Geoelectric structure of the Proterozoic Wopmay Orogen and adjacent terranes, Northwest Territories, Canada

Xianghong Wu, Ian J. Ferguson*, Alan G. Jones

*Corresponding author for this work

Research output: Contribution to journalArticle

21 Citations (Scopus)

Abstract

Magnetotelluric (MT) soundings were made along a transect in northern Canada crossing the Proterozoic Wopmay Orogen, Fort Simpson basin, and adjacent parts of the Slave craton and the Nahanni terrane. The results are used to define the geoelectric structure and constrain the crustal and lithospheric structure and evolution. Across the Wopmay Orogen, geoelectric strikes at crustal depths average N34°E and are interpreted to be related to transcurrent faulting that occurred during late distal collisions at the western margin of the orogen. Weak two-dimensionality in the Fort Simpson basin is interpreted to be due to the sedimentary rocks in the basin. At longer periods, geoelectric strikes across the Wopmay Orogen rotate from ∼N43°E at uppermost mantle penetration to ∼N62°E at a depth of 100 km. The uppermost mantle strikes are interpreted to be due to ductile shearing linked to the transcurrent faulting in the overlying crust. The deeper strikes may be caused by shearing at the base of the present-day lithosphere. Within the Wopmay Orogen, the MT results image a conductor at the margin of the Fort Simpson and Hottah terranes interpreted to be related to the collision of these terranes. Conductive crust beneath the western margin of the Great Bear magmatic arc suggests correlative rocks of the Coronation margin extend south of the Slave craton. Lastly, decreased resistivity in the Hottah terrane at mantle depths is interpreted to be caused by the introduction of graphitic or sulphidic rocks during subduction prior to the Hottah-Slave and Fort Simpson - Hottah collisions.

Original languageEnglish
Pages (from-to)955-981
Number of pages27
JournalCanadian journal of earth sciences
Volume42
Issue number6
DOIs
Publication statusPublished - Jun 2005
Externally publishedYes

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