东昆仑左行走滑韧性剪切带形成时代的锆石U-Pb年龄证据  

EVIDENCE OF ZIRCON U-Pb AGES FOR THE FORMATION TIME OF THE EAST KUNLUN LEFT-LATERAL DUCTILE SHEAR BELT

作　　者：张紫程[1] 张绪教[1] 高万里[1] 胡道功[2] 陆露[2] 

机构地区：[1]中国地质大学地球科学与资源学院,北京100083 [2]中国地质科学院地质力学研究所,北京100081

出　　处：《地质力学学报》2010年第1期51-58,共8页Journal of Geomechanics

基　　金：中国地质调查局项目(编号:1212010711510)资助

摘　　要：巴颜咯拉—松潘甘孜地体与东昆仑南地体晚三叠纪斜向碰撞形成大规模的东昆仑左行走滑韧性剪切带,新生代时期韧性剪切转为脆性左旋走滑并构成青藏高原向东逃逸的北部边界。为了确定早期韧性剪切变形时代,对剪切带上2个同构造花岗斑岩脉进行了激光探针(LA-MC-ICP MS)测年研究,获得了196.4±2.3 Ma和195.1±1.6 Ma的锆石206Pb/238U加权平均年龄,表明东昆仑左行走滑韧性剪切带形成于燕山早期。The large-scale East Kunlun left-lateral ductile shear belt was formed by an oblique collision between the Bayan Har-Songpan-Ganzi terrain and the southern East Kunlun terrain during the Late Triassic.During the Cenozoic,this ductile shear belt was transformed into a brittle leftlateral strike-slip belt,and became the north boundary for the eastward ＂escape＂of the Qinghai-Tibet Plateau.The La-MC-ICPMS dating for two syntectonic granite-porphyry veins in the large ductile shear belt yielded two weighted zircon 206Pb /238 U ages of 196.4 ± 2.3 Ma and 195.1 ± 1.6 Ma.These ages suggest that the East Kunlun left-lateral ductile shear belt should form during the early Yanshanian Movement.

关 键 词：韧性剪切带 锆石U-Pb年龄 燕山早期 东昆仑造山带 

分 类 号：P597[天文地球—地球化学]