Sequence Stratigraphic Study of the Majiagou Formation of the Ordovician System in the Zichang-Yanchuan Area
In this study,a sequence stratigraphic division scheme is proposed based on the previous research results.According to the scheme,the Ordovician strata in the study area are subdivided into two supersequences and eight tertiary sequences.The Majiagou Formation is composed of five sequences,OSQ4-OSQ8,with the exception of OSQ4,which is a type I sequence interface,and the others are a type II sequence interface.