Constitution of Rocks and Evolution of Sedimentary Cover in North China Platform

This paper has discussed volumes and mass of each period sedimentary strata in North China platform .The constitution of rocks has been calculated and compared with other main platform in the world. The sedimentary cover of North China plateform is composed of one/thind carbonate and two/thinds terrigenous rocks. The constitution of rocks is similar to Laurasia and North China platform. But there are poor evaporite and extensive distrubution of carbonate. Compared with the earthy s sedimentary shell, North China Platform is characterized by that terrigenous rock is rich in clastic rock(41 percent of grass rock volum ) and percentage of argillaceous rock is low(26. 7 percent of grass rock volum). However,Character of constitute of rocks of each sedimentary time is greatly different from each other, which is determined by special history of geological development in North China Platform. Periodically tectonic and thermal event changed the resource of sedimentary rock and rate of sedimentation. It makes mass, volume constitution of rocks change with tectonic cycle, and is main base of variation of constitute,volume,mass. Only in Longer period of geological time,will the influence of recycling of sediment be obvious. Because the influence of tectonic一thermal event is averaged in this case. The influence of recycling of sediment also exist in the stable period of tectonic activity .Only considering tectonic event and recycling of sediment can we realize the variation of the constitute of sedimentary rocks and mass. Simulating calculation shows that the 90% of sedimentary rock in North China Platform have been recycled during the period of sedimentary cover development which indicates that it is main recycling of sedimentary rocks during sedimentary cover development.