Seismic Evidence of Partial Melt Within a Possibly Ubiquitous Low-Velocity Layer at the Base of the Mantle
Seismic Evidence of Partial Melt Within a Possibly Ubiquitous Low-Velocity Layer at the Base of the Mantle
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DOI：
10.1126/science.277.5326.670
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发表时间：
1997-08
期刊：
影响因子：
56.9
通讯作者：
J. Revenaugh;R. Meyer
中科院分区：
文献类型：
--
作者：
J. Revenaugh;R. Meyer
三个源区显示出在核幔边界顶部存在厚度小于15公里的低速层的证据，并且需要约3：1的剪切-压缩速度降低比，这与部分熔融一致。层厚与地震相位的走时残差相关，地震相位对最低地幔速度最敏感。这些观测结果表明，该层在下地幔之下变薄，但沿核幔边界沿着到处都有。低粘度伴随部分熔融可以本地化的上涌加热地幔，使低速层地幔柱的一个合理的来源。
Three source regions show evidence of a low-velocity layer that is less than 15 kilometers thick on top of the core-mantle boundary and require about a 3:1 ratio of shear-to-compressional velocity reduction, which is consistent with partial melt. Layer thickness is correlated with travel time residuals of the seismic phases that are most sensitive to the lowermost mantle velocity. These observations suggest that the layer is thinned beneath downwellings but is present everywhere along the core-mantle boundary. Low viscosity accompanying partial melt can localize the upwelling of warmed mantle, making the low-velocity layer a plausible source of mantle plumes.