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A reverse energy cascade for crustal magma transport
Nature Geoscience ( IF 18.3 ) Pub Date : 2017-07-10 00:00:00 , DOI: 10.1038/ngeo2982
Leif Karlstrom , Scott R. Paterson , A. Mark Jellinek

Direct constraints on the ascent, storage and eruption of mantle melts come primarily from exhumed, long-frozen intrusions. These structures, relics of a dynamic magma transport network, encode how Earth’s crust grows and differentiates over time. Furthermore, they connect mantle melting to an evolving distribution of surface volcanism. Disentangling magma transport processes from the plutonic record is consequently a seminal but unsolved problem. Here we use field data analyses, scaling theory and numerical simulations to show that the size distribution of intrusions preserved as plutonic complexes in the North American Cordillera suggests a transition in the mechanical response of crustal rocks to protracted episodes of magmatism. Intrusion sizes larger than about 100m follow a power-law scaling expected if energy delivered from the mantle to open very thin dykes and sills is transferred to intrusions of increasing size. Merging, assimilation and mixing of small intrusions into larger ones occurs until irreversible deformation and solidification dissipate available energy. Mantle magma supply over tens to hundreds of thousands of years will trigger this regime, a type of reverse energy cascade, depending on the influx rate and efficiency of crustal heating by intrusions. Identifying regimes of magma transport provides a framework for inferring subsurface magmatic processes from surface patterns of volcanism, information preservation in the plutonic record, and related effects including climate.

中文翻译:

地壳岩浆输送的反向能量级联

地幔熔体上升,储存和喷发的直接制约因素主要来自发掘,长期冻结的入侵。这些结构是动态岩浆传输网络的遗迹,它们编码地壳如何随着时间增长和分化。此外,它们将地幔融化与不断演化的地表火山分布联系起来。因此,从岩浆记录中解脱岩浆运移过程是一个开创性但尚未解决的问题。在这里,我们使用现场数据分析,缩放理论和数值模拟来表明,在北美科尔迪勒拉中保存为深成岩复合体的侵入体的大小分布表明,地壳岩石对长期岩浆作用的机械响应发生了转变。入侵大小大于约100如果从地幔传递来打开很薄的堤坝和窗台的能量转移到越来越大的侵入体上,则m遵循幂律定标。将小的侵入体合并,吸收并混合成较大的侵入体,直到不可逆的变形和凝固消散了可用的能量。数万到数十万年的地幔岩浆供应将触发这​​种状态,这是一种反向能量级联,取决于入侵的地壳加热速度和效率。识别岩浆运移的方式提供了一个框架,可以从火山的地表模式,深部记录中的信息保存以及包括气候在内的相关影响中推断地下岩浆过程。
更新日期:2017-07-11
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