The impact of a volcanic edifice on intrusive and eruptive activity
The impact of a volcanic edifice on intrusive and eruptive activity
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火山大厦对侵入和喷发活动的影响
DOI：
10.1016/j.epsl.2014.09.016
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发表时间：
2014
期刊：
影响因子：
--
通讯作者：
C. Jaupart
中科院分区：
文献类型：
--
作者：
A. Roman;C. Jaupart
在火山地区，岩脉的方向和组成记录了岩浆系统的发展，为侵入和喷发活动提供了补给。在科罗拉多的西班牙峰，弯曲的岩脉轨迹从一个单一的焦点地区发出已被归因于水平传播从加压中央水库在偏构造应力场。然而，这些岩脉与中央侵入体没有任何接触，比中央侵入体年轻约1百万年，并且不充满相同的岩浆。它们位于较浅的深度（0.11公里），那里的局部应力场对表面载荷非常敏感。在这里，我们表明，它们的轨迹可以设置的火山建筑物在构造应力场的负载。西班牙峰岩脉的方向和分布在200万年的时间里随着岩浆的化学演化而发生了变化。早期岩脉相互平行，充满原始熔体，记录了区域构造应力场的上升。它们被弯曲的岩脉所取代，岩脉携带着演化的熔体，这记录了相当大的火山建筑物的影响。在这座建筑物之下，诱发的压缩阻止了密集的原始岩浆在焦点区域喷发，并使中间岩浆转向侧面。这个巨大的火山锥的增长可能是形成岩浆库的原因。形成西班牙峰岩墙群的机制可能控制着许多活火山区喷发中心的空间分布和迁移。
In a volcanic area, the orientation and composition of dikes record the development of the magmatic system that feeds intrusive and eruptive activity. At Spanish Peaks, Colorado, curved dike trajectories issuing from a single focal area have been attributed to horizontal propagation from a pressurized central reservoir in a deviatoric tectonic stress field. These dikes, however, are nowhere in contact with the central intrusion, are younger than it by about 1 My and are not filled with the same magma. They were emplaced at shallow depths (≈ 1 km), where the local stress field is very sensitive to surface loads. Here, we show that their trajectories can be set by the load of a volcanic edifice in a tectonic stress field. The orientation and distribution of the Spanish Peaks dikes have changed in the course of two million years as magmas were evolving chemically. Early dikes that were parallel to each another and filled with primitive melts document ascent in the regional tectonic stress field. They were replaced by curved dikes carrying evolved melts, which record the influence of a sizable volcanic edifice. Beneath this edifice, the induced compression prevented dense primitive magmas from erupting in the focal area and diverted intermediate magmas sideways. The growth of this large volcanic cone was probably responsible for the formation of a magma reservoir. The mechanisms that have shaped the Spanish Peaks dike swarm may control the spatial distribution and migration of eruptive centers in many active volcanic areas.