The coal-bearing rock series in the south part of Xuanwei coalfield belong to upper Permian Longtan (P3l) and Changxing (P3c) formations. Coal-bearing strata thickness is 145.82~250.07 m, generally 191.24 m. Structures are complex in the study area;main structures have the Dehei syncline and NE-trending thrusts. The structures have controlled coal seams extending, presented buried depth configuration of shallow west, deep east and shallow south, deep north on the whole, and impacted largely on coal thickness in part of the area. The coal accumulation area is situated in a favorable belt of basalt lacking, relatively low-lying basement and terrestri-al-marine transitional zone. The lithofacies of coal-bearing strata in the area belongs to mainly fluvial environmental upper delta sedi-mentary system that is from fan delta, braided river transition to braided river, in which, distributary channel and flood plain sediments had co-developed. Coal seams in study area have features of multi-seamed, thick single seam, multiple mineable seams and abundant resources. In which, Longtan Formation contains more mineable coal seams with better coal quality, Changxing Formation basically con-tains no mineable coal seams and coal quality is rather poor.%宣威煤田南部地区含煤岩系主要为上二叠统龙潭组(P3l)和上二叠统长兴组(P3c),含煤地层厚度为145.82~250.07 m,一般厚度191.24 m.研究区主要构造为德黑向斜和北东向的逆冲断裂.构造控制了煤层的展布形态,整体呈现西浅东深,南浅北深的特点,在部分地区对煤层厚度影响较大;聚煤区处于玄武岩缺乏、基底相对低洼、海陆过渡等有利聚煤环境带内.本区含煤地层岩相是以河流环境为主的上三角洲沉积体系,即由扇三角洲、辫状河,而后过渡为网状河,其间分流河道与泛滥平原沉积共同发育.研究区及周边煤层层数多,单层厚度大,可采煤层多,资源量丰富,其中龙潭组含可采煤层较多,煤质较好,长兴组基本不含可采煤层且煤质较差.
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