键构造部位复合造山作用研究》(编号:CHD2011TD020)和中国地质调查局地质调查项目《天水市幅1∶25万区域地质调查(修测)》(编号:200013000154) （批准号:40972136）
