Chuanshan Fm
Type Locality and Naming
The type section is located at Chuanshan, 3 km southwest of Shima Temple, Zhejiang, Jiangsu Province. It was named by Ding Wenjiang in 1919.
Lithology and Thickness
Limestone. The formation at Chuanshan is mainly composed of gray thick-bedded oncolite-bearing micritic limestone and bioclastic limestone, intercalated with dark-gray medium- to thick-bedded micritic limestone, rich in fusulinids, corals and other fossils. About 40 m thick.
The thickness is relatively small in Jiangsu, northern-central Zhejiang, Anhui, northwestern Jiangxi and Hubei, generally less than 70 m, and only 0.8−2.6 m along Jingshan Mt. western Hubei, where it is dominated by light-gray thick-massive bioclastic limestone, consisting mainly of bioclastic micritic limestone. The “Chuanshan balls” are mainly enriched in the upper part. In Hunan, Guangdong and southern-central Jiangxi, the thickness varies greatly, being less than 60 m in areas like Yangchun of Guangdong, 531 m at Qujiang River, 250 m at Meixian County, 400 m in central Hunan, 240−400 m around Gao’an and 620 m at Jishui of Jiangxi. Although it is dominated by light-gray−gray limestones, it is intercalated with large amounts of dark-gray limestones, chert bands and dolomites. It is composed completely of dolomite in some local areas of central Hunan, dominated by dark-gray limestone in southern-central Jiangxi, and intercalated with clastic rocks along Jinhua−Zhuji near the Min-Zhe (Fujian-Zhejiang) old land.
Relationships and Distribution
Lower contact
Conformable contact with the underlying Huanglong Fm in most areas: Its bottom is discriminated from the light-gray thick-bedded limestone in the underlying Huanglong Fm by the occurrence of thin-bedded lime conglomerate. But in disconformable contact in some local areas such as Chuanshan of Zhejiang, Tongling and Susong.
Upper contact
Regional extent
It is similar to the Huanglong Fm in lithology, distribution and thickness variation = widely distributed in Jiangsu, Zhejiang, Anhui, Jiangxi, Hubei, Hunan, Guangdong and other provinces.
GeoJSON
Fossils
In the Ningzhen Mountain area, Fusulinids can be divided into three zones: the lower Triticites zone, the middle-upper Sphaeroschwagerina moelleri zone, and the top Schwagerina tschernyschewi zone. The top fusulinid zone was previously classified into the Qixia Fm, but considering that S. tschernyschewi and its associated Eoparafusulina are mainly enriched in the top dark-gray thin-bedded limestone of the Chuanshan Fm, and rarely seen in the bottom limestone of the Qixia Fm, it should be attributed to the Chuanshan Fm. Tetracorals are divided into two zones, the lower Chuanshanophyllum zone, which can be further divided into the Lytvophyllum mengi and Pseudocarniaphyllum spiniforme subzones, and the upper Parawentzellophyllum zone.
Age
Depositional setting
It is interpreted as normal neritic.
Additional Information