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DOI | 10.1073/pnas.2014519117 |
Configurational entropy of basaltic melts in Earth’s mantle | |
Sung Keun Lee; Jed L. Mosenfelder; Sun Young Park; A. Chim Lee; Paul D. Asimow | |
2020-08-24 | |
发表期刊 | Proceedings of the National Academy of Science |
出版年 | 2020 |
英文摘要 | Although geophysical observations of mantle regions that suggest the presence of partial melt have often been interpreted in light of the properties of basaltic liquids erupted at the surface, the seismic and rheological consequences of partial melting in the upper mantle depend instead on the properties of interstitial basaltic melt at elevated pressure. In particular, basaltic melts and glasses display anomalous mechanical softening upon compression up to several GPa, suggesting that the relevant properties of melt are strongly pressure-dependent. A full understanding of such a softening requires study, under compression, of the atomic structure of primitive small-degree basaltic melts at their formation depth, which has proven to be difficult. Here we report multiNMR spectra for a simplified basaltic glass quenched at pressures up to 5 GPa (corresponding to depths down to ∼150 km). These data allow quantification of short-range structural parameters such as the populations of coordination numbers of Al and Si cations and the cation pairs bonded to oxygen atoms. In the model basaltic glass, the fraction of [5,6]Al is ∼40% at 5 GPa and decreases to ∼3% at 1 atm. The estimated fraction of nonbridging oxygens at 5 GPa is ∼84% of that at ambient pressure. Together with data on variable glass compositions at 1 atm, these results allow us to quantify how such structural changes increase the configurational entropy of melts with increasing density. We explore how configurational entropy can be used to explain the anomalous mechanical softening of basaltic melts and glasses. |
领域 | 地球科学 |
URL | 查看原文 |
引用统计 | |
文献类型 | 期刊论文 |
条目标识符 | http://119.78.100.173/C666/handle/2XK7JSWQ/293151 |
专题 | 地球科学 |
推荐引用方式 GB/T 7714 | Sung Keun Lee,Jed L. Mosenfelder,Sun Young Park,等. Configurational entropy of basaltic melts in Earth’s mantle[J]. Proceedings of the National Academy of Science,2020. |
APA | Sung Keun Lee,Jed L. Mosenfelder,Sun Young Park,A. Chim Lee,&Paul D. Asimow.(2020).Configurational entropy of basaltic melts in Earth’s mantle.Proceedings of the National Academy of Science. |
MLA | Sung Keun Lee,et al."Configurational entropy of basaltic melts in Earth’s mantle".Proceedings of the National Academy of Science (2020). |
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