黔北煤田吴家寨地区晚二叠世煤层地球化学特征及聚煤环境分析  

Geochemical Characteristics and Coal Accumulating Environment Analysis of Late Permian Coal Seams in Wujiazhai Area,North Guizhou Coalfield

作　　者：杨旭[1] 刘志臣[1] 秦先进 肖林 陈磊 李隆富 汪洋[1] YANG Xu;LIU Zhi-chen;QIN Xian-jin;XIAO Lin;CHEN Lei;LI Long-fu;WANG Yang(Geological Party,Guizhou Bureau of Geology and Mineral Exploration and Development,Zunyi 563003,Guizhou,China)

机构地区：[1]贵州省地矿局102地质大队,贵州遵义563003

出　　处：《贵州地质》2021年第3期299-308,共10页Guizhou Geology

基　　金：贵州省优秀青年科技人才,黔科合平台人平[2019]5654项目、贵州省地质矿产勘查开发局地质科研项目资助。

摘　　要：为了探讨煤层地球化学特征和成煤环境的关系,根据黔北煤田吴家寨地区上二叠统龙潭组煤样地球化学特征分析数据,评价了该地区晚二叠世煤的总体煤质特征,重点探讨了煤灰成分指数、微量元素和稀土元素与成煤环境的联系。结果表明,研究区灰成分指数(Fe_(2)O_(3)+CaO+MgO)/(SiO_(2)+Al_(2)O_(3))、SiO_(2)+Al_(2)O_(3)平均0.28,属较强还原型;灰成分中CaO+MgO、Fe_(2)O_(3)+SO_(3)、SiO_(2)+Al_(2)O_(3)三个组分的百分含量中,SiO_(2)+Al_(2)O_(3)含量最高,说明粘土矿物为代表的陆源矿物类型多与淡水介质注入有关。煤中灰分产率、煤灰成分指数以及灰成分三端元分析均揭示研究区的聚煤环境为:从陆源区水浅、水动力较强、还原性较强的环境向远离陆源区水深、水动力较弱而还原性较强的环境变化。研究区微量元素Sr/Ba均值为0.15,表明为淡水环境。研究区稀土元素地球化学参数Eu负异常,Ce均未出现明显负异常。故研究区主要为陆相聚煤环境,成煤环境受海水影响很小。综合分析认为,吴家寨地区晚二叠世聚煤环境主要与古气候、沉积环境等因素有关。In order to discuss the relation between geochemical characteristics of coal seams and coal forming environment,based on the analytical data of geochemical characteristics of coal samples from Longtan formation of upper Permian in Wujiazhai area of North Guizhou coalfield,the overall coal quality characteristics of late Permian coal in this area were evaluated,and the relation between coal ash composition index,trace elements and rare earth elements and coal forming environment was mainly discussed.The results show that the ash composition index(Fe_(2)O_(3)+CaO+MgO)/(SiO_(2)+Al_(2)O_(3))and SiO_(2)+Al_(2)O_(3) in the study area are 0.28 on average,which belong to strong reduction type;The content of SiO_(2)+Al_(2)O_(3) is the highest in CaO+MgO,Fe_(2)O_(3)+SO_(3) and SiO_(2)+Al_(2)O_(3),which indicates that the terrigenous minerals represented by clay minerals are mostly related to fresh water injection.The three terminal element analysis of ash yield,ash composition index and ash composition reveals that the Coal Accumulating Environment in the study area changes from the environment with shallow water,strong hydrodynamic force and strong reducibility in the terrigenous source area to the environment with deep water,weak hydrodynamic force and strong reducibility far away from the terrigenous source area.The average value of trace element Sr/BA in the study area is 0.15,indicating that it is a freshwater environment.The geochemical parameters of rare earth elements in the study area are EU negative anomaly and CE negative anomaly.Therefore,the study area is mainly continental coal accumulation environment,and the coal forming environment is little affected by sea water.Comprehensive analysis shows that the Late Permian coal accumulation environment in wujiazhai area is mainly related to paleoclimate,sedimentary environment and other factors.

关 键 词：煤层 二叠纪龙潭组 地球化学 聚煤环境 吴家寨地区 

分 类 号：P618.11[天文地球—矿床学]