Enrichment And Differentiation Mechanism Of Associated Elements In Permo-Carboniferous Coal In Gaoyang Mine,Shan Xi Province

Based on the theories of Coalfield Geology,Coal Petrology,Mineral Petrology,Coal Chemistry,Organic Geochemistry,Element Geochemistry and Mathematical Statistics,this paper applies X-ray fluorescence spectrometry(XRF),optical microscope,electron probe with energy spectrum(EPMA-EDX),inductively coupled plasma mass spectrometer(ICP-MS)and so on.This paper makes an in-depth analysis on the distribution of elements and the mechanism of mineral enrichment and differentiation in Gaoyang 9-10-11^#coal-bearing series,Shanxi Province.The main factors affecting the mineralogical and geochemical composition of Gaoyang9-10-11 coal in Shanxi Province include:(1)Terrigenous clastic input of the sedimentary source area;(2)The influence of seawater during coal formation and coalification;(3)Multi-stage hydrothermal leaching.The main mineral composition of Gaoyang 9-10-11^#coal-bearing series is quartz,kaolinite,Illite,mixed-layer illite/smectite,pyrite,calcite,siderite,and anatase;there is a small amount of k-feldspar,plagioclase,allophane,Marcasite,goyazites,apatite,rhodochrosite and so on.The Coal of Gaoyang 9-10-11^#is enriched in Li,and the enrichment coefficient is 6.17.Coal is slightly enriched with Sr(285.44?g),Zr(72.99?g),La(26.50?g),Ce(46.70?g),Hf(2.54?g),Ta(0.57?g),Pb(17.46?g),Th(7.02?g).Their enrichment coefficients relative to the world average coal are 2.59,2.03,2.41,2.02,2.12,2.05,2.24 and 2.13,respectively.The range of total rare earth elements(REY)is 8.72 ug/g,and the average content is 121.71?g/g,which is 1.78 times of the average value of world coal(68.47 ug/g).The distribution pattern of rare earth elements is L-type,relatively flat,due to the influence of seawater on the coal-forming period.Most of the coal stratification shows a weak negative Eu anomaly,which is closely related to the control of source rocks in Yinshan paleo-continental source area and the regulation of seawater.The Y/Ho varies from 26.39 to43.54,and the average value is 30.The negative correlation between REY and Y/Ho indicates that the terrigenous detritus from Yinshan Paleo-continent is the main factor leading to the distribution pattern of rare earth elements in coal.Sr/Ba ranges from 0.58 to46.14,with a mean of 4.17.Sr/Ba is negatively correlated with ash(r=-0.1),indicating that terrigenous materials are related to freshwater.With the gradual increase of metamorphic degree,the organic affinity of medium and heavy rare earth elements decreases,and the medium-heavy rare earth elements are released from organic matter.The OA binding state of rare earth elements is transformed into an inorganic binding state.The Al₂O₃/Ti O₂ratio ranges from 30 to 94.15,with an average of 50.41,indicating that the terrigenous region is feldspathic(k-feldspar granite of Yinshan paleo-continent).The CIA values in parting and floor are 98.58 and 88.86,respectively,which reflects the strong chemical weathering in the source area relatively,the ICV values are 0.57 and 0.24,respectively.The lower ICV values indicate that the weathering after cycling or deposition has an essential influence on the Gaoyang 9-10-11^#coal-bearing series.