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TitleTiming and provenance of Paleoproterozoic supracrustal rocks in the central Thelon tectonic zone, Canada: implications for the tectonic evolution of western Laurentia from ca. 2.1 to 1.9 Ga
AuthorDavis, W JORCID logo; Sanborn-Barrie, MORCID logo; Berman, R GORCID logo; Pehrsson, S
SourceCanadian Journal of Earth Sciences vol. 58, issue 4, 2021 p. 378-395, Open Access logo Open Access
Alt SeriesNatural Resources Canada, Contribution Series 20200302
PublisherCanadian Science Publishing
Mediapaper; on-line; digital
File formatpdf; html
Lat/Long WENS-121.1700 -80.0178 73.6278 56.1700
SubjectsScience and Technology; tectonics; provenance; Laurentia; Buffalo Head terrane; Chinchaga terrane; Precambrian
Illustrationslocation maps; photographs; diagrams; charts; photomicrographs
ProgramGEM2: Geo-mapping for Energy and Minerals Rae Province
Released2021 03 10
AbstractDepositional ages and provenance of metasedimentary rocks provide constraints on the architecture of the interface between the Slave and Rae cratons and processes related to the Thelon Orogen. Clastic rocks analysed from the central Thelon tectonic zone are Paleoproterozoic in age, and not remnants of the Archean Yellowknife Supergroup (Slave Province), as originally considered. Two assemblages are recognized. An older clastic assemblage deposited after 2.09 Ga contains detrital zircon age modes of 2.17 Ga and 2.3 Ga, with subordinate Neoarchean and Paleoarchean detritus. It's deposition is interpreted to predate Thelon magmatic activity given that it lacks ca. 2.01-1.97 Ga detritus of Thelon magmatic origin, and correlative clastic rocks occur as inclusions in Thelon plutons and contain ca. 2.0 Ga metamorphic monazite. This assemblage is correlative with both the Mary Frances and Rutledge River groups, establishing a >800 km long basin at ca. 2.1 Ga that received detritus from the western Rae and/or Buffalo Head terrane(s). Separation from the Slave craton at this time is consistent with the absence of any Slave-affinity detritus. A younger assemblage deposited after 1.95 Ga and prior to 1.91 Ga, contains mainly 2.02-1.95 Ga detrital zircon, age modes comparable to adjacent Thelon convergent-margin plutonic rocks. The younger assemblage records deposition of the uplifted and eroded Thelon magmatic arc in an intermontane or foreland basin setting during the later stages of post-collisional convergence. These U-Pb zircon data support a tectonic model for western Laurentia that reconciles differences between the Thelon and Taltson magmatic zones involving ca. 2.1 Ga rifting, ca. 2.01-1.97 Ga convergence, followed by <1.95 Ga thrust-driven exhumation.
Summary(Plain Language Summary, not published)
Detrital zircon age data identify two distinct Paleoproterozoic sedimentary sequences in the central Thelon tectonic zone, establishing these rocks are not correlative with the Archean Yellowknife Supergroup, Slave craton. The older assemblage was deposited after 2.09 Ga, contains no Thelon arc detritus, and has modes of 2.3, 2.17-2.11 Ga and minor Archean detritus as old as 3.4 Ga, consistent with derivation from the western Rae craton (+Queen Maud block) and/or the Buffalo Head/Chinchinga terrane and deposition prior to ca. 2.0 Ga Thelon plutonism. Correlation of this older assemblage, the Mary Francis paragneiss and Rutledge River basin establishes linkage of some 800-km strike length at ca. 2.13-2.05 Ga of basement to the Thelon and Taltson magmatic suites. Assemblage 2 was deposited between 1.95-1.90 Ga and is interpreted to represent the eroded detritus of exhumed Thelon magmatic arc rocks, subsequently buried during ongoing convergence and thickening until ca. 1.89 Ga.

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