The basin-filling features and sequence division in the Paleogene Huangxian fault basin,Shandong

Three sequences(third-order sequence)can be distinguished for the Huangxian Paleo-gene fault basin.Sequence I is interrupted.Both Sequences Ⅱ and Ⅲare composed of three basic units:lowstand systems tract(LST),expanding systems tract(EST)and reducing systems tract(RST).There are two kinds of sequence boundary:regional tectonic plane and basin tectonic stress transform plane-systems tract transform plane.Coal and oil accu-mulation took place mainly in the lowstand to expanding periods,and thus coal seams and parent strata of oil and gas(oil-generating strata)are hosted dominantly in the lowstand and expanding systems tracts.