Study on Stratum and Sedimentary Facies of “Didao Formation ”and Dongrong Formation in Suibin Depression of Sanjiang Basin

Key words: 
• Suibin depression /
• Didao Formation /
• Dongrong Formation /
• heteropical deposits /
• sequence

Abstract: By comparing and analyzing the lithology, the seismic reflection fabric and the sequence development characteristics between “Didao Formation” and Dongrong Formation in Suibin depression, it is found that the lithology of the lower part of “Didao” and Dongrong Formation are sandy conglomerate and conglomerate; the middle part are mainly of fine sandstone and siltstone; the upper part sediments all includes volcanic rocks. “Didao Formation” includes coal bed, but Dongrong Formation does not. In seismic profile the amplitude and continuity of Dongrong Formation are better than “Didao Formation”.Both “Didao” and Dongrong Formation experience twice sea level changes in sequence development process and they have pertinence. It is marine sediments of Dongrong Formation in northeast of Suibin depression and in the southwest “Didao Formation” is fan delta lake sediments. So the author considers that “Didao Formation” should be included in Dongrong Formation , and it is heteropical deposits of Dongrong Formation and hereby indicates that Didao and Dongrong Formation have well source rockreservoircap combination.