Foraminifers in the Holkerian Stratotype, regional substage in Britain: key taxa for the Viséan subdivision Foraminifers in the Holkerian Stratotype, regional substage in Britain: key taxa for the Viséan subdivision
Foraminifers in the Holkerian Stratotype, regional substage in Britain: key taxa for the Viséan subdivision Foraminifers in the Holkerian Stratotype, regional substage in Britain: key taxa for the Viséan subdivision
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霍尔克层型中有孔虫，英国区域亚级：维塞亚区的关键类群 霍尔克层型中有孔虫，英国区域亚级：维塞亚区的关键类群
DOI：
10.1127/nos/2021/0674
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发表时间：
2022
影响因子：
2.2
通讯作者：
Cózar P
中科院分区：
文献类型：
--
作者：
Cózar P
在英国坎布里亚郡南部霍尔克霍尔的Barker Sar，对英国Holkerian层型进行了有孔虫修订，允许将该剖面细分为CF4？、CF5？和CF5？亚带(后者进一步细分为下层CF5？1和上层CF5？2)。位于C层底部的CF5？亚带底部和距C层中部的CF5？亚带底部分别位于K层Holkerian传统底界下方14m和10.5m处。这些有孔虫亚带的下界位于剖面中受白云石化作用影响的主层段内，这就给准确确定这些亚带的底面带来了困难。然而，尽管有白云石化作用，但或多或少连续的有孔虫记录允许CF5？的底部与Liian亚带(比利时定义，但也在法国使用)中保存下来的演替相关联，并假设该亚段的底部应与CF5？亚带的底部相对应。CF5亚带的底部可以与俄罗斯图连亚阶段的底部进行对比，因为它包含许多与Holkerian相同的分类群。然而，需要进一步的研究来建立霍尔克亚阶段更高的其他水平的相关性(例如，CF5？亚区的基础)。所有这些问题表明，应该重新考虑霍尔克期，特别是巴克刀疤层型剖面，并寻找和调查一个新的准层型剖面，理想情况下没有白云石化作用，以便与巴克刀疤层型中识别的那些相比较，证实CF5和CF5？有孔虫亚带的存在。这些修改将允许识别一个明显的同步动物群事件，形成未来Viséan的细分的基础。
Foraminiferal revision of the Holkerian Stratotype of Britain at Barker Scar, Holker Hall, south Cumbria, UK, allows the subdivision of the section into the Cf4¿, Cf5¿ and Cf5ß subzones (the latter being further subdivided into lower Cf5ß1 and upper Cf5ß2 intervals). The base of Cf5¿ subzone at the base of bed C and base of Cf5ß subzone from the middle part of bed C, occur at 14 m and 10.5 m, respectively, below the traditional basal boundary of the Holkerian at bed K. The lower boundaries of these foraminiferal subzones occur within the main interval affected by dolomitization in the section, which poses problems in defining precisely the bases for these subzones. Nevertheless, in spite of the dolomitization, a more or less continuous foraminiferal record allows a solid correlation of the base of the Cf5ß with the preserved succession in the Livian Substage (defined in Belgium, but also used in France), and it is assumed that the base of this substage should correspond to the base of the Cf5¿ subzone. The base of the Cf5¿ subzone can be correlated with the base of the Russian Tulian Substage, since it contains many taxa in common with the Holkerian. However, further investigation is needed to establish other levels of correlation (e. g., base of the Cf5ß subzone) higher up in the Holkerian substage. All of these problems suggest that the Holkerian, as it is currently recognised, and the Barker Scar stratotype section, in particular, should be reconsidered, and a new para-stratotype section, ideally devoid of dolomitization, should be located and investigated, in order to corroborate the occurrence of the Cf5¿ and Cf5ß foraminiferal subzones compared to those recognised in the Barker Scar Stratotype. These modifications would allow identification of an apparent synchronous faunal event forming the basis of a future subdivision of the Viséan.