In South China，the Permian Chihsia Formation contains several organic-rich dark rock series，which are the potential source rocks of hydrocarbon. Their formations is mainly related with the redox conditions and the ocean current system of paleo-Tethys Ocean. However，the formation model of this anoxic-dysoxic environment during the Chihsian stage is still needed more geological evidences. We carried on the REE，trace element Th/U raio and the carbonate-associated sulfate sulfur isotopic composition in the calcareous shale interbedded with carbonate rock in the stinkstone member of the Chihsia Formation in the Enshi section，West Hubei Province. Our results show that the lower part of the stinkstone member was anoxic-dysoxic environments while the upper part reflects oxic-dysoxic environments. This anoxic-dysoxic environment resulted from the upwelling. This upwelling brought the oxygen-depleted bottom water in the deep-water environment to the shallow water of the slope environment，resulting in an interted triangle-shape oxygen-depleted water zone and depositing the dark-gray thin-bedded limestones or calcareous shale of the Chihsia Formation.
Jiang Zengguang Wei Hengye Qiu Zhen Yu Yongshan. Formation model of anoxic-dysoxic environments in the Lower Chihsia Formation in the Enshi section[J]. Chinese Journal of Geology, 2017, 52(1): 218-229.