Mechanisms of low-flux intraplate volcanic fields—Basin and Range (North America) and northwest Pacific Ocean
Mechanisms of low-flux intraplate volcanic fields—Basin and Range (North America) and northwest Pacific Ocean
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DOI：
10.1130/g30427.1
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发表时间：
2010
期刊：
影响因子：
5.8
通讯作者：
G. Valentine;N. Hirano
中科院分区：
文献类型：
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作者：
G. Valentine;N. Hirano
我们比较了两个板内，上新世-更新世火山场在不同的构造背景-中央盆地和山脉和西北太平洋。这两个领域的特点是广泛分散，小体积，碱性玄武岩火山;领域内，每个火山显然起源于一个单独的，挥发物富集的父熔体从上地幔。没有证据表明，在任何领域的局部异常热流或持续引入新的流体进入上地幔，如可能发生以上的俯冲板。我们的结论是，火山领域反映变形驱动的收集已经存在的部分熔融在一个异质上地幔。变形驱动的熔体收集可能是一个重要的机制，为其他扩散板内火山领域，这是一致的构造控制，低通量的板内领域的岩浆活动是一个被动的响应区域变形的端部成员。这两个领域之间的分馏和污染程度的差异被推断为有关弯曲引起的垂直变化的方向在西北太平洋的主应力，这会导致失速的上升岩脉在岩石圈。
We compare two intraplate, Pliocene-Pleistocene volcanic fields in different tectonic settings—the central Basin and Range and the northwest Pacific Ocean. Both fields are characterized by widely scattered, small-volume, alkali basaltic volcanoes; within the fields, each volcano apparently originates from a separate, volatile-enriched parental melt from the upper mantle. There is no evidence at either field for locally anomalous heat flow or ongoing introduction of new fluids into the upper mantle such as might occur above a subducting slab. We conclude that the volcanic fields reflect deformation-driven collection of already existing partial melts in a heterogeneous upper mantle. Deformation-driven melt collection may be an important mechanism for other diffuse intraplate volcanic fields, and this is consistent with a tectonically controlled, low-flux end member for intraplate fields where magmatism is a passive response to regional deformation. Differences in the degree of fractionation and contamination between the two fields are inferred to be related to flexure-induced vertical variations in the orientation of principal stresses in the northwest Pacific Ocean, which cause stalling of ascending dikes in the lithosphere.