Electrical conductivity structure of the Purcell Anticlinorium in southeast British Columbia and northwest Montana

Magnetotelluric data from almost 200 sites were acquired over the Precambrian Purcell Anticlinorium west of the Rocky Mountains of Canada and the US. Fifteen east-west profiles cross the anticlinorium between latitudes of 48 and 49.5°N, and provide a grid suitable for a regional three-dimensional study of the electrical structure of predominantly the upper crust. The data show essentially a resistive uppermost crust, varying from 2 to 6 km in thickness, over a strongly conductive widespread electrical "basement.' The general electrical strike of this conductive basement is found to be N30°W, which concurs with the surface geological trend of the region. The data from all profiles were inverted one dimensionally, and from two of the profiles two dimensionally, using different algorithms, to test the accuracy of the one-dimensional images. -from Authors