CENOZOIC FAULTING ALONG THE SOUTHEASTERN EDGE OF THE TIBETAN PLATEAU IN THE YANYUAN AREA AND ITS TECTONIC IMPLICATIONS

作     者：Wang Erchie 1, Burchfiel B. Clark 2[WT5,5”BX](1 Institute of Geology and Geophysics, Chinese Academy of Science,Beijing 100029,China 2 Department of Earth, Atmospheric and Planetary Sciences, MIT,Cambridge, MA 02139,UK) 

出 版 物：《地学前缘》 (Earth Science Frontiers)

年 卷 期：2000年第7卷第S1期

页      面：269-269页

核心收录：

学科分类：0709[理学-地质学] 081803[工学-地质工程] 07[理学] 08[工学] 0818[工学-地质资源与地质工程] 

主　　题：southeastern edge of the Tibetan plateau Yanyuan thrust shee t crustal shortening and uplift normal faulting gravitational collapse 

摘      要：The southeastern edge of the Tibetan plateau is marked by several thrust sheets trending roughly in E\|W direction. The Yanyuan thrust sheet is bounded by three arcuate thrust belts, marked by high mountain ranges with the Jinhe belt on the north, the Qianhe belt on the south and the Ninglang belt on the west. Within the Yanyuan thrust belt are sedimentary cover rocks of the Yangtze platform, with ages ranging from Sinian to Triassic. In the north, the thrust sheet is overlain by the Muli thrust sheet along the Jinhe belt, while in the south, it is underlain by the Kangdian paleoland along the Qianhe belt. The youngest rocks on the foot wall are late Eocene to Oligocene in age, indicating that the thrusting occurred in the late Tertiary. The top of the Yanyuan thrust belt is truncated by a flat erosion surface similar to that on the plateau to the north. Along a north\|dipping normal fault bordering the Yanyuan basin on the south, the erosion surface is tilted to the south against Triassic rocks. The basin is filled with coal\|bearing clastic sediments of Pliocene and early Pleistocene age, which gives the timing of the normal faulting. Based on the faulting pattern, we propose that the southeastern edge of the Tibetan plateau underwent a large amount of N\|S shortening and uplift along the Yanyuan thrust sheet in the late Tertiary, while the subsequent normal faulting that had occurred along the Yanyuan basin during the Pliocene and Pliocene can be interpreted to have accommodated gravitational collapse of the crust.