Electrical conductivity of olivine, a dunite, and the mantle

Journal Article · Thu May 10 00:00:00 EDT 1990 · Journal of Geophysical Research; (United States)

DOI:https://doi.org/10.1029/JB095iB05p06967· OSTI ID:5095701

Constable, S ^[1]; Duba, A ^[2]

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1. Scripps Inst. of Oceanography, La Jolla, CA (United States)
2. Lawrence Livermore National Lab., CA (United States)

Laboratory studies of the electrical conductivity of rocks and minerals are vital to the interpretation of electromagnetic soundings of the Earth's mantle. To date, the most reliable data have been collected from single crystals. The authors have extended these studies with electrical conductivity measurements on a dunite from North Carolina, in the temperature range of 600-1,200 C and under controlled oxygen fugacity. Observations of conductivity as a function of oxygen fugacity and temperature demonstrate that conduction in the dunite is indistinguishable from conduction in single olivine crystals. Thus the common practice of exaggerating the single-crystal conductivities to account for conduction by grain boundary phases in the mantle is unnecessary. Because the dunite conductivity is consistent with that published for single crystals under similar conditions, the authors have made a combined analysis of these data. Conductivity as a function of temperature between 600 and 1,450 C displays three conduction mechanisms whose activation energies may be recovered by nonlinear least squares fitting, yielding activation energies of 0.21 {plus minus} 2.56 {times} 10{sup {minus}19} J below 720 C, 2.56 {plus minus} 0.02 {times} 10{sup {minus}19} J between 720 C and 1,500 C and 11.46 {plus minus} 0.90 {times} 10{sup {minus}19} J above 1,500 C. The behavior of conductivity as a function of oxygen fugacity is well explained by a model in which an f{sub O{sub 2}}-independent population of charge carriers is supplemented at high oxygen fugacities with a population that is proportional to f{sub O{sub 2}}{sup 0.3}. This parametrization produces a clear correlation of the f{sub O{sub 2}} dependent term with iron content, which is otherwise obscured by variations in conductivity among olivines.

• OSTI ID: 5095701
• Journal Information: Journal of Geophysical Research; (United States), Vol. 95:B5; ISSN 0148-0227
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
15 GEOTHERMAL ENERGY
58 GEOSCIENCES
EARTH MANTLE
ELECTROMAGNETIC SURVEYS
OLIVINE
ELECTRIC CONDUCTIVITY
ACTIVATION ENERGY
GRAIN BOUNDARIES
HIGH TEMPERATURE
IMPURITIES
MATHEMATICAL MODELS
NORTH CAROLINA
OXYGEN
VAPOR PRESSURE
VERY HIGH TEMPERATURE
CRYSTAL STRUCTURE
DEVELOPED COUNTRIES
ELECTRICAL PROPERTIES
ELECTRICAL SURVEYS
ELEMENTS
ENERGY
FEDERAL REGION IV
GEOPHYSICAL SURVEYS
MICROSTRUCTURE
MINERALS
NONMETALS
NORTH AMERICA
PHYSICAL PROPERTIES
SILICATE MINERALS
SURVEYS
THERMODYNAMIC PROPERTIES
USA
360603* - Materials- Properties
152002 - Geothermal Data & Theory- Properties of Minerals & Rocks
580000 - Geosciences