Upper Paleozoic-Lower Mesozoic in the Coqên basin, Tibet, China:A potential petroleum-bearing sedimentary sequence.

The latest stratigraphic and paleontological studies indicate that in the Coqen basin there was no 75 Ma sedimentary hiatus during the Late Paleozoic-Early Mesozoic. Among the deposits, marine carbonate rocks were deposited during the Late Permian to Late Triassic Norian and continental-margin clastic rocks were deposited during the Late Triassic Rhetian to Early-Middle Jurassic. They are in unconformable contact. The Coqen basin was a marine carbonate basin during the Late Permian to Late Triassic Norian and still a low-lying area that received very thick deposits during the Late Triassic Rhetian to Early-Middle Jurassic. In the context of the strategic evaluation of macroscopic petroleum exploration, the Middle Permian Qixiaan to Late Triassic Norian carbonate rocks in the basin have the properties of source rocks and the Late Triassic Rhetian to Early-Mid Jurassic clastic rocks have the properties of cover rocks;the unconformity between them has the properties of reservoir rocks. The Middle Permian-Lower Jurassic in the Coqen basin form a favorable sequence for petroleum exploration, which is named the Guge sequence.