Millennial storage of near-Moho magma
Millennial storage of near-Moho magma
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DOI：
10.1126/science.aax4092
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发表时间：
2018-12
期刊：
影响因子：
56.9
通讯作者：
E. Mutch;J. Maclennan;T. Holland;I. Buisman
中科院分区：
文献类型：
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作者：
E. Mutch;J. Maclennan;T. Holland;I. Buisman
千年岩浆储备熔岩以岩浆的形式储存在地下深处后喷发出来。像皮纳图博火山这样的火山所特有的富含二氧化硅的岩浆可以储存数千到数十万年。然而，我们对像冰岛火山那样的更深的玄武岩岩浆的时间尺度知之甚少。Mutch等人利用铬和铝原子的扩散表明，这些岩浆在地壳-地幔边界储存了数百至数千年。这一发现阐明了了解岩浆如何产生、储存以及如何喷发的时间尺度。玄武岩岩浆在地壳和地幔的交界处储存了大约1000年。下地壳在地幔融化过程中起着至关重要的作用，并通过从更深的岩浆供应引发火山喷发。由于浅层过程叠加了深部信号，我们对岩浆系统深层部分的理解变得模糊不清。我们通过研究冰岛Borgarhraun火山喷发的超基性结核，提供了岩浆在地壳深部玄武岩系统中停留时间的直接估计。对尖晶石晶体中铬-铝相互扩散的建模提供了一种1000年的长期岩浆储存记录。这对幔源岩浆的总地壳停留时间有严格的限制，对模拟跨地壳岩浆系统的生长和演化具有重要意义。
Millennial magma reserves Lava erupts after being stored as magma deeper underground. Silica-rich magmas characteristic of volcanoes like Pinatubo are stored for thousands to hundreds of thousands of years. However, we have little understanding of the time scales for deeper basaltic magma like that supplying Icelandic volcanoes. Mutch et al. used diffusion of chromium and aluminum atoms to show that these magmas are stored for hundreds to thousands of years at the crust-mantle boundary. This discovery elucidates the time scale for understanding how magma is created and stored and how it erupts. Science, this issue p. 260 Basaltic magma is stored at the boundary of the crust and mantle for ~1000 years. The lower crust plays a critical role in the processing of mantle melts and the triggering of volcanic eruptions by supply of magma from greater depth. Our understanding of the deeper parts of magmatic systems is obscured by overprinting of deep signals by shallow processes. We provide a direct estimate of magma residence time in basaltic systems of the deep crust by studying ultramafic nodules from the Borgarhraun eruption in Iceland. Modeling of chromium–aluminum interdiffusion in spinel crystals provides a record of long-term magmatic storage on the order of 1000 years. This places firm constraints on the total crustal residence time of mantle-derived magmas and has important implications for modeling the growth and evolution of transcrustal magmatic systems.