Rates of magma transfer in the crust: Insights into magma reservoir recharge and pluton growth
Rates of magma transfer in the crust: Insights into magma reservoir recharge and pluton growth
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DOI：
10.1130/g36224.1
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发表时间：
2015-03-01
期刊：
影响因子：
5.8
通讯作者：
de Saint Blanquat, Michel
中科院分区：
文献类型：
--
作者：
Menand, Thierry;Annen, Catherine;de Saint Blanquat, Michel
长期以来，人们一直将深成岩体视为大型岩浆库的结晶残余，这一概念现在受到高精度地质年代学数据和热模型的挑战。类似地，长期岩浆库缓慢区分镁铁质充注的岩浆喷发的经典观点正在受到岩石学和地球物理研究的质疑。在这两种情况下，一个关键而尚未解决的问题是地壳中岩浆转移的速度。在这里，我们使用热分析的岩浆运输，以计算通过岩脉岩浆转移的最小速率。我们发现，除非地壳异常热，岩浆库的补给需要至少类似于0.01 km（3）/年的岩浆供应速率，远高于岩体的长期生长速率，这明确表明火成岩体必须递增。这一分析还认为，岩浆库是短暂的，并迅速喷发后，由已经分化的岩浆再充。这些发现对监测休眠火山系统和我们解释与初期喷发有关的大地测量表面信号的能力具有重大意义。
Plutons have long been viewed as crystallized remnants of large magma reservoirs, a concept now challenged by high-precision geo-chronological data coupled with thermal models. Similarly, the classical view of silicic eruptions fed by long-lived magma reservoirs that slowly differentiate between mafic recharges is being questioned by petrological and geophysical studies. In both cases, a key and yet unresolved issue is the rate of magma transfer in the crust. Here, we use thermal analysis of magma transport to calculate the minimum rate of magma transfer through dikes. We find that unless the crust is exceptionally hot, the recharge of magma reservoirs requires a magma supply rate of at least similar to 0.01 km(3)/yr, much higher than the long-term growth rate of plutons, which demonstrates unequivocally that igneous bodies must grow incrementally. This analysis argues also that magma reservoirs are short lived and erupt rapidly after being recharged by already-differentiated magma. These findings have significant implications for the monitoring of dormant volcanic systems and our ability to interpret geodetic surface signals related to incipient eruptions.