Hongqin Fm
Type Locality and Naming
The type section is located in the area of Hongqin, Shexian County, Anhui Province, with its reference section being situated in the vicinity of Yantian region, Xiuning County, Anhui Province. It was named by the Regional Survey Party of Anhui Province in 1971.
Synonym: （洪琴组）
Lithology and Thickness
Lower part is composed of dark-violet thick-bedded and massive conglomerates and pebble-bearing sandstone. Middle part is multiple rhythmite consisting of yellow-violet and grey-green medium-bedded and medium-, and fine-grained sandstone, feldspar-sandstone and siltstone, containing calcareous concretions. Upper part is alternating layers of medium-, and fine-grained feldspar-sandstone and argillaceous siltstone, intercalated locally with stratified andesite. Its lower part is with a thickness of 8 m, and its upper part is with a thickness of about 227 m. The thickness of the middle part is not known.
Relationships and Distribution
Lower contact
Its basal part is in a disconformable contact with the underlying Yuetang Fm or in an unconformable contact with the underlying still older strata.
Upper contact
Regionally, the schematic strat column in previous "red Chinese Lexicon" indicates the next younger unit as conglomerate of the Bingqiu Fm
Regional extent
It is distributed mainly in the areas of Wucheng and Linxi of Xiuning County, and Yencun Village, Fangcun Village, Yentian and Hongqin of Shexian, as well as at Tunxi City, Anhui Province. Except for a greater change in its lithology of its basal part, the lithology and rock facies of it in various regions are more or less consistent. In the area of Yantian major rock types are represented by conglomerate, sandstone and mudstone, which constitute three rhythmic layerings, containing a small amount of gold, with a thickness of about 1383-1562 m.
GeoJSON
Fossils
It yields the Psilunio-Lamprotula-Cuneopsis assemblage of bivalves consisting of at least 6 genera and 21 species, including although such species as Sibireconcha and Tutuella, yet they tend to take only a secondary position in the above-mentioned assemblage.
Age
Depositional setting
The formation belongs to fluvial-lacustrine deposits.
Additional Information