【摘要】 湖南桑植仁村坪剖面茅口组中—上段地层的牙形l类资料显示,该剖面具有相对完整的卡匹敦阶(Capitanian)牙形类化石带,但缺失瓜德鲁普统-乐平统界线附近的Jinogondollela granti-Clarkina postbitteri postbitteri的3个牙形类化石带。该阶底部Jinogondollela postserrata牙形类化石带起始于茅口组下段顶部的礁边缘相生屑灰岩沉积的底部(-4.1m处);茅口组中段"孤峰组"硅(泥)质岩段属于牙形类J.shannoni化石带的沉积;茅口组上段含白云质团块的巨厚层亮晶灰岩基本属于牙形类J.xuanhanensis化石带的沉积。该剖面卡匹敦阶的层序地层分析显示出一个完整的三级层序变化过程。其底界SB3位于茅口组下段顶部9cm厚度的薄层白云岩之顶,代表东吴运动的第二幕(鸣山运动);后继高水体系域沉积表现为茅口组中段的硅(泥)质沉积岩段,属于牙形类J.shannoni化石带;茅口组上部灰岩段代表低水位体系域的碳酸盐台地边缘相灰泥丘沉积,属于牙形类J.xuanhanensis化石带,可与广西"来宾灰岩"的生物时代和沉积环境相对比;茅口组顶部覆盖的"王坡煤系"代表二级层序界面(SB2),与东吴运动的主幕(第三幕)相对应。更多还原

【Abstract】 Conodont fossils in the middle-late Units of Maokou Formation at the Rencunping Section,Sangzhi County of Hunan reveal a relatively continuous sequence of the Permian Capitanian Stage,but missing the records from the Jinogondollela granti to Clarkina postbitteri postbitteri zone around the Guadalupian-Wuchiapingian boundary.The conodont Jinogondollela postserratazone is represented by the low Unit of the Maokou Formation.The"Kufeng"siliceous(or argillaceous)rock unit in the middle Unit of Maokou Formation is deposits of the conodont J.shannoni zone.The overlying unit of massive biosparite in the upper Unit of Maokou Formation belongs to the conodont J.xuanhanensis zone.Sequence stratigraphic analysis reveals that a third-order sequence boundary(SB-3)occurs at the topmost surface of a 9cm thick dolomite layer of the low Unit of the Maokou Formation,which represents the occurrence of the second epoch of Dongwu Movement(also termed as Wushan Movement).The siliceous(or argillaceous)rock unit represents deposits during the following HST system,and might have resulted in the weathering mafic minerals in the Emeishan basalt during the conodont J.shannoni zone.The massive biosparite in the upper Unit of the Maokou Formation is characterized by the shallow water sea-mount in the carbonate platform,which could temporally correlated to the epoch of"Laibin Limestone"in Guangxi in terms of biostratigraphy and depositing environment.The overlying bed of"Wangpo Coal Seam"on the Maokou Formation marks a second-order interface(SB-2)that prevailed in southern China and is indicative of the third epoch of Dongwu Movement.更多还原