On the orientation of tensile dikes in a ridge-centered plume
On the orientation of tensile dikes in a ridge-centered plume
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关于以山脊为中心的羽流中拉伸堤的方向
DOI：
10.1016/j.tecto.2006.01.030
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发表时间：
2008
期刊：
影响因子：
2.9
通讯作者：
H. Schmeling
中科院分区：
文献类型：
--
作者：
Ruedas;H. Schmeling
我们给出了扩展脊下羽流上升以及伴随的熔体生成和地壳形成的三维数值模型，该模型使用依赖于压力、温度、熔体含量和可选的水含量的地幔粘度。根据这些对流模式的速度场，我们计算了地幔中的粘性应力张量。假定富熔体通道或充满熔体的岩墙与最大压应力平行，我们计算了这些岩墙在羽流头部部分熔融区和山脊下方的方位。对于羽流的中心部分，我们发现在羽头较浅的部分，岩脉方向平行于脊线，而在较深的地方，它们是垂直于脊线的。这两个区域之间的边界向下移动，因为富含水的羽流在融化时会脱水。不同岩脉或熔融通道取向的两个区域似乎与地震观测的随深度变化的地震各向异性很好地吻合，表明我们的湿模式是首选的。我们发现，在这两个模式中，融化向正常脊线下方的扩散中心有适度的聚焦，但在模式中包含水的羽流头部完全脱水的部分也是如此；这些区域基本上是上升流的被动区域。相反，无水模式中的羽流和含水模式中唯一部分脱水的羽流倾向于形成岩墙方向，使熔体远离扩散中心；这些区域的特征是活跃的上升流。活动上升地幔中熔体的散焦沿羽流轴具有径向对称性，即岩墙的向外方向不仅在垂直于山脊的平面上可见，而且沿山脊方向也可见。
We present three-dimensional numerical models of the ascent of a plume under a spreading ridge and the concomitant melt generation and crust formation using a mantle viscosity which depends on pressure, temperature, melt content, and, optionally, water content. From the velocity field of these convection models we compute the viscous stress tensor in the mantle. Assuming that melt-rich channels or melt-filled dikes are oriented parallel to the maximum compressional stress, we calculate the orientation of such dikes in the partially molten zone of the plume head and beneath the ridge. For the central part of the plume we find dike orientations parallel to the ridge in shallow parts of the plume head, while they are ridge-perpendicular at greater depth. The boundary between these two regimes is shifted downwards for a water-rich plume which dehydrates upon melting. The two regimes of different dike or melt channel orientations seem to be in good agreement with seismic observations on depth-dependent seismic anisotropy, indicating a preference of our wet model. We find a modest focusing of melt towards the spreading center beneath normal ridge in both models, but also in the fully dehydrated parts of the plume head in the model where water was included; those are regions where upwelling is essentially passive. In contrast, the plume in the water-free model and the only partly dehydrated parts of the plume in the water-bearing model tend to develop a dike orientation which moves melt away from the spreading center; these regions are characterized by active upwelling. The defocusing of melt in actively upwelling plume mantle has radial symmetry about the plume axis, i.e. an outward orientation of the dikes is not only visible in planes perpendicular to the ridge, but also along the ridge.
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DOI：
10.1098/rsta.1993.0004
发表时间：
1993
期刊：
Philosophical Transactions of the Royal Society of London. Series A: Physical and Engineering Sciences
影响因子：
--
作者：
G. Ceuleneer;M. Monnereau;M. Rabinowicz;C. Rosemberg
通讯作者：
C. Rosemberg
岩浆运输和储存
影响因子：
64.8
作者：
M. P. Ryan;Storage from Source to Eruption Site
通讯作者：
Storage from Source to Eruption Site
以山脊为中心的羽流的温度和融化，适用于冰岛。
影响因子：
2.8
作者：
T. Ruedas;H. Schmeling;G. Marquart;A. Kreutzmann;A. Junge
通讯作者：
A. Junge
影响因子：
64.8
作者：
T. Mizukami;S. Wallis;J. Yamamoto
通讯作者：
T. Mizukami;S. Wallis;J. Yamamoto
层状地幔柱源的熔体动力学
DOI：
--
发表时间：
1998
期刊：
影响因子：
--
作者：
S. Maaløe
通讯作者：
S. Maaløe