Hongyanjing Gr
Type Locality and Naming
The type section is located at 2 km north of Hongyanjing area 85 km to the east of the Xingxing Gorge, Subei County, Gansu Province. It was named by the 2nd Regional Geological Survey Party of Gansu Province in 1968.
Lithology and Thickness
Clastics. Lower part is composed of grey-green and black carbonaceous shales, silty-shale, greywacke quartz-sandstone and feldspar-quartz-sandstone, intercalated with carbonaceous sandy slate and clayey shale. Middle part is composed of feldspathic greywacke and quartz-feldspar-rich sandstone. Upper part is composed of grey-green and black-green carbonaceous shale, greywacke, feldspathic greywacke and pebble-bearing greywacke. Total thickness is 4369 m.
Relationships and Distribution
Lower contact
Unconformable contact with the underlying strata. Partly coeval with Fangshankou Fm (put over it for graphic purposes), and next older regional unit is Jinta Fm
Upper contact
No top being found. Next higher regional unit is the Erduanjing Gr of lower Triassic.
Regional extent
Distributed in the Malianjing and Hongliucun Village areas of the Anxi County, with a thickness of over 2700 m; and in the Yemaying area of Subei County the thickness of the formation is of 602 m.
GeoJSON
Fossils
Plant fossils (phytolites) such as Zamiopteris glossopteroides, Callipteris, Iniopteris sibirica, as well as gastropod and bryozoan fossils.
Age
Depositional setting
It seems to represent littoral-basin deposits.
Additional Information