Yunlong Fm
Type Locality and Naming
The naming section is located at Guolang west of Yunlong County, Yunnan. Named by the First Regional Survey Party, Yunnan Bureau of Geology, in 1973.
Lithology and Thickness
The formation belongs to red sandy mudstone with evaporite of saline lake facies and is one of the major ore-hosting horizons for saline ore deposits in Yunnan. Mainly brownish red mudstone and siltstone, intercalated with salt-bearing muddy conglomerate; sometimes only muddy conglomerate is found without salt, but gypsum is common. After weathered, muddy conglomerate geomorphologically occurs as earth columns, which is a good indication for looking for gypsum and halite. The thickness of the formation varies greatly and has a tendency to increase northward. In the vicinity of Lanping the thickness increases to >2000 m..
Relationships and Distribution
Lower contact
At the base of the section there is a bed of light brownish red muddy conglomerate, which disconformably overlies the Cretaceous Hutousi Fm.
Upper contact
The top of the formation is conformably overlain by the Guolang formation and their boundary is marked by the appearance of the ostracod Limnocythere.
Regional extent
GeoJSON
Fossils
Fossils are abundant, including the charophyte flora represented by the Obtusochara-Peckichara-Gyrogona assemblage and the ostracod Sinocypris-Parailyocypris-Eucypris assemblage. In addition, there are also the Paraleptestheria and gastropod fossils.
Age
Depositional setting
Additional Information