Beiya Fm

It was named by P. Misch in 1947. The type section is located in Jidiping Village, Heqing County, Yunnan Province.

Synonym: The origin definition of “Baiyang Limestone” referred to the strata that lay between the middle Triassic Yuliucun Fm and Upper Triassic Songgui Fm, represented by limestone and marlstone and. Subsequently, the “Baiyang Limestone” was subdivided into two parts by Jinke Zhao et al. (1962), including the limestone dominated “Baiyang Formation” in the lower part and marlstone predominated “Lanping Formation” in the upper part. At the meantime, time interval of Baiyang formation was designed Ladinian of Middle Triassic. Later, the “Baiyang Formation” and the underlain Yuliucun Fm was combined and ascribed to Beiya Fm by the first regional geological survey of Yunnan in 1966, and suggestive of Middle Triassic. The definition by Jinke Zhao et al. (1962) was followed in this book.

The Beiya formation is twofold subdivided. Lower part is predominated by greyish dolomite with thickness of 378 m. Upper part is mainly massive limestone of 71 m. The base of this formation was marked first occurrence of thick dolomite and the top was indicated by the disappearance of thick limestone.

Fossils are largely found in the upper part, including Bivalves: Halobia cf. comata, Leptochondris sp., Newaogia sp., Plagiostoma sp., Entolium discites, Neoschizodus sp.; Ammonoids: Leophyllites cf. confucii, Joannite sp., Ptychites sp.

Shallow marine facies