When Wyoming became Superior: Oblique convergence along the southern Trans-Hudson orogen

Abstract

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.