湖北宜昌地区下-中奥陶统界线疑源类生物地层学意义

ACRITARCHS FROM THE LOWER-MIDDLE ORDOVICIAN BOUNDARY(DAPINGIAN) IN YICHANG REGION,SOUTH CHINA:THEIR BIOSTRATIGRAPHICAL IMPLICATION

根据牙形类Baltoniodus?triangularis的首现,中奥陶统和大坪阶底界已界定于湖北宜昌黄花场剖面大湾组底界之上10.57 m。对黄花场剖面以及邻近的大坪剖面大湾组疑源类研究表明,某些疑源类属种具有生物地层学意义,其首现可用于识别奥陶系下/中统界线。

The base of the Middle Ordovician Series and Dapingian has been defined at a point 10.57 m above the base of the Dawan Formation in the Huanghuachang Section at Yichang,Hubei Province,South China by the first appearance of the conodont Baltoniodus? triangularis.The results of acritarch investigation into the Dawan Formation at the Huanghuachang and the nearby Daping sections indicates that based on their FADS,some of the acritarch taxa may be of biostratigraphical potential for recognition of the Lower-Middle Ordovician boundary.