Preliminary deep crustal investigations, using magnetotellurics, to locate the Archean/Proterozoic suture zone in the Great Basin

The Archean/Proterozoic suture zone is exposed in eastern Utah and southwestern
Wyoming and has a west-southwest strike. In the Great Basin, the strike of the
Archean/Proterozoic suture zone is poorly constrained because it is largely concealed
below a Neoproterozoic-Paleozoic miogeocline and basin fill. Two-dimensional resistivity
modeling of two regional south-north magnetotelluric sounding profiles in western
Utah and eastern Nevada reveals a steep, deep (greater than 10-km depth),
conductive (1 to 20 ohm-m) zone about 40- to 55-km in breadth interpreted to be a major
regional shear zone that may be related to or inherited from the Archean/Proterozoic
suture zone. The major shear zone may have formed during Proterozoic rifting of the
continent and reactivated during Paleozoic tectonism. The magnetotelluric profiles
suggest the major shear zone is not manifest by a single structure with a uniform
strike in western Utah and eastern Nevada. Rather, it appears to be comprised of two
or more broad, deep conductive structures with orientations that vary from westsouthwest
in western Utah to northwest in eastern Nevada and follows the general
trend of the approximate edge of Archean crust proposed by Reed (1993).