西湖凹陷古近系花港组风暴沉积研究

通过岩心观察，发现花港组典型的风暴沉积构造主要包括风暴侵蚀形成的渠模、冲刷沟槽、冲刷面，风暴涡流形成的撕扯构造、菊花状构造，风暴重力流形成的粒序层理，风暴浪形成的丘状交错层理、浪成沙纹层理、平行层理，同生变形构造及生物逃逸构造.运用岩石相组合分析的方法，发现花港组风暴垂向沉积序列发育不完整.其理想的序列由A~G共7段构成。根据花港组垂向沉积序列类型、沉积构造特点总结出了A+B+G、A+B+C、A+B+D、B+C+D、C+E+G、E+F+G等6种风暴沉积序列和原地风暴岩、近源风暴岩和远源风暴岩3种风暴岩类型.

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.