Nanpanjiang Fm
Type Locality and Naming
The type section is located at the east bank of the Nanpanjiang River, 2.5 km north of Panxi Town of Huaning County, Yuxi Shi, Yunnan Province. It was named by Sun Yunzhu in 1945.
Synonym: Nanpanchiang Limestone
Lithology and Thickness
Limestone. It is composed of thin- to medium-bedded, gray to dark-gray, bioclastic limestone and clayey limestone with some interbeds of shelly limestone. The exposure of the formation is incomplete, only 15-70 m thick.
Relationships and Distribution
Lower contact
The base is a faulted contact to the sandstone of the underlying Cuifengshan Gr
Upper contact
The top is a conformable contact to the sandstone of the overlying Haikou Fm.
Regional extent
Its distribution is unclear due to incomplete outcrops in Penxi.
GeoJSON
Fossils
The formation contains abundant Corals Dendrostella trigemme, Grypophyllum tenue, Maageea crassoseptatum, Neospsongophyllumisactis, Diplochone tungshanense, Columnaria sp.; and Brachiopods Bornhardtina ex gr. uncitoides, B. (Parabornhardtina) yunnanensis, Acrothyris kwangsiensis, A. nanpanjiangensis, Eoreticularia maueri.
Age
Depositional setting
It is interpreted as an open platform facies.
Additional Information
Whether the unit belongs to Haikou Formation or to an independent formation is still debated. In Yuanjiang-Jianping area there are two lithologic units: fine-grained dolomite below and bioclastic limestone above. They are overlain by equivalent of Haikou Fm bearing-Bothriolepis and correlated to Nanpanjiang Member. The thickness reaches up to190-285 m. In the Kunming-Qujing area, the so-called Nanpanjiang Member is mainly dolostone, perhaps representing supratidal or lagoon conditions.