The Sedimentary Formation and Analyses for Dynamic Evolution of Jiuxi Cretaceous Basin, Gansu Province

In Gansu province,Jiuxi Cretaceous Basin is a monotype basin, in which grows sedimentary system of fan shaped alluvial fan delta, subgravity flow, lacustrine and fluvial facies. It was made up of some patterns combined by sedimentary system of fan shaped alluvium fan delta shallow lakeshore gravelly braided stream, subgravity flow mid deep lacustrine fan delta and fan delta mid shallow fluvial facies. According to isochronic surface, filled sequences in lacustrine basin can be divided into three tectonic sequences corresponding respectively to three evolutionary stages of embryonic rift, spread rift thermal attenuationary subsidence and basin shrinkage closure. On the basis of these evidences, it can be seen that either formation and attenuation of mantle's thermal column or remote stress ,such as Yanshan movement, etc.,controlled the evolution of the Jiuxi Cretaceous Basin.