ELECTRICAL-CONDUCTIVITY OF ULTRAMAFIC ROCKS TO 1820 KELVIN

Electrical conductivity, σ, of six ultramafic rocks (garnet-bearing peridotites and an eclogite) has been investigated in the temperature range 670-1820 K under known f{hook}O environment. Between 670 and ∼1320 K σ increases with 1/T monotonically, first slowly, by 1-1.5 orders of magnitude. Above 1320 K σ increases sharply; an increase of 3-4 orders of magnitude is observed between 1320 and 1670 K. In the same temperature range the σ values for all the six rocks fall within 1.5 orders of magnitude, the lowest conductivity being for a spinel lherzolite. The range of σ values is narrowed at higher temperatures. The differences in σ values above 1470 K may be explained on the basis of varying degrees of partial melting in the rocks. Over the entire range of temperature, the σ values for the ultramafic rocks are lower than those reported for basalts but higher (by 1-2 orders of magnitude) than those for single-crystal olivines. © 1978.