Did a proto-ocean basin form along the southeastern Rae cratonic margin? Evidence from U-Pb geochronology, geochemistry (Sm-Nd and whole-rock), and stratigraphy of the Paleoproterozoic Piling Group, northern Canada

Research Article| November 01, 2014 Did a proto-ocean basin form along the southeastern Rae cratonic margin? Evidence from U-Pb geochronology, geochemistry (Sm-Nd and whole-rock), and stratigraphy of the Paleoproterozoic Piling Group, northern Canada Natasha Wodicka; Natasha Wodicka † Geological Survey of Canada, 601 Booth Street, Ottawa, Ontario K1A 0E8, Canada †E-mail: Natasha.Wodicka@NRCan-RNCan.gc.ca Search for other works by this author on: GSW Google Scholar Marc R. St-Onge; Marc R. St-Onge Geological Survey of Canada, 601 Booth Street, Ottawa, Ontario K1A 0E8, Canada Search for other works by this author on: GSW Google Scholar David Corrigan; David Corrigan Geological Survey of Canada, 601 Booth Street, Ottawa, Ontario K1A 0E8, Canada Search for other works by this author on: GSW Google Scholar David J. Scott; David J. Scott Geological Survey of Canada, 601 Booth Street, Ottawa, Ontario K1A 0E8, Canada §Current address: Canadian Polar Commission, 360 Albert Street, Ottawa, Ontario K1R 7X7, Canada Search for other works by this author on: GSW Google Scholar Joseph B. Whalen Joseph B. Whalen Geological Survey of Canada, 601 Booth Street, Ottawa, Ontario K1A 0E8, Canada Search for other works by this author on: GSW Google Scholar GSA Bulletin (2014) 126 (11-12): 1625–1653. https://doi.org/10.1130/B31028.1 Article history received: 08 Nov 2013 rev-recd: 28 Apr 2014 accepted: 29 May 2014 first online: 08 Mar 2017 Cite View This Citation Add to Citation Manager Share Icon Share MailTo Twitter LinkedIn Tools Icon Tools Get Permissions Search Site Citation Natasha Wodicka, Marc R. St-Onge, David Corrigan, David J. Scott, Joseph B. Whalen; Did a proto-ocean basin form along the southeastern Rae cratonic margin? Evidence from U-Pb geochronology, geochemistry (Sm-Nd and whole-rock), and stratigraphy of the Paleoproterozoic Piling Group, northern Canada. GSA Bulletin 2014;; 126 (11-12): 1625–1653. doi: https://doi.org/10.1130/B31028.1 Download citation file: Ris (Zotero) Refmanager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentBy SocietyGSA Bulletin Search Advanced Search Abstract The Paleoproterozoic Piling Group along the southeastern Rae margin, northern Canada, is characterized by thick, deep marine turbidite deposits not observed in time-equivalent, intracratonic basin units further southwest. Models invoked to explain this feature include development of a full-ocean, back-arc, or proto-ocean basin followed by turbidite sedimentation. We present new and existing U-Pb geochronological, Nd isotope, geochemical, and stratigraphic evidence that support a proto-ocean basin model, and we explore the events leading to the formation and closure of such a rift basin during the middle Paleoproterozoic. Sedimentation initiated largely after ca. 2160 Ma with deposition of craton-derived, shallow marine siliciclastic strata (Dewar Lakes formation). Continued extension resulted in accumulation of south-facing carbonate beds (Flint Lake formation) and likely concomitant, arc-like tholeiitic to picritic volcanism and voluminous volcaniclastic sedimentation (lower Bravo Lake formation) farther outboard at ca. 1980 Ma. Accumulation of intrabasinal siliciclastic strata above lower Bravo Lake formation rocks may mark a hiatus in mafic-ultramafic magmatism. By ca. 1923 Ma, upper Bravo Lake formation, within-plate–type alkaline sill emplacement and volcanism occurred within highly extended crust. The oceanic island basalt–like signatures of the Bravo Lake formation rocks (but lack of depleted, mid-ocean-ridge basalt–type compositions) suggest that by this time the thinned Rae continental lithosphere had fragmented into small crustal block(s) and narrow zone(s) of incipient oceanic crust farther outboard of the Piling Group basin. Rapid subsidence of the southeastern Rae margin ensued, leading to deposition of euxinic (Astarte River formation) and overlying turbiditic strata (Longstaff Bluff formation). The post–ca. 1915 Ma northern turbiditic sedimentary units were likely derived from a thoroughly mixed, two-component source with possible input from the Snowbird tectonic zone and Bravo Lake formation, whereas the post–ca. 1930 Ma southern turbidite unit may have been sourced from the Meta Incognita microcontinent, presently exposed further south. We favor a rift margin over a foreland basin setting for the deposition of the northern turbidite deposits. Subsequent mantle upwelling associated with incipient ocean formation may have triggered melting of highly thinned continental crust resulting in emplacement of late-stage, ca. 1897 Ma, contaminated rapakivi granite and highly differentiated mafic sills. Our results are most consistent, albeit not exclusively, with the much debated model of asthenospheric upwelling and incipient rifting along the Rae-Hearne boundary farther southwest at ca. 1.9 Ga. Later accretion of the Meta Incognita microcontinent led to basin closure and development of a north-verging fold-and-thrust belt after ca. 1883 Ma. You do not have access to this content, please speak to your institutional administrator if you feel you should have access.

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