海南岛南好组剖析

南好组是海南岛目前使用最广泛的地层单位之一 ,代表该岛整个下石炭统 ,但其选层型为下志留统而非岩关阶 ,保亭南好地区并不存在下石炭统 ;其副层型原本是青天峡组的层型。据此 ,南好组应予废弃。根据新近发现的吉维特期胞石 Eisenackitina castor、Grahanichitina pilosa、L agenochitina amottensis;法门期牙形刺 Palmatolepisgracilis gracilis、P.gracilis sigmoidalis、Polygnathus germanus;以石燕贝类为主的岩关期腕足动物群 Spirifercf.subgrandis、Fusella cf.fornacensis、Palaeochoristites sp.、Chonetipustula sp.、Marginatia sp.、Rhipidomellaspp.和牙形刺 Siphonodella isosticha- S.cooperi组合 ;以及滑石板期—达拉期牙形刺 Mesogondolella clarki组合 ,岛西北部地区的南好组废弃后可划分出 :中泥盆统吉维特阶 (?) (组名待建 )、上泥盆统法门阶昌江组、下石炭统岩关阶鸡实组 (新名 )、大塘阶青天峡组下段及三棱山组等不同地层单元

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.