Bianyang Fm

The type section is located in Bianyang Town, Luodian County, Guizhou Province, which was named by Xiangfu Long et al. in 1958, and was publicly cited by 108 team of Guizhou Geological Survey in 1966 for the first time. Originally, the Bianyang formation represented the clastic dominated strata with Ladinian age. But Zunzhou Wang et al. (1992) suggested that most of the Bianyang formation was deposited during Ladinian, but the upper part could extend into early Late Triassic.

Synonym:

The Bianyang Formation is characterized by Flysch-type sediments, which are comprised of sandstone, clay and few limestones and was threefold divided. Lower member of Bianyang Formation is represented by rhythmic greyish sandstone, siltstone and clay with thickness 303-1273 m. Bouma sequences, load casts and flute casts are well-developed at the sole surfaces. Second member is dominated by rhythmic yellowish green, greyish green sandy clay, calcareous clay and laminated or convolute-bedded sandstone. The thickness is 832-1112 m. Upper member is mainly comprised of grayish green and grey calcareous sandstone, siltstone, and clay, interbedded with bioclastic limestone and sandy marlstone, with thickness around 359-582 m. Total thickness of 1976-2764 m

Ammonoids: Trachyceras sp., Monophyllites sp., Leophylites sp., Protrachyceras sp.

Bivalve zones: Daonella varifurcata-Posidonia bakevelliaformis zone; Daonella densisulcata zone, Daonella bulongensis bifurcata-Halobia kui zone.

Sub-abyssal trough turbidite deposition