Paleomagnetic constraints on Paleogene-Neogene rotation and paleo-stress in the northern Qaidam Basin  

作　　者：Ling SUN Junliang JI Bingshuai LI Xingbo LI Wujun WU Kexin ZHANG 

机构地区：[1]Hubei Key Laboratory of Critical Zone Evolution,School of Geography and Information Engineering,China University of Geosciences,Wuhan 430074,China [2]School of Earth Sciences,East China University of Technology,Nanchang 330013,China [3]Jiangsu Oilfield Company,Sinopec,Yangzhou 225009,China [4]Research Institute of Petroleum Exploration and Development-Northwest,PetroChina,Lanzhou 730020,China [5]Institute of Geological Survey,China University of Geosciences,Wuhan 430074,China

出　　处：《Science China Earth Sciences》2022年第12期2385-2404,共20页中国科学（地球科学英文版）

基　　金：supported by the National Natural Science Foundation of China(Grant Nos.42274105,41972208,42172251);the Geological Survey of China(Grant No.DD20190370);the National Oil and Gas Major Science and Technology Project(Grant No.2016ZX05003-006).

摘　　要：Knowing the rotation and paleo-stress history in Qaidam Basin is a fundamental parameter to quantify the mechanism of intracontinental deformation in Tibetan Plateau.However,few studies have been conducted on tectonic rotation and stress evolution over long timescales in the Qaidam Basin.Here,we report new magnetic declination and the anisotropy of magnetic susceptibility(AMS)from a~52–7 Ma sequence of fluvial and lacustrine sediments in the Dahonggou(DHG)section in the northern Qaidam Basin.The magnetic declination revealed that the northern Qaidam Basin underwent a clockwise rotation 25.1°±8.6°during~33–17 Ma,followed by a counterclockwise rotation 16.9°±6.8°during~17–13.5 Ma.The AMS results showed that the“earliest deformation”fabrics were interrupted by the“pencil structure”fabrics in the intervals of~52–45 and~21–15 Ma.The interruption,synchronous with the marked deceleration of the India-Asia convergence rate,indicates pulse of strong tectonic compressive stress.In addition,the AMS results documented a transition in stress direction from S-N to SW-NE at~15 Ma,suggesting a kinematic shift in the northeastern TP.Our constraints on the rotation and stress from the northern Qaidam Basin support the two-stage evolution of the Altyn Tagh Fault(ATF).The fast-rate slip motion on the ATF during the early Oligocene caused the clockwise rotation in the northern Qaidam Basin;the second stage with enhanced thrusting since the middle Miocene caused extensive crustal shortening and dispersive NW-trending folds and faults in the Qaidam Basin and the northeastern TP.

关 键 词：Tectonic rotation STRESS Anisotropy of magnetic susceptibility Paleo-Neogene Northern Qaidam Basin Tibetan Plateau 

分 类 号：P318.44[天文地球—固体地球物理学]