Tuanshan Fm
Type Locality and Naming
The type section of Tuanshan Formation was measured between Qingkeng and Huangboling, Qingyang, Anhui Province (118°01’35” E, 30°37’00”N). Qingkeng lies 6 km southeast of the seat of Youhua Township, or about 20 km east of the seat of Qingyang County. The section is measured by Qian et al. (1964). In this section, the Tuanshan Formation is 180.0 m thick. The Tuanshan Formation was named by Qian et al. (1964). The name is derived from Tuanshan Hill, Qingyang County, Chizhou City, southern Anhui Province.
Lithology and Thickness
The Tuanshan Formation is a carbonate sequence with scarce or without dolomitic content. The formation is dominated by grey to dark grey, thick-bedded microcrystalline limestone, brecciated microcrystalline limestone, limestone breccia, and thin-bedded striped argillaceous limestone.
Relationships and Distribution
Lower contact
The Tuanshan Fm is in conformable contact with the underlying Yangliugang Fm. The lower and upper boundaries of the formation are defined by lithological change although the underlying and overlying formations are also carbonate sequences. The lower boundary of the Tuanshan Fm is defined by the appearance of the brecciated microcrystalline limestone at its base, which differs from the underlying thin- to medium-bedded argillaceous limestone of Yangliugang Fm.
Upper contact
The Tuanshan Fm is in conformable contact with the overlying Chingkeng Fm in southeastern Anhui Province or Guanyitai Fm in southern Jiangsu Province. The lower and upper boundaries of the formation are defined by lithological change although the underlying and overlying formations are also carbonate sequences. The upper boundary is defined by the grey thin-bedded microcrystalline limestone at the base of the overlying Chingkeng Fm.
Regional extent
The Tuanshan Formation is exposed in the Jiangnan Slope Area of South China Region, distributed in southern Anhui, including, from northeast to southwest, Jingxian, Qingyang, Shitai, Dongzhi counties. It is also known, by drill hole, in southern Jiangsu Province.
GeoJSON
Fossils
The Tuanshan Formation yields rich trilobites, including Bergeronites sp., Blackwelderia sp., Cyclolorenzella sp., Distazeris (Paradistazeris) sp., Glyptagnsotus reticulatus, Ordosia sp., Proceratopyge sp., Prodamesella sp., Shengia sp., Homagnostus sp., Pseudagnostus sp., and Yakutiana sp. In addition, trilobites Fenghuangella striata, Hadranagnostus kunshanensis, Kormagnostus latilimbatus, Palaeadotes obtusa, and Liostracina jiangsuensis, and brachiopods Lingulella sp., and Acrotreta sp. are found from drill core of the formation in Kunshan County of southern Jiangsu Province.
Age
Depositional setting
Additional Information