An analysis of sedimentary characteristics and model of Silurian Xiaoheba Formation in southeastern Sichuan Province

In order to determine sedimentary characteristics and model of the Late Early Silurian strata,the authors comprehensively studied outcrop sedimentary features and a large number of core and well logging data of the Silurian Xiaoheba Formation.The results show that the late Early Silurian transitional sedimentary system group and marine sedimentary system group are developed in southeastern Sichuan Province and include three kinds of sedimentary facies and lots of sub-facies as well as micro-facies.Delta deposits are developed in southeast Sichuan-western Hunan area close to Xuefeng Mountain uplift.Carbonate platform deposits are developed in southern Sichuan-northern Guizhou area.Shelf deposits are developed in the Yibin-Chongqing area.Sedimentary model shows that southeastern Sichuan area was a confined basin in early Silurian Xiaoheba period controlled by the uplift.In the east,controlled by Jiangnan-Xuefeng Mountain uplift,there exist a set of upward coarsening delta deposits.In the south,controlled by the relatively stable Guizhou uplift,carbonate platform deposits are existent on the northern side.The new understanding has an important theoretical and practical significance for more accurately predicting the distribution of the sandstone of Xiaoheba Formation in southeastern Sichuan Province,forecasting favorable accumulation zones and further deploying oil and gas exploration.