鱼卡五彩煤矿5号煤中微量元素地球化学特征及沉积环境

Coal No.5 Trace Element Geochemical Features and Sedimentary Environment in Wucai Coalmine,Iqe

微量元素的地球化学特征研究对煤中有益元素开发利用以及有害元素的污染防治具有重要意义,同时也可以为盆地沉积环境研究提供信息。应用电感耦合等离子质谱(ICP-MS)分析了五彩煤矿5号煤和顶底板中微量元素含量,并结合煤岩煤质特征、工业分析以及常量元素含量,研究煤中微量元素的富集特征,并讨论了五彩煤矿5号煤的沉积环境。结果表明,五彩煤矿5号煤中微量元素含量普遍偏低,与世界煤中微量元素相比,五彩煤矿5号煤中Sc、Cr、Co、Ni、Cu、Sr、Nb、Cd、Hf、Ta、W和Th元素含量正常,其余微量元素含量相对亏损。5号煤中矿物主要包括高岭石、石英和金红石。北部的祁连造山带可能是这些矿物的主要来源。煤中Sr/Ba和Sr/Cu比值表明五彩煤矿5号煤形成于干旱气候条件,随着湖平面上升,盐度逐渐降低,从咸化湖水、半咸水转变为淡水。Cu/Zn和Ni/Co比值表明五彩煤矿5号煤主要形成于富氧环境。

The study of trace element geochemical features has significance on exploitation and utilization of beneficial elements and pollution control of harmful elements in coal,meanwhile can provide information for basin sedimentary environment study.Using inductively coupled plasma mass spectrometry(ICP-MS)has analyzed trace element contents in the Wucai coalmine coal No.5 and its roof and floor.Combined with coal petrological and coal quality features,proximate analysis and macroelement contents have studied trace element enrichment features in coal;discussed coal No.5 sedimentary environment in Wucai coalmine.The result has shown that trace element contents are generally on the lower side in coal No.5,comparing to the world trace element in coal,Sc,Cr,Co,Ni,Cu,Sr,Nb,Cd,Hf,Ta,W and Th contents in coal No.5 are normal,while other trace elements relatively deficient.Minerals in coal No.5 have mainly kaolinite,quartz and rutile.The Qilian orogenic belt to the north could be the source of these minerals.Sr/Ba and Sr/Cu ratios in coal No.5 have indicated coal No.5 in Wucai coalmine had been formed under drought climate conditions,with lacustrine level ascended,salinity gradually lowered down,lacustrine water transformed from saline water,brackish water into fresh water.Cu/Zn and Ni/Co ratios have indicated the coal No.5 had been formed in oxygen enriched environment.