Stability of hydrous melt at the base of the Earth's upper mantle
Stability of hydrous melt at the base of the Earth's upper mantle
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DOI：
10.1038/nature04352
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发表时间：
2006-01
期刊：
影响因子：
64.8
通讯作者：
T. Sakamaki;A. Suzuki;E. Ohtani
中科院分区：
文献类型：
--
作者：
T. Sakamaki;A. Suzuki;E. Ohtani
地震观测表明，在地球上地幔底部410公里深处的不连续面上方存在低速和高衰减区。有人认为，少量的熔体可能是造成这种异常现象的原因。已在高压下测量了干燥条件下硅酸盐熔体的密度，发现其密度大于周围的固体，从而使熔体保持在一定深度。但至今还没有对含水熔体密度的实验研究。在这里，我们提出的数据约束压力下的含水玄武质熔体的密度，以检查熔体的稳定性以上的410公里的不连续性。我们推断，410公里以上的不连续部分熔融形成的含水岩浆可能确实是重力稳定的，从而支持的想法，低速或高衰减区上方的地幔过渡带可能会导致熔体的存在。
Seismological observations have revealed the existence of low-velocity and high-attenuation zones above the discontinuity at 410 km depth, at the base of the Earth's upper mantle,. It has been suggested that a small amount of melt could be responsible for such anomalies,,. The density of silicate melt under dry conditions has been measured at high pressure,,,,,,,,and found to be denser than the surrounding solid, thereby allowing the melt to remain at depth. But no experimental investigation of the density of hydrous melt has yet been carried out. Here we present data constraining the density of hydrous basaltic melt under pressure to examine the stability of melt above the 410-km discontinuity. We infer that hydrous magma formed by partial melting above the 410-km discontinuity may indeed be gravitationally stable, thereby supporting the idea that low-velocity or high-attentuation regions just above the mantle transition zone may result from the presence of melt.