• 主题
高级搜索  >
历史搜索 清空历史
首页> 外文期刊>Journal of Volcanology and Geothermal Research >How does tephra deposit thickness change over time? A calibration exercise based on the 1980 Mount St Helens tephra deposit
【24h】

How does tephra deposit thickness change over time? A calibration exercise based on the 1980 Mount St Helens tephra deposit

机译：Tephra沉积厚度如何随时间变化？基于1980年ST Helens Tephra Dectent的校准练习

获取原文
获取原文并翻译 | 示例
           
页面导航
  • 摘要
  • 著录项
  • 相似文献
  • 相关主题

摘要

Tephra layers are frequently used to reconstruct past volcanic activity. Inferences made from tephra layers rely on the assumption that the preserved tephra layer is representative of the initial deposit. However, a great deal can happen to tephra after it is deposited; thus, tephra layer taphonomy is a crucial but poorly understood process. The overall goal of this research was to gain greater insight into the taphonomy of terrestrial tephra layers, specifically the extent to which deposit thickness is altered over time, with implications for tephra volume estimation. We approached this by a)conducting a new survey of the tephra layer from the recent, well-studied eruption of Mount St Helens on May 18th, 1980 (MSH1980); b)modelling the tephra layer thickness using a mathematical technique and c)comparing our results with an equivalent model based on measurements taken immediately after the eruption. In this way, we aimed to quantify any losses and transformations that have occurred. During our study, we collected measurements of tephra layer thickness from 86 locations ranging from 20 to 600 km from the vent. Geochemical analysis was used to identify tephra of uncertain origin. Our results indicated that the extant tephra layer at undisturbed sites was representative of the original deposit: overall, preservation in these locations (in terms of thickness, stratigraphy and geochemistry) had been remarkably good. However, the isopach maps generated from our measurements diverged from isopachs produced in the same way, but derived from the original survey data. Furthermore, our estimates of the quantity of tephra produced during the eruption greatly exceeded previous estimates of the fallout volume. In our study, inaccuracies in the modelled fallout arose from issues of sampling strategy, rather than taphonomy. Our results demonstrate the sensitivity of volcanological reconstructions to measurement location, and the great importance of reliably measured low/zero values in reconstructing tephra deposits. (C) 2020 Elsevier B.V. All rights reserved.
机译：Tephra层经常用于重建过去的火山活性。由Tephra层制成的推论依赖于保存的Tephra层代表初始沉积物的假设。但是，在沉积后，Tephra可能会发生很大的交易;因此，Tephra层Taphonomy是一个至关重要的但理解的过程。该研究的总体目标是对陆地Tephra层的Tawhonomety进行更大的洞察力，特别是随着时间的推移改变沉积物厚度的程度，具有对Tephra体积估计的影响。我们通过A）通过1980年5月18日（MSH1980）的近期学习St Helens山区初爆的Tephra层进行了新的调查（MSH1980）; b）使用数学技术和c）使用数学技术建模Tephra层厚度，并将我们的结果与基于在爆发后立即进行的测量进行的等效模型进行比较。通过这种方式，我们旨在量化发生的任何损失和转变。在我们的研究期间，我们从86个位置收集了从86个位置距离通风口600公里处的Tephra层厚度的测量。地球化学分析用于识别不确定的原点的Tephra。我们的结果表明，未受干扰地点的现存Tephra层是原始押金的代表：总体而言，这些地点（在厚度，地层和地球化学方面）的保存是非常好的。然而，从我们的测量中生成的ISOpach映射与以相同方式产生的ISopach分歧，而是从原始调查数据产生的。此外，我们对在爆发期间产生的Tepharra的数量的估计大大超过了对辐射体积的先前估计。在我们的研究中，模拟辐射中的不准确性来自采样策略的问题，而不是Taphonomy。我们的结果证明了火山学重建对测量位置的敏感性，并且在重建Tephra沉积物中可靠地测量的低/零值的重要性。 （c）2020 Elsevier B.v.保留所有权利。

著录项

相似文献

  • 外文文献
  • 中文文献
  • 专利
获取原文

客服邮箱：kefu@zhangqiaokeyan.com

京公网安备：11010802029741号 ICP备案号：京ICP备15016152号-6 六维联合信息科技 (北京) 有限公司©版权所有

  • 客服微信

  • 服务号