Bocigou Fm

The type section is located around the Bocigou, Baoxing County, Sichuan Province, which was named by second team of Bureau of Geology of Sichuan in 1965. Originally, the Bocigou formation represented the limestone and slate dominated strata within the Upper Permian and Zagunao formation of Middle Triassic, and mainly distributed in West Sichuan Province. Based on the found fossil of Pseudoclaraia cf. wangi, it was constrained within the Induan of Early Triassic by Jinke Zhao et al. (1982). But 1991, the Bocigou formation was divided into two parts by Sichuan Bureau of Geology and Mineral Resources, the lower part that was consisted of dark grey slate and metamorphic siltstone interbedded with limestone with bivalve Claraia cf. wangi, was still ascribed to Bocigou Fm, but the upper part of varied-colored strata, containing conodont of Gladigondolella tethydis, was assigned to the new established Rilagou Formation. The definition of Sichuan Bureau of Geology and Mineral Resources (1991) was followed herein.

Synonym: Botzigou Fm. Hengyakuang Fm was once constructed by the first survey team of Sichuan Geological Survey in 1972, representing the strata that were correlative to Bocigou Fm and Rilagou Fm which distributed mainly in west Markang-Yajiang.

The Bocigou Formation is dominated by greyish clayey slate and silty slate interbedded with limestone, argillaceous limestone, and metamorphic sandstone. The base is characterized by the interbedded grey argillaceous limestone and greyish green tuffaceous sandstone. The thickness is 149.6 m.

Continental slope facies to debris of continental shelf, corresponding to the lithological features.