Baliu Fm
Type Locality and Naming
The type section is located in the Baliu Country, Mojiang County, Yunnan Province (101°58′, 23°02′). It was named by the Yunnan Bureau of Geology and Mineral Resources in 1990.
Lithology and Thickness
Mixed facies. Composed of interbeds of siliceous rock, clastic rock and carbonate rock. Lower part is interbedded grey and dark-grey dolomitic limestone, siliceous limestone together with bio-limestone, with clayey siltstone, silty siltstone, siltstone and quartz-sandstone, intercalated with cherts and intermediate-acidic tuffs. Upper part is interbedded grey-black and dark-grey siliceous sponge-spicule rocks together with quartz-sandstone, fine-grained sandstone, siltstone and silty siltstones, intercalated with cherts and layered tuffs. Very variable thickness (see Regional extent), with average being about 500 m.
Relationships and Distribution
Lower contact
Unknown contact with underlying strata. Regionally, the Daxinshan Fm is the next younger.
Upper contact
Unknown contact with overlying strata. Regionally, the Lazhuhu Fm might be the next older.
Regional extent
The formation is distributed northwesterly in the area of Mojiang County, Yunnan Province, with a change in thickness from being thinner at NW to being thicker at SE in a range of 134-1188.6 m (Yunnan Bureau of Geology and Mineral Resources, 1996). The amount of limestone is increasing southeasterly from the area of Xiamidyi, and in the Luchunlujiao area it has become totally limestone, but no complete exposures of it have been found, with a thickness of tens of meters. In the Bulong area of Mojiang County there are not volcanic rocks, where the lower part of the formation is composed of sandy shale, with its upper part being composed of chert, with a thickness of 823.6 m. In the Naluo and Guangma areas of Zhenyuan County in the northwestern part of the province there occurs limestone, whose lower part is intercalated with sandy slate, with a thickness of 284-466.87 m. In the Ximenyanzi area of Pu’er County the formation is characterized by the predominance of intermediate-acidity volcaniclastic rocks, with its lower part being intercalated with sandy siltstones and with its upper part being intercalated with limestone and cherts, with a thickness of over 294 m. In the Guanmuzhai area of Jinghong County, this formation represents sandy slates, intercalated with limestones, with the top part of the formation being intercalated with siliceous limestone and siliceous-rock lenses, with a thickness of 748.5 m.
GeoJSON
Fossils
Among the biotic fossils occur Fusulinida as represented by Neoschwagerina simplex and Sumatrina longissima, and Brachiopods represented by Plicatifera sp..
Age
Depositional setting
Additional Information
GeoJSON estimate by Runan Yong, Suxiao Li and Wen Li (Chengdu Univ. Tech. students)