Geochemistry Characteristics Of Rare Earth Elements In The Upper Paleozoic Coal Of Eastern Ordos Basin

Take the Carboniferous-Permian coal in Jungar Coalfield,Hedong Coalfield and Weibei Coalfield in the east of Ordos Basin as research subject.Characteristics of coal quality,coal petrology,coal mineralogy and coal geochemistry were analyzed by means of proximate analysis,ICP-MS,XRF,XRD,SEM-EDX and incident light microscope.Compare the enrichment regulations,distribution patterns and occurrences of REY(rare earth element and yttrium)in coal in different geological conditions.Then discuss the geological significance and influencing factor of REY.The results prove that average value of ?REY in coal in Shanxi Formation is120.90?g/g,and average value of ?REY in coal in Taiyuan Formation is 120.72?g/g.Both of them are lower than the average value of ?REY in coal in Chinese coal but higher than that in World coal.Type of REY enrichment in coal in Taiyuan Formation is H—REY and that in Shanxi Formation is L—REY.Most of ?Eu in coal appear to negative anomaly,others in the southern study area appear to positive anomaly which shows a strong inheritance of material sources.?Ce in coal also appear to negative anomaly that indicate sedimentary environment of peat swamp is between the reduction and the weak oxidation.In study area,the inorganic affinity of REY is much stronger and mineralogical modes of occurrence of REY are dominated by clay minerals and apatite.Correlation between LREE and clay minerals and correlation between LREE apatite are both better.The enrichment degree of rare earth elements in pyrite and calcite is low,and type of REY enrichment in both minerals is H—REY.Rare earth elements can also be enriched in organic matter,but the content of REY is low.Type of REY enrichment in vitrinite and inertinite is H — REY.In certain acid reduction conditions,REY,especially heavy rare earth elements,are more easily absorbed by organic matter.The total content of REY is controlled by the distance to the material sources,and the different material sources would affect the distribution pattern of REY.Metamorphic grade of coal mainly influences the REY in organic matter,and REY adsorption capacity of organic matter increases with the increase of coal metamorphism degree.In general,the distribution pattern of REY would be affected by transgression which makes ?Ce appear to negative anomaly significantly larger,but the formation water leaching may increase the content of REY.In study area,the provenance of northern and central regions is mainly derived from sedimentary rock,granite,alkali basalt and continental tholeiite of Yinshan Ancient Land.The provenance of southern regions is mainly derived from sedimentary rock and granite of North Qinling.On the whole,the coal deposition environment of Shanxi Formation was more obviously oxidized than the coal deposition environment of the Taiyuan Formation.The coal deposit environment of Taiyuan Formation was affected by the sea water to a greater degree.