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Title: X-ray Raman scattering study of MgSiO₃ glass at high pressure: Implication for triclustered MgSiO₃ melt in Earth's mantle

Abstract

Silicate melts at the top of the transition zone and the core-mantle boundary have significant influences on the dynamics and properties of Earth's interior. MgSiO{sub 3}-rich silicate melts were among the primary components of the magma ocean and thus played essential roles in the chemical differentiation of the early Earth. Diverse macroscopic properties of silicate melts in Earth's interior, such as density, viscosity, and crystal-melt partitioning, depend on their electronic and short-range local structures at high pressures and temperatures. Despite essential roles of silicate melts in many geophysical and geodynamic problems, little is known about their nature under the conditions of Earth's interior, including the densification mechanisms and the atomistic origins of the macroscopic properties at high pressures. Here, we have probed local electronic structures of MgSiO{sub 3} glass (as a precursor to Mg-silicate melts), using high-pressure x-ray Raman spectroscopy up to 39 GPa, in which high-pressure oxygen K-edge features suggest the formation of tricluster oxygens (oxygen coordinated with three Si frameworks; {sup [3]}O) between 12 and 20 GPa. Our results indicate that the densification in MgSiO{sub 3} melt is thus likely to be accompanied with the formation of triculster, in addition to a reduction in nonbridging oxygens. The pressure-inducedmore » increase in the fraction of oxygen triclusters >20 GPa would result in enhanced density, viscosity, and crystal-melt partitioning, and reduced element diffusivity in the MgSiO{sub 3} melt toward deeper part of the Earth's lower mantle.« less

Authors:
; ; ; ; ; ; ; ; ; ; ; ; ; ; ;  [1]
  1. SNU
Publication Date:
Research Org.:
Argonne National Lab. (ANL), Argonne, IL (United States). Advanced Photon Source (APS)
Sponsoring Org.:
USDOE
OSTI Identifier:
1006629
Resource Type:
Journal Article
Journal Name:
Proceedings of the National Academy of Sciences of the United States of America
Additional Journal Information:
Journal Volume: 105; Journal Issue: (23) ; 06, 2008; Journal ID: ISSN 0027-8424
Publisher:
National Academy of Sciences, Washington, DC (United States)
Country of Publication:
United States
Language:
ENGLISH
Subject:
58 GEOSCIENCES; DENSITY; DYNAMICS; EARTH MANTLE; ELECTRONIC STRUCTURE; ELEMENTS; GLASS; MAGMA; OXYGEN; PRECURSOR; PRESSURE RANGE MEGA PA 10-100; RAMAN SPECTROSCOPY; REDUCTION; SCATTERING; SILICATES; VISCOSITY; ZONES

Citation Formats

Lee, Sung Keun, Lin, Jung-Fu, Cai, Yong Q, Hiraoka, Nozomu, Eng, Peter J, Okuchi, Takuo, Mao, Ho-kwang, Meng, Yue, Hu, Michael Y, Chow, Paul, Shu, Jinfu, Li, Baosheng, Fukui, Hiroshi, Lee, Bum Han, Kim, Hyun Na, Yoo, Choong-Shik, NSRRC), SBU), LLNL), CIW), UC), Nagoya), WSU), and Okayama). X-ray Raman scattering study of MgSiO₃ glass at high pressure: Implication for triclustered MgSiO₃ melt in Earth's mantle. United States: N. p., 2008. Web. doi:10.1073/pnas.0802667105.
Lee, Sung Keun, Lin, Jung-Fu, Cai, Yong Q, Hiraoka, Nozomu, Eng, Peter J, Okuchi, Takuo, Mao, Ho-kwang, Meng, Yue, Hu, Michael Y, Chow, Paul, Shu, Jinfu, Li, Baosheng, Fukui, Hiroshi, Lee, Bum Han, Kim, Hyun Na, Yoo, Choong-Shik, NSRRC), SBU), LLNL), CIW), UC), Nagoya), WSU), & Okayama). X-ray Raman scattering study of MgSiO₃ glass at high pressure: Implication for triclustered MgSiO₃ melt in Earth's mantle. United States. doi:10.1073/pnas.0802667105.
Lee, Sung Keun, Lin, Jung-Fu, Cai, Yong Q, Hiraoka, Nozomu, Eng, Peter J, Okuchi, Takuo, Mao, Ho-kwang, Meng, Yue, Hu, Michael Y, Chow, Paul, Shu, Jinfu, Li, Baosheng, Fukui, Hiroshi, Lee, Bum Han, Kim, Hyun Na, Yoo, Choong-Shik, NSRRC), SBU), LLNL), CIW), UC), Nagoya), WSU), and Okayama). Fri . "X-ray Raman scattering study of MgSiO₃ glass at high pressure: Implication for triclustered MgSiO₃ melt in Earth's mantle". United States. doi:10.1073/pnas.0802667105.
@article{osti_1006629,
title = {X-ray Raman scattering study of MgSiO₃ glass at high pressure: Implication for triclustered MgSiO₃ melt in Earth's mantle},
author = {Lee, Sung Keun and Lin, Jung-Fu and Cai, Yong Q and Hiraoka, Nozomu and Eng, Peter J and Okuchi, Takuo and Mao, Ho-kwang and Meng, Yue and Hu, Michael Y and Chow, Paul and Shu, Jinfu and Li, Baosheng and Fukui, Hiroshi and Lee, Bum Han and Kim, Hyun Na and Yoo, Choong-Shik and NSRRC) and SBU) and LLNL) and CIW) and UC) and Nagoya) and WSU) and Okayama)},
abstractNote = {Silicate melts at the top of the transition zone and the core-mantle boundary have significant influences on the dynamics and properties of Earth's interior. MgSiO{sub 3}-rich silicate melts were among the primary components of the magma ocean and thus played essential roles in the chemical differentiation of the early Earth. Diverse macroscopic properties of silicate melts in Earth's interior, such as density, viscosity, and crystal-melt partitioning, depend on their electronic and short-range local structures at high pressures and temperatures. Despite essential roles of silicate melts in many geophysical and geodynamic problems, little is known about their nature under the conditions of Earth's interior, including the densification mechanisms and the atomistic origins of the macroscopic properties at high pressures. Here, we have probed local electronic structures of MgSiO{sub 3} glass (as a precursor to Mg-silicate melts), using high-pressure x-ray Raman spectroscopy up to 39 GPa, in which high-pressure oxygen K-edge features suggest the formation of tricluster oxygens (oxygen coordinated with three Si frameworks; {sup [3]}O) between 12 and 20 GPa. Our results indicate that the densification in MgSiO{sub 3} melt is thus likely to be accompanied with the formation of triculster, in addition to a reduction in nonbridging oxygens. The pressure-induced increase in the fraction of oxygen triclusters >20 GPa would result in enhanced density, viscosity, and crystal-melt partitioning, and reduced element diffusivity in the MgSiO{sub 3} melt toward deeper part of the Earth's lower mantle.},
doi = {10.1073/pnas.0802667105},
journal = {Proceedings of the National Academy of Sciences of the United States of America},
issn = {0027-8424},
number = (23) ; 06, 2008,
volume = 105,
place = {United States},
year = {2008},
month = {6}
}