Maoxian Gr

Tan Xichou and Li Chunyu proposed the Maoxian System in 1935 with no type section clearly indicated. The Wu'an section in Beichuan County of Sichuan Province can be taken for the reference section.

Synonym: (茂县群)

It is subdivided into two subgroups. Lower subgroup, 387 m in thickness, includes two members; the lower member consists of gray to dark gray slate intercalated with metamorphosed quartzose fine-grained sandstone; the upper member is composed of grayish green, black and gray slate, intercalated with lenticular carbonaceous limestone and gray-pink metamorphosed quartzose siltstone at the middle and upper parts. The Upper subgroup is subdivided into three formation complexes. The first formation complex, 1680 m in thickness, is dominated by gray and grayish green sericitic slate intercalated with silty limestone, and with 5 m thick varicolored calcareous quartzose sandstone at the base. The second formation complex, 291 m thick, consists of interbeds of gray thin-bedded micrite, argillaceous limestone and green sericitic slate at its middle and lower parts, and of gray thin-bedded and medium-bedded-to-massive micrite and argillaceous crystalline limestone at its upper part. The third formation complex, 495 m in thickness, is composed of green sericitic slate intercalated with fine-grained argillaceous limestone, and with 32 m-thick limestone at the top as well.

It yields graptolites Monograptus cf. crispus, Pristiograptus kueichihensis, P. cyprus, etc. at the lower member of the lower subgroup. It bears corals Favosites sp., Mesofavosites sp., Heliolites sp. and brachiopods Protathyris sp., Striispirifer sp. etc. in the first formation complex. It contains corals Somphopora sp., Pilophyllum sp., Helioplasmolites sp. etc. at the upper part of the second formation complex. It yields trilobite Coronocephalus sp., brachiopod Protathyris sp. at the lower part and corals Squameofavosites sp., Spongophyllum sp., graptolite Monograptus tumescens, etc. at the upper part of the third formation complex