Study of Sedimentary Facies, Lithofacies Palaeogeography of Four Member of Xujiahe Formation of Upper Triassic in the Weidong-Anyue Area,Anhui Province
Based on rock types, sedimentary structures and section structure features, this paper divided the Xujiahe Formation into delta and lake facies, and the former is further divided into delta plain and delta front sub-facies, while the latter only shows the development of shallow-lake sub-facies in the area studied, and then made a study in detail of the compositional features of micro facies of each sedimentary facies. On the basis of the above-mentioned study, with each sub-facies of the Xusi member as map formation units, the authors prepared lithofacies palaeogeographic map for each sub-facies and researched into their time framework of evolution. The results indicated that the sub-facies of the Xusi member are expressed from south to north as delta plain, delta front and shallow lake. The results serve as basic geological data for further prognosis of reservoir.