RUI: The Effect of Ash Flows on Shallow Marine Sedimentation: An Example from the Ordovician Capel Curig Volcanic Formation, North Wales

本研究的目的是探讨两个假设 涉及与浅部侵位有关的沉积作用， 海相火山灰流凝灰岩 具体而言，这些假设是：1） 卡佩尔克里格火山的奥陶纪灰流凝灰岩 在水下安置和焊接，2） 爆发性火山活动对影响 浅海沉积模式。 奥陶纪火山岩和 卡佩尔克里格火山岩组的火山碎屑岩 是检验这些假设的理想实验室 与火山灰流凝灰岩有关的沉积岩 北威尔士的奥陶纪出露良好， 沉积构造 英国地质勘探局的详细地图 调查提供了一个明确的地层背景， 工作 此外，许多这些灰流凝灰岩已经 被解释为是在水下安放和焊接的，尽管 这一假设一直存在争议。 然而卡佩尔的凝灰岩 克里格火山形成仍然是教科书的例子之一 在浅海中焊接。 本研究将确定 伴生沉积岩的沉积环境 在凝灰岩和古水深处， 波浪涟漪的暴露。 环境的确定 沉积将测试水下焊接的可能性。 将凝灰岩形成前的环境与 凝灰岩侵位将决定这些凝灰岩对 沉积模式。 这项工作的顺利完成将为今后的工作提供数据。 解决威尔士当地的地质问题。 这 该项目将直接涉及水下焊接问题 以及最常被用来支持 在中等深度的水中焊接。 此外， 来自卡佩尔克里格火山的火山碎屑沉积 形成将被开发，可以应用于许多未来 研究并用于确定爆炸物的影响 火山作用影响着海洋陆架沉积的模式。

The purpose of the research is to investigate two hypotheses involving sedimentation associated with the emplacement of shallow marine ash-flow tuffs. Specifically, these hypotheses are: 1) that Ordovician ash-flow tuffs of the Capel Curig Volcanic Formation were emplaced and welded underwater, and 2) that explosive volcanism has a significant impact on influencing patterns of shallow marine sedimentation. Ordovician volcanic and volcaniclastic rocks of the Capel Curig Volcanic Formation provide an ideal laboratory for testing these hypotheses. Sedimentary rocks associated with ash-flow tuffs in the Ordovician of North Wales are well exposed and contain numerous sedimentary structures. Detailed mapping by the British Geological Survey has provided a well-defined stratigraphic context for this work. Furthermore, many of these ash-flow tuffs have been interpreted to have been emplaced and welded underwater, although this hypothesis has been controversial. Yet the tuffs of the Capel Curig Volcanic Formation have remained one of the textbook examples of welding in shallow marine water. The study will determine environments of deposition in the associated sedimentary rocks beneath the tuffs and paleowater depths from numerous bedding plane exposures of wave ripples. Determination of the environments of deposition will test the likelihood of subaqueous welding. Comparing pre-tuff environments with ones that existed following tuff emplacement will determine the effect that these tuffs had on patterns of sedimentation. Successful completion of this work will provide data far beyond that of solving a local geological problem in Wales. This project will bear directly on the question of subaqueous welding and on the specific examples that have been most often to support welding in intermediate depth water. Also, models of volcaniclastic sedimentation from the Capel Curig Volcanic Formation will be developed that can be applied in many future studies and used to determine the influence that explosive volcanism plays on patterns of marine shelf sedimentation.