Late Cretaceous Sedimentary Evolution Characteristics in Songliao Basin, Northeastern China

Late Cretaceous Yaojia-Nengjiang Formation in Songliao Basin is a set of sedimentary formation with the integrated base level rising and falling. The oil shale, formed during the maximum flooding surface period at the bottom of K(2)n(2), distributed steadily in the whole basin. The oil shale was not only the standard interface for sequence and stratigraphic correlation, but also an important source rock and cap rock. K(2)y and K(2)n(1) are large-scale lacustrine and retrograded delta sediment formed in lacustrine transgression period. Sediments of K(2)n(2) and K(2)n(5) were large-scale lacustrine and procreation delta sediment formed in forced lacustrine regression period. Gravity flow channel and terminal turbidity fan were developed in the major axis direction of the material source during the lacustrine transgression period of K(2)n(1). Large-scale slump fan sediment was developed in front of the procreation delta during the forced lacustrine transgression period of K(2)n(2).