As a component of long-term base-level decreasing cycle, Shanxi Formation constitutes a medium-term cycle, which can be subdivided into 5 short-term cycles in ascending order(SSC1,SSC2,SSC3,SSC4,SSC5).

• 作为晚古生代长期基准面下降旋回的组成部分,山西组构成一个中期基准面旋回(MSC2),自下而上划分为五个短期旋回(SSC1、SSC2、SSC3、SSC4、SSC5);