LOWER TO MIDDLE ORDOVICIAN CONODONTS FROM THE ZITAI FORMATION OF SHITAI,ANHUI PROVINCE,E CHINA

The Lower to Middle Ordovician Zitai Formation consists of a sequence of purple red,nodular argillaceous limestone and has a stable spatial distribution,along the southeastern margin of the Yangtze Platform.The Zitai Formation is stratigraphically correlative to the Meitan Formation and the Dawan Formation developed on the Yangtze Platform.Based on the collection from the Zitai Formation of Liushuting Section,Shitai County,Anhui Province,East China,conodonts are systematically studied,including 24 species of 20 genera.Four conodont biozones are re-cognized,ascendingly the Oepikodus evae Biozone,the Baltoniodus triangularis Biozone,the Baltoniodus navis Biozone and the Paroistodus originalis Biozone.The conodont biozones in the Zitai Formatin can be correlated to those of other areas,such as Yichang region of South China,Europe and Pre-Cordillera of Argentina.