Seismic Evidence for Sharp Lithosphere-Asthenosphere Boundaries of Oceanic Plates
Seismic Evidence for Sharp Lithosphere-Asthenosphere Boundaries of Oceanic Plates
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DOI：
10.1126/science.1169499
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发表时间：
2009-04-24
期刊：
影响因子：
56.9
通讯作者：
Suyehiro, Kiyoshi
中科院分区：
文献类型：
--
作者：
Kawakatsu, Hitoshi;Kumar, Prakash;Suyehiro, Kiyoshi
岩石圈在较弱的软流圈上的活动性构成了板块构造的基本要素，因此对岩石圈-软流圈边界（LAB）过程的理解对于理解我们的星球如何运作至关重要。对于大洋板块来说尤其如此，因为它们相对简单的形成和演化应该能够容易地阐明LAB。钻孔宽频带海底地震仪的数据表明，太平洋和菲律宾海板块下的LAB是尖锐的和年龄相关的。所观察到的大剪切波速度降低在LAB需要一个部分熔融的软流圈组成的水平熔体丰富的层嵌入在不熔化的地幔，这占了大的粘度对比度在LAB，促进水平板块运动。
The mobility of the lithosphere over a weaker asthenosphere constitutes the essential element of plate tectonics, and thus the understanding of the processes at the lithosphere-asthenosphere boundary (LAB) is fundamental to understand how our planet works. It is especially so for oceanic plates because their relatively simple creation and evolution should enable easy elucidation of the LAB. Data from borehole broadband ocean bottom seismometers show that the LAB beneath the Pacific and Philippine Sea plates is sharp and age-dependent. The observed large shear wave velocity reduction at the LAB requires a partially molten asthenosphere consisting of horizontal melt-rich layers embedded in meltless mantle, which accounts for the large viscosity contrast at the LAB that facilitates horizontal plate motions.