Structural Characteristics of the Basement beneath Qiangtang Basin in Qinghai-Tibet Plateau: Results of Interaction Interpretation from Seismic Reflection/Refraction Data

作     者：LI Qiusheng GAO Rui FENG Shaoying LU Zhanwu HOU Hesheng GUAN Ye LI Pengwu WANG Haiyan YE Zhuo XIONG Xiaosong LIU Jinkai HE Rizheng 

作者机构：Institute of Geology CAGS Earthprobe and Geodynamics Open Laboratory of CAGS The Geophysical Exploration center CEA East China Petroleum Geology Bureau China Petrochemical Corporation 

出 版 物：《Acta Geologica Sinica(English Edition)》 (地质学报（英文版）)

年 卷 期：2013年第87卷第2期

页      面：358-377页

核心收录：

学科分类：070904[理学-构造地质学] 0709[理学-地质学] 0819[工学-矿业工程] 07[理学] 0818[工学-地质资源与地质工程] 0708[理学-地球物理学] 0816[工学-测绘科学与技术] 

基　　金：supported by the National Natural Science Foundation of China (Grant Nos. 40874045 and 41174081) the Special Funds for Sciences and Technology Research of Public Welfare Trades (Grant No.201011042) 

主　　题：seismic reflection seismic refraction basement structure Qiangtang basin Qinghai-TibetPlateau 

摘      要：The studies on configuration, character/property of the basement of Qiangtang basin is helpful for evaluating petroleum and nature gas resources as well as understanding the basin evolvement. Recently a moderate to high-grade metamorphic gneiss rock was found underlying beneath very low metamorphic Ordovician strata in Mayer Kangri to the north of the central uplift. That fact actually proved existence of the crystalline basement just the distribution and structures of pre-Paleozoic crystalline basement still remain puzzle. In recent years a number of active sources deep seismic profiling, to aim at lithospheric structure of northern Tibet and petroleum resources of the Qiangtang basin, had been conducted that make it possible to image the structure of the basement of the Qiangtang. Near vertical reflection profiles, included those acquired previously and those during 2004 to 2008, have been utilized in this study. By through the interaction process and interpretation between the reflection profiles and the wide-angle profile, a model with the detailed structure and velocity distribution from surface to the depth of 20 km of Qiangtang basin has been *** on the results and discussions of this study, the preliminary conclusions are as follows： （1） The velocity structure section （~20 kin） that is interactively constrained by the refraction and reflection seismic data reveals that the sedimentary stratum gently lie until 10 km in the south Qiangtang basin. （2） The basement consists of fold basement （the upper） and crystalline basement （the lower）.The fold basement buried at the average depth of 6 km with a velocity of 5.2-5.8 km/s. The shallowest appear at range of the central uplift. The crystalline basement is underlying beneath the fold basement at the average depth of 10 km with a velocity of 5.9-6.0 km/s except near Bangong-Nujiang suture. （3） The high-velocity body at the depth range of 3-6 km of the central uplift is considered as a fragment of the cryst