Dachenling Fm
Type Locality and Naming
The type section of Dachenling Formation is located at Dachenling, Dachen, Jinagshan, Zhejiang Province (118°35’E, 28°49’ N). The section lies about hundred meters south of the seat of Dachen Township, or about 10 km northwest of the seat of Jiangshan City, and was measured by Li and Yu (1965). In the type section, the formation is 32.50 m thick. The Dachenling Formation was named by Li and Yu (1965). The name is derived from Dachenling Hill in southeast of Dachen Township, Jiangshan City (county level), Quzhou Prefectural City, Zhejiang Province.
Synonym: （大陈岭组）
Lithology and Thickness
The Dachenling Formation is a carbonate sequence, consisting of dark grey, thin-bedded to massive dolomitic limestone with nodular chert, foliated siliceous bands and dolomitic bands. In the type section, the formation is divided into eight lithologic beds, from bottom up: 1, dark grey massive dolomitic limestone (3 m); 2, dark grey massive dolomitic limestone with nodular chert (6 m); 3, thick-bedded to massive dolomitic limestone with dolomitic bands (5 m); 4, medium-bedded dolomitic limestone (3.5 m); 5, massive dolomitic limestone with nodular chert (3 m); 6, thin-bedded, striped dolomitic limestone (2 m); 7, thin- to medium-bedded limestone with foliated siliceous bands of 1 to 3 mm thick (2 m); 8, dark grey, striped dolomitic limestone (8 m).
Relationships and Distribution
Lower contact
The Dachenling Fm rests conformably on the underlying Hetang Fm. The lower boundary of the formation is defined by the disappearance of the black, platy siliceous shale or carbonaceous shale (bone coal bed) of the Hetang Fm
Upper contact
It is conformably overlain by the Yangliugang Fm. The upper boundary is defined by the appearance of dark grey, argillaceous limestone of the Yangliugang Fm
Regional extent
The Dachenling Formation is exposed in both the Jiangnan Slope and the Jiangbei Slope areas of South China Region, distributed in western and northwestern Zhejiang Province (Jiangshan, Changshan, Kaihua, Fuyang, and Anji counties), and southeastern and southern Anhui Province (Chuzhou, Quanjiao, Dongzhi, Guichi, Jingxian, Xiuning, Ningguo, Shexian, Shitai, and Yixian counties). Thickness of the formation is usually 30 to 36.5 m thick, but varies between 29 and 109.4 m.
GeoJSON
Fossils
In the type section of Dachenling Formation, the Bed 1 and Bed 3 each yields trilobite Oryctocarella sp. (belonging very possibleky to Oryctocarella duyunensis). In other localities, the formation yields trilobites Oryctocarella fenshuiensis, Bathynotus sp., Changaspis placenta, Kootenia longa, Nangaops intermedia, and Prabowmania transversa; brachiopods Lingulella sp., Homotreta sp., and Acrothele sp.; and hyolithid Hyolithes sp.
Age
Depositional setting
Additional Information