Wengxiang Fm

The name was proposed by Wang Yuelun, Xiong Yongxian and Wu Xizen (1938). The type section is located at Wengxiang, 15 km northeast of Kaili County, Guizhou Province. The Wengxiang Fm exposed in Kaili were further subdivided by local geologists (Zhou Xiyun et al, 1981) into the following formations, namely being in ascending order: the Jibozai Fm (dominated by pelite, siltstone intercalated with micritic sandstone), the Luomian Fm (mainly consisting of pelite, calcareous pelite, intercalated with marl and limestone lenses and bearing abundant shelly fossils and conodont: the Spathognathodus parahassi-S. guizhouensis zone and the Pterospathodus celloni zone), the Hauzizai Fm (dominated by micritic sandstone, siltstone and pelitic siltstone) and the Gangao Fm (mainly composed of pelite, silty pelite intercalated with limestone; the base conglomerate pseudo-conformably resting on the limestone of the Lower or Middle Ordovician). The establishment of this suite of lithostratigraphic units has provided important contents for further subdividing the Wengxiang Fm.

Synonym: (翁项组); Wenghsiang Fm

The base of the Wengxiang Fm consists of gray pebbly marl of several dozens’ centimeters in thickness. Upwards in the Lower part of the formation, the gray green to dark gray silty marl bears rather rich anthozoa Brachyelasma, Cystiphyllum, Troedssonites, Ceriaster, Palaeofavosites, etc. The Middle and Upper parts are composed of yellow green, gray green pelite and siltstone, intercalated with several layers of purplish red pelite and limestone lenses and yield brachiopods Eospirifer, Striispirifer, Nalivkinia, Nucleospira. The Wengxiang Fm is about 5898 m in thickness. The formation is 210-380 m in thickness. [? Which is correct thickness ?]

The upper part and the pelitic quartzose sandstone with limestone lenses of the lower part of the formation bear rare fossils, but the yellow green, gray green and dark gray pelite, siltstone intercalated with pelite, and marl in the upper part of the formation yield abundant fossils, such as: graptolites Stomatograptus sinensis, Monograptus priodon; cephalopods Jangziceras, Kailiceras,Sichuanoceras, etc.; brachiopod Nalivkinia, Nucleospira, Howellella, etc.; trilobites Coronocephalus, Rongxiella, Kailia; bivalve Orthonota; gastropod Discodichilus; conodonts Kailidontus typicus, Lonchodina fluegeri, Hibbardella luomianensis, Pterospathodus celloni, etc.