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arXiv 0911.3183cond-mat.mtrl-sci
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钙钛矿MgSiO3在地幔压力和温度下的弹性常数

The elastic constants of MgSiO3 perovskite at pressures and temperatures of the Earth's mantle

A. R. Oganov, J. P. Brodholt, G. D. Price

摘要:

与热对流1有关的地幔温度异常可以从地震层析成像中推断出来,前提是地幔矿物的弹性特性是地幔压力下温度的函数。然而,目前,这些信息很难直接通过实验室实验获得。因此,我们利用计算机技术的最新进展,并进行了有限温度从头计算分子动力学模拟的弹性性质的MgSiO3钙钛矿,下地幔的主要矿物,在相关的热力学条件。当结合断层图像的地幔的结果,我们的研究结果表明,下地幔是显着的滞弹性或成分不均匀的大尺度。我们发现,在给定的深度,地幔的最冷和最热的区域之间的温度差,在1000公里,约为800 K,1500 K在2000公里,并可能超过2000 K的核幔边界。

英文摘要:

The temperature anomalies in the Earth's mantle associated with thermal convection1 can be inferred from seismic tomography, provided that the elastic properties of mantle minerals are known as a function of temperature at mantle pressures. At present, however, such information is difficult to obtain directly through laboratory experiments. We have therefore taken advantage of recent advances in computer technology, and have performed finite-temperature ab initio molecular dynamics simulations of the elastic properties of MgSiO3 perovskite, the major mineral of the lower mantle, at relevant thermodynamic conditions. When combined with the results from tomographic images of the mantle, our results indicate that the lower mantle is either significantly anelastic or compositionally heterogeneous on large scales. We found the temperature contrast between the coldest and hottest regions of the mantle, at a given depth, to be about 800K at 1000 km, 1500K at 2000 km, and possibly over 2000K at the core-mantle boundary.

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