海南岛东方早二叠世双壳类动物群及其古生物地理学研究──兼评南龙杂砾岩的冰川成因说

DISCOVERY OF FOSSIL BIVALVES FROM EARLY PERMIAN OF DONGFANG,HAINAN ISLAND WITH A REVIEW ON GLACIOMARINE ORIGIN OF NANLONG DIAMICTITES

在海南岛东方县江边地区下二叠统南龙组中发现双壳类９属１０种，其中２新种。除新种外，这些双壳类常见于华南和日本的茅口期晚期地层，其它动、植物化石的研究也得出了相同结论，本区无疑是华夏生物区系的组成部分。海南岛的琼中地体不大可能在石炭一二叠纪仍位于冈瓦纳大陆北缘或其附近，南龙杂砾岩应属裂谷成因，与冰川无关。

Here described is a Permian bivalve fauna from the Nanlong Formation in the Jiangbian 'area of Dongfang,Hainan Island,with 10 species belonging to 9 genera,including 2 new species,namely,Schizodus jiangbianensis sp.nov.and Wilkingia hainanensis sp.nov.The bivalves and associated bryozoans,brachiopods and ammonoids indicate a late Maokouan or Murgabian age o.f the Early Permian(in Chinese usage).The Nanlong bivalve fauna-is dominated by Schizodus jiangbianensis sp.nov.(27%),Neoschizodus kitakamiensis(22%),Phestia hunanensis(16%),Bakevellia bicarinata(14%)and Sanguinolites kamiyassensis(9%),totally accounting for 88% of the total specimens examined in this study.This fauna has strong affinities to the Toeling fauna(Palaeolima--Paradoxipecten assemblage) of Hunan,China(Fang,1987) and those of the Tenjinnok Formation and Kanokura Formation(Shigejizawa'Member) from Kitakami Massif,Northeast Japan(Nakazawa and Newed,1968).Of the seven old species,Phestia hunanensis,P.zhejiangensis,Palaeolima tenuilineata and Nuculopsis wrmmensis are identical with those of the Toeling Formation from Hunan,China (Fang,1987) while Neoschizodus kitakamiensis,Sanguinolites kaviiyassensis and Bakevellia bicarinata with those from Kitakami Massif.Except Nuculopsis apmmensis and Bakevellia bicarinata,none of them are found beyond the Cathaysian bioprovince(Fang,1985).There is no doubt that the Nanlong fauna,which should be included in the Cathaysian province,has nothing to do with the Gondwanan Realm.The discoveries of Parafusulina-Misellina fauna(Sheng,1965 3 Zhang,1992) and Cathaysian flora (Tingia,Lobatannularia) also support this conclusion.It seems impossible that the Qiongzhong terrane of Hainan Island was still attached or near to the margins of Gondwanaland until the Early Permian.