In early Permian period,the epicontinental sea of North China Platform receded conti-nously to the south,thus the-coal accumulations of continental delta facies are generated inthe southeast of North China Platform.

• 二叠纪早期，华北地台的陆表海不断向南退缩，从而在华北地台东南部开始了陆相三角洲的聚煤作用。