The Study On Coal Seam Hosting And Coal-controlling Factors Of Beishan Rigion Of Yuqia Coalfield

The paper is based on current geological exploration data of Yuqia coal field of Beishan region of Qinghai province and the previous research results,which guided by theories of sedimentology and coal geology.To study the coal accumulation is as the main line,the paper focused on the research of coal bearing areas,and conclusion of the geological background and coal seam hosting pattern of study area.Then to analyze the law sedimentary and the structural controlling coal.Finally summarizing the distribution law of coal resources in the process of basin evolution.The exploration region of Beishan is located on 45 km of the north-west of Da chaidan town,Haixi state,Qinhai province,whose square is 24km2.The whole structural configuration is a anticline,and has some associated fault whose structural complexity is middle to complex.The coal-bearing strata is coal-bearing member of Shimengou group and Dameigou group of middle Jurassic,including M5,M6,M7 which are stratified and compared coal groups,and main coal bed is more stable type.The study area was always being on denudation stage before Triassic.Middle Yanshan movement,it was gradually accepting sedimentary of Jurassic.During the period of middle and late whole Yanshan movement,it experienced process of increasing,decreasing and decreasing again,which the coal bearing area of Jurassic of Yuqia region was forming during decreasing.The coal bearing strata of study area of Jurassic are all continental deposit,and mainly coal accumulating environment contains alluvial,braided river,braided river delta,meandering river delta and river coal accumulating environment.The most favorable area to forming coal of the study area is peat swamp of delta,especially in flood basin and depression where the ground is low,the water is shallow,nutrition is rich that is benefit for growth of plants and accumulation of peat,forming thick coal seam.The worse environment is braided river and braided river delta.Due to the influence of frequent lifting of surface of lake,the worst environment is lakeshore swamp.The mainly control coal fracture of the study area are reverse faults(F7 and F1).The reverse fault of F7 is located on the north of coal bearing area of Beishan,the hanging wall of the fault not only losses coal bearing strata,but also was eroded because of outcropping ground.However,the coal bearing strata of the footwall is saved very well,especially 1st member in Dameigou group,2st member in Dameigou group and 1st in Shimengou group,whose environment is braided river accumulating environment and has a better potential to prospect.