Publication 101
Electrical resistivity imaging of the central Trans-Hudson Orogen in eastern Saskatchewan, Canada
Ferguson, I.J. K.M. Stevens and A.G. Jones
Abstract
Magnetotelluric (MT) measurements were made on a profile across the Trans-Hudson orogen in 1992 as part
of the Lithoprobe transect. The present study includes analysis of results from a 300 km-long section of the profile in
which allocthonous Paleoproterozoic juvenile terranes and arc rocks of the western Trans-Hudson orogen have been
juxtaposed against the Archean Sask craton. Impedance tensor decomposition of data from the 40 MT sites in the area
indicates a geoelectric strike of N28ˇĆE. Two-dimensional inversion of the data using a non-linear conjugate gradient
algorithm provided images of the resistivity structure. Resistivity images reveal that the crust of the Sask craton is
relatively resistive (>2000 ohm.m). In contrast, the rocks of the Flin Flon belt, Glennie domain, and La Ronge domain
are mostly relatively conductive (<100-1000 ohm.m). In the east of the study area, the images suggest that the Tabbernor
fault juxtaposes more conductive rocks of the Glennie domain in the west against more resistive Archean rocks in the
east in the upper 20 km of the crust. In the west of the study area, the images confirm that the North American Central
Plains conductor occurs within westward-dipping rocks of the La Ronge domain. The resistivity images also reveal that
the lower crust beneath the west of the Glennie domain, within a crustal culmination defined by seismic reflection
data, is electrically conductive (<100 ohm.m). An explanation for the enhanced conductivity is that part of the lower crust
beneath the western Glennie domain is of Proterozoic age. In this case, a possible source for the enhanced conductivity,
based on its location at the edge of the Sask continental block, is Proterozoic ocean margin rocks.
Source
Canadian Journal of Earth Sciences, 42, 495-515, 2005.
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