Using dissolved H2O in rhyolitic glasses to estimate palaeo-ice thickness during a subglacial eruption at Bláhnúkur (Torfajökull, Iceland)
Using dissolved H2O in rhyolitic glasses to estimate palaeo-ice thickness during a subglacial eruption at Bláhnúkur (Torfajökull, Iceland)
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使用流纹岩玻璃中溶解的 H2O 来估计 Bláhnökur（冰岛托法jökull）冰下喷发期间的古冰厚度
DOI：
10.1007/s00445-012-0601-5
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发表时间：
2012
影响因子：
3.5
通讯作者：
Owen J
中科院分区：
文献类型：
--
作者：
Owen J
在过去的十年中，已经看到了一种技术的改进，用于重建古冰厚度的基础上使用保留的H2O和CO2含量在玻璃状喷发沉积物推断淬火压力，因此冰的厚度。这里的方法适用于Bláhnúkur，一个冰下喷发的流纹岩在冰岛。水含量从0.7wt.%在基础上增加至≤ 0.3 wt.%在建筑物顶部的冰表明，在喷发时，冰厚达400米。由于Bláhnukur比周围的地形高出350米，这意味着喷发完全发生在冰内，这证实了早期岩相研究中获得的证据。本文介绍了最大的数据集（40个样品），迄今为止获得的残留挥发性成分的沉积物从冰下喷发。一个重要的结果是，它使水含量的微妙但显着的变化变得明显。特别地，存在异常样品，其富含水（高达1重量%），或贫水（≤ 0.2重量%），前者被解释为在玻璃碎屑岩内侵入形成，后者代表在喷发前挥发性差的岩浆批次。大型数据集还提供了使用挥发物推断古冰厚度的优点和缺点的进一步见解，并突出了所涉及的许多不确定性。通过使用Bláhnúkur的例子，这种技术的定量使用进行评估。然而，揭示了Bláhnúkur的喷发机制和同喷发冰川响应的相对压力条件表明，尽管绝对值存在不确定性，但挥发性方法可以为冰下流纹岩喷发机制提供有用的见解，这是从未观察到的。
The last decade has seen the refinement of a technique for reconstructing palaeo-ice thicknesses based on using the retained H2O and CO2content in glassy eruptive deposits to infer quenching pressures and therefore ice thicknesses. The method is here applied to Bláhnúkur, a subglacially erupted rhyolitic edifice in Iceland. A decrease in water content from ∼0.7 wt.% at the base to ∼0.3 wt.% at the top of the edifice suggests that the ice was 400 m thick at the time of the eruption. As Bláhnúkur rises 350 m above the surrounding terrain, this implies that the eruption occurred entirely within ice, which corroborates evidence obtained from earlier lithofacies studies. This paper presents the largest data set (40 samples) so far obtained for the retained volatile contents of deposits from a subglacial eruption. An important consequence is that it enables subtle but significant variations in water content to become evident. In particular, there are anomalous samples which are either water-rich (up to 1 wt.%) or water-poor (∼0.2 wt.%), with the former being interpreted as forming intrusively within hyaloclastite and the latter representing batches of magma that were volatile-poor prior to eruption. The large data set also provides further insights into the strengths and weaknesses of using volatiles to infer palaeo-ice thicknesses and highlights many of the uncertainties involved. By using examples from Bláhnúkur, the quantitative use of this technique is evaluated. However, the relative pressure conditions which have shed light on Bláhnúkur’s eruption mechanisms and syn-eruptive glacier response show that, despite uncertainties in absolute values, the volatile approach can provide useful insight into the mechanisms of subglacial rhyolitic eruptions, which have never been observed.
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DOI：
10.1144/gsl.sp.2002.202.01.01
发表时间：
2003-05
期刊：
Geological Society, London, Special Publications
影响因子：
--
作者：
J. Smellie;M. Chapman
通讯作者：
J. Smellie;M. Chapman
冰岛南部拉斑岩 Veidivötn 裂隙引发的碱性硅质托尔法冰川中央火山的岩浆混合和杂交过程
影响因子：
2.9
作者：
S. Blake
通讯作者：
S. Blake
1996 年冰岛瓦特纳冰川冰盖 Gjálp 喷发：传热效率、冰变形和冰下水压
影响因子：
3.5
作者：
M. Gudmundsson;F. Sigmundsson;H. Björnsson;Thórdís Högnadóttir
通讯作者：
Thórdís Högnadóttir
冰-火山相互作用
DOI：
--
发表时间：
2011
期刊：
影响因子：
--
作者：
H. Tuffen
通讯作者：
H. Tuffen
流纹质岩浆中的气体传输和气泡破裂：一种实验方法
影响因子：
3.5
作者：
H. Westrich;J. Eichelberger
通讯作者：
J. Eichelberger