Structure and properties of forsterite-MgSiO3 liquid interface: molecular dynamics study

被引：7

作者：

Noritake F. ^{[1
]}

Kawamura K. ^{[1
]}

机构：

[1] Graduate School of Environmental and Life Science, Okayama University, 3-1-1, Tsushimanaka, Kita-Ku, 700-8530, Okayama

来源：

Progress in Earth and Planetary Science | / 1卷 / 1期

基金：

日本学术振兴会;

关键词：

Forsterite; Molecular dynamics simulation; Silicate liquid; Solid-liquid interface;

D O I：

10.1186/2197-4284-1-14

中图分类号：

学科分类号：

摘要：

The mechanical properties of partially molten rock, such as their permeabilities and viscosities, are important properties in geological processes. We performed molecular dynamics simulations in terms of structures and diffusivities in forsterite-MgSiO3 liquid interfaces to obtain the nanoscale dynamic properties and structure of the interface. The characteristic structure of the forsterite-MgSiO3 liquid interfaces was observed in the simulations. In the layered structure of the altered surfaces, Si-rich and Mg-rich layers exist alternately in the vicinity of the crystal-liquid interfaces. The layered structure might be formed by the strength difference between Si-O covalent bonds and Mg-O ionic bonds. The difference in the layered structure, indicated by the thickness of the MgSiO3 liquid film, might be caused by the difference in degrees of freedom of the configuration in the liquid film. The two-dimensional diffusivity of oxygen atoms parallel to the interface is controlled by two factors. One factor is the thickness of the liquid film, which decreases oxygen diffusivity with decreasing film thickness. The other is the composition of the sliced layer, where oxygen diffusivity increases with increasing Mg/Si ratio. The effect of the crystal-liquid interface found in this study is negligible in texturally equilibrated rocks. However, the interface can affect the melt flow in deformed samples because a grain boundary melt film with a thickness of several nanometers exists stably in deformed partially molten rock. © 2014, Noritake and Kawamura; licensee Springer.

引用

共 30 条

[1]

Adjaoud O., Steinle-Neumann G., Jahn S., Transport properties of Mg2SiO4 liquid at high pressure: physical state of magma ocean, Earth Planet Sci Lett, 312, pp. 463-470, (2011)

[2]

Angel R.J., Hugh-Jones D.A., Equations of state and thermodynamic properties of enstatite pyroxenes, J Geophys Res, 99, pp. 19777-19783, (1994)

[3]

Bockris J.O.M., Mackenzie J.D., Kitchener J.A., Viscous flow in silica and binary liquid silicates, Trans Faraday Soc, 51, pp. 1734-1748, (1955)

[4]

De Kloe R., Drury M.R., van Roermund H.L.M., Evidence for stable grain boundary melt films in experimentally deformed olivine-orthopyroxene rocks, Phys Chem Min, 27, pp. 480-494, (2000)

[5]

De Koker N.P., Stixrude L., Karki B., Thermodynamics, structure, dynamics, and freezing of Mg2SiO4 liquid at high pressure, Geochim Cosmochim Acta, 72, pp. 1427-1441, (2009)

[6]

Duffy T.S., Zha C., Downs R.T., Mao H., Hemley R.J., Elasticity of forsterite to 16 GPa and the composition of the upper mantle, Nature, 378, pp. 170-173, (1995)

[7]

Dunn T., Oxygen diffusion in three silicate melts along the join diopside-anorthite, Geochim Cosmochim Acta, 46, pp. 2293-2299, (1982)

[8]

Faul U.H., Jackson I., The seismological signature of temperature and grain size variations in the upper mantle, Earth Planet Sci Lett, 234, pp. 119-134, (2005)

[9]

Fujino K., Sasaki S., Takeuchi Y., Sadanaga R., X-ray determination of electron distributions in forsterite, fayalite and tephroite, Acta Crystallogr B, 37, pp. 513-518, (1981)

[10]

Gurmani S.F., Jahn S., Brasse H., Schilling F.R., Atomic scale view on partially molten rocks: molecular dynamics simulations of melt-wetted olivine grain boundaries, J Geophys Res, 116, (2011)

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