Factors controlling the distribution of oil shale layers in the Eocene Fushun Basin, NE China

The Fushun Basin is a typical continental basin filled with organic-rich fine-grained sedimentary rocks, such as coal, oil shale and greyish green mudstone. Currently, research on this predominantly focuses the enrichment mechanisms of organic matter in coal controlling factors seam transformation to shale. However, during stage, deposition ceased was converted interbeds grey mudstone thin layers. control mechanism type succession still not clear. In study, thick upper part Jijuntun Formation (Unit I) high-frequency interbedded Xiloutian (Units II III) were analysed key strata. Organic inorganic geochemical data reconstruct various types sources including palaeoclimate, palaeoweathering, bioproductivity, terrigenous clastic input, palaeosalinity, redox conditions. Among these, Unit I affected by humid climate conditions predominantly. water depth volume large, input debris low. Freshwater algae blooms anoxic led supply that well preserved. This further resulted high abundance rocks. semihumid-semiarid arid lake became shallower while palaeosalinity increased; these changes represented transition stage from freshwater brackish water. exhibited suboxic/anoxic conditions, but biological living space decreased, resulting limited low sediment. III continued increase. had water, decreased matter. stratification occurred lake, which created strongly environment good preservation secondary A comprehensive analysis indicates environmental change caused palaeoclimate main factor driving cease onset deposit Basin, Northeast Asia.