Electromagnetic images of the Trans-Hudson orogen

The North American Central Plains anomaly revealed

Alan G. Jones*, Juanjo Ledo, Ian J. Ferguson

*Corresponding author for this work

Research output: Contribution to journalReview article

52 Citations (Scopus)

Abstract

Magnetotelluric studies of the Trans-Hudson orogen over the last two decades, prompted by the discovery of a significant conductivity anomaly beneath the North American Central Plains (NACP), from over 300 sites yield an extensive database for interrogation and enable three-dimensional information to be obtained about the geometry of the orogen from southern North Dakota to northern Saskatchewan. The NACP anomaly is remarkable in its continuity along strike, testimony to along-strike similarity of orogenic processes. Where bedrock is exposed, the anomaly can be associated with sulphides that were metamorphosed during subduction and compression and penetratively emplaced deep within the crust of the intemides of the orogen to the boundary of the Hearne margin. A new result from this compilation is the discovery of an anomaly within the upper mantle beginning at depths of ∼80-100 km. This lithospheric mantle conductor has electrical properties similar to those for the central Slave craton mantle conductor, which lies directly beneath the major diamond-producing Lac de Gras kimberlite field. While the Saskatchewan mantle conductor does not directly underlie the Fort à la Corne kimberlite, which is associated with the Sask craton, the spatial correspondence is close.

Original languageEnglish
Pages (from-to)457-478
Number of pages22
JournalCanadian journal of earth sciences
Volume42
Issue number4
DOIs
Publication statusPublished - Apr 2005
Externally publishedYes

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