SEDIMENTARY FACIES ANALYSIS ON THE LOWER PERMIAN ANGJIE FORMATION OF THE CUOQIN BASIN IN TIBET AREA

The research of sedimentary facies is an important foundational work for the exploration and evaluation of petroliferous basins. According to data obtained from measured sections in Lajiadang, Juncang town, Nima county, Tibet, the lithological features, the types of sedimentary facies, the vertical sedimentary evolution of sections and the regional sedimentary characteristics of the Lower Permian Angjie Formation are analyzed in this paper. This formation is dominated by a set of sandstone-mudstone dark clastic rock series which belongs to marginal marine deposit at the end of the Gondwana Carboniferous-Permian glacier period. Its sedimentary type has the characteristics of both the stable deposit of Gondwana continent and the low energy deposit under coastal conditions, and mainly consists of a set of tidal-flat sedimentary assemblage whose sedimentary environment is related to short-period and small-scale inshore glacier activities.