The effect of pressure on grain‐growth kinetics of olivine was investigated up to 10 GPa at 1773 K under relatively water‐poor conditions. The results are interpreted using a relation to obtain the activation volume = 5.0 ± 1.1 cm³/mol for n = 2 or = 5.2 ± 1.1 cm³/mol for n = 3. The small activation volume means that grain‐growth kinetics in pure olivine aggregates is fast even in the dry deep upper mantle, implying that grain‐size is controlled by the pinning by other phases or by dynamic recrystallization except for the early stage after the phase transformation from wadsleyite in upwelling materials. The present results are applied to seismic wave attenuation that is likely controlled by grain‐boundary processes. The inferred peak in attenuation just below the oceanic lithosphere‐asthenosphere boundary from the NoMelt array is difficult to be explained by the pressure effects assuming the absorption band behavior because such a model requires a much larger activation volume than determined in this work and it also fails to explain high attenuation in the deep asthenosphere. This suggests that either melt accumulation or other processes such as elastically accommodated grain‐boundary sliding (EAGBS) is responsible for the peak in attenuation. The present results are also applied to EAGBS. We suggest that the deep upper mantle is likely to be relaxed by EAGBS, which implies that the shear velocity of the deep upper mantle can be several percent smaller than that inferred from single crystal elasticity.

中文翻译：

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压力对某些地球物理应用对橄榄石聚集体晶粒长大动力学的影响

在相对缺水的条件下，在1773 K时高达10 GPa的压力下，研究了压力对橄榄石晶粒生长动力学的影响。该结果是使用关系解释，以获得活化体积= 5.0±1.1厘米³ /摩尔为Ñ  = 2或= 5.2±1.1厘米³ /摩尔为Ñ =3。小的活化体积意味着即使在干燥的深上地幔中，纯橄榄石聚集体的晶粒生长动力学也很快，这意味着晶粒大小受其他阶段的钉扎或动态重结晶控制，但之后的早期除外。沃兹利石在上升流材料中的相变。目前的结果被应用于可能由晶界过程控制的地震波衰减。从NoMelt阵列推断的海洋岩石圈-软流圈边界正下方的衰减峰值很难用假设吸收带行为的压力效应来解释，因为这种模型需要比本研究确定的激活量大得多的激活量，而且也失败了解释深流软流圈中的高衰减。这表明，熔体积累或其他过程（例如弹性适应的晶界滑动（EAGBS））是造成衰减峰值的原因。本结果也适用于EAGBS。我们认为，EAGBS可能会使深部上地幔松弛，这意味着深部上地幔的剪切速度可能比单晶弹性推断的速度小百分之几。