Degassing of Cl, F, Li, and Be during extrusion and crystallization of the rhyolite dome at Volcán Chaitén, Chile during 2008 and 2009
Degassing of Cl, F, Li, and Be during extrusion and crystallization of the rhyolite dome at Volcán Chaitén, Chile during 2008 and 2009
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2008 年和 2009 年智利柴滕火山流纹岩圆顶挤压和结晶过程中 Cl、F、Li 和 Be 的脱气
DOI：
10.1007/s00445-012-0663-4
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发表时间：
2012
影响因子：
3.5
通讯作者：
P. Larson
中科院分区：
文献类型：
--
作者：
J. Lowenstern;H. Bleick;J. Vazquez;J. Castro;P. Larson
我们于2008-2009年调查了柴登火山浮岩、黑暗岩和结晶穹顶岩中氯、氟、锂和铍的分布，以探索这些元素在火山爆发和喷发活动期间的行为。电子和离子探针分析表明，浮岩、黑铁矿和微晶岩穹顶岩石的基质和包裹体玻璃在接近地表后，在结晶过程中主要失去了氯和其他元素。浮石和不含微粒岩的黑碧岩中的玻璃具有888ppm± ；121ppm的氯，而演化的富含微粒岩的穹顶岩中的残留玻璃通常保留较少的氯(低至<；100ppm)。估计氯损失可能为0.7亿公吨氯，整个0.8千米的穹顶可能最大损失1.8亿公吨氯。元素变化反映了Cl >； 1.7的整体体积分配比(脱气或进入晶体的氯比留在熔体中的多1.7倍)。由于氯主要在最后的H2O被脱气时损失，并且氯被最小限度地(如果有的话)分配成微升，因此氯的综合蒸气/熔体分配比超过200(放出的蒸气中的氯比熔体中的氯多200倍)。氯很可能以氯化氢的形式消失，在低压下很容易分解成岩浆蒸气。由于微晶的生长，残留熔体的成分发生变化，加速了CL的损失。CL损失也可能受到开放系统气体通量的影响。Li、F和Be的综合汽液分配比均超过1,000。在脱气时，这些挥发物中的一部分未知部分可以立即溶解在雨水中。
We investigated the distribution of Cl, F, Li, and Be in pumices, obsidians, and crystallized dome rocks at Chaitén volcano in 2008–2009 in order to explore the behavior of these elements during explosive and effusive volcanic activity. Electron and ion microprobe analyses of matrix and inclusion glasses from pumice, obsidian, and microlite-rich dome rock indicate that Cl and other elements were lost primarily during crystallization of the rhyolitic dome after it had approached the surface. Glass in pumice and microlite-free obsidian has 888 ± 121 ppm Cl, whereas residual glass in evolved microlite-rich dome rock generally retains less Cl (as low as <100 ppm). Estimated Cl losses were likely >0.7 Mt Cl, with a potential maximum of 1.8 Mt for the entire 0.8-km3 dome. Elemental variations reflect an integrated bulk distribution ratio for Cl > 1.7 (1.7 times more Cl was degassed or incorporated into crystals than remained in the melt). Because Cl is lost dominantly as the very last H2O is degassed, and Cl is minimally (if at all) partitioned into microlites, the integrated vapor/melt distribution ratio for Cl exceeds 200 (200 times more Cl in the evolved vapor than in the melt). Cl is likely lost as HCl, which is readily partitioned into magmatic vapor at low pressure. Cl loss is accelerated by the change in the composition of the residual melt due to microlite growth. Cl loss also may be affected by open-system gas fluxing. Integrated vapor-melt distribution ratios for Li, F, and Be all exceed 1,000. On degassing, an unknown fraction of these volatiles could be immediately dissolved in rainwater.
2008 年 5 月智利 Chaitén 喷发的火山灰地层和喷发量
影响因子：
3.5
作者：
Alfano F
通讯作者：
Alfano F
影响因子：
--
作者：
P. Wallace;M. Edmonds
通讯作者：
P. Wallace;M. Edmonds