Sequence stratigraphy of the Upper Carboniferous strata along the margins of the Xuefeng ancient land

The Upper Carboniferous strata in the Yuanling region along the margins of the Xuefeng ancient land are characterized by limestones interbedded with dolomitic limestones,calcirudites,conglomerates and sandstones. The remarkable relative sea-level changes in these strata are considered to facilitate the sequence stratigraphic approach. The Upper Carboniferous strata as a third-order sequence overlie the Sinian Liuchapo Formation and underlie the Lower Permian Qianyang Formation,bounded by the type 1 sequence boundary at the top and the base,respectively. These strata consist of the lowstand systems tract,transgressive systems tract and highstand systems tract, which may be grouped,according to stratal stacking patterns,into two parasequence sets:transgressive systems tract and highstand systems tract.