Based on the structural geology, sedimentology, palaeontology and geochemistry, the sedimentary facies and evolution patterns are developed in Songnan area from the studies of seismic data, cores, well logs, palaeontology and geochemistry. The result indicates that nearshore subaqueous fan, fan delta, braid delta and lacustrine had been developed in the fault depressions of Songnan area. From the margin to the depocenter of the basin, the sedimentary environments gradually changed from nearshore subaqueous fan, fan delta or braid delta to shore-shallow sediments and middle depth-deep lacustrine. Two stages are divided for the sedimentary evolution of Songnan area, namely the prior stage which appears with Yixian formation developing lava facies and pyroclastic facies; the other is the detrital rock facies ,which are developed from formation Jiufotang to Fuxin, is composed of nearshore subaqueous fan, fan delta, braid delta and lacustrine. Conclusion can be made that those sedimentary facies are controlled by the depth of water variation, which changed from shallow to deep, and then to shallow. Multiple source-reservoir-cap assemblage in vertical provided favourable condition for oil and gas pool forming.
