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TitleCurrent research part C: Canadian Shield / Recherches en cours partie C: Bouclier Canadien
LicencePlease note the adoption of the Open Government Licence - Canada supersedes any previous licences.
AuthorGeological Survey of Canada
SourceGeological Survey of Canada, Paper no. 88-1C, 1988, 372 pages, Open Access logo Open Access
Lang.English; French
Mediapaper; on-line; digital
RelatedThis publication contains the following publications
File formatpdf
AreaCanadian Shield
Subjectsmetallic minerals; surficial geology/geomorphology; geochemistry; geochronology; radioactive minerals; igneous and metamorphic petrology; mineralogy; structural geology; stratigraphy; economic geology; geophysics
Released1988 01 01; 2013 10 17
AbstractThe 1.9 Ga continental rift sediments and volcanic rocks, transitional-crust and true oceanic crust (Purtuniq ophiolite) are contained in thrust sheets bounded by south-verging thrust faults (D 1) and preserved in the Cape Smith Belt as the result of two post-thrusting episodes (D2, D3) of thick-skinned crustal folding. The D 1 thin-skinned thrustjold belt is characterized by a basal décollement, localized at the basement­cover interface, which displays a frontal ramp that exposes up to 30 m of footwall autochthonous fluvio­deltaic sandstone and ironstone. lmbricates of more proximal rift-basin ironstone and sandstone are struc­turally overlain by more outboard (rift basin) semipelite and proximal fan arkosic sandstone deposits which pass upwards into LREE-enriched basalts, gabbro sills and minor rhyolite. More internal thrust sheets contain transitional-crust basalts (komatiitic to MORB- like) which are imbricated with distal fan sandstones and semipelites. Deep water laminated graphitic pelites are structurally sandwiched between underlying transitional-crust basalts and hangingwall ophiolitic units. Imbricates of the ophiolite contain either (1) sheeted dykes overlain by pillowed and massive basalt flows intruded by mafic dykes and sills; or (2) mafic and ultramafic cumulates. D 1 out-of-sequence thrusting associated with interleaving of base­ment and caver units, resulted in re-imbrication of the thrust stack and further southward transport.

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