Melt inclusions track pre-eruption storage and dehydration of magmas at Etna
Melt inclusions track pre-eruption storage and dehydration of magmas at Etna
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DOI：
10.1130/g30040a.1
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发表时间：
2009-06-01
期刊：
影响因子：
5.8
通讯作者：
Maclennan, J.
中科院分区：
文献类型：
--
作者：
Collins, S. J.;Pyle, D. M.;Maclennan, J.
在意大利埃特纳火山，公元 2001 年、2002 年和 2003 年发生了剧烈的富气体喷发，随后在 2004 年、2006 年和 2007 年发生了贫气体喷发。对这些最新的橄榄石熔体包裹体中的挥发性（CO2、H2O、S、Cl、F）、半挥发性（Cu）和非挥发性（Nb、La）元素进行了分析喷发揭示了渗透气相与储存岩浆之间持续相互作用的影响。熔体包裹体成分表明，2004年至2007年喷发的岩浆是2001年至2003年喷发的残余物，并且熔体挥发物含量显示出显着的演变。如果熔体在储存期间和作为熔体夹杂物被捕获之前与富含 CO2 的气体重新平衡，则可以解释这些熔体夹杂物观察结果以及火山气体 C/S 的变化。持续的气体渗滤导致不断演变的熔体中的水份损失和二氧化碳含量的增加，并可能强烈影响铜的行为，铜可能会分配到气相中。岩浆储存期间的蒸气-熔融相互作用是持续脱气火山岩浆演化的重要控制因素。
At Mount Etna, Italy, vigorous gas-rich eruptions in A. D. 2001, 2002, and 2003 were followed by gas-poor eruptions in 2004, 2006, and 2007. Analyses of volatile (CO2, H2O, S, Cl, F), semivolatile (Cu), and involatile (Nb, La) elements trapped in olivine-hosted melt inclusions from these latest eruptions reveal the effects of the sustained interaction between a percolating gas phase and the stored magma. Melt inclusion compositions indicate that magmas erupted from 2004 to 2007 were residual from the 2001-2003 eruptions, and show significant evolution in the volatile content of the melt. These melt inclusion observations, and variations in the C/S of volcanic gases, can be accounted for if melts reequilibrated with CO2-rich gases during storage and prior to entrapment as melt inclusions. Sustained gas percolation caused loss of water and enhancement of CO2 in the evolving melt and may strongly influence the behavior of Cu, which potentially partitions into the gas phase. Vapor-melt interactions during magma storage are important controls on magma evolution at persistently degassing volcanoes.