Journal
GEOPHYSICAL RESEARCH LETTERS
Volume 40, Issue 1, Pages 94-99Publisher
AMER GEOPHYSICAL UNION
DOI: 10.1029/2012GL054372
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Funding
- National Science Foundation [EAR-1118869]
- UK National Environmental Research Council [NE/ F01787/1]
- Directorate For Geosciences
- Division Of Earth Sciences [1118869] Funding Source: National Science Foundation
- Natural Environment Research Council [NE/I010734/1, hpc010001, NE/F017871/1] Funding Source: researchfish
- NERC [hpc010001, NE/F017871/1, NE/I010734/1] Funding Source: UKRI
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The viscosity of silicate liquids at high temperature is crucial to our understanding of chemical and thermal evolution of the Earth since its early stages. First-principles molecular dynamics simulations of seven liquids across the MgO-SiO2 binary show that the viscosity varies by several orders of magnitudes with temperature and composition. Our results follow a compensation law: on heating, the viscosity of all compositions approaches a uniform value at 5000 K, above which pure silica becomes the least viscous liquid. Viscosity depends strongly on composition (fourth power), implying a strong nonlinear dependence of the configurational entropy on composition. Using the simulation results, we derive and evaluate different types (Arrhenius and non-Arrhenius) of models for accurate description of the viscosity-temperature-composition relationship. Our results span the thermal regime expected in a magma ocean, and indicate that melt migration is important for understanding the generation and preservation of melts from frictional heating at very fast slip in impact processes. Citation: Karki B. B., J. Zhang, and L. Stixrude (2013), First principles viscosity and derived models for MgO-SiO2 melt system at high temperature, Geophys. Res. Lett., 40, 94-99, doi: 10.1029/2012GL054372.
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