Shijia Fm
Type Locality and Naming
North Anhui. The Shijia Fm was named by the Jiangsu and Anhui Parties of Regional Geological Survey in 1976 and was formally published on the Guidebook of 1 : 200 000 Scale Geological Map of Xuzhou Sheet in 1978. Lacking a complete section, the Shijia Formation is represented by the Shijia section (for its upper part) and the Heifengling section (for its lower part) in Xieji Township of Suxian County, Anhui Province.
Synonym: （史家组）
Lithology and Thickness
The Shijia Fm is subdivided into two parts. Lower part is grayish yellow, medium- to thick-bedded, banded dolomitic limestone, thin-bedded marl intercalated with calcareous shale and lenses of limestone, dominated upward by greenish yellow shale intercalated with siltstone and lenses of limestone, and the lowermost over 10 m is variegated shale and clay. Upper part is greenish yellow to purple red shale intercalated with minor glauconitic sandstone, siltstone and pelitic limestone. The thickness is 402 m.
[Figure: Outcrop photo of the Shijia Fm]
Relationships and Distribution
Lower contact
The basal contact relationship with the underlying strata is not clear. Schematic stratigraphic column implies next older regional unit is the Weiji Fm.
Upper contact
The Shijia Fm is conformably overlain by the Wangshan Formation.
Regional extent
North Anhui. It has a limited distribution in the Suxan district.
GeoJSON
Fossils
The Shijia Formation yields stromatolites: Kutavia dalijiaensis, Gymmnosolen f. etc., Microplants: Asperatopsophosphaera sp., Michystridium sp., Brochopsophosphaera minumus, Laminarites antiquissimus, Trachysphaeridium sp. etc.; Macroscopic fossil algae: Chuaria circularis, Shouhsienia sp., Ellipsophysa axicula etc.
Age
Depositional setting
Additional Information
Recent data (Zheng Wenwu, 1994, 1995) have proposed amendments and doubts about the the naming sections. The ‘Shijia Formation' (23 m) in Weiji to Baishan section is in fact the Jinshanzhai Fm (belonging to Cambrian) and in the naming locality (Shijia village), the ‘Shijia Formation' is correlated with the Liulaobei Fm, whose contact relationship with the underlying strata is not clear.