Menggongao Fm
Type Locality and Naming
The type section is located at Menggongao, east of Lingnan in Shaodong County, Hunan Province.
It was named by Tian Qijun et al. in 1932.
Lithology and Thickness
Shale, limestone. It is characterized by interbeds of limestone with shale, commonly with an upward trend of decreasing sand-silt and increasing calcareous content. Lower part mainly consists of shale and siltstone intercalated with limestone. Upper part is composed of interbeds of shale with marl and limestone. Limestone is medium bedded and often displays graded bedding.
In the south to Qiyang area, limestone increases and with only a few shale intercalations, and there is a bed of bird-eye limestone developed at the top. The thickness is commonly about 100 m.
Relationships and Distribution
Lower contact
The base is a conformable transition from the underlying Shaodong Fm and is placed at the appearance of limestone.
Upper contact
At its top is often a bed of quartz sandstone.
Regional extent
GeoJSON
Fossils
Fossils are mainly coral Cystophrentis sp., brachiopods Cyrtospirifer sp., Ptychomalatoechia kinlingensis; conodont Icriodus sp., Polygnathus obliquicostatus; spore Retispora lepidophyta; foraminifera Qusiendothyra kobeitusana; and stromatopora.
Age
Depositional setting
It is interpreted as a normal-salinity marine subtidal environment
Additional Information