Publication 106
The electrical resistivity structure of Archean to Tertiary lithosphere along 3,200 km of
SNORCLE profiles, northwestern Canada
Jones, A.G., J. Ledo, I.J. Ferguson, C. Farquharson, X. Garcia, N. Grant, G.W. McNeice,
B. Roberts, J. Spratt, G. Wennberg, L. Wolynec, and X. Wu
Abstract
Magnetotelluric (MT) measurements to image the three-dimensional resistivity structure of the North American
continent from an Archean core to a region of Tertiary assembly were recorded at almost 300 sites along 3200 km of
profiles on the Lithoprobe Slave – Northern Cordillera Lithospheric Evolution (SNORCLE) transect in northwestern
Canada. At the largest scale, the MT results indicate significant lithospheric thickness variation, from 260 km at the
southwest margin of the Slave craton to significantly <100 km at the southwestern end of the SNORCLE transect in
the Cordillera. At intermediate scale, the resistivity results allow broad terrane subdivisions to be made. Several anomalously
conductive zones along the SNORCLE transect, in rocks ranging in age from Archean to Tertiary, are attributed to the
introduction of either water or carbon into the crust and mantle during subduction processes. At the local scale, the MT
data image two major faults crossing the study area, the Great Slave Lake shear zone and the Tintina Fault. The resistivity
images show that both the Tintina Fault and Great Slave Lake shear zone form crustal-scale features, and that the Tintina
Fault has a remarkably uniform resistivity signature over a 400 km strike length in the study area. Arguably the most
controversial conclusion reached is that the MT data do not support the western extension of North American autochthonous
basement suggested from interpretation of the seismic reflection data.
Source
Canadian Journal of Earth Sciences, 42, 1257-1275, 2005.
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Alan G Jones / 21 April 2006 /
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