Yangliujing Fm
Type Locality and Naming
Type locality located in Yangliujing Village, 2 km southwest of Yongning Town, Guanling County, Guizhou Province. Named in 1963 by Wang Yu et al. It was firstly named "Yangliujing limestone", and it refers to a set of dolomite-based dolomites strata distributed between the underlying Middle Triassic Guanling Fm and the overlying Middle Triassic Zhuganpo Fm limestone in western Guizhou. Yin Hongfu (1962) classified the "Yangliujing limestone" into the Guanling Formation, which was then called the Yangliujing section, and the age was set as the Middle Triassic Anisian. In 1992, Wang Zunzhou et al. classified the upper limestone section into the Zhuganpo section of the Falang Formation, and the Yangliujing Fm only included the lower dolomite section of the original Yangliujing limestone. We followed this latter connotation in this lexicon.
Synonym:
Lithology and Thickness
The Yangliujing Formation is mainly composed of gray and light gray thin layers to massive micrite to coarse crystalline dolomite, breccia dolomite and muddy dolomite. Dolomite is often occurred in rhythm from micrite to thick coarse crystals, with gypsum pseudo-crystals.. With a thickness about several hundred to thousand meters.
Relationships and Distribution
Lower contact
It is in conformable contact with the underlying Guanling Fm. The first appearances of dolomite is the sign of the bottom boundary.
Upper contact
It is in conformable contact with the overlying Franco Fm (= Falang Fm). The last appearances of dolomite is the sign of the top boundary of the Yangliujiang Fm.
Regional extent
It is mainly distributed in western and central Guizhou, with stable lithology and stratum, and large thickness variations. It is 156.6 m thick in the Langdai area and 225.3 m thick in the Nayong area.
GeoJSON
Fossils
Rare in fossils. Contain foraminifera: Trocholina multispira, T. biconvexa, T. cordevolica, Krokoumbilica pileiformis, Turritullela mesotriasica etc.
Age
Depositional setting
It is interpreted as saline sea sediments.
Additional Information