鄂尔多斯盆地东胜煤田侏罗系煤中元素地球化学特征及其古环境意义  

Geochemical characteristics of Jurassic coal in the Dongsheng coalfield of Ordos basin and their paleoenvironmental implications

作　　者：李美芬[1,2] 马丹 李磊 韩智 蒋恒宇 崔曦 李瑶 李佳鑫[1] 邱旺 王树斌 LI Meifen;MA Dan;LI Lei;HAN Zhi;JIANG Hengyu;CUI Xi;LI Yao;LI Jiaxin;QIU Wang;WANG Shubin(College of Geoscience and Surveying Engineering,Taiyuan University of Technology,Taiyuan,Shanxi 030024,China;Key Laboratory of Coal Science and Technology,Ministry of Education,Taiyuan,Shanxi 030024,China;Inner Mongolia Coal Geology Exploration(Group)Geological Exploration Company,Hohhot,Inner Mongolia 010010,China)

机构地区：[1]太原理工大学地球科学与测绘工程学院,山西太原030024 [2]煤科学教育部重点实验室,山西太原030024 [3]内蒙古煤炭地质勘查(集团)地质勘查公司,内蒙古呼和浩特010010

出　　处：《地质学报》2024年第8期2409-2423,共15页Acta Geologica Sinica

基　　金：国家重点研发计划项目(编号2021YFC2902002);山西省科技创新人才团队专项(编号202304051001028);NSFC-山西煤基低碳联合基金项目(编号U1910204)联合资助的成果。

摘　　要：本文以鄂尔多斯盆地东胜煤田塔然高勒矿区锡尼布拉格勘查区6-5号钻孔延安组煤为研究对象,在工业分析和元素分析的基础上,采用X射线荧光光谱仪(XRF)和电感耦合等离子体质谱仪(ICP-MS)测定了煤中常量元素及微量元素含量,对煤中元素的富集程度进行了分析,并利用煤相参数和地球化学参数对延安组不同煤层的沉积古环境进行了重建。结果表明:不同煤层样品以低水分含量、(特)低灰分产率、特低硫含量和中高挥发分产率为特征,煤中硫以有机硫为主;不同煤层煤中常量元素均以SiO_(2)和Al_(2)O_(3)为主,其次为CaO、Fe_(2)O_(3)和Na_(2)O;煤中微量元素富集程度不同,3#煤中富集Cr、Zr、Nb、Ta和Th,轻度富集V、Cu、Zn、Ga、Y、Ba、Yb、Hf、W、Pb和U,4#煤中富集Sb,轻度富集Ba、Be、Co,5#煤中轻度富集Be和Co,6#煤中轻度富集Cr和V;稀土元素结果表明,3#煤和6#煤以重稀土富集型为特征,4#煤和5#煤以中/重稀土富集型为特征,不同煤层均存在Eu正异常现象;不同煤层煤岩显微组分均以惰质组为主,其中4#煤中惰质组含量最低;各煤层沉积水体均为氧化环境占主导,其中3#、5#及6#煤形成于酸性、富氧—次富氧、水动力较弱的干燥森林沼泽相,而4#煤形成于酸性、富氧—次富氧、水动力较弱的干燥森林沼泽相与碱性、缺氧—极贫氧环境、水体环境波动较大的潮湿森林沼泽相,这两种环境交替出现。This study investigated the geochemical characteristics and sedimentary paleoenvironment of the Yanan Formation from borehole No.6-5 in the Xinibulage exploration area of the Dongsheng coalfield,Ordos basin.Proximate and ultimate analyses,an X-ray fluorescence spectrometer(XRF),and an inductively coupled plasma-mass spectrometer(ICP-MS)were employed to determine the major and trace element compositions of coal.The results showed that coal samples from different seams exhibit low moisture content,(extra)low ash yield,extremely low sulfur content(with organic sulfur being the primary form),and medium to high volatile matter yield.Major elements are predominantly SiO_(2) and Al_(2)O_(3),followed by CaO,Fe_(2)O_(3),and Na_(2)O.Trace element enrichment varies among seams:coal 3#is enriched in Cr,Zr,Nb,Ta,and Th,with slight enrichment in V,Cu,Zn,Ga,Y,Ba,Yb,Hf,W,Pb,and U;coal 4#is enriched in Sb and slightly enriched in Ba,Be,and Co;coal 5#shows slight enrichment in Be and Co;and coal 6#exhibits slight enrichment in Cr and V.Rare earth element analysis indicates that coal 3#and 6#are characterized by heavy rare earth element enrichment,while coal 4#and 5#are enriched in medium/heavy rare earth elements.All coal seams display a positive Eu anomaly.Inertinite is the dominant maceral in all seams,with coal 4#exhibiting the lowest inertinite content.Sedimentary paleoenvironmental reconstruction suggests that all coal seams formed in predominantly oxidative environments.Coal 3#,5#,and 6#likely originated in oxidative,acidic,oxygen-rich to sub-oxygenrich,and hydraulically weak dry forest swamp facies.Coal 4#experienced fluctuating conditions,alternating between oxidative,acidic,oxygen-rich to sub-oxygen-rich,and hydraulically weak dry forest swamp facies,and reducing,alkaline,highly fluctuating water body environments characteristic of anoxic to extremely hypoxic moist forest swamp facies.

关 键 词：鄂尔多斯盆地 侏罗系延安组 地球化学 古环境 

分 类 号：P618.11[天文地球—矿床学] P595[天文地球—地质学]