Deep-Water Combined-Flow Sedimentary Structure in the Xujiajuan Formation of Xiangshan Group, Ningxia
Deep-water deposits in the Xujiajuan Formation of Xiangshan Group are composed of grayish green, yellowish green, fine- to medium-grained light metamorphic sandstone, calcareous sandstone, siltstone and shale (slate). Based on the flume experiment and observation of modern ocean sedimentation, this study in combination with previous researches set up a facies diagram of combined flow bottom, and a schematic diagram of combined flow sedimentation caused by flows and waves in relatively shallow water. The result shows that the combined-flows are responsible for the formation of the combined-flow ripple lamination, quasi-planar lamination and asymmetric small-scale hummocky cross stratification in the Xujiajuan Formation.