Huanggangliang Fm

The type section is located at Shihuiyao, Yandanzi Mt., Huanggangliang area, Keshiketeng Banner, Inner Mongolia, and the lower part of the reference section is represented by the Xinanshan and Baishilazi sections in the Shihuiyao area of Huanggangliang District, with the upper part of the reference section is at the Seribeng point. It was named by the Geological Party of Chengde City, Hebei Province in 1958; and was issued in a Report on the Regional Geological Reconnaissances in Hebei Province in 1959.

Limestone and Sandstone. It is divisible into two members: Lower member is composed of dark-grey and grey-white marble, limestone and calcareous sandstone, intercalated with a small amount of slate and intermediate-acidic volcanic rocks, with a thickness of 450 m. The base of the Upper member is composed of yellow-brown and grey-green sandy conglomerate, and upwards it is becoming to be composed mainly of purple-grey tuffaceous siltstone, intercalated with slate, with a thickness of 1007 m. Total thickness range is 466-2600 m.

Lower member yields Brachiopods such as Spiriferella keilhavii, Neospirifer moosakhailensis, Licharewia sp., etc.; Corals such as Lytvolasma, Lophophyllidium and Tachylasma magnum; Bryozoan represented by Fistulipora, Stenopora sp.

Upper member yields Brachiopods such as Waagenoconcha, Yakovlevia, Compressoproductus, etc., as well as Bivalves as represented by Aviculopecten.

It is interpreted as a shallow-sea and littoral-facies.

The formation contains a major ore-bearing stratigraphic horizon for iron ores and polymetallic mineral resources in the region.