Sequence stratigraphic framework and lithologic traps in the Jiufotang Formation, Ludong depression, Kailu Basin, Inner Mongolia

With the aid of Vail's sequence stratigraphic theory, the present paper deals with the examination of sequence stratigraphic framework and the development of the lithologic traps in the Jiufotang Formation, Ludong depression, Kailu Basin, Inner Mongolia on the basis of seismic data, cores and well logs. The top and basal surfaces of the Jiufotang Formation are found to be onlap surface and truncation surface, respectively, while the initial flooding surface and maximum flooding surface are observed within the Formation. The Jiufotang Formation encompasses the fan delta facies, nearshore turbidite fan facies, offshore turbidite fan facies and lake facies, and consists of one third-order sequence including lowstand, transgressive and highstand systems tracts. The trap types include structural-litholigic traps in the steep slope zone; the sandstone lenses traps in the depression, and sandstone thinning out-upward traps in the ramp zone.