SIGNIFICANCE OF THE SUBMARINE FAN OF LOWER PERMIAN SHOUSHANGOU FORMATION IN WEST UJIMQIN-QI, INNER MONGOLIA

The recognition about the sedimentary environment of Shoushangou Formation still lacks conclusive evidences at present. Based on the investigation in Tabinmiao forestry center, the Shoushangou Formation is recognized as a series of marine clastic deposition, characterized mainly by feldspathic litharenite, with graded beddings and parallel beddings, belonging to the Bouma sequence, developed with the zoophycos facies of trace fossil assemblagethe deposition is thus recognized as submarine fans. According to the rock types, thickness of single sandstone layer, and the ratio of sandstone and mudstone, three subfacies are divided, i.e. inner fan, middle fan and outer fan. The inner fan develops channel conglomerate; while the outer fan develops flysch trace fossils. The thick black mudstone of Shoushangou Formation could be the good hydrocarbon source rocks. The fan bodies are possibly effective reservoirs, with great prospects for oil and gas exploration.