Some possible boundary-stratotypes for the base of the Cenomanian and Turonian Stages
Some possible boundary-stratotypes for the base of the Cenomanian and Turonian Stages
复制标题
塞诺曼阶和土伦阶底部的一些可能的边界层型
DOI：
10.37570/bgsd-1984-33-10
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发表时间：
1984
影响因子：
1.2
通讯作者：
J. Hancock
中科院分区：
文献类型：
--
作者：
J. Hancock
阶段的历史定义不足以满足现在要求的地层学精确标准。在突尼斯Djebel Hameima北部具有边界层型的schneegansi - Hypoturri/ites - Zone的底部最好地定义了Cenomanian的基底。下塞诺曼尼亚格雷森尼动物群是特提斯的，可能没有迁移到北方地区。以M. opa/ensis Kauffman non Bose为代表的育虫群Mytiloides主要发育的出现最好地定义了Turonian的基础。这与弯曲假蛛螺的菊石带基部重合。边界层型可能分布在德克萨斯州西南部；最合适的可能是卡尔弗特峡谷。
Historical definitions of stages are inadequate for the standards of precision in stratigraphy now required. The base of the Cenomanian is best defined by the base of the Zone of Hypoturri/ites schneegansi with a boundary-stratotype north of Djebel Hameima in Tunisia. The Lower Cenomanian Graysonites fauna is Tethyan and probably failed to migrate to boreal regions. The base of the Turonian is best defined by the appearance of the main development of the inoceramid Mytiloides as represented by M. opa/ensis Kauffman non Bose. This coincides with the base of the ammonite Zone of Pseudaspidoceras flexuosum. Possible localities for the boundary-stratotype are in south-west Texas; the most suitable is probably in Calvert Canyon.