ANALYSIS ON STRUCTURAL SECTIONS IN THE CENOZOIC PAMIR-WESTERN KUNLUN FORELAND FOLD-AND-THRUST BELT
Wu Xiufang1, Liu Sheng2, Wang Xin1, Yang Shufeng1, Gu Xuemei3
1. Geosciences Department of Zhejiang University, Hangzhou 310027; 2. Tarim Oil Field Branch Company, China National Petroleum Corp., Korla, Xinjiang 841000; 3. Exploration & Development Research Institute, Jidong Oilfield, China National Petroleum Corp., Tangshan, Hebei 063004
The Pamir-Western Kunlun foreland fold-and-thrust belt was very important to study intraplate deformation in central Asia and hydrocarbon exploration. Based on detailed structural analysis of three cross sections which synthesized by seismic profiles, outcrops and drilling data in the area, the structural characters were studied and structural models of the Pamir-Western Kunlun foreland fold-and-thrust belt established. In the foreland fold-and-thrust belt there mainly were low-angle blind thrusts in addition to high-angle thrusts along the mountain’s piedmont. Two structural styles were presented: the thrust related structures due to underlying thrusts slipping from orogen to foreland basin in the Wupor zone, and the triangle zones formed by stack of 2～3 imbricate thrust sheets which plugged in undeformed strata towards foreland basin by means of wedges, so as to creat three rows of folded belt in the Sugaite Qimugen Fusha zone. The main tectonic deformation in the Pamir-Western Kunlun foreland fold-and-thrust belt started in Early Pliocene(about 4.6 Ma ago), and migrated gradually from the orogen to the foreland basin, with the faulting and folding becoming younger and weakened in the basin. The tectonic shortening amount increased from 23.3 km in the Wupor zone to 68 km in the Fusha zone, but the tectonic shortening rate kept in the range of 35%～50%. In addition, the possible hydrocarbon traps in the Pamir-Western Kunlun foreland fold-and-thrust belt were analyzed.