Chingkeng Fm
Type Locality and Naming
The type section of the Chingkeng Formation was measured between Qingkeng and Huangbailing, Qingyang County (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. In the type locality, the upper part of Chingkeng Formation is not exposed because of fault cutting. The formation is completely exposed near Tangcun Village, Jingxian County, Xuancheng City, southern Anhui Province, where a section, the Tangcun section (118°09’40” E, 30°40’39” N, is measure as auxiliary section for the formation. The section is measured by Qiu et al. (1985). In this section, the Chingkeng Formation is 453.28 m thick. The Chingkeng Formation was named by Zhang et al. (1951). The name is derived from Chingkeng (spelled Qingkeng in Hanyu Pinyin) Village, Qingyang County, Chizhou City, southern Anhui Province. Originally the unit was called Chingkeng Limestone by Zhang et al. (1951) and was renamed Chingkeng Formation by Qian et al. (1964).
Synonym: （青坑组）
Lithology and Thickness
The Chingkeng Formation is a carbonate sequence. It is dominated by grey, thick-bedded dense limestone, argillaceous striped limestone, bioclastic limestone, micritic limestone, and sandy limestone.
Relationships and Distribution
Lower contact
The Chingkeng Fm is in conformable contact with the underlying Tuanshan Fm. The lower and upper boundaries of the formation are defined by lithological changes although the underlying and overlying formations are also carbonate sequences. Its lower boundary is defined by the disappearance of the greyish black medium-bedded, brecciated limestone at the top of the Tuanshan Fm
Upper contact
The Chingkeng Fm is in conformable contact with the overlying Guangyintai Fm. The lower and upper boundaries of the formation are defined by lithological changes although the underlying and overlying formations are also carbonate sequences. The upper boundary is defined by the appearance of the greyish white massive dolomite at the base of the Guangyintai Fm
Regional extent
The Chingkeng Formation is exposed in the Jiangnan Slope Area of South China Region, distributed in southern Anhui Province, from northeast to southwest, in Jingxian, Qingyang, Shita, Dongzhi counties. The formation increases dolomitic content and decreases thickness southwestward. In Dongzhi County, the formation is about 220 m thick and bears numerous interbeds of sandy dolomite and pelletal dolomitic limestone.
GeoJSON
Fossils
The Chingkeng Formation is richly fossiliferous, yielding trilobites Archikainella vomerina [=Chencunia chencunensis], Beigongia bigranulata, Coosia sp., Eugonocare sp.，Glyptagnostus reticulatus, Jingxiania tangcunensis, Ketyna sp., Koldinioidia pustulosa, Onchonotellus sp. Paraacidaspis hunanica, Parakoldinioidia sp., Peichiashania，Proceratopyge fenghwangensis, Prochuangid granulosa, Prosaukia diversa, Saukia jingxianensis, Shengia sp., Shitaia jingxianensis, Stigmatoa anhuiensis, Tamdaspis intermedia, Wannania latilimbata, Wanwanspis wannanensis, Glyptagnostus reticulatus, Homagnostus sp., lnnitagnostus inexpectans, Micragnostus chencunensis, Neoagnostus quadratus, Peratagnostus sp., Pseudagnostus communis, P. idalis, Pseudocalvinella spinosa, Rhaptagnostus sp., and Trisulcagnostus anhuiensis.
Age
Depositional setting
The formation represents deposits of slope facies.
Additional Information