Research on petrology and sedimentary sequences of phosphorites in Weng'an,Guizhou

The Petrology Characteristics of phosphatic series inWeng'an and its connection to the sedimentary environments were discussed.And the diversification in profile of the characteristics of structure as well as material components of phosphorites in each layer have been studied too.The type was carbonatite phosphatic series, varieties of structural types of phosphorite showed different causes and different sedimentary environments. With undertaking the partition of sequence stratigraphic on the Chuan Yan-dong section inWeng'an,the strata of the Doushantuo Formation may be grouped into six shallowing-upward depositional sequences.Because the sealevel's rising and falling constantly,the plentiful phosphatic seawater carried by upwelling oceanic currents entered into the shallow marine areas rhythmicly and deposited.The sediments had the feature of cyclic in the vertical and multiple sequential.