NEW MATERIAL OF EARLY ORDOVICIAN CONODONTS FROM THE BANQIAO SECTION,LIN'AN,ZHEJIANG AND THEIR BIOSTRATIGRAPHIC SIGNIFICANCE

New material of Early Ordovician conodonts has been recovered from carbonate strata at the Banqiao section in Lin'an of Zhejiang Province.Based on the conodont assemblages from the Liuxia,Shijiatou,and Jingshan formations,five conodont zones are recognized.They are,in ascending order,the Cordylodus angulatus Zone,Chosonodina herfurthi Zone,Paltodus deltifer Zone,Paroistodus proteus Zone,and Prioniodus elegans Zone,indicating an age ranging from the early Tremadocian to middle Floian of the Early Ordovician.The overlying siliceous shales of the Hulo Formation have been dated at the middle Darriwilian by graptolites.The new conodonts and graptolites indicate a significant discontinuity from late Floian to Early Darriwilian at the Banqiao section,and therefore offer important insights into stratigraphic subdivision and correlation in the region.