Abstract:Deep-water deposits in Xujiajuan Formation of Xiangshan Group is made up of gray-green, yellow-green, fine- to medium-grained sandstone, calcareous sandstone, siltstone and shale(slate)with slightly metamorphic. Combined-flow-ripple lamination and quasi-planar lamination and asymmetric small-scale hummocky cross stratification are found in medium beds calcareous siltstone interlayer in gray-green shale of the upper part, and the small-scale ripple marks which suggests the sedimentary characteristics of combined-flow in both their shapes and distribution of wave length and wave height are also found on the top surface of gray-green medium to thick feldspar-quartz sandstone of the lower part. In this paper, the interpretation of: (1) the evolution of small-scale 2-D ripple marks to 3-D ripple marks; and (2) the sequence of combined-flow ripple lamination, quasi-planar lamination and small-scale hummocky cross stratification as well as the relationship between the flow direction suggests by lamina of cross bedding and the turbidity current direction while deposited according to: (1) the combined-flow bed-phase diagram summarized from flume experiments and observation of modem marine deposit; and (2) the combined-flow deposition cartoon was given by previous researchers from the ancient deposition of combined-flow which is produced by hyperpycnal flows and waves in relatively shallow water. The result shows that the combined-flow ripple lamination and quasi-planar lamination and asymmetric small-scale hummocky cross stratification exist in Xujiajuan Formation are produced by combined-flow, and we interpret the combined-flow as a interaction of high frequency internal wave and turbidity current according to the deposition of internal wave. This perhaps is the first discovery of deep-water sedimentary structure of combined-flow origin as well as the combined-flow deposition produced by internal wave and turbidity current.