Stacked sills forming a deep melt-mush feeder conduit beneath Axial Seamount
Stacked sills forming a deep melt-mush feeder conduit beneath Axial Seamount
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DOI：
10.1130/g47223.1
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发表时间：
2020-07-01
期刊：
影响因子：
5.8
通讯作者：
Nedimovic, Mladen
中科院分区：
文献类型：
--
作者：
Carbotte, Suzanne M.;Arnulf, Adrien;Nedimovic, Mladen
岩浆系统由熔体堆积和晶体糊组成，它们随着熔体输送而演化，有助于火成岩过程、火山动力学和喷发触发。对活火山的地球物理研究揭示了浅层次熔体储层的细节，但对以晶体泥为主的较深层次的精细尺度熔体分布知之甚少。在这里，我们提出了新的地震反射图像从轴海山，东北太平洋，揭示了一个3-5公里宽的管道垂直堆叠的熔体透镜体，以300-450米的近规则的间距延伸到推断糊状区的中到下地壳。这列透镜体位于上地壳岩浆库最浅的熔融物富集部分的下方，三个岩脉侵入和喷发事件在此开始。管状区域的几何形状和深度范围相似的火山膨胀源建模从大地测量记录，我们推断，熔体上升的多孔流集中在熔体透镜导管导致的膨胀引发的喷发。多个近水平的透镜被解释为熔体丰富的层通过糊状压实，解释支持的粘弹性基质中的多孔流动的一维数值模型。
Magmatic systems are composed of melt accumulations and crystal mush that evolve with melt transport, contributing to igneous processes, volcano dynamics, and eruption triggering. Geophysical studies of active volcanoes have revealed details of shallow-level melt reservoirs, but little is known about fine-scale melt distribution at deeper levels dominated by crystal mush. Here, we present new seismic reflection images from Axial Seamount, northeastern Pacific Ocean, revealing a 3-5-km-wide conduit of vertically stacked melt lenses, with near-regular spacing of 300-450 m extending into the inferred mush zone of the mid-to-lower crust. This column of lenses underlies the shallowest melt-rich portion of the upper-crustal magma reservoir, where three dike intrusion and eruption events initiated. The pipe-like zone is similar in geometry and depth extent to the volcano inflation source modeled from geodetic records, and we infer that melt ascent by porous flow focused within the melt lens conduit led to the inflation-triggered eruptions. The multiple near-horizontal lenses are interpreted as melt-rich layers formed via mush compaction, an interpretation supported by one-dimensional numerical models of porous flow in a viscoelastic matrix.