SQ6 sequence: This sequence is equivalent to the early and middle Tata sedimentation. The bottom interface of the sequence is I-type interface, which is paleoweathering crust surface, lithologic and lithofacies transition surface and erosion erosion surface, and the top interface is lithologic and lithofacies transition surface. The transgressive system tract consists of sand flat and mixed flat, and the lithology is gray fine sandstone, medium sandstone and siltstone mixed with mudstone. The high system tract is composed of interbedded medium sandstone, argillaceous siltstone and mudstone. It has the sequence structure characteristics of TST>HST.
Figure 4- 15 Sequence Stratigraphic Profile of Silurian System in Shun 1 Well in Tarim Basin
Figure 4- 16 Silurian Sequence Stratigraphic Profile of Zhong 1 Well in Tarim Basin
SQ7 sequence: This sequence is equivalent to the middle and late deposition of Tatakhta grid. The top and bottom interfaces of the sequence are all transition surfaces of lithology and lithofacies, which are type II interfaces. The transgressive system tract is composed of light gray fine-grained sandstone, siltstone and mudstone interbeds, which are sand flat and mixed flat facies; The high system tract is composed of gray argillaceous siltstone and mudstone in mud flat facies. It has the sequence structure characteristics of TST>HST.
SQ8 sequence: This sequence corresponds to the late deposition of Tatahetag network. The top and bottom interfaces of the sequence are all type II interfaces, the bottom interface is a lithologic-lithofacies transition surface, and the top interface is a weak scouring surface. The transgressive system tract consists of gray medium sandstone, gray fine sandstone and thin argillaceous siltstone, with mixed flat and sand flat facies; The high system tract consists of gray medium-fine sandstone, silty mudstone and gray argillaceous siltstone interbedded with mixed flat and mud flat facies. It has TST.