Tectonothermal Evolution of the Eastern Tibetan Plateau Foreland: Fission-Track Thermochronology of the Southern Dabashan Fold-Thrust Belt

作     者：张增宝 沈传波 邵春 刘昭茜 

作者机构：Key Laboratory of Tectonics and Petroleum Resources of Ministry of Education China University of Geosciences Faculty of Earth Resources China University of Geosciences 

出 版 物：《Journal of Earth Science》 (地球科学学刊（英文版）)

年 卷 期：2013年第24卷第4期

页      面：479-490页

核心收录：

学科分类：081803[工学-地质工程] 08[工学] 0818[工学-地质资源与地质工程] 0708[理学-地球物理学] 0704[理学-天文学] 

基　　金：supported by the National Natural Science Foundation of China (No. 40902038) the Petro China Innova-tion Foundation (No. 2009D-5006-01-08) the Project of China Geological Survey (No. 12120113094200) 

主　　题：fission-track fold-thrust belt Dabashan tectonothermal evolution eastern Tibetan Plateau. 

摘      要：Apatite fission-track dating and thermal-history modeling were carried out on samples from the Dabashan （大巴山）, a fold-thrust belt, northeast of the Sichuan （四川） Basin and east of the Tibetan Plateau. A first cooling event in the Late Cretaceous is followed by a prolonged period of ther- mal stability with exhumation rates of 〈0.025 mm/a, as determined from age vs. elevation relationships. The preservation of age vs. elevations relationships and the lack of distinct age changes across tectonic structures indicate that the Dabashan fold-thrust belt formed prior to the Late Cretaceous, consistent with the current view of Triassic-Early Cretaceous shortening. Relatively short mean track lengths （-12 μm） indicate that the samples remained in the partial annealing zone for a prolonged time. The knick points in the best-fitting temperature-time models suggest that the onset of late-stage accelerated cooling commenced at 〈11 Ma. Related exhumation rates are 0.3-0.2 mm/a assuming geothermal gra- dients of 20 and 30 ℃/km. We speculate that this late-stage event results from eastward growth of the Tibetan Plateau and overstepping of the Sichuan Basin, it is likely responsible for the youthful mor- phology of the Dabashan.