Sedimentary Facies and Distribution of Delta Front-Fluxoturbidite in the Western Slope of South Songliao Basin

In order to understand the sedimentary characteristics and distribution of the turbidites developed at the gentle slope of depression basins,the upper Cretaceous Qing12 members at the western slope of South Songliao basin is chosen as the research object.Its sedimentary facies and distribution are studied by investigating the cores,logging data and seismic interpretation.This area mainly developed delta front-fluxoturbidite system,and the fluxoturbidites in the study area which are the oil and gas reservoir can be divided into the following three micro-facies: turbidite channel,turbidite lobe and turbidite sheet sand.Based on the sedimentary facies correlation and distribution analysis,the depositional model of the fluxoturbidites developed on the gentle slope of depression basins was built,which is the linear-source mud/sand turbidites model.Compared with rift basins,the scale of fluxoturbidites developed in depression basins is relatively smaller and the grain size of it is finer because the fault activity of gentle slope in depression basin is very weak and its slope with lower angle.Furthermore,different from the rift basin,fluxoturbidites in depression basin mainly developed in the base level rise phase of 3rd sequence and its accumulation is also closely related to the transgression in the 4th sequence.