The seismic anomaly beneath Iceland extends down to the mantle transition zone and no deeper
The seismic anomaly beneath Iceland extends down to the mantle transition zone and no deeper
复制标题
冰岛下方的地震异常延伸至地幔过渡带，但没有更深
DOI：
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发表时间：
2000
期刊：
影响因子：
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通讯作者：
K. Vogfjörd
中科院分区：
文献类型：
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作者：
G. Foulger;M. J. Pritchard;B. Julian;J. R. Evans;R. Allen;G. Nolet;W. J. Morgan;B. Bergsson;P. Erlendsson;S. Jakobsdóttir;S. Ragnarsson;R. Stefánsson;K. Vogfjörd
冰岛下地幔的一个3-D的超分辨率层析成像图像揭示了一个近垂直的低波速异常，在上面250公里的圆柱形，但在下面的平板。这种形态的转变是朝着底部的浮力上升流。因此，我们的观察表明，在冰岛热点的岩浆活动是美联储从地幔过渡带上升的流动。这一结果有助于正在进行的关于上地幔和下地幔是单独对流还是作为一个对流的争论。图像还表明，物质从冰岛沿着雷克雅内斯海脊在上部200公里处向外流动，但在Tjornes断裂带下方的上部150公里处被阻挡。这为断裂带阻挡沿着山脊的侧向流动的理论提供了直接的观测支持。
A 3-D teleseismic tomography image of the upper mantle beneath Iceland of unprecedented resolution reveals a subvertical low wave speed anomaly that is cylindrical in the upper 250 km but tabular below this. Such a morphological transition is expected towards the bottom of a buoyant upwelling. Our observations thus suggest that magmatism at the Iceland hotspot is fed by flow rising from the mantle transition zone. This result contributes to the ongoing debate about whether the upper and lower mantles convect separately or as one. The image also suggests that material flows outwards from Iceland along the Reykjanes Ridge in the upper 200 km, but is blocked in the upper 150 km beneath the Tjornes Fracture Zone. This provides direct observational support for the theory that fracture zones dam lateral flow along ridges.