SEDIMENTARY FACIES,SEDIMENTARY MODEL AND EVOLUTION OF THE SHINIULAN FORMATION OF EARLY SILURIAN IN THE SOUTHEAST SICHUAN

Based on detailed research on six drilling wells data,14geological sections,drilling cores and over 200thin sections,the characteristics of sedimentary facies and the sedimentary model of the Shiniulan Formation in the southeast Sichuan were analyzed and constructed,and the distribution map of sedimentary facies was compiled and the depositional evolution was discussed.It is showed that the Shiniulan Formation belongs to marine deposit which can be classified into limited platform,platform margin shoals,platform margin organic reefs,carbonate ramp,continental shelf,onshore and delta facies respectively.Affected by second-grade sea level changes,the transgressive reef-beach bodies were well developed in Changxing Formation,forming two types of favorable reservoirs.The reef-beach facies migrated and uplift in vertical direction and developed in zonal form on both sides of the basin,and controlled by sedimentary facies.Overall,the deposition of the southeast Sichuan was characteristic of carbonate slope facies and platform edge reef-bank facies in the Shiniulan Age,and the depositional model belongs to the gentle slope sedimentary mode.