Based on the data and regional geological survey, the authors bring out a complex sedimentary dynamic model: Crust extension-differential subsidence-hydrothermal water raises (companied with volcano-quick transgression (companied with rising ocean current)-anoxic event. It is to say, because of crust extension, the volcano was taken place, and the siliceous rocks developed widely in shelf facies in southeast margin of Yangtze block, persisting extension increased differential subsidence, and made the platform facies farther uplifting and being eroded, and on the other hand, the siliceous rocks developed continually in slop and shelf facies.