Abstract

COCORP (Consortium for Continental Reflection Profiling) deep-reflection profiles crossing the northern Williston basin show (1) dipping reflections within the crust of the underlying Trans-Hudson orogen that extend downward into the upper mantle and (2) no clearly defined reflection Moho. In contrast, Lithoprobe (Canada's national geoscience project) profiles crossing the Trans-Hudson orogen north of the basin show dipping reflections within the crust that terminate at a sharply defined subhorizontal reflection Moho—a reflection character typical of the interior of collapsed Phanerozoic orogens. We suggest that a crustal root produced during Hudsonian collision was incompletely removed by “normal” postorogenic extension in the region now underlain by the Williston basin. This remnant crustal keel much later underwent eclogite-facies metamorphism, which overprinted a new nonreflective Moho across the root and induced the subsidence of the Williston basin.

This content is PDF only. Please click on the PDF icon to access.

First Page Preview

First page PDF preview
You do not currently have access to this article.