Hongshanzui Fm

The type section is located at Hongshanzui on the Sino-Mongolia border, on the north side east of Altay, Xinjiang. It was named by the No. 4 Geological Party of Xinjiang Bureau of Geology in 1966, and formally cited in The Paleozoic Erathem of Xinjiang in 1991.

Volcanics, Volcaniclastics and Limestone. Composed of intermediate-acid volcanic rocks and pyroclastic rocks in the Lower part, and varicolored marine clastic rocks in the Upper part. At the Hongshanzui section, the Lower part, of intermediate-acid volcanic rocks and organic limestone; the Middle part is gray-green marl intercalated with porphyrite andesitic and quartz-rich albite porphyry volcanics; the Upper part consists of varicolored and gray sandstones and slate intercalated with marl. Total thickness 500−700 m.

Northwest of Haba River, it is composed of green-gray shale, sandstone and conglomerate, 2600 m thick. In the middle reaches of Zhengge River, Fuyun County, it consists of dark-gray and gray-black carbonaceous and clayey siltstones to slates, medium-grained lithic quartzose sandstone and fine-grained sandstone, intercalated with calcareous siltstone and gray-black limestone, containing coral Zaphrentoides sp. brachiopod Striatifera sp., etc., 1270 m thick.

Around Kaladuergen, metamorphism is of a relatively high degree, with the appearance of schist, phyllitized clayey siltstone and crystalline limestone, most of which are destroyed by later structures, so that the top and bottom strata are incomplete.

Lower part contains brachiopod Gigantoproductus sp. and bryozoan Rhombopora sp.,

It is interpreted as a suite of intermediate-acid volcanic rocks and varicolored marine clastic rocks