黔北晚奥陶世Hirnantian期观音桥层四射珊瑚新资料及其地质意义

报道黔北毕节、仁怀和石阡地区晚奥陶世Hirnantian期观音桥层中首次发现的四射珊瑚Axiphoria,Bodophyllum,Dalmanophyllum,Leolasma,Brachyelasmaunicum(Neuman),Grewingkiaanguinea(Scheffen),结合前人报道的该层所产的Borelasma,Kenophyllum,Streptelasma,Ullernelasma等属,进一步表明黔北观音桥层四射珊瑚动物群与斯堪的纳维亚(Scandinavia)、中亚、阿尔泰地区同期珊瑚群关系密切。该动物群对阐明晚奥陶世四射珊瑚古地理关系具有重要意义。黔北观音桥层四射珊瑚十分丰富,总计有18属39种。文中共描述10属12种,其中1新属3新种,即AmplexobrachyelasmaHeetChengen.nov.,GrewingkiadensicolumnaHeetChensp.nov.,KenophyllumfossulatumHeetChensp.nov.,LeolasmaqianbeienseHeetChensp.nov.。

NEW MATERIAL OF RUGOSE CORALS FROM THE UPPERMOST ORDOVICIAN (HIRNANTIAN) IN NORTHERN GUIZHOU AND THEIR GEOLOGICAL SIGNIFICANCE

The latest Ordovician(Hirnantian) rugose coral fauna from the Guanyinqiao Beds in Bijie, Renhuai and Shiqian districts of northern Guizhou are studied in detail, and some genera and species are reviewed. 4 genera and 2 species of rugose corals are reported from the Guanyinqiao Beds in northern Guizhou for the first time, they are Axiphoria, Bodophyllum, Dalmanophyllum, Leolasma, Brachyelasma unicum (Neuman), and Grewingkia anguinea (Scheffen). In the past, quite a number of rugosan taxa, including the genera Borelasma, Kenophyllum and Ullernelasma, etc.had been discovered in the Guanyinqiao Beds (He, 1978, 1985). The present new material thus further enrich the content of the latest Ordovician (Hirnantian) rugosan fauna in the Upper Yangtze region and indicate the close affinities of the Late Ordovician rugosan faunas in the Yangtze region to those of Scandinavia and central Asia.Up to now, totally 39 species of 18 genera have been found from the Guanyinqiao Beds (see Table I). Among them, 12 species of 10 genera of rugosan are described in this paper, including 1 new genus and 3 new species, namely Amplexobrachyelasma He et Chen gen. nov., Grewingkia densicolumna He et Chen sp. nov., Kenophyllum fossulatum He et Chen sp. nov. and Leolasma qianbeiense He et Chen sp. nov.