Study On Sedimentary Evolution And Coal Accumulation Pattern Of Shanxi Formation In Gujiao Yangzhuang Mine

After the interpretation and contrast of rock cores, logging data of 42 boreholes in the area, as well as coal mining revealed data, combined with rock association,sedimentary structure, section configuration, logging facies association and North China Late Paleozoic Early Permian Epoch epicontinental sea basin geological setting,analyzed lithologic combination, extending characteristics and evolution history of the Shanxi Formation. The study has considered that the Shanxi Formation was under shallow water delta environment, in delta frontal subfacies identified mouth bar,underwater natural levee, interdistributary bay and underwater distributary channel microfacies; in plain subfacies identification onshore natural levee, marsh and distributary channels are microfacies. Through the analysis of sedimentary facies plane distribution characteristics, concluded the sedimentary model and evolution evolution law of Shanxi Yangzhuang mine as follows: in Shanxi period, Yangzhuang area developed the shallow water delta sedimentary system, especially the delta plain subfacies, followed by delta frontal subfacies; and formed the main area of the coal seam in delta plain subfacies; Then under the paleogeography background, analyzed the coal accumulating pattern of the Shanxi Formation in Yangzhuang exploration area. The variation of coal thickness was mainly controlled by sedimentary environment and later stage local scouring, and might not be associated with basement environment. The sedimentary environment evolution of Shanxi Formation and thick coal seam extending characteristics has demonstrated that the minefield was within the North China Late Paleozoic Early Permian Epoch stable craton basin. Finally,analyzed the control factors of the coal seam, such as the ancient tectonic, the sedimentary environment of the ancient geography, the sedimentation rate of the substrate and the change of the lake level.