西藏冈底斯中段南缘曲水地区早中新世隆升剥露历史及控制机制OA

The Quxu area,is located in the southern margin of the central Gangdese Magmatic Arc.The Cenozoic uplift and exhumation history of this area holds significant implications for deciphering the tectono-geomorphic evolution of the Gangdese Magmatic Arc and even the entire Tibetan Plateau.This study focuses on the uplift and exhumation history of the Quxu area.Nine samples were systematically collected at equal intervals along a 950 m vertical profile through Paleocene-Eocene granodiorites.Apatite(U-Th)/He thermochronology analyses of these samples produced ages ranging from 13.7 Ma to 12.6 Ma.The combination of thermochronological data and thermal history modeling indicated that the Quxu area underwent a rapid cooling event during the Early Miocene(19.0-11.5 Ma).During this interval,the total cooling was 299.4 ℃ at a cooling average rate of 40.0 ℃/Ma,corresponding to an exhumation magnitude of 9.8 km and average exhumation rate of 1.3 km/Ma.Since 11.5 Ma,the area has undergone a phase of slow cooling,characterized by a total cooling of 11.7 ℃ at a rate of 1.0 ℃/Ma that corresponds to an exhumation magnitude of 0.35 km and rate of 0.03 km/Ma,respectively.The study proposes that the Early Miocene rapid exhumation in the Quxu area was predominantly controlled by the Xietongmen-Quxu Shear Zone.South-directed thrusting along this shear zone drove crustal shortening and thickening,which induced isostatic adjustment and consequently led to intense regional exhumation.After 11.5 Ma,the exhumation rate in the Quxu area decreased significantly,driven by cessation of the Xietongmen-Quxu Shear Zone activity,regional transition to an extensional tectonic regime,and climate aridification induced by the rapid uplift of the southern Himalayas.