Title: Theoretical considerations of electrical conductivity in a partially molten mantle and implications for geothermometry
Abstract: Journal of Geophysical Research (1896-1977)Volume 79, Issue 26 p. 4003-4010 Theoretical considerations of electrical conductivity in a partially molten mantle and implications for geothermometry Harve S. Waff, Harve S. WaffSearch for more papers by this author Harve S. Waff, Harve S. WaffSearch for more papers by this author First published: 10 September 1974 https://doi.org/10.1029/JB079i026p04003Citations: 241AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onEmailFacebookTwitterLinkedInRedditWechat Abstract Relationships between bulk effective electrical conductivity, melt fraction, and liquid path connectivity are derived for a partially melted material. Hashin-Shtrikman bounds are determined for the conductivity on the basis of entropy production and compared with results obtained for exact geometrical models for the limiting cases of isolated melt pockets and complete grain boundary wetting. Models used are (1) a spherical particle assemblage of an infinite number of different-sized composite spheres, each containing an inner core of one phase, surrounded by an outer shell of a second phase, and (2) a three-dimensional periodic array of identical-sized cubes of one phase, surrounded by a second phase that extends continuously throughout the body. Both models yield the same expressions as those of the upper Hashin-Shtrikman bound for the bulk conductivity dependence on melt fraction for small melt fractions with complete liquid bridging. A small dependence on grain size and shape is inferred. Partial melting in the form of isolated melt pockets is found to be ineffective in raising bulk conductivity significantly over that of the solid phase material. Quasi-continuous grain boundary wetting is considered in terms of analog modeling. Melt fraction and liquid path connectivity are found to be main determining factors for electrical conductivity. It is concluded that grain boundary and/or edge wetting is necessary for partial melting to raise bulk conduction in the mantle appreciably over that of its solid phase material. Such wetting is therefore inferred to be a highly probable mechanism responsible for high conductivity anomalies observed in deep geomagnetic soundings. Implications for geothermometry are considered. 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Publication Year: 1974
Publication Date: 1974-09-10
Language: en
Type: article
Indexed In: ['crossref']
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Cited By Count: 287
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