Latest drilling cores from recent shale gas exploration efforts reveal that storm deposits widely occurred in the Early Silurian shallow marine unit in the Lower Yangtze Region. Based on a detailed core observation and description， sedimentary characteristics of the storm deposits in the middle and upper part of the lower member of the Lower Silurian Gaojiabian Formation were analyzed and the effect caused by giant storms on the fine-grained sediment （mud） was discussed in the present study. The result shows that the tempestites are mainly composed of siltstones and are characterized by high content of quartz， textural immaturity， and two types of grain-size cumulative probability curves. Sedimentary structures of the storm deposits observed includes bottom scoured surface， massive bedding， parallel bedding， hummocky cross-stratification （HCS）， wave-ripple bedding， and soft-sediment deformation structure （SSDS）. Four storm sequences are identified according to the association of sedimentary structures vertically. These storm sequences are generally marked by sharp-base contact and fining upward， and were formed by different strength of flow energy. The origin of storms responsible for the Early Silurian deposits in the Lower Yangtze Region are associated with the paleogeographic and paleoclimatic settings. Giant storms impose a great influence on properties of muddy sediments in the shelf deep-water area， such as reducing the content of organic matter， reducing the bed thickness， destroying the vertical continuity， changing the original sedimentary structure and lateral stability， and thus generally reducing the quality of mudstone and shale. Accordingly， we suggest that more attention should be paid to the impact of storms on the original muddy sediments in the deep-water area of continental shelf during the exploration and evaluation of shale gas.

Keywords：Storm deposit;Storm effect;Early Silurian;Lower Yangtze Region