Sedimentary characteristics and evolution of the Denglouku Formation in the southeast uplift area of southern Songliao basin was studied based on analyses of sedimentary facies distribution and evolution in the context of sequence framework.The results show that the provenance of the Formation were distributed around the basin and supplied sediments from all directions to the center of the basin and the sedimentary facies distribution was controlled by basin tectonic evolution.Five major sedimentary facies were recognized in the area:alluvial fan

fan delta

braided river

braided delta

and lake.The sequence Ⅳ-d1 was formed during the early stage of transformation from a fault depression to a sag.The deposition was mostly controlled by the fault depression and the sediments were downloaded rapidly

restricting the distance of progradation to the inner basin.There developed five separated fault depressions and two small fault depression.Alluvial fan sedimentary systems were developed on the paleohighs around the fault depressions

fan delta systems were located around the fault depressions

while the fronts of the fan delta extended into the mouth of the lake.The sedimentary facies were dominated by alluvial fan

fan delta and lake.Sequence Ⅳ-d2 was formed during the late stage of transformation from fault depression to a sag when an unified sediment unloading area was developed

and the lake expanded.The sedimentary facies were dominated by alluvial fan

fan delta

braided river

braided river delta

littoral and lake.The contact zone of the flood plains and the shore-shallow lake can be regarded as a boundary

to the west of which formed allu-vial fan and braided river systems with sediments sourced from the western and the northern highland provenances;and to the east of which developed retrograded fan deltas of different scales with clastic sediments sourced from highlands.Among the facies

the fan delta front and braided river delta front are considered to be home to hydrocarbon reservoirs and therefore are the most promising exploration targets for oil and gas.