Geochemistry characteristics and sedimentary environment of oil shale from the Eocene Bahuli Formation in Liushuhe Basin, Heilongjiang Province

Several layers of oil shale were developed in the Eocene Bahuli Formation of Liushuhe Ba_sin,Heilongjiang Province.Based on the characteristics of major,trace and rare earth elements,sedi_mentary environment of oil shale was analyzed.In the oil shale of Bahuli Formation of Liushuhe Basin, major elements are characterized by rich in Al2 O3 ,Fe and CaO,and poor in SiO2 ,MgO,Na2 O and K2 O; trace elements are generally depleted in different degree,and the amount of rare earth elements ([Sigma]REE) averages 1 40.7x1 0 -6 ,which show mild enrichment of light rare earth elements.Relatively con_sistent change trend of rare earth elements indicates that the provenance and sedimentary environment were relatively stable.The ratio of Mn /Ti shows that the transported distance of material composed oil shale ex_perienced changes from far to near,then to far,which reflects that the depth of water changed from deep to shallow,then to deep.The ratios of Sr /Cu and Rb /Sr indicate that the climate was relatively hot and dry.T