EARLY SILURIAN GRAPTOLITE ZONES IN SOUTHWESTERN HENAN PROVINCE

In Henan province, the strata containing early Silurian graptolites, a typical sequence of mixed facies, are only exposed in Xichuan, which yield abundant graptolites associated with some trilobites and brachiopods. The graptolites discussed in the paper were collected from the Lower Silurian near the Houwa-Lingshang area, Xichuan, Henan. They belong to 22 species in 9 genera with a new species （Pristiograptus sp. nov.）. According to their stratigraphical distribution, the graptolites fall into the following four zones in ascending orders: 4. Monograptus sedgwickii zone 3. Demirastrtes convolutus zone 2. Demirastrites triangulatus zone 1. Coronograptus leei zone They can be correlated with the graptolite zones of the eastern Changjiang （Yangtze） Gorges of China and the standard graptolite zone of Britain. The graptolites were not found below the strata in which Coronograptus leei（Hsu） was obtained during our work in the area. At present, it is still uncertain whether the Monograptus sedgwickii zone is the highest graptolite zone in the area for lack of graptolites in the upmost part of the section.