Sedimentary characteristics of Yingcheng formation in Longfengshan area of Changling fault depression

In the western structural belt of Longfengshan area of Changling fault depression, there developed the braided river delta sedimentary system, two sub-facies of delta plain and delta front, and six microfacies. While in the southeast slope belt, there developed the fan delta sedimentary system, fan delta front sub-facies and four microfacies. In the sedimentary period of Yingcheng formation, there were three kinds of source supplies, namely the metamorphic rock source area in the southwest, the magmatic rock source area in the south and the magmatic rock source area in the southeast. The multi-physical source leads to a strong regional zonation of rock and mineral components and the great difference in composition. During YingⅦ sand group to YingⅢ sand formation sedimentary period, the sedimentary sand bodies of different provenances carried forward from south to north, with increased material supply capacity and gradually expanded sedimentary range.