Coal-accumulating Pattern Of The Main Minable Seamin Dongsheng Bojianghaizi Exploration Region

Dongsheng Bojianghaizi exploration region is located at the northwestward margin of Dongsheng coal field as the important coal base of our country with rich coal resources, fine coal quality and simple mining condition. Structural feature is dominated by northwest tilted uniclinal structure, the variation of strike and dip are much smaller for attitude of stratum. Middle-lower Jurassic Yan’an formation is the main coal-bearing stratum which contains5～16coal seams, having only6minable coal seams.Use the method and theory of coal accumulating basin analysis and petrology, sedimentology, structural geology and coal geology, etc. Integrated various kinds of geological data and previous research results, dividing the depositional system of Yan’an formation, it shows braided river, delta and meandering river in profile from bottom to top. It goes through three stages of fill and level up, overlapping spread and recession by analyzing the lithofacies paleogeographic condition in this area in the period of Yan’an formation. This paper found out the correlation between the main minable coal seam and the lower part of sand body by comparative analysis of their thickness contour map. Besides, this paper analyzed the controlling factors in coal formation process, such as paleoclimate, paleogeography and paleostructure, and then preliminary study and summarize coal-accumulating pattern of Yan’an formation in this area.