Heshan Fm
Type Locality and Naming
The type section is located in the area of Heshan City, Guangxi, with its reference section being situated at Matan in the vicinity of Heshan City. It was named by Sun Yunzhu in 1939.
Lithology and Thickness
Limestone with Coal. Representing a carbonate coal-bearing stratum between the Maokou Fm and the Dalong Fm, and is divisible into three members: Lower member is composed of dark-grey and grey limestone and cherty limestone, intercalated with coal seams, yielding Fusulinida and brachiopods fossils, with a thickness of 63.35 m. At the base of the formation there occurs a 2 m-thick layer of grey-white pyrite-bearing Fe-Al-rich sediment (ferralite). Middle member consists of grey medium- and the thick-bedded limestones, containing a small amount of chert nodules, yielding Fusulinida fossils, with a thickness of 38 m. Upper member consists of dark-grey limestone and cherty limestone, intercalated with coal seams, with a thickness of 51 m.
Relationships and Distribution
Lower contact
Upper contact
At individual localities such as the Laibin area there exists a continuous transition resulting in a conformable contact with the overlying Dalong Fm.
Regional extent
Distributed in the West and Central Guangxi in the southern part of the Yangtze River stratigraphic subregion. Its thickness is increasing gradually from the Central Guangxi in a S-N-trend, reaching as great as 48-100 m till the Shangli-Binyang area and 209-260 m up to the Yishan-Mashan area. Such a trend could be seen in the West Guangxi as well, where the thickness of the formation is of 221 m at Tiandong, and of 543 m at Nandan, but with the coal-bearing capability becoming worse and worse.
GeoJSON
Fossils
Abundant biocommunities, with the Fusulinida represented mainly by Codonofusiella, Palaeofusulina, Nankinella and Eoverbeekina; and Ammonoids with the Prototoceras as the most common one.
Age
Depositional setting
This formation might have been formed in a setting of basinal slope fan.
Additional Information