HR: 0830h
AN: GP11A-0252    [PDF]
TI: The Electrical Roots of the Slave and Superior Provinces, Canada.
AU: * Craven, J A
EM: craven@NRCan.gc.ca
AF: Geological Survey of Canada, 615 Booth St., Ottawa, ON K1A 0E9 Canada
AU: Ferguson, I J
EM: ferguso@Ms.UManitoba.CA
AF: Department of Geological Sciences, University of Manitoba, Winnipeg, MN R3T 2N Canada
AB: Evidence from over five years of magnetotelluric data collection across the Slave craton and western Superior Province reveal dramatic spatial variation and upper mantle conductors with resistivities as low as 10 Ohm m embedded within the cratonic lithosphere. The conductivity of these anomalies is approximately two orders of magnitude higher than laboratory studies and petrophysical modelling predict for an olivine or pyroxene mineralogy dominated upper mantle. Given the depth location, age, and tectonic setting as well as the observed conductivity of these electrical conductors, we conclude that they are likely due to carbon in the form of interconnected graphite. The evidence for deep-seated graphitic conductors spatially related to other deep-seated geophysical and geochemical anomalies may be taken together with independent estimates of upper mantle oxygen fugacities within two log units of the iron-wstite buffer to suggest that partial melting and formation of the cratonic root may be related to redox melting during Meso and NeoaArchean times.
DE: 0925 Magnetic and electrical methods
DE: 1025 Composition of the mantle
SC: Geomagnetism and Paleomagnetism [GP]
MN: 2003 Fall Meeting