| The Jurassic Buqu Formation in Qiangtang area of Xizang is an important oil and gas reservoir. Due to the limitation of basic geological data, the distribution of lithofacies paleogeography in the Jurassic Buqu Formation in Qiangtang area is controversial, and the precise characterization of lithofacies paleogeographic evolution is lacking. In order to explore the stratigraphic characteristics of the Jurassic Buqu Formation and the lithofacies paleogeographic evolution of different periods, the lithofacies paleogeographic distribution and evolution characteristics of the Jurassic Buqu Formation are studied in the stratigraphic framework through the field geological profile investigation, drilling core observation and the study of various sedimentary markers in the periphery of Qiangtang area. The results show that in the Middle Jurassic, the Qiangtang Basin inherited the evolution history of cracking and stretching since the Early Jurassic. Under the influence of ocean basin stretching, the Qiangtang basin mainly developed passive continental margin basin, and its upper facies paleogeographic units mainly developed confined platform and open platform. The facies belt spread along north-south direction and gradually deepened from north to south. The main development is confined to platform-open platform-shelf sediments. In the first member of Buqu Formation, there exists dolomite under limited platform evaporation environment in the first member of Buqu Formation in North Qiangtang, which belongs to high quality reservoir and is the main exploration target in the future. |