Ages of detrital and metamorphic zircons and monazites from a pre-Taltson magmatic zone basin at the western margin of Rae Province

Abstract

The western edge of Rae Province, prior to indentation of Slave Province, is conceived as a compressional tectonic margin in which Archean plutonic rocks were intruded by syntectonic granites of 2.4–2.3 Ga age as a result of eastward subduction. Subsequently this margin was intruded by the 2.0–1.90 Ga granites that characterize the Taltson magmatic zone. The latter granites engulf remnants of a widespread supracrustal assemblage of lower granulite facies metamorphic grade, the age of which has heretofore been unknown. We use U–Pb zircon and monazite geochronology to limit the age of cessation of deposition of these metasediments in a pre-Taltson granite basin to between 2.13 and 2.09 Ga.Similarities in geochronology and isotope geochemistry between western Rae Province and Buffalo Head domain, together with the presence of mafic to ultramafic rocks both within the basin and along the western Rae margin, suggest that basin formation was by rifting. Influx of 2.15 Ga detrital zircons probably from the west, and high-grade metamorphism accompanying basin closure at 2.09 Ga, suggest an eastward (inward) movement of magmatism at that time. A second similar eastward migration of magmatism occurred in association with the Slave–Churchill collision (2.0–1.9 Ga). These relations suggest a complex record of crustal accretion within Buffalo Head and Chinchaga domains, the details of which remain to be established.

Queen Maud block: A newly recognized Paleoproterozoic (2.4–2.5 Ga) terrane in northwest Laurentia

“…Evidence for this orogeny includes ca. 2.35 Ga metamorphism in the Committee Bay belt ~200 km to the east of the Queen Maud block (Berman et al, 2005) and 2.3-2.4 Ga metamorphism and plutonism in the southwestern Rae domain and Taltson-Thelon magmatic zone basement (Bostock and van Breemen, 1994;McNicoll et al, 2000;Hartlaub et al, 2007). The Arrowsmith orogeny in these distal regions has been attributed to far-fi eld effects of eastward-dipping subduction and orogenesis along the western margin of the Rae domain (Hoffman, 1989;Berman et al, 2005;Hartlaub et al, 2007).…”

Evolution of migmatitic granulite complexes: Implications from Lapland Granulite Belt, Part II: Isotopic dating

“…However, arc magmatism and deformation of about the same age or slightly older as in the LGB are found in the Taltson-Thelon magmatic zone in the Western part of the Canadian Shield (Bostock & van Breemen, 1994;Plint & McDonough, 1995;Ross et al, 1995) and in the Aldan Shield (Frost et al, 1998). In the western Canadian Shield, 2.3 − 2.0 Ga juvenile crust is present in the Wopmay orogen, which could be potential a provenance for the sedimentary protoliths of the LGB metapelites (Hoffman, 1988).…”

Deformation and extensional exhumation of 1.9 Ga high-pressure granulites along the Wholdaia Lake shear zone, south Rae craton, Northwest Territories, Canada

“…1) also exhibit significant 1.94-1.90 Ga metamorphism at grades up to granulite facies (Knox et al, 2011;Bethune et al, 2013;Ply, 2016), and in the far west, the potentially correlative Rutledge River basin units were deformed and metamorphosed to lower-granulite-facies conditions during foreland basin closure at ca. 2.10 Ga prior to 1.99-1.91 Ga plutonism within the Taltson magmatic zone (Bostock and van Breeman, 1994).…”

“…Various younger ca. 2.17-1.95 Ga Paleoproterozoic metasedimentary packages (Bostock and van Breeman, 1994;McDonough and McNicoll, 1997;Martel et al, 2008;Ashton et al, 2013Ashton et al, , 2017aShiels et al, 2016;Ply, 2016;Thiessen et al, 2017) overlie the basement rocks. The Paleoproterozoic cover and Archean substrate were subsequently variably deformed and intruded by 1.8-1.75 Ga magmatic suites (Peterson et al, 2002).…”