Waveform Tomography Reveals Channeled Flow at the Base of the Oceanic Asthenosphere
Waveform Tomography Reveals Channeled Flow at the Base of the Oceanic Asthenosphere
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DOI：
10.1126/science.1241514
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发表时间：
2013-10-11
期刊：
影响因子：
56.9
通讯作者：
Romanowicz, Barbara
中科院分区：
文献类型：
--
作者：
French, Scott;Lekic, Vedran;Romanowicz, Barbara
地球物理学家仍然难以理解驱动板块运动的不同尺度对流与热点火山活动之间的关系。利用全波形地震层析成像技术，我们对低剪切速度水平细长带进行了成像，最突出的是在200至350公里深度之间，延伸到发育良好的低速带下方。这些波长接近2000公里的准周期指状结构平行于板块绝对运动方向数千公里。在深度400公里以下，速度结构被组织成数量较少、起伏但垂直相干的低速羽状特征，这些特征似乎根植于下地幔。这表明，在低速区板块驱动的流动和在移动的顶边界层下水平偏转的深地幔源的低刚性物质的活跃流入之间存在动态相互作用。
Understanding the relationship between different scales of convection that drive plate motions and hotspot volcanism still eludes geophysicists. Using full-waveform seismic tomography, we imaged a pattern of horizontally elongated bands of low shear velocity, most prominent between 200 and 350 kilometers depth, which extends below the well-developed low-velocity zone. These quasi-periodic fingerlike structures of wavelength similar to 2000 kilometers align parallel to the direction of absolute plate motion for thousands of kilometers. Below 400 kilometers depth, velocity structure is organized into fewer, undulating but vertically coherent, low-velocity plumelike features, which appear rooted in the lower mantle. This suggests the presence of a dynamic interplay between plate-driven flow in the low-velocity zone and active influx of low-rigidity material from deep mantle sources deflected horizontally beneath the moving top boundary layer.