Basin evolution and oil shale deposition during Upper Cretaceous in the Songliao Basin (NE China): Implications from sequence stratigraphy and geochemistry

Primary productivity is suggested as the main controlling factor on differences in oil shale quality and source rock potential between the two formations, whereas the variations in quality within each formation mainly depend on the preservation of organic matter. The high thickness, wide spatial distribution and excellent hydrocarbon potential of the Upper Cretaceous oil shales in the Songliao Basin are suggested to have been the result of large accommodation space, stable palaeoenvironmental conditions, and high primary productivity.