Fenxiang Fm

The type section is on the hill slope north of Nüwamiao west of Fenxiang Town 13 km northwest of Yichang City, Hubei. The Fenxiang Fm is derived from the Fenxiang Series proposed by Wang Yu in 1938.

The strata of the previously defined Fenxiang Series were inferred to the 40 m thick sequence containing Arenig fauna in the upper part of the Yichang Limestone. Chi (1940) found the Tremadocian sediments in the lower 20 m thick shale and Arenigian sediments in the upper 20 m thick sequence, and named the former the Fenxiang Shale. Yang Jingzhi et al. (1954) confined the Fenxiang Fm to be the strata yielding graptolite Acanthograptus sinensis. Considering the fact that the Fenxiang Shale is actually composed of dominantly limestone intercalated with yellowish green shale, Zhang Wentang (1957) renamed it the Fenxiang Bed, which in turn renamed the Fenxiang Fm (1962). In 1983, Zeng Qingluan et al. found an about 45 m thick limestone between the previously defined Fenxiang Fm and the Nanjinguan Fm, which is not exposed in Fenxiang because of coverage of fluvial deposits. They enlarged the Fenxiang Fm to include the strata of the previously defined Fenxiang Fm, the medium-bedded and thin-bedded intercalated with thick-bedded bioclastic limestone without siliceous bands. The enlarged Fenxiang Fm is divided into two parts, and can be correlated with the conodont Paltodus deltifer range-zone. Considering its similar lithology to that of the underlying Nanjinguan Fm and the sequence hiatus between the lower and upper parts, the lower part of the Fenxiang Fm should be included in the Nanjinguan Fm.

Synonym: (分乡组）

Reference Section:

The reference section is at Huanghuachang 5 km northwest of Yichang City (Zeng Qingluan et al., 1983).

The formation is composed of limestone, bioclastic limestone intercalated with yellowish green shale. In the type area, the Fenxiang Fm is 68 m thick.

At Three Gorges area, the Fenxiang Fm yields conodonts of late Paltodus deltifer range-zone to early Paroistodus proteus range-zone; graptolites of Acanthograptus sinensis range-zone in the lower part and Adelograptus-Kiaerograptus assemblage zone in the upper part; Chitinozoan of Conochitina symmetrica range-zone (part) and trilobites of Tungtzella assemblage zone.