Sedimentary Laws of Thin layer, Fine grain Turbidites of Distant-gentle Slope: A case from the 1st member of Qingshankou Formation in Dabusu area of west slope, south Songliao basin

Key words: 
• west slop of south Songliao basin /
• thinlayer /
• finegrain /
• turbidites /
• sedimentary rules /
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Abstract:  Based on the study of highresolution sequence stratigrapghy and sedimentology, isochronic stratigraphy framework of high accuracy in fifthlevel has been established, and tested by the analysis of maximum entropy spectrum, a case study of the 1st member of Qingshankou formation in Dabusu area of west slope, south Songliao basin. Using cores, logging and seismic responses, sedimentary characteristics and differences with delta front deposits were concluded. With the analysis of single wells, connective wells amd RMS, the position of slope break belt and distribution law of turbidte deposites were verified. The turbidite deposits in this area belong to the origin of distantmild slope slumping of mouth bars in delta front subfacies, and were also attributed to linearsource and mudsand rich type. The sedimentary law of thinlayer, finegrain turbidites certificated that  ①slumps were mostly located in the falling period of baselevel cycles, near the sequence boundary, thick thickness, superimposed or interlayed with turbidite channels vertically, and thickening upwards. ②turbidite channels were usually near the sequence boundary, thick thickness, and conducted as mainbodies of boxing logs in the rising period. But turbidite channels were usually near the flooding surface, thin thickness, conducted as flanks of aciculatefinger logs in the falling period of baselevel cycle. The thickness of turbidite channels was thinner with the rising of base level, and was thicker with the falling of base level. ③turbidite sand sheets were mainly distributed in deeper and near maximum flooding surfaces, thin thickness, superimposed or interlayed with lacustrine muds, turbidite channel flanks or slumps vertically.Exloration practices indicated that highoil reserves can be found in thinlayer, finegrain turbidites of this area.