Despite its highly extended and thinned crust, much of the western Cordillera in the United States is elevated more than 1km above sea level. Therefore, this region cannot be thought of as thick crust floating isostatically in a uniform mantle; rather, the lithospheric mantle and/or the upper asthenosphere must vary in thickness or density across the region. Utilizing crustal thickness and density constraints, the residual mass defcicit that must occur in the mantle lithosphere and asthenosphere beneath the western Cordillera was modelled. A major hot spot broke out during a complex series of Cenozoic tectonic events that included lithospheric thickening, back-arc extension, and transition from subduction to a transform plate boundary. It is suggested that many of the characteristics that make the western Cordillera unique among extensional provinces can be attributed to the mantle plume that created the Yellowstone hot spot. -Authors
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Mantle plume influence on the Neogene uplift and extension of the US western Cordillera?