云南保山地区的下石炭统

The Lower Carboniferous of Baoshan, Yunnan

云南保山地区下石炭统及其生物群曾引起许多学者的兴趣，其主要原因于丰富而特殊的生物的生物类群，悬而未决的地层问题以及独特的生物地理位置。本文以４条剖面（图１）为基础，依据多门类的生物化石对诸如本区杜区／维宪阶界线、Ｓｉｐｈｏｎｏｐｈｙｌｌｉａ－Ｋｅｙｓｅｒｌｉｎｇｏｐｈｙｌｌｕｍ（ｈｕｍｂｏｌｄｔｉａ）动物群的时代、冷水（凉水）珊瑚动物群，岩石地层单位等问题进行讨论。

Five Lower Carboniferous formations are described from Baoshan, Yunnan, including Tournaisian Yudong Formation, Tournaisian-Lower Visean Shihuadong Formation, Qingshu-igou Formation, Upper Visean Yunruijie Formation and Jiangjiawan Formation.In the Yudong section, as macrofossils have their limitations in the distribution, cono-dont biostratigraphy is favoured. The Tournaisian-Visean boundary is drawn at the base of the Gnathodus taxanus Zone in the Shihuadong Formation. The large solitary rugosans, i.e. Keyserlingophyllum (Humboldtia) and Siphonophyllia in the formation occur above the conodont Zone.Two distinct coral biofacies can be recognized in the Baoshan area. One is distributed in the Yudong and Jiangjiawan Formations characterized by small cornuted solitary rugosans of Hill's Cyathaxonia fauna. The other occurs in the Shihuadong and Yunruijie Formations characterized by solitary rugosans with dissepiments of Hill's Caninid-Clisiophyllid fauna. Meanwhile the Lower Carboniferous rugose corals in the area are grouped into 7 assemblages. Palaeobiogeographically, Lower Carboniferous of Baoshan may have a close relationship with that of Western Europe and South China in the light of corals, brachiopods and crinoids.