Abstract:

Storm deposits has been found for the first time in the 2nd member of Xujiahe Formation ( Upper Triassic) in western Sichuan Basin.Based on the micro-facies of cores,the main types of tempestite sedimentary characteristics have been identified, including gutter cast, scouring surface, truncated structure, storm lag deposit, hummocky cross-stratification,convoluted laminations, V-shaped structures generated by wave. A detailed study of sedimentary structures and petrological features of storm deposits has been made, such as individual laminates,thickness of storm deposit, and so on. The storm deposits are characterized by their lithologic features, and storm sedimentary sequence are related to storm activity and similar to the typical Bouma sequence.The sedimentary environment of tempestites is discussed,and the storm sedimentary model is explored.

Key words: Xujiahe Formation, tempestites, deposit characteristcs, sedimentary model