Provenance and palaeocurrent direction of Upper Cretaceous Nenjiang Formation in northern Songliao Basin

The provenance and palaeocurrent direction of the Upper Cretaceous Nenjiang Formation in the northern Songliao Basin were analyzed by means of strata slicing in seismic-sedimentologic studies and combined with detrital and heavy mineral components tests.A sedimentary distribution model of meandering river-delta-ake sedimentary systems in the Nenjiang Formation was established based on the studies of palaeocurrent direction.It was concluded that the deposition of the Nenjiang Formation was controlled by the eastern and northeastern deltas.The northeastern sources played important roles during the deposition of the 1st member of the Nenjiang Formation and the palaeocurrents were SN oriented along down-slop.After the maximum lake flooding during the 2nd and 3rd members of the Nenjing Formation,the northeastern sources were taken place by the eastern ones and the palaeocurrents changed to be EW oriented along down-slope.The sedimentary model provides geologic support for petroleum exploration in Heidimiao reservoir in the north of the Songliao Basin.