Study on sequence stratigraphy of Upper Permian in Panxian Mining Area of Guizhou

In order to explore the the sequence stratigraphy characteristics of coal bearing formation with marine-continental transitional facies, the high resolution sequence stratigraphy theory and method were applied to the study on the Upper Permian in Panxian county, western Guizhou, by a number of features such as the biostratigraphy and chronostratigraphy data, well vertical sedimentary sequences, well log response and geochemical characteristics. The study showed that based on five third-order sequence boundary, such as the regional tectonic unconformity surface, regional regression unconformity surface, exposure unconformity surface, regional transgression unconformity surface and drowning unconformity surface, Upper Permian in study region was divided into four third-order sequences. The sequence structure was the typical dual characteristic. Transgressive system tract (TST) and highstand system tract (HST) were the main part in sequence structure, and lowstand system tract (LST) was not well-developed. It presented the characteristics of slow transgression and rapid regression. The thick seams in the study region mainly distributed in the the early and middle TST. At the moment, the foundation subsidence was gently slow, the accommodation space increased rate and the peat accumulation rate was basically kept in the balances.