Coal Controlling Factor Analysis In Santanghu Coalfield,Xinjiang Province,NW China

The Santanghu coalfield located in Trupan-Hami basin, Xinjiang Province, is one of the major coalfields. Based on the coal exploration data collected from Xinjiang Bureau of Coal Geology Coal Geological Exploration, the paper analyses coalfield tectonic,stratigraphic sequence, coal-forming environment, sedimentary evolution and coal accumulation to provide some reference for exploration and development of coal seam in this region in the future. The following is these conclusions.(1) Based on the two important unconformity, two local unconformity and erosion surface, the middle-lower Jurassic in the Santanghu coalfield is subdivided into three third-order sequences and nine system tracts. Sequence consists of low stand system tract,transgressive system tract and high stand system tract. SQ1 corresponds to the Badaowan Formation and SQ2 corresponds to the Sangonghe Formation as well as SQ3 corresponds to the Xishanyao Formation. These are also applied in Santanghu coalfield.(2) Based on these analyse of color of Jurassic strata, fossils and pollen data,the paloeclimate is humid subtropical during the early lower Jurassic, which is favorable for plant growth and peat accumulation. The major sediement-source regions for the Santanghu coalfield are the Dahaputike mountain, Sutuhai mountain and Shuangyan mountain located to the north of the Santanghu basin.(3) Based on these analyse of core, logging and analysis data, the sedimentary faces consist mainly of fan delta, delta, lakes, swamps and flood plain. These depositional systems will be subdivided into 10 subfaces and 22 micro-faces.(4) The paper studies the sedimentary faces within framework of sequence stratigraphy.In addition, based on the well profile, cross-section profile, sandstone isogram and sandstone/mudstone ratio isogram, the paper represents these distributions of sedimentaryfaces of nine system tracts.(5) The Santanghu basin represents various sedimentary faces controlled predominantly by basin tectonic. The overlying sequence accedes these sedimentary faces of underlying sequence.(6) Based on the base-level and accommodation changes, the paper reconstructs the sequence models of middle-lower Jurassic in the Snatanghu basin and analyses coal accumulation within sequence framework. The coal thickness are mainly controlled by lake level change, palaeogeomorphology and depositional environment. The delta plain is favorable location for peat accumulation during the period of lowstand system and highstand system tract.