Geology of the Paloproterozoic Piling Group and underlying Archean gneiss, central Baffin Island, Nunavut

Abstract

New mapping has refined the stratigraphic relationships within the Paleoproterozoic PilingGroup (NTS 37 A, 27 B), as well as its relationship to underlying Archean basement orthogneiss of the Rae Craton. Across the project area, basal quartzite and rare psammite (Dewar Lakes Formation) are in tectonic contact with underlying orthogneiss, and are interpreted as a subsidence-related clastic sheet deposited on Rae basement. In the northern part of the area, carbonate units (Flint Lake Formation) overlie the quartzite, and are overlain by sulphidic pelite and iron-formation (Astarte River Formation), interpreted as a shelf that subsequently foundered. In the south, quartzite is overlain by mafic volcanic rocks and ultramafic to mafic sills interlayered with siliciclastic rocks (Bravo Lake Formation). Psammite/ pelite turbidites (Longstaff Bluff Formation) blanket the entire area, and are interpreted as an orogenic molasse that might have had a source area other than the Rae Craton. Deformation and consequent metamorphism occurred during the1.8 Ga Trans-Hudson Orogeny.

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

“…It is generally regarded as a continental margin succession (Morgan et al, 1975(Morgan et al, , 1976 originally deposited on the southeastern margin of the Archean Rae craton and subsequently deformed and metamorphosed during the ca. 1.92-1.80 Ga Trans-Hudson orogen (Corrigan et al, 2001;Scott et al, 2002;St-Onge et al, 2005, and references therein). Traditionally, it has been correlated with the Penrhyn Group on Melville Peninsula and the Karrat Group in western Greenland ( Fig.…”

“…White-to gray-weathering dolostone, marble, and calc-silicate strata of the Flint Lake formation are interlayered with minor to rare semipelite, pelite, quartzite, iron formation, and chert, and stratigraphically overlie the upper member of the Dewar Lakes formation (Morgan et al, 1976;Corrigan et al, 2001;Scott et al, 2002;St-Onge et al, 2005). The exposed thickness of this formation varies considerably both along and across strike, from several meters to 500-1000 m in the thickest exposures.…”

“…1), comprises shallow-water siliciclastic-carbonate strata, mafi c-ultramafi c volcanic rocks, and deep-water basinal strata (e.g., Morgan et al, 1976;Henderson et al, 1979;Henderson and Tippett, 1980;Tippett, 1984a;Jackson, 2000;Corrigan et al, 2001;Scott et al, 2002Scott et al, , 2003. It is generally regarded as a continental margin succession (Morgan et al, 1975(Morgan et al, , 1976 originally deposited on the southeastern margin of the Archean Rae craton and subsequently deformed and metamorphosed during the ca.…”

“…The exposed thickness of this formation varies considerably both along and across strike, from several meters to 500-1000 m in the thickest exposures. The overall decrease in carbonate material toward the south led Scott et al (2002Scott et al ( , 2003 to suggest that the Flint Lake formation originally formed a relatively narrow (75-100 km wide) southfacing carbonate shelf adjacent and parallel to the southeastern edge of the Rae craton, with signifi cant along-strike variation in primary thickness.…”

“…1; St-Onge et al, 2000), which comprises dominantly ca. 2680-1950 Ma orthogneiss, a heterogeneous volcanic-bearing supracrustal assemblage (Schooner Harbour sequence), a clastic-carbonate shelf succession (the < 2.01 Ga > 1.90 Ga Lake Harbour Group), a structurally overlying succession of feldspathic quartzite and pelite (Blandford Bay assemblage), and intrusive monzogranite to on October 30, 2014 gsabulletin.gsapubs.org Downloaded from lesser quartz diorite plutons of the 1.865-1.847 Ga Cumberland batholith and younger 1.84-1.82 Ga granitoid plutons (e.g., Scott, 1997;Scott and Wodicka, 1998;Scott et al, 2002;Wodicka et al, 2010;St-Onge et al, 2009;Whalen et al, 2010). St-Onge et al (2006) proposed that accretion of the Meta Incognita microcontinent to the southeastern margin of the Rae craton occurred between 1883 ± 5 and 1865 +4/-2 Ma.…”