Water in volcanic pyroclast: Rehydration or incomplete degassing?
Water in volcanic pyroclast: Rehydration or incomplete degassing?
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DOI：
10.1016/j.epsl.2013.03.041
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发表时间：
2013-05-01
影响因子：
5.3
通讯作者：
Gonnermann, H. M.
中科院分区：
文献类型：
--
作者：
Giachetti, T.;Gonnermann, H. M.
测量和编制了中到高岩浆火山喷发样品中基质玻璃水的浓度。它们的范围从0.1重量%到超过3.5重量%，并显示出与囊泡表面积与玻璃体积比的正相关性。水扩散的建模表明，这种相关性的大部分可以通过外部水在大气温度和压力下喷发后扩散到基质玻璃中来解释，这一过程称为再水化。虽然原生水（岩浆水）与次生水（大气降水）的精确比例无法通过我们的分析确定，但我们发现，大多数样品可以通过在沉积和样品收集之间的时间间隔内对初始“干燥”样品进行逐步再水化来模拟，平均再水化扩散率约为10（-23）m（2）s（-1）。这种扩散率估计值是一致的，在文献中提供的黑曜石水化测年和外推的扩散率配方为低的温度和压力的熔体。由爱思唯尔公司出版
The matrix-glass water concentrations in samples from volcanic eruptions of intermediate to highly silicic magmas were measured and compiled. They range from 0.1 wt% to more than 3.5 wt% and show a positive correlation with vesicles surface area over glass volume ratio. Modeling of water diffusion suggests that most of this correlation can be explained by the post-eruptive diffusion of external water at atmospheric temperature and pressure into the matrix-glass, a process referred to as rehydration. Although the precise proportion of primary (magmatic) to secondary (meteoric) water is not determined by our analysis, we find that most samples can be modeled by progressive rehydration of an initially 'dry' sample during the time interval between deposition and sample collection at an average rehydration diffusivity of approximately 10(-23) m(2) s(-1). This diffusivity estimate is consistent with values provided in the literature on obsidian hydration dating and with the extrapolation of diffusivity formulations for silicic melts to lower temperatures and pressures. Published by Elsevier B.V.