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A new 3-D resistivity model, estimated from inversion of magnetotelluric data, images crustal and upper-mantle structure of the Wyoming Province and adjacent areas. The Archean province is imaged as a coherent resistive domain, in sharp contrast to active tectonic domains of the western U.S. Prominent high-conductivity belts define the northern, eastern, and southern margins of the Wyoming Province and are interpreted as sutures marking the remnants of Paleoproterozoic orogens. The model results suggest the northern boundary of the Wyoming Province is located 150 km south of its traditional placement and adjacent to a composite orogen separating the Wyoming Province and Medicine Hat block. The eastern province boundary is clearly imaged along the Black Hills, whereas the western margin is obscured by Cenozoic extension and magmatism. An internal boundary within the Wyoming Province is interpreted to represent a Neoarchean suture; in stark contrast to Proterozoic sutures, though, it is not marked by a high-conductivity belt. This difference in conductivity is speculated to reflect changes in the subduction process through time. The absence of high-conductivity along Archean sutures appears to be global in nature and related to reduced continental freeboard in the Archean which limited continental weathering and the delivery of carbon-rich sediments to the seafloor. Although the entire Wyoming Province has been proposed to have undergone lithospheric modification that lessened its stability, the resistivity model suggests a thick lithospheric root remains in place except along its western margin. These results suggest that Archean cratons may be more resistant to lithospheric modification by influx of heat and fluids associated with extension and plumes than previously thought, and that metasomatism does not necessarily weaken the lithosphere and set a craton on the path to destruction. [ABSTRACT FROM AUTHOR]

The Trans‐Hudson orogen (THO) is one of the best‐preserved Proterozoic orogens on Earth, largely unaffected by subsequent tectonism, yet its southern extent lies concealed beneath the North American Central Plains. A new 3D resistivity model over the southern orogen is developed and interpreted alongside borehole, potential field, and seismic reflection data. We present the first synoptic crustal view of the southern THO and a new tectonic model of the orogen. Our model reveals high‐conductivity belts marking paleo‐subduction zones while the orogen center consists of deeply exhumed relatively dense and mostly magnetic juvenile crust preserved between the deformed margins of the Wyoming and Superior cratons. Complex structure along the western margin suggests convergence began with oblique subduction and the northward transport of severed fragments of the Wyoming Province. High‐conductivity belts are in places offset from upper‐crustal geophysical boundaries, consistent with the thrusting of accreted arcs over the Archean margins during terminal closure. Plain Language Summary: Ancient orogens, the remnants of past mountain ranges, mark the location of tectonic plate collisions. The Trans‐Hudson orogen (THO) is a particularly well preserved orogen, but much of its southern portion is concealed beneath the North American Central Plains. A new 3D resistivity model over the southern orogen is developed and interpreted alongside other geological and geophysical data. We present the first synoptic crustal view of the southern THO and a new tectonic model constrained by all existing data. Our models reveal deep‐crustal high‐conductivity belts marking the location of past subduction. The geometry of these belts suggests a previously unrecognized early stage of convergence during which fragments of the Wyoming craton were transported along the edge of the orogen. Key Points: The Trans‐Hudson orogen (THO) is bordered by two high‐conductivity belts marking paleosubduction zones of opposite polarityThe southern THO consists of deeply exhumed juvenile arc terranes and fragments of the Wyoming cratonGeophysical data indicate convergence began along a transpressive margin with considerable along‐strike transport [ABSTRACT FROM AUTHOR]