Yangliujing Formation

The Yangliujing Formation is a Middle Triassic geologic unit found in the Guizhou and Yunnan Provinces of southern China.

Yangliujing Formation
Stratigraphic range: late Anisian-Ladinian 246–242 Ma PreꞒ Ꞓ O S D C P T J K Pg N ↓
Type	Geological formation
Underlies	Zhuganpo Formation
Overlies	Guanling Formation
Lithology
Primary	Dolomite
Other	Limestone
Location
Coordinates	25.9°N 105.5°E / 25.9; 105.5
Approximate paleocoordinates	12.3°N 94.5°E / 12.3; 94.5
Region	Guizhou & Yunnan Provinces
Country	China
Extent	Yunnan–Guizhou Plateau
Yangliujing Formation (China) Show map of China Yangliujing Formation (Guizhou) Show map of Guizhou

Description

Most of the formation is represented by massive dolomites, indicative of a shallow-water depositional environment. Fossils are generally rare, but conodonts from the Anisian-Ladinian boundary (namely several species of Neogondolella) are known from the lower part of the formation. Some marine reptiles have been found in dolomitic limestone near Dingxiao, an area of Guizhou sometimes considered to preserve the upper part of the Yangliujing Formation. However, under a more restrictive definition of the Yangliujing Formation, the fossils of Dingxiao would instead belong to the overlying Zhuganpo Formation.^[1][2]

Fossil content

The following fossils have been reported from the formation:

Fish

• Omanoselache contrarius
• ?Parvodus sp.
• ?Semionotiformes indet.

Brachiopods

• Mentzelia sp.
• Nudispiriferina sp.

Bivalves

• Asoella illyrica
• Unionites sp.

Crinoids

• Traumatocrinus hsui

Conodonts

• Ozarkodina kockeli