The Characteristics of Storm Current Deposits in the Proterozoic Fengshanying Formation,Huili Group,Sichuan

A suite of storm current deposits with a thickness of 845 m is developed in the upper part of the Proterozoic Fengshanying Formation in the Hongchuanqiao area, Huili County, Sichuan Province. These tempestite beds comprise the overlapping lenticular layers composed mainly of grey and dark grey silty calcisiltites, locally of argillaceous limestones. The common sedimentary structures include parallel lamination, wave ripple cross-lamination of hummocky crossstratification, storm wave ripples and convolute structure,etc.. The vertical sequences of the storm current deposits in the Hongchuanqiao section consist generally of the association of parallel beds and hummocky cross beds, occasionally of the association of parallel beds, wave ripples and lag beds. Graded beds and sole erosion structure, however, are rare. It follows that the storm current deposits should be the distal deposits near wave base on clear-water shelf.