Paleogeography and basin type of the early and middle Jurassic in the northern margin of Qaidam Basin

In the late stage of the Jurassic,the northern margin of Qaidam Basin is intensely remade,and its formation occurrence is complex.Based on core data,outcrop data,drilling data,seismic data and so on,the paleogeography of the early and middle Jurassic is quantitatively studied by using single-factor analysis and multi-factor mapping method.It is held that in the early and middle Jurassic,lake facies develop in the region,and it is mainly shore shallow-half-deep lake facies;its recent distribution range is not the boundary of primary sedimentary basin,and the northern border of the primary sedimentary basin is near the thrust faults of the Southern Qilian Mountains;the northern margin of Qaidam Basin is extensional faulted depression basin during the early and middle Jurassic.