吉林李家窑范家屯组中的二叠纪北温带牙形刺动物群

A CONODONT FAUNA OF PERMIAN NORTHERN TEMPERATE ZONE FROM THE FANJIATUN FORMATION AT LIJIAYAO, JILIN

在吉林省九台市三台乡李家窑附近的二叠系范家屯组中采到一特殊的牙形刺动物群。多数牙形刺都较小 ,锯齿发育 ,齿脊细齿不愈合。由一些未见报道的新分子组成。本文描述了 4个新种 (Mesogondolella changcunensis sp.nov.,M. jilinensis sp. nov.,M.multiserrata sp. nov.,M.pseudoaltudaensis sp.nov.)和 3个未命名新种 (Mesogondolella sp.nov. A,M. sp. nov. B,M.sp.nov.C)。这一牙形刺动物群的时代可能为 Wordian- Capitanian,前者的可能性更大。范家屯组中的菊石既有世界性的属种 ,也有只限特提斯暖水域的属种和北方冷水域的属种 ,反映出冷暖混合的特征。范家屯组中的牙形刺多为新种 ,可能多数代表温凉水域的分子 ,如 Mesogondolella jilinensissp.nov.,M.multiserrata sp.nov.,M.sp.nov.B,但 Mesogondolella pseudoaltudoensis sp.nov.有与 M.altudaensis相似的口面 ,而 M.sp.nov.C也有与 M.shannoni相似的口面 ,可能属特提斯暖水域分子 ,也可能全部都属温凉水域的分子。结合古地磁和构造地质资料分析 ,作者认为范家屯组中的牙形刺动物群生活于二叠纪北温带温凉的水域。

A very special conodont fauna has been found from one sample collected by the authors from the Fanjiatun Formation at Lijiayao village, Santai Township of Jiutai City, Jilin Province, China. The conodont fauna consists of following conodont new taxa: Mesogondolella changcunensis Wang sp. nov., M. jilinensis Wang sp. nov., M. multiserrata Wang sp. nov., M. pseudoaltudaensis Wang sp. nov., M. sp. nov. A, M. sp. nov. B and M. sp. nov. C. Most conodont elements are small and have serrated platform with unfused carina. The age of this fauna could be Wordian or Wordian to early Captanian. The Fanjiatun Formation yields a special ammonoid fauna (Liang, 1982), including cosmopolitan ammonoids: Agathiceras, Propinacoceras, Thalassoceras; Tethyan ammonoids: Prostacheoceras, Stacheoceras, Tauroceras, Waagenoceras; and Boreal ammonoids: Tumaroceras, Doubichites, Mongoloceras, indicating relative cool water facies in Temperate latitude. Mesogondolella changcunensis Wang sp. nov., M. jilinensis Wang sp. nov., M. multiserrata Wang sp. nov., M. sp. nov. A and M. sp. nov. B could belong to cool water facies. Mesogondolella pseudoaltudaensis Wang sp. nov., and M. sp. nov. C are suggested to be Tethyan conodont elements, because they are similar to M. altudaensis and related species, but it is also possible that all fauna belong to cool water facies. Based on palaeomagnetic data and tectonic analysis, the present authors concluded that this conodont fauna were from Permian Northern Temperate Zones.