帕米尔东北缘晚新生代旋转运动新证据  

New evidence for rotation of Northeastern Pamir since Late Cenozoic

作　　者：周在征 裴军令[1,2] 李建锋[1] 刘锋[1] 盛美[1,2] 赵越[1] 

机构地区：[1]中国地质科学院地质力学研究所,北京100081 [2]国土资源部古地磁与古构造重建重点实验室,北京100081 [3]中国地质大学(北京)地球科学与资源学院,北京100083

出　　处：《地球物理学报》2016年第2期633-642,共10页Chinese Journal of Geophysics

基　　金：国家自然科学基金面上项目(41172177)资助

摘　　要：为进一步研究帕米尔东北缘晚新生代演化特征,在塔里木盆地西部英吉沙背斜上新世地层中采集了11个采点共111块古地磁样品.对样品进行系统热退磁测定,揭示了一组高温特征剩磁分量,获得了采样剖面的上新世古地磁极.特征剩磁方向为:Dg=342.4°,Ig=59.2°,κg=32.3,α95=8.6°;Ds=352.4°,Is=49.9°,κs=59.1,α95=6.3°,相对应的古地磁极位置为:79.7°N,295.9°E,dp=5.6°,dm=8.4°,α95=6.9°.这一高温分量通过了倒转检验,代表了研究区上新世时期的原生特征剩磁.通过对英吉沙背斜周缘断裂及形成的大地构造背景分析,结合其地貌特征、GPS数据,认为英吉沙背斜在开始形成至今经历了明显的逆时针构造旋转,该旋转同晚新生代以来帕米尔东北缘喀什凹陷发生刚性构造旋转运动有着密切的关系.The Pamir-western Himalayan syntaxis lies at the western end of the India-Asia collision zone and is bounded by the Main Pamir Thrust to the north,and the Main Boundary Thrust and Main Frontal Thrust to the south.To facilitate the study on the deformation history of the northeastern Pamir in response to the India-Asia collision,paleomagnetic samples were collected from 11 sites in the Pliocene sedimentary rock adjacent to the western Kunlun mountains.A stable magnetic component was isolated by stepwise thermal demagnetization of111 samples from this section,which is characterized by apositive C-class reversal test.The mean direction of residual magnetism is Dg=342.4°,Ig=59.2°,κg=32.3,α95=8.6°;Ds=352.4°,Is=49.9°,κs=59.1,α95=6.3°,corresponding to a paleopole atλp=79.7°N,φp=295.9°E,dp=5.6°,dm=8.4°,α95=6.9°.The paleomagnetic study on sedimentary rock developed in the Tarim basin offers a useful method for researching tectonic evolution.Combining with geomorphology and GPS data,ourresults suggest that the Yengisar anticline has undergone significant counterclockwise rotation since Pliocene.Comparisons of this paleomagnetic pole with adjacent regions imply the tectonic rotation in Kashi depression is associated with Northeastern Pamir evolution during the late Cenozoic.

关 键 词：帕米尔 晚新生代 古地磁 构造旋转 喀什凹陷 

分 类 号：P318[天文地球—固体地球物理学] P542[天文地球—地球物理学]