内蒙古潮水盆地西部侏罗系煤的岩石学、矿物学及地球化学特征

Petrographical,Chemical and Geochemical Characteristics of Jurassic Coal in Western Chaoshui Basin,Inner Mongolia

潮水盆地位于内蒙古西南部和甘肃省东部地区,是我国中新生代含煤断陷盆地。采用粉晶X衍射、ICP-MS、ICP-AES方法,从煤的岩石学、煤化学及煤地球化学的理论出发,对潮水盆地西部煤样进行了煤化学、显微组分、矿物学及地球化学分析。其研究结果表明潮水盆地西部煤以中等水分、低-中灰分和硫质量分数、高挥发分产率为特征,煤级为烟煤—亚烟煤;煤中有机显微组分以镜质组为主,惰性组次之,煤相类型以潮湿森林沼泽相为主,其次为较浅覆水森林沼泽相;煤中的常量矿物以石英和高岭石为主,部分样品中含有黄铁矿、方解石、菱铁矿和少量的微斜长石;煤中除Sr、B和Cs质量分数相对较高外,其他微量元素质量分数普遍较低。Cr、Ga、Pb、Li、Cu、Ge、V、Sc、Be、W、Th和As,以及Ti和Nb主要与硅铝酸盐矿物有好的亲和性;B和Sr可能主要以碳酸盐矿物的形式存在;S和Mo可能主要以硫化物矿物的形式存在;另外,Ti、Zr、Nb和Ta有好的相关性,可能与重矿物有关。

Chaoshui Basin, one of Mesozoic and Cenozoic faulted basins in China, locates in the southwest of Inner Mongolia and the east of Gansu Province. This study focuses on the petrography, chemistry and geochemistry of the coals from the western of Chaoshui Basin by maceral analysis, proximate analysis and inductively coupled plasma atomic-emission spectrometry （ICP-AES）, and inductively coupled plasma mass spectrometry （ICP-MS）. The results show that the coal rank ranges from the high volatile bituminous to subbituminous. The coal is characterized by low ash and sulfur contents. The major macerals are vitrinite and secondly inertinite. Major mineral phases presented in the coals are quartz, kaolinite, secondly Pyrite, calcite, siderite and a small amount of amazonite and microcline. The coaly facies are mainly wet forest swamp facies, and partly of shallow forest swamp facies. Except Sr, B and Cs contents are relatively high. Other trace element content are low in coal. Cr, Ga, Pb, Li, Cu, Ge, V, Se, Be, W, Th, As, Ti and Nb have a positive correlation with aluminium-silicates. B and Sr may mainly exist in the form of carbonate minerals. S and Mo may mainly exist in the form of sulfide minerals. In addition, the high relevance be- tween Ti, Zr, Nb and Ta show that they may exist in the form of heavy minerals.