Sedimentary characteristics of Alshan formation of lower cretaceous in Ha 301 fault block

Based on the establishment of sequence stratigraphic framework, the structural evolution characteristics of sedimentary paleogeomorphology of Ha301 fault block in Manit depression of Erlian basin are analyzed by using core, well logging, well drilling, logging and seismic data. The results show that braided delta front sub facies were developed in this area, which could be divided into subaqueous distributary channel, estuary dam, sheet sand and subaqueous distributary channel. In the sedimentary stage of A3 member, the buried hill uplift in the southwest margin and the mountainous area in the north jointly controlled the sedimentary distribution of the study area, forming two braided river delta systems in the north and south regions. With the differential tectonic subsidence movement of buried hill uplift, the braided river delta depositional system in the south of the basin was still a sedimentary pattern of the north-south sub-region during the sedimentary period of the lower A4 member of the basin. During the sedimentary stage of the uppermiddle A4 member, the whole tectonic subsidence occurred in the southern uplift and received buried hill draping sediments from the northern provenance, which proved that the supply direction of provenance, the sedimentary distribution and space-time evolution of Ha 301 fault block were all controlled by tectonic evolution of the sedimentary paleogeomorphology and the buried hills.