T-R Sequence Of Sangonghe Formation And Deposition Mode Of Depression Lake Basin In The Hinterland Of The Junggar Basin

The central area of the Junggar Basin in China was a large-scale shallow depression basin during the Sangonghe Formation period, which was characterized by a wide lake basin, shallow lake water and no slope break zone. In this paper, we have conducted a systematic analysis of the sequence framework and sedimentary environment of the Sangonghe Formation in the central area of the Junggar Basin using seismic, logging, and core data. The initial flooding surface, the largest lake flooding surface and the unconformity surface sequence interface were identified. At the same time, the Sangonghe Formation was divided into two tertiary T-R sequences. The precise identification of the T-R sequence is based on the identification of the initial flooding surface and the largest flooding surfaces. In addition, we also discussed the deposition mode of the depression lake basin. Shallow water deltas have narrow plain facies belts, and the range of their delta fronts varies greatly. The estuary dam deposits are easy to be transformed by lake waves, so they are not easy to preserve. The front delta is difficult to identify. Lakeshore sand dams are widely developed inside the lake basin, and the shallow water depression lake basin has the sedimentary characteristics of "full basin of sand distribution".