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TitleIndenter tectonics in the Canadian Shield: a case study for Paleoproterozoic lower crust exhumation, orocline development, and lateral extrusion
AuthorCorrigan, DORCID logo; van Rooyen, D; Wodicka, NORCID logo
SourcePrecambrian Research vol. 355, 106083, 2021 p. 1-23,
Alt SeriesNatural Resources Canada, Contribution Series 20200723
PublisherElsevier B.V.
Mediapaper; on-line; digital
File formatpdf; html
Lat/Long WENS -95.2744 -53.8950 70.8733 49.6486
SubjectsScience and Technology; tectonics; oroclines; plate tectonics; Trans-Hudson; Paleozoic; Proterozoic
Illustrationslocation maps; cross-sections; diagrams; photographs
Released2021 02 01
AbstractThere are lingering questions about how far back in geologic time plate tectonic processes began. In the Paleoproterozoic of eastern Laurentia, accretion of intra-oceanic juvenile terranes along the leading edge of the Superior craton apex (Ungava indenter) during the interval 1.87-1.83 Ga was followed by collision with the Churchill plate at ca. 1.83-1.79 Ga. Orthogonal shortening along the indenter led to early obduction of the juvenile terranes including the ca. 2.0 Ga Watts Group ophiolite, followed by out-of-sequence thrusting at ca. 1.83 Ga of granulite-facies crystalline basement of the Sugluk block (Churchill plate) along the Sugluk suture. Exhumation and erosion of the Sugluk block led to deposition of a foreland/delta fan sequence in the Hudson Bay re-entrant (Omarolluk and Loaf formations of the Belcher Group), with detritus sourced exclusively from the Sugluk block. Continued collision led to critical wedge development and orocline formation in the Hudson Bay re-entrant, forming a strongly arcuate fold-thrust belt. On the other (eastern) side of the indenter, material flow during crustal shortening was accommodated by lateral extrusion of microplates towards a then open ocean basin, in a manner similar to present-day extrusion of Indochina as a response to India - South China craton convergence. In the Churchill plate hinterland W-NW of the indenter, propagating strike-slip faults resulted in the far-field extrusion and oblique exhumation of Archean crustal slices of the Rae crustal block. The 1.83-1.79 Ga Superior-Churchill collision accommodated a minimum of 500 km of continent-continent convergence, with resulting style and mechanisms of orogenic growth and material flow similar to those observed in the Alpine-Himalayan orogenic system.

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