Japan Geoscience Union Meeting 2016

Presentation information

International Session (Oral)

Symbol S (Solid Earth Sciences) » S-IT Science of the Earth's Interior & Techtonophysics

[S-IT06] Interaction and Coevolution of the Core and Mantle

Mon. May 23, 2016 9:00 AM - 10:30 AM 304 (3F)

Convener:*Satoru Tanaka(Department of Deep Earth Structure and Dynamics Research Japan Agency for Marine-Earth Science and Technology), Taku Tsuchiya(Geodynamics Research Center, Ehime University), Chair:Tetsuo Irifune(Geodynamics Research Center, Ehime University), Hiroyuki Kagi(Geochemical Research Center, Graduate School of Science, University of Tokyo)

9:30 AM - 9:45 AM

[SIT06-03] Viscosity of Basaltic Melt under High Pressure: ab initio molecular dynamics simulations

*Satoshi Ohmura1, Tatsuyuki Arai2, Taku Tsuchiya3 (1.Hiroshima Institute of Technology, 2.Tokyo Institute of Technology, 3.Ehime University)

Keywords:basaltic melt, viscosity, ab initio molecular dynamics

High-pressure behavior of basaltic aluminosilicate melt has been intensively studied due to its importance in deep Earth science related to such as early magma ocean and subsequent differentiation processes (Agee 1998; Ohtani and Maeda 2001; Suzuki, et al. 2005).
Experimental studies reported that the viscosity of basaltic melt decreases with increasing pressure (Allwardt, et al. 2007; Sakamaki, et al. 2013). They suggested based on the results of classical molecular dynamics simulation (Nevins and Spera 1998) and 27Al magic-angle spinning nuclear magnetic resonance (Allwardt, et al. 2007) that this anomalous behavior is related to the coordination change of Al. However, so far there exist no ab initio simulations of basaltic melt in the pressure range, where the anomaly in viscosity is observed experimentally. In this study we therefore perform ab initio molecular dynamics simulations gradually changing volume and successfully reproduce a viscosity minimum in the pressure range corresponding to the experiments. We analyze relationships between the anomalous pressure response of viscosity and variations in the atomic-scale local structure.
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Allwardt, J. R. et al. Am. Mineral. 92, 1093 (2007)
Sakamaki, T. at al. Nature Geoscience 6, 1041 (2013)