Geochemical occurrences of rare earth elements in oil shale from Huadian

Distribution characteristics and occurrence modes of rare earth elements (REE) in oil shale from Huadian, Jilin province were determined by sequential chemical extraction process. Content of REE were determined by inductively coupled plasma-mass spectrometry (ICP-MS). The results show that the enrichment of light rare earth elements (LREE) in Huadian oil shale is richer than that of heavy rare earth elements (HREE), relative to those in coals from China. The REE in oil shale are positively correlated with terrigenous clastic rock, and the supply of terrigenous materials is relatively stable. The fractionation between LREE and HREE is clear and shows a moderate LREE-enriched pattern. The occurrence of rare earth elements are mainly in minerals fractions. The enrichment of sulfide fractions inclines to LREE; besides, carbonate fractions, ferromanganese oxyhydroxides bound fraction and aluminosilicate bound fraction are more inclined to enrich HREE. Moreover, here is lack of the contents of rare earth elements in exchangeable and organic matter fractions. Additionally, the fractionation effects of rare REEs in different substances have some differences under various sedimentary environments.