The study on fine sedimentary system of mud shale is the frontier of sedimentology. Taking the fine-grained mud shale from the upper submember of Member 4 and lower submember of Member 3 of Shahejie Formation in Jiyang depression as an example, using core description, thin section observation, geochemical tests and other methods, this paper investigates the fine-grained sedimentary system of lacustrine shale. It is considered that the mud shale from the upper submember of Member 4 and lower submember of Member 3 of Shahejie Formation in Jiyang depression is a product of the combined action of mechanical and biochemical mixed sedimentation under the relatively stable water environment. Based on the basic characteristics of mud shale in this study area mainly composed of allogenic terrestrial clastic rocks outside the basin and authigenic carbonate rocks inside the basin, the sedimentary facies are divided to exogenous facies, hybrid-source facies and the endogenous facies according to the material sources. Furthermore, mainly based on the orderly combination of sedimentary dynamics and lithofacies, in combination with the paleo-topography, the exogenous facies is divided into slope edge subfacies and outer slope subfacies; the hybrid-source facies is divided into inner slope subfacies and deep sag subfacies; the endogenous facies is divided into underwater bulge subfacies and panland subfacies. The sedimentary system is controlled by the evolution of sedimentary environment vertically. As the climate evolves from drought to moisture, the material source injection is enhanced. From bottom to top, endogenous facies, hybrid-source facies, and exogenous facies are developed. In the lateral direction, due to the symmetric supply of material source along the short axis of the basin, the sedimentary facies are characterized by symmetric distribution. From the gentle slope to the steep slope, the exogenous facies, hybrid-source facies, endogenous facies, hybid-source facies, exogenous facies are developed successively. In plane view, controlled by paleo-provenance, paleo-salinity and paleo water depth, the sedimentary facies is roughly distributed around the geometric center of the basin and distributed in a ring-like shape. The endogenous facies is mainly distributed in the underwater bulge and panland, the hybrid-source facies is mainly developed in the semi-deep lake area, and the exogenous facies is mainly distributed on the edge of coarse clastic rock system.
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