Mayilashan Gr

It was named by the Party of Regional Geological Survey of Xinjiang Bureau of Geology in 1959. the name was first quoted by the Compiling Group of the Regional Stratigraphical Scale of the Xinjiang Uygur Zizhiqu in 1981. No type section is indicated.

Synonym: (玛依拉山群)

It is subdivided into two subgroups. The Lower subgroup is 3600-3717 m in thickness; the Lower part of the lower subgroup consists of gray green, purplish red thin-to-medium-bedded tuffaceous micritic sandstone intercalated with basaltic porphyrite, spilite, sandy pelite, pelitic siltstone and minor conglomerate; the Middle part is composed of gray green, purplish red medium-bedded or lesser laminar tuffaceous micritic sandstone and tuff intercalated with abundant almond-shape basalt, tuff, greywacke, pelite and sandy conglomerate; the Upper part is characterized by gray green, gray violet siltstone, tuffaceous siltstone, micritic sandstone and minor medium-to-coarse-grained sandstone and tuff intercalated with tuff, greywacke, pelite and sandy conglomerate. The Upper subgroup, 4230-5042 m in thickness, consists of gray green, gray violet phyllitized and schistosized tuffaceous siltstone, volcanic tuff, siliceous slate, siltstone and silty pelite intercalated with sandy conglomerate, arkosic sandstone, andesitic porphyrite, basalt, diabase-porphyrite, jasper rock and conglomerate.

It yields corals Favosites, Heliolites, Microplasma; brachiopods Atrypa, Chonetes; graptolites Saetograptus cf. chimaera var. solweyi, Pristiograptus cf. colonus var. compactus.