Mixing in mantle magma reservoirs prior to and during the 2011-2012 eruption at El Hierro, Canary Islands
Mixing in mantle magma reservoirs prior to and during the 2011-2012 eruption at El Hierro, Canary Islands
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DOI：
10.1130/g35165.1
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发表时间：
2014-04-01
期刊：
影响因子：
5.8
通讯作者：
Stix, John
中科院分区：
文献类型：
--
作者：
Longpre, Marc-Antoine;Kluegel, Andreas;Stix, John
了解滋养火山的岩浆系统对于准确解释监测数据并最终预测火山喷发至关重要。2011年10月至2012年3月，加那利群岛的耶罗岛发生了历史上第一次火山喷发，距离海岸约2公里。我们对熔岩样本的详细岩石学分析表明，至少有两种不同的岩浆最初来自地幔中的储层，在15-25公里的深度（即，也主要在El Hierro下方的上地幔内）发生了杂交。对带状橄榄石晶体的扩散计时法表明，岩浆混合开始于喷发前地震活动期间，并在喷发开始后持续数周。我们的数据还捕获了下地壳10-15公里深度的岩浆停滞水平，这与岩浆快速转移到海底之前侵入物的横向传播一致。El耶罗岩石学和地球物理数据的显著时空相关性表明，观测到的地震活动记录了岩浆混合和强侵入以及随后的储层动力学。这些结果表明，耶罗火山的喷发主要受深层过程控制，受浅层地壳水平的影响很小，这对监测长期休眠火山的新动荡具有重要意义。
Understanding magmatic systems feeding volcanoes is critical for accurate interpretation of monitoring data and, ultimately, eruption forecasting. Following 3 months of precursory unrest, the first historical eruption at El Hierro, Canary Islands, took place similar to 2 km offshore from October 2011 to March 2012. Our detailed petrological analysis of lava samples reveals that at least two distinct magmas initially supplied from reservoirs in the mantle underwent hybridization at 15-25 km depth, i.e., also largely within the upper mantle beneath El Hierro. Diffusion chronometry applied to zoned olivine crystals indicates that magma mixing began during the period of preeruptive seismicity and continued for weeks after the eruption onset. Our data also capture a magma stagnation level at 10-15 km depth in the lower crust, consistent with lateral propagation of an intrusion over substantial distances before rapid magma transit to the seafloor. The remarkable spatial and temporal correlation of petrological and geophysical data at El Hierro suggests that the observed seismicity records magma mixing and forceful intrusion as well as subsequent reservoir dynamics. These results demonstrate that eruptions at El Hierro are controlled principally by deep-seated processes, with little influence from shallow crustal levels, and have important implications for monitoring of renewed unrest at long-dormant volcanoes.