Partial-melt electrical conductivity: Influence of melt composition

Jeffery J. Roberts, James Tyburczy

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Abstract

The electrical conductivity of a partial melt is influenced by many factors, including melt conductivity, crystalline conductivity, and melt fraction, each of which is influenced by temperature. We have performed measurements of bulk conductivity as a function of temperature of an Fo80-basalt partial melt between 684° and 1244°C at controlled oxygen fugacity. Melt fraction and composition variations with temperature calculated using MELTS [Ghiorso and Sack, 1995] indicate that the effect on melt conductivity of changing melt composition is balanced by changes in temperature (T). Thus bulk conductivity as a function of T or melt fraction in this system can be calculated assuming a constant melt conductivity. The bulk conductivity is well modeled by simple parallel calculations, by the Hashin-Shtrikman upper bound, or by Archie's law (σpartial meltmelt = C1Xmn). We estimate apparent values of the Archie's law parameters between 1150° and 1244°C as C1 = 0.73±0.02 and n=0.98±0.01. Estimates of the permeability of the system are obtained by using an electrical conductivity-critical scale length relationship and range from ∼10-14 to 10-18 m2, comparing favorably with previously published values.

Original languageEnglish (US)
Article number1998JB900111
Pages (from-to)7055-7065
Number of pages11
JournalJournal of Geophysical Research: Solid Earth
Volume104
Issue numberB4
StatePublished - Apr 10 1999

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ASJC Scopus subject areas

  • Geophysics
  • Geochemistry and Petrology
  • Earth and Planetary Sciences (miscellaneous)
  • Space and Planetary Science

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