Magma plumbing for the 2014-2015 Holuhraun eruption, Iceland
Magma plumbing for the 2014-2015 Holuhraun eruption, Iceland
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DOI：
10.1002/2016gc006317
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发表时间：
2016-08-01
影响因子：
3.5
通讯作者：
Harris, Chris
中科院分区：
文献类型：
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作者：
Geiger, Harri;Mattsson, Tobias;Harris, Chris
2014-2015年冰岛的Holuhraun火山喷发位于Askja裂缝群内，但伴随着西南45公里处Baroarbunga中央火山的破火山口下沉。对火山爆发的地球物理监测发现，在两周的时间里，有一个震群从Baroarbunga迁移到Holuhraun火山爆发地点。为了更好地了解这种横向Baroarbunga和Holuhraun之间的连接，我们提出了矿物纹理和成分，矿物熔体平衡计算，全岩和微量元素数据，并选择Holuhraun样品的氧同位素比值。Holuhraun熔岩的成分与Baroarbunga火山系统记录的历史喷发相似，但与附近Askja系统的历史喷发产物不同。热压计计算表明，一个多压岩浆管道系统的Holuhraun喷发，其中单斜辉石和斜长石结晶在平均深度约为17公里和约5公里，分别。晶体再吸收纹理和氧同位素的变化意味着，这种多级管道系统促进岩浆混合和同化低O-18冰岛地壳喷发前。结合现有的地球物理证据的横向迁移，我们的研究结果支持的模型，最初的垂直岩浆上升的Baroarbunga管道系统内，然后横向运输的聚合岩浆批次在上地壳的Holuhraun喷发现场。
The 2014-2015 Holuhraun eruption on Iceland was located within the Askja fissure swarm but was accompanied by caldera subsidence in the Baroarbunga central volcano 45 km to the southwest. Geophysical monitoring of the eruption identified a seismic swarm that migrated from Baroarbunga to the Holuhraun eruption site over the course of two weeks. In order to better understand this lateral connection between Baroarbunga and Holuhraun, we present mineral textures and compositions, mineral-melt-equilibrium calculations, whole rock and trace element data, and oxygen isotope ratios for selected Holuhraun samples. The Holuhraun lavas are compositionally similar to recorded historical eruptions from the Baroarbunga volcanic system but are distinct from the historical eruption products of the nearby Askja system. Thermobarometry calculations indicate a polybaric magma plumbing system for the Holuhraun eruption, wherein clinopyroxene and plagioclase crystallized at average depths of approximate to 17 km and approximate to 5 km, respectively. Crystal resorption textures and oxygen isotope variations imply that this multilevel plumbing system facilitated magma mixing and assimilation of low-O-18 Icelandic crust prior to eruption. In conjunction with the existing geophysical evidence for lateral migration, our results support a model of initial vertical magma ascent within the Baroarbunga plumbing system followed by lateral transport of aggregated magma batches within the upper crust to the Holuhraun eruption site.