鄂尔多斯盆地西缘煤中微量元素共生组合特征

Paragenetic Association Features of Trace Elements in Coals in Western Margin of Ordos Basin

以鄂尔多斯盆地西缘石炭-二叠系和侏罗系延安组煤样中Ga、Ru、W、Li、Ge、U等多种微量元素测试结果为基础,分析研究了煤中微量元素的富集特征、展布规律以及各微量元素之间的相关性。研究表明,石炭-二叠系煤中微量元素主要存在于黏土矿物中,其中V、Cr、Co、Ni、Rb、Cs、Ba、Tl等8种元素之间高度正相关,Li、Ga、REE之间正相关,除Ga和REE元素外,Sr与其他元素均为负相关;侏罗系煤中,Li、Sc、Cr、Zn、Ga、Rb、In、Sb、Cs、Pb、Bi、Th、U、REE之间高度正相关。石炭-二叠系煤中微量元素的含量普遍高于侏罗系煤中微量元素含量,是因为石炭-二叠系属海陆交互相,侏罗系为陆相,海洋浮游生物能富集一些微量元素,提供较丰富的物质来源,更主要的是海水改变了泥炭沼泽的p H值、Eh值和H2S含量,产生特定的地球化学障,使之有利于微量元素富集。

On the basis of multiple trace elements tested results of Ga, Ru, W, Li, Ge and U from Ordos Basin western margin PermoCarboniferous Yanan Formation coal samples, analytically studied the study area coal trace elements enrichment features, distribution pattern and interdependency between them. The study has shown that in Permo-Carboniferous coals, 8 elements of V, Cr, Co, Ni, Rb,Cs, Ba and Ti have high level positive correlation mutually, Li, Ga and REE positive correlation mutually, mainly existed in clay minerals, besides Ga and REE elements, Sr and other elements are all negatively correlated. In Jurassic coals, Li, Sc, Cr, Zn, Ga, Rb, In, Sb,Cs, Pb, Bi, Th, U and REE have high level positive correlation mutually. Trace element contents in Permo-Carboniferous coals are generally higher than in Jurassic coals, because of Permo-Carboniferous belongs to marine-terrestrial facies, while Jurassic terrestrial facies. Marine plankton can enrich some trace elements, provide rather abundant material source, more importantly is the sea water changed peat bog pH value, Eh value and H2 S content, produce particular geochemical barrier to the advantage of trace elements enrichment.