Sedimentary environments and controlling factors of Permian source rocks in northeastern Sichuan Basin：A case study of Muguakou profile in Chengkou

Based on previous analyses as well as filed outcrop observations and sample tests, a case study of the Permian profile in the Chengkou area of the northeastern Sichuan Basin was carried out. Palaeoenvironment was restored according to the parameters of macroelement (oxidizing material) and microelement, and the relationship between palaeoenvironment and source rock development was analyzed. The controlling factors for the vertical and horizontal distributions of source rock were discussed. Several conclusions were made as followed. 1) On plane map, the source rocks of deepwater marine shelf and interplatform basin facies had the highest organic matter abundance and were most widespread in Permian in the study area. The source rocks of innerplatform depression subfacies had lower organic matter abundance. 2) Vertically, the Permian source rocks mainly developed in transgressive hemicycle, and reached the highest organic matter abundance during the maximum flooding period. 3) Organic matter abundance was controlled by ancient biological productivity and organic matter preservation condition. Both of the 2 factors were necessary for high organic matter abundance.