陕西典型矿区煤系关键金属元素富集特征及其成因机制  

Enrichment characteristics and mechanism of critical metal elements enrichedin coals from typical coalfields in Shaanxi Province

作　　者：李晶[1] 王园 袁伟 庄新国[1] 李宝庆[1] 上官云飞 杨光华 潘磊 LI Jing;WANG Yuan;YUAN Wei;ZHUANG Xinguo;LI Baoqing;SHANGGUAN Yunfei;YANG Guanghua;PAN Lei(Faculty of Earth Resources,China University of Geosciences(Wuhan),Wuhan 430074,China;Inner Mongolia Coal Geological Exploration(Group) Co.,Ltd.,Hohhot 010010,China;Xi’an Institute of Geology and Mineral Exploration,Xi’an 710100,China)

机构地区：[1]中国地质大学(武汉)资源学院,湖北武汉430074 [2]内蒙古煤炭地质勘查(集团)有限责任公司,内蒙古呼和浩特010010 [3]西安地质矿产勘查开发院,陕西西安710100

出　　处：《煤炭学报》2022年第5期1808-1821,共14页Journal of China Coal Society

基　　金：国家重点研发计划资助项目(2021YFC2902000);国家自然科学基金资助项目(41972179)。

摘　　要：煤型关键金属矿床的研究现已成为国内外煤地质学和矿床学研究的重要内容,也是当前国际矿产地质界的前沿问题。陕西煤炭资源丰富,含煤岩系涵盖石炭—二叠系(太原组,山西组)、三叠系(瓦窑堡组)及侏罗系(延安组),不同煤田及不同时代煤层煤质特征差异较大,部分地区煤中存在关键金属的富集。为了查明陕西煤系关键金属的富集分布特征及成因机制,选取主要煤田10个典型煤矿的含煤岩系为研究对象,系统开展煤的工业分析、全硫分析和微量元素地球化学测试。陕西煤中关键金属富集主要分布于石炭—二叠系煤系,在渭北及陕北石炭—二叠系煤系中普遍存在Li-Ga-Nb-Ta-REY关键金属组合的共富集。这些关键金属主要赋存于高岭石、勃姆石、磷酸盐等矿物中,且在靠近煤层夹矸及顶底板的煤系中更为富集。陕西石炭—二叠系煤中关键金属的富集与华北地台沉积基底及本溪组古风化壳密切相关,关键金属元素主要由盆地周缘蚀源区古风化壳黏土质和铝土质碎屑物质经水系搬运进入泥炭沼泽,通过有机质与无机质相互作用而富集;此外,也可能受同沉积火山灰输入及大地构造的部分影响。石炭—二叠系为陕西煤型关键金属矿产的富集层位,煤系Ga,Li,Nb,Ta等关键金属普遍达工业利用品位,REY在金华山煤矿太原组和桑树坪煤矿山西组煤系中也达工业利用品位,具有良好的勘查前景。其中,渭北石炭—二叠纪煤田和陕北石炭—二叠纪煤田府谷矿区可作为陕西煤型关键金属矿产勘探开发的首选靶区。Research on coal-hosted critical metal ore deposits has been one of the important subjects in coal geology and mineral deposit,and has also been the frontier issue of international mineral geology.There are abundant coal resources widely distributed in coal-bearing sequences of the Permo-Carboniferous Taiyuan and Shanxi Formation,the late Triassic Wayaobao Formation,and the middle Jurassic Yanan Formation,in Shaanxi Province,and the coals formed in different geological ages and different coalfields present some distinctive characteristics.Critical metal enrichment has been found in several coal-bearing sequences in Shaanxi.In order to elaborate on the enrichment characteristics and mechanism of critical metals in the Shaanxi coals,the present study carried out systematical proximate,total sulfur,and trace element geochemistry analyses on the coal-bearing sequences in 10 typical coal mines from the main coalfields in Shaanxi.The enrichment of critical metal assemblages-Li,Ga,Nb,Ta,rare earth element,and Yttrium(REY)were found in the Weibei and Shanbei Permo-Carboniferous coals.Lithium,Ga,Nb,Ta,and REY mainly occur with kaolinite,boehmite,and phosphate minerals were more enriched in the coal measures adjacent to the parting,roof,and floor of coal seams.The enrichment of these critical metals was mainly derived from the sedimentary basement and the Benxi Formation weathering crust in the North China Platform.The critical metal elements from the bauxite weathering crust of the erosion provenance were migrated to the peat swamp by an aqueous solution and eventually enriched in coal seam through interaction between organic matter and inorganic matter.Furthermore,the synsedimentary volcanic ash also contributed to the Li-Ga-Nb-Ta-REY enrichment in both coals.The Permo-Carboniferous coal-bearing sequence is considered as the enrichment bed for critical metal ore deposits in coal-bearing strata in Shaanxi,in which Li-Ga-Nb-Ta critical metal assemblages reach the industrial grade,and REY also reach the industrial grade in

关 键 词：煤系关键金属 陆源碎屑 古风化壳 火山灰 石炭—二叠系 

分 类 号：P618.11[天文地球—矿床学]