Conductivity of western Superior Province upper mantle in northwestern Ontario

Magnetotelluric (MT) measurements at the Earth’s surface are sensitive to charge carriers that may be introduced into an insulating crystalline lithosphere due to active or ancient tectonomagmatic processes operating within the crust and upper mantle. During 1998 and 2000, MT data were acquired within the western Superior LITHOPROBE and NATMAP study area to image conductive lithospheric structures that may be associated with Archean accretionary tectonics. The MT responses observed on either side of the 3 Ga North Caribou terrane are aligned subparallel to ca. 2.7 Ga transpressional zones. An initial 3-D model that reproduces the observed MT data within, and south of the North Caribou terrane locates the conductive structures within the uppermost mantle. We suggest that this upper mantle conductivity aligned subparallel to major zones of transpression, is the residue of partial melting related to synto late-Kenoran magmatism and deformation. CURRENT RESEARCH RECHERCHES EN COURS 2001 Article Article Titles Titres Purchase Information Information pour acheter 2001-E6 J.A. Craven et al. 1 1 Department of Geological Sciences University of Manitoba 233 Wallace Building Winnipeg, Manitoba R3T 2N2 2 Department of Physics University of Toronto 60 St. George Street Toronto, Ontario M5W 1A7