Sedimentary characteristics and evolution of the carbonate platform-margins in the Changxing Formation-Feixianguan Formation in Yuanba,northeastern Sichuan

The carbonate platform-margin deposits consist of organic bank and oolitic bank deposits in the Changxing Formation-Feixianguan Formation in Yuanba,northeastern Sichuan.The carbonate platform-margins went through the evolution from the initiation of the platform margins during the late Wujiapingian,through the development and termination of the platform-margin reefal bank during the Changiangian,to the development and termination of the platform-margin oolitic bank during the early Indian,and finally to the filling of the platform margins during the late Indian.The controlling factors include topography,hydrodynamics,depositional rates and increasing rates of accommodation spaces,all of which have consequences for lithology and the styles of the accumulation and migration of the platform-margin deposits.