Cross section of a magma conduit system at the margin of the Colorado Plateau
Cross section of a magma conduit system at the margin of the Colorado Plateau
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DOI：
10.1130/g19550.1
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发表时间：
2003-08
期刊：
影响因子：
5.8
通讯作者：
K. Putirka;C. Condit
中科院分区：
文献类型：
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作者：
K. Putirka;C. Condit
我们目前的结晶深度与温度的估计单斜辉石斑晶从Springerville火山场，亚利桑那州。这些计算揭示了几个有趣的模式，有相当大的影响岩浆运输和成因。首先，部分结晶发生在很宽的深度范围（0-60公里），但大多数部分结晶发生在0和30公里之间。第二，低结晶温度，低密度岩浆和演化的液体成分完全来自两个深度间隔，0-12和23-30公里。这些间隔与上地壳的密度对比和中地壳底部的流变学对比相吻合。它们也与两个高地震反射深度间隔相吻合。这些关系表明：（1）莫霍面不是火山喷发的中转区，（2）上地壳的密度差和中地壳的流变性差控制着岩浆的运移和流体演化，（3）岩浆通道可能是岩浆浆柱，在0-12和23-30 km范围内以岩床为主;地震反射层是与第三纪-全新世火山活动有关的岩床。此外，这些岩床似乎代表了岩浆演化的主要场所。
We present crystallization depth vs. temperature estimates for clinopyroxene phenocrysts from the Springerville volcanic field, Arizona. These calculations reveal several intriguing patterns that have considerable implications for magma transport and genesis. First, partial crystallization occurs over a wide depth range (0–60 km), but most partial crystallization occurs between 0 and 30 km. Second, low crystallization temperatures, low-density magmas, and evolved liquid compositions derive exclusively from two depth intervals, 0–12 and 23–30 km. These intervals coincide with a density contrast in the upper crust and a rheology contrast at the base of the middle crust. They also coincide with two highly seismically reflective depth intervals. These relationships indicate that (1) the Moho is not a staging area for volcanic eruptions; (2) density contrasts in the upper crust, and a rheology contrast in the middle crust, control magma transport and liquid evolution; (3) magma conduits are probably magma mush columns, with a preponderance of sills within the 0–12 and 23–30 km intervals; and (4) seismically reflective layers are sills related to Tertiary–Holocene volcanic activity. Moreover, these sills appear to represent the principal sites of magma evolution.