Chaqupu Gr

The type section is around the Chaqupu River, Duilongdeqing District, Tibet Autonomous Region. It was named by geological bureau of Tibet in 1976 and was cited publicly by Regional Geological Survey group of bureau of geological of Xizhang for the first in 1979. Originally, the strata were divided into Lielonggou, Chaqupu and Mailonggang formations in ascending order, representing the Early, Middle and Late Triassic, respectively. But in 1981, the Lielonggou Formation was ascribed to Late Permian by Dongli Sun, and in the meantime, the Chaqupu Formation was renamed as Chaqupu Group, representing time interval ranging from Early Triassic to early Middle Triassic. This definition was followed by Rongbiao Rao et al. (1987), with revised interval from Early to Middle Triassic.

Synonym: Triassic strata around Xilaiwuzangbumaila, North of Zhongba County, was ascribed to Maila Fm by Xian Xu et al. (1982) and was indicate of Early Triassic

The group was divided into two parts. The lower part is dominated by limestone, with greenish massive andesite, tuff and tuffaceous sandstone interlayers. Thickness for this part is 315 m. The upper part is mainly greyish conglomeratic tuff, andesitic breccia and pyroxene andesite, intercalated with tuffaceous sandstone and siltstone. Thickness is large than 881 m.

Mainly found in the lower part, but no fossils were found in the upper part. Ammonoid: Paraceratites trinodosus, Acrochordiceras and Reiflingites. Conodont: Neospathodus horneri

Marine volcanic-sediment sequence.