A DISCUSSION OF THE NANHAO FORMATION OF THE HAINAN ISLAND, SOUTH CHINA

The Nanhao Formation is one of the stratigraphic units most widely used for the Hainan Island at present, representing the entire Lower Carboniferous of this island, but its lectostratotype is of Lower Silurian Series, and is not of Yanguanian Stage. No Lower Carboniferous strata have known from the Nanhao area of Baoding and its parastratotype is the stratotype of the original Qingtianxia Formation. Therefore based on this, the name Nanhao Formation should be abandoned. Many fossils were recently found in the Nanhao Formation in the northwestern area of Hainan Island, including the Givetian(?) chitinozoans Eisenackitina castor, Grahanichitina pilosa, Lagenochitina amottensis; the Famennian conodonts Palmatolepis gracilis gracilis, P. gracilis sigmoidalis, Polygnathus germanus; the Tournaisian brachiopods Spirifer cf. subgrandis, Fusella cf. fornacensis, Palaeochoristites spp., Chonetipustula sp., Marginatia sp., Rhipidomella spp. and conodonts Siphonodella isosticha-S. cooperi Assemblage, and the conodonts of Huashibanian—Datangian (Bashkirian—Moscovian) Mesogondolella clarki, Idiognathoides sulcatus, Declinognathodus noduliferus noduliferus. Accordingly, the Nanhao Formation in northwestern area of Hainan Island, where it has a rather widely distribution, has also to be abandoned. Furthermore, the Nanhao Formation may be replaced by the following four formations. They are: the Changjiang Formation of Upper Devonian, the Jishi Formation (new name) of Yanguanian (Tournaisian), the Qingtianxia Formation (Lower Member) of Datangian (Visean), and the un-named formation represented the Givetian.