Archean and Paleoproterozoic cratonic rocks of Baffin Island

Abstract

Archean and Paleoproterozoic cratonic rocks of Baffin Island define four stacked structural levels that are juxtaposed within the middle Paleoproterozoic Trans-Hudson Orogen. From north to south, and highest to lowest structural level, these comprise:1) the Archean Rae Craton, unconformably overlain along its southern margin by middle Paleoproterozoic supracrustal cover (Piling Group) and stratigraphically similar units of the Hoare Bay Group on Cumberland Peninsula; 2) Archean to middle Paleoproterozoic metaplutonic units and middle Paleoproterozoic metasedimentary cover (Lake Harbour Group), collectively termed the 'Meta Incognita microcontinent'; 3) middle Paleoproterozoic orthogneiss, interpreted as a deformed arc-magmatic terrane (Narsajuaq terrane) or alternatively as Narsajuaq-age intrusions emplaced in the Meta Incognita microcontinent; and 4) Archean orthogneiss, interpreted as the northern continuation of the lower-plate Superior Craton, and associated middle Paleoproterozoic continental-margin supracrustal cover (Povungnituk Group).

Emplacement of the Franklin large igneous province and initiation of the Sturtian Snowball Earth

“…716.9-to 716.5-Ma volcanic tuffs (14). The ropey texture, hyaloclastic breccia, bulbous isolated pillow basalts, and lack of obvious subaqueous textures in member E were interpreted to record subaerial eruption (42), consistent with predating global glacial onset ( 14); however, similar tubular and (14,47,48,76). Because all analyses used the same technique and same isotopic tracer, only internal uncertainties were plotted for comparison.…”

“…Stratigraphic constraints on the onset of the Sturtian glaciation. Franklin LIP data from this study compared to existing constraints on the onset of the Sturtian glaciation(14,47,48,76). Because all analyses used the same technique and same isotopic tracer, only internal uncertainties were plotted for comparison.…”

Quantitative elemental mapping of granulite‐facies monazite: Textural insights and implications for petrochronology

“…Southern Baffin Island forms part of the northeastern segment of the Trans‐Hudson Orogen (THO), which is a Himalayan‐scale composite accretionary orogenic belt extending across North America that formed during gradual ocean basin closure between the lower Superior and upper Churchill plates from 1.92 to 1.80 Ga (Figure 1; Corrigan, Pehrsson, Wodicka, & de Kemp, 2009; Hoffman, 1988; St‐Onge, Van Gool, Garde, & Scott, 2009). In the southern Baffin Island region (Figure 2), three stacked tectonic levels have been identified (St‐Onge et al, 2020; Weller, Dyck, St‐Onge, Rayner, & Tschirhart, 2015): Archean tonalitic to granitic orthogneiss, interpreted as the northern continuation of the Superior craton crystalline basement (St‐Onge, Hanmer, & Scott, 1996). Middle Palaeoproterozoic dominantly monzogranitic and granodioritic orthogneiss, interpreted as a deformed magmatic arc terrane (Narsajuaq terrane; Scott, 1997; St‐Onge et al., 2009); and Archean to middle Palaeoproterozoic orthogneiss and middle Palaeoproterozoic supracrustal cover (Lake Harbour Group; Jackson & Taylor, 1972), collectively termed the Meta Incognita microcontinent by St‐Onge, Scott, and Lucas (2000), which either represents crust rifted from the Rae or Superior craton, or is exotic to both.…”

“…Geological map of southern Baffin Island (from St‐Onge et al, 2020), showing the three structural levels and two study samples (blue boxes)…”

The south-verging Isortoq Nappe of Baffin Island, Canada: implications on the framework of the northeastern Trans-Hudson Orogen

“…1B; Natural Resources Canada 2020); a pronounced magnetic low southeast of the ISZ contrasts with magnetic highs to the northwest. The northeastern extension of this aeromagnetic signature is less clear: the zone is inferred by some to continue towards the northeastern coast of Baffin Island (see review by St-Onge et al 2020), while others invoke the presence of a northeast Baffin thrust zone that truncates the aeromagnetic break ~50 km inland from the coast (Jackson et al 1990). Regionally, the ISZ juxtaposes orthopyroxene-bearing felsic plutonic rocks and granulite facies assemblages to the northwest (Dexterity granulite belt) against lower grade, upper-amphibolite-facies rocks to the southeast (Jackson 2000;Saumur et al 2018).…”