Shijiagou Fm
Type Locality and Naming
The type section is located at Shijiagou, Luohe Village of Xunyang County, Shaanxi Province. The reference section is at Fengzigou, Luohe Village of Xunyang County. It was named by No. 1 Geological Team of Shaanxi Province in 1964, and published in the “Paleontological Atlas, Volume Shan-Gan-Ning” in 1983.
Lithology and Thickness
The Shijiagou Formation is divided in to two lithologic members.
Marls. Lower member, 113.6 m in thickness, is composed of gray to dark-gray thin- to medium-bedded marls, clayey limestone and reefal limestone, intercalated with calcareous slate.
Dolomite. Upper member, 40.1 m in thickness, consists of light-grey medium- to thick-bedded dolomite with silty slate intercalations in the lower part and silty slate with siltstone, sandstone and limestone intercalations in the upper part.
Relationships and Distribution
Lower contact
It rests conformably on the dolomite of the Gongguan Fm.
Upper contact
Conformably overlain by the Dafenggou Fm.
Regional extent
Westward to Fengxian-Wafanba area, the formation overlaps on the Silurian, and is composed of thin-bedded sandy limestone, mudstone and slate with a basal conglomerate, and contains Athyrisina sp., Utaratuia sp., and its thickness decreases to 86 m.
GeoJSON
Fossils
The main fossils are Athyrisina spp., Utaratuia sp., Astrictophyllum sp., and stromatoporoids in the lower member, and Sociophyllum sp., Thamnopora sp. in the upper member.
Age
Depositional setting
Additional Information