The Jurassic Basin Type and Its Evolution Characteristic in Qaidam Basin
ZENG Lian-bo~1 JIN Zhi-jun~1 ZHANG Ming-li~2 TANG Liang-jie~1 YOU Fu-bao~3 LEI Bing-zu~3 1(University of Petrolum,Beijing 102200) 2(Institute of Geomechanics,CAGS, Beijing 100081) 3(Qinghai Petroleum Administration,Dunhuang Gansu 736202)
According to comprehensive analysis of Jurassic strata distribution, sedimentary characteristic and tectonic evolution, the Qaidam Basin experienced the development and super imposition of two types of basins during the Jurassic period, the middle Yanshan orogeny at the end of the Middle Jurassic was the transformation time of the basin types. During the Early Middle Jurassic, it was in an extensional tectonic environment and formed a series of minor-scale fault basin group, which was distributed in the south of Qilian Mountain and nearby the southern Altyn fault. During the Late Jurassic and cretaceous, it was in the compressional tectonic setting and formed the down-warped basin, which was controlled by the overthrust tectonic regime in the front of Qilian Mountain, the deposition scope was obviously widening.