[Objective]Conglomerate is unique oil and gas reservoir, and understanding its sedimentary origin and evolution is important for accurately predicting the distribution of high-quality reservoir. [Methods]Based on core logging, petrology identification, heavy mineral and grain size analysis, combined with well logging data, the sedimentary characteristics, spatial distribution and sedimentary provenance of the Lower Triassic Baikouquan Formation conglomerate in the Madong slope area are defined, the sedimentary mechanism of the formation is clarified and the sedimentary model is established. [Results]The results show that the Baikouquan Formation was deposited in the shallow-water fan delta, and the fan body developed three subfacies, namely fan delta plain, fan delta front and pro-fan delta, including 9 microfacies, containing debris flow, braided channel, flood deposit, subaqueous debris flow, subaqueous main channel, subaqueous branch channel, sandy clastic flow, far sand bar and pro-fan delta mudstone deposits. It contains 10 types of lithofacies. [Conclusion]Combined with the paleoclimate background of the early Triassic which changed from drought to moisture, the conglomerate is the sedimentary product of flood induced gravity flow, which has the characteristics of complex lithofacies associations, significant signs of eventful deposition, sedimentary model dominated by paleoclimate, and obvious transformation of lake wave. In terms of spatial extent, the grain size of the Baikouquan Formation conglomerate in the Madong slope region gradually becomes finer from bottom to top, which reflects the sedimentary sequence of the lake transgression and presents the signature of a multi-period superposition of debris flows, underwater debris flows, and subaqueous channel deposits.
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