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

RUI：灰流对浅层海洋沉积的影响：以北威尔士奥陶纪 Capel Curig 火山地层为例

• 批准号: 9017590
• 负责人: William Fritz
• 金额: $ 4万
• 依托单位: Georgia State University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 1991
• 资助国家: 美国
• 起止时间: 1991-03-01 至 1992-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=9017590&HistoricalAwards=false
• 关键词: RUI; Effect; Ash; Flows; Shallow

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.

本研究的目的是调查与浅海灰流凝灰岩就位有关的沉降的两个假设。具体来说，这些假设是：1)卡佩尔-库里格火山组的奥陶系灰流凝灰岩在水下被放置和焊接；2)爆发火山作用对浅海沉积的影响模式有显著影响。卡佩尔居里火山组的奥陶系火山岩和火山碎屑岩为验证这些假设提供了理想的实验室。北威尔士奥陶系与灰流凝灰岩伴生的沉积岩暴露良好，含有大量的沉积构造。英国地质调查局的详细制图为这项工作提供了一个明确的地层背景。此外，许多这些火山灰流凝灰岩被解释为是在水下放置和焊接的，尽管这个假设一直存在争议。然而，卡佩尔库里火山组的凝灰岩仍然是浅海中焊接的教科书范例之一。该研究将确定凝灰岩下伴生沉积岩的沉积环境，并从波浪波纹的大量层理平面暴露中确定古水的深度。沉积环境的测定将检验水下焊接的可能性。将前凝灰岩环境与凝灰岩侵位后存在的环境进行比较，将确定这些凝灰岩对沉积模式的影响。这项工作的成功完成将提供远远超出解决威尔士当地地质问题的数据。本项目将直接涉及水下焊接的问题，以及最常支持在中深水中进行焊接的具体实例。此外，将开发卡佩尔库里火山组的火山碎屑沉积模型，可用于许多未来的研究，并用于确定爆炸性火山作用对海洋陆架沉积模式的影响。