Graptolites from the Wufeng Formation (Latest Ordovician) in the Yangtze Region of China - by Chen Xu & Lucy Anne Muir & Wang Hongyan & Fan Junxuan

Book Synopsis

The age and stratigraphic division of the Wufeng Shale has buried an unresolved issue in the Chinese geological community for a long time since its birth. A paper "On the Wufeng Shale" was published in 1954 (Mu, 1954) with a reliable conclusion obtained that the Wufeng Formation belongs to the Upper Ordovician.

There are too much insignificant species or subspecies and many wrong identification in the monograph "Upper Ordovician Graptolites of Central China Region" (Mu et al., 1993). It makes confusion of age duration of the Wufengian species. This is the one of reasons for the need to restudy the Wufengian graptolites.

In the past two decades, two black shales, the Wufeng Formation (uppermost Ordovician) and the Lungmachi Formation (lower Silurian) in the Yangtze Region have become important shale gas production horizons. Among them, the division and precise comparison of graptolite biozones is an important basis for downhole determination and comparison of shale gas sweet spots. This requires the accuracy and recognized graptolite classification. This is the other one of most important reasons for restudying the Wufengian graptolites.

Since 1990s of last century, a large number of Ordovician graptolites, including Wufengian graptolites have been collected for the research on the global boundary stratification of the Ordovician stages in South China. Recently some better preserved graptolite specimens, in particular a few three-dimensional graptolite specimens, have been obtained from Shuibatang section in Guizou. It provided a good opportunity for restudying the Wufengian graptolites. In this book, all the Wufengian graptolites in South China are restudied and revised, in order to clarify their morphological characteristics, systematic classification, temporal and spatial distribution, and evolutionary significance.