STUDY ON THE STORM DEPOSITS OF PALEOGENE HUAGANG FORMATION IN XIHU SAG

Based on the core observation, it is found that the typical storm-generated sedimentary structures of Huagang Formation mainly include gutter casts, scour holes and scour surfaces by erosion, tear and chrysanthemum-like structures by storm eddy, graded bedding by storm gravity flow, hummocky cross stratification, wave ripples and parallel bedding by storm wave, as well as syngenetic deformation and escape structures. Through analyzing the lithofacies combination, the results show that the vertical storm sedimentary sequences are incompletely developed in comparison to the ideal sequences which consist of bottom-up seven layers from A to G. Six sequences of storm deposits, namely A+B+G, A+B+C, A+B+D, B+C+D, C+E+G and E+F+G, and three types of tempestite(in-situ, proximal and distal) are summed up on the basis of the vertical sedimentary sequences and structure features.