龙街向斜石炭系煤岩煤质特征及其成煤环境

Petrography and quality characteristics of carboniferous coal and its coal-forming environment for coal from Longjie syncline

贵州威宁-兴义片区石炭系发育良好,层序完整,相带齐全,是我国研究海相石炭系既重要又典型的地区。为明确威宁片区龙街向斜煤岩煤质与成煤环境的关系,简述勘查区的地质概况及含煤地层,从煤岩煤质和地球化学特征入手,详细分析了各可采煤层的镜质体与惰质组之比、灰分、硫分、灰分指标以及成煤标志、聚煤环境特征、成煤演化等其它相关成煤环境参数,探讨其对成煤环境的指示意义。研究表明,区内5号、9号煤层属于低灰、高硫的高变质无烟煤;原煤硫分与灰分分布规律十分相似,靠海覆水较深的区域硫分含量高,灰分含量也较高;靠近陆源区硫分含量低,灰分含量也低;原煤全硫含量与灰分指数、古盐度、CaO/MgO值等所反映的成煤环境具有较高的一致性,为半咸水泻湖相(浅水)泥潭沼泽成煤环境;成煤环境受控于古地理、古气候作用明显。

The Carboniferous system in Weining-Xingyi area of Guizhou province is well developed with complete sequence and facies belts.It is an important and typical area to study marine Carboniferous system.In order to clarify the relationship between coal quality and coal-forming environment of Longjie syncline coal in Weining area,the coal quality and Coal-bearing stratum of the exploration area was introduced,from geological survey and geochemical characteristics,this paper analyzed the mirror/inerting ratio,ash content,sulfur content,ash composition index,coal forming mark,environmental characteristics of coal accumulation and coal forming evolution,this paper also probed its indicating significance to coal-forming environment.The results show that No.5 and No.9 seams in the zone belong to high metamorphic anthracite with low ash and high sulfur.The distribution rules of sulfur content and ash content of raw coal are very similar.The sulfur content and ash content are low near the land source area.The total sulfur content of raw coal has a high consistency with the coal-forming environment reflected by ash index,ancient salinity and CaO/MgO values.Coal-forming environment was controlled by paleogeography and paleoclimate.