【作者】 赖才根；

【Author】 Lai Caigen (Institute of Geology,Chinese Academy of Geological Sciences)

【机构】 中国地质科学院地质研究所；

【摘要】 <正>一九七五年,林宝玉、郭振明和作者调查陕、甘、宁西南缘的奥陶系时,划分耀县桃曲坡地区的奥陶系为三道沟组、桃曲坡组和背锅山组(桃曲坡组是新命名的地层单位)。三道沟组为灰及深灰色块状灰岩夹少量砾状灰岩,顶部10米岩层变薄,总厚80米。桃曲坡组和背锅山组以灰色薄层泥质灰岩为主,厚100米。以紫红色团块状灰岩做背锅山组的底界更多还原

【Abstract】 The Sandaogou formation and overlying Taoqupo formation constitute the Ordovician of the Yaoxian area,Shaanxi.Two cephalopod faunas are recognized.Tofangoceras shaanxiense fauna occurs in the top of Sandaogou formation and the lowest part of Taoqupo formation,and belongs to the Pagoda or Miaopo-Pagoda stage.The other fauna Yaoxianoceras latilobatum occurs in the top of Taoqupo formation and belongs to the early Wufeng stage.Therefore the Lower-Upper Ordovician boundary lies within the San- daogou formation.According to Zhang Wentang,the middle part of Taoqupo formation bearing graptolites corresponds to the Sijiagou formation of Qilian Province.It stands to reason that there is no break in the interval between the Sandaogou and Taoqupo formations.更多还原