The Major Two‐stage Shortening Deformation of the Northern Tibet and Tian Shan Area Since the Latest Oligocene

Abstract

AbstractIt seems to be progressively recognized that the stress of the India‐Asia convergent front can be transferred rapidly through the southern and central Tibetan lithosphere to the northern Tibet, hence leading to the crustal thickening deformation there during or immediately after the onset of the India‐Asia collision (ca. 55 Ma). This study focuses on the late Cenozoic deformation and tectonic uplift of the northern Tibet and Tian Shan area. Detailed compilations of a variety of proxy data from sediments and bedrocks suggest that the northern Tibet and Tian Shan area underwent one stage of approximately synchronous widespread contractile deformation since 25–20 Ma, which seemed to decrease at circa 18 Ma as revealed by low‐temperature thermochronological data. The latest Oligocene‐early Miocene was also significant basin‐forming episodes when many intermontane subbasins began to receive syntectonic sedimentation in the northeastern Tibet. Subsequently, the other phase of compressional deformation began to encroach more widely into the northern Tibet and Tian Shan area in episodic steps or continuously from 16–12 Ma to present.