Constraining the exhumation history of the north-western margin of Tibet with a comparison to the adjacent Pamir

Abstract

Regional variations in the evolution of the Tibetan plateau has important implications for our understanding of crustal deformation processes. The evolution of the NW margin of the plateau and its transition to the Pamir to the west is one under-studied region. We focus on this region with a multi-technique detrital study of two sedimentary sections in the Tarim Basin. Our provenance data show that an appreciable component of the detrital material in the sedimentary sections was derived from the Songpan-Ganzi – Tianshuihai composite terrane, with some contribution from the Karakoram and/or the West Qiangtang. Given the proximity of the West Kunlun to the sedimentary sections under study, and its long history of exhumation, this terrane in all likelihood also contributed to the studied successions. Our thermochronological data record phases of exhumation in the hinterland in the Triassic, Early Cretaceous and Oligo-Miocene. Similar to the Pamir, the Triassic and Oligo-Miocene periods of exhumation are attributed to the Cimmerian and Himalayan orogenies respectively. The Early Cretaceous signal may reflect the distal effects of the Lhasa–Qiangtang collision. Coevality with deformation in Pamir suggests a coupled geodynamic system, with retroarc deformation associated with NeoTethyan subduction in the west, and terrane accretion in the east. Supplementary material: https://doi.org/10.6084/m9.figshare.c.7040686