Lithogeochemical and Nd isotopic constraints on felsic magmatism in the Makkovik Orogen, Labrador, Canada: Implications for assembly of the supercontinent Nuna

Localized Backarc Extension in an Overall Compressional Setting During the Assembly of Nuna: Geochemical and Isotopic Evidence From Orosirian (1883–1848 Ma) Mafic Magmatism of the Aillik Group, Labrador, Canada

“…3), contains foliated granitoid clasts from unknown sources, but the absence of gneissic clasts suggests that NAC Archean basement rocks were not exposed, or absent, when the unit was deposited (Hinchey et al, 2020). Immature sedimentation was followed by felsic volcanism, characterized an up to 10 km thick pile of alkaline, ferroan (A-type) felsic tuffs and rhyolites (Hinchey, 2021) punctuated by the eruption of intermittent basalt magmatism.…”

“…Previous models proposed that the onset of backarc felsic volcanism began by 1883 Ma, prior to the terminal phases of the IHBPS, and suggested that this may reflect a change from arc to backarc magmatism, potentially related to a slowing of the subduction rate, or due to isolated rifting caused by strike-slip or continental escape (Hinchey, 2021) . This interpretation is inconsistent with the model of formation of the Aillik Group post arc-accretion due to tectonic loading (see Moumblow et al, 2019) A backarc basin would have begun to form prior to ca.…”

“…The inset map shows the various domains established for the belts. Modified after Hinchey (2021a), Bagas et al. (2020), Ketchum et al.…”

“…The Makkovik Province has been divided into three domains termed, from northwest to southeast, the Kaipokok, Aillik, and Cape Harrison domains (Kerr et al., 1996). However, based on recent bedrock mapping, in combination with geochronological, petrological, lithogeochemical, and isotopic data, Hinchey (2021a) suggested that the boundary between the Aillik and Cape Harrison domains is likely arbitrary and that the domains should be merged. Hinchey (2021a) proposed that the Makkovik Province should maintain the division of the Kaipokok Domain, as it correlates with the Northern Domain of the Ketilidian Orogen (Bagas et al., 2020).…”

“…However, based on recent bedrock mapping, in combination with geochronological, petrological, lithogeochemical, and isotopic data, Hinchey (2021a) suggested that the boundary between the Aillik and Cape Harrison domains is likely arbitrary and that the domains should be merged. Hinchey (2021a) proposed that the Makkovik Province should maintain the division of the Kaipokok Domain, as it correlates with the Northern Domain of the Ketilidian Orogen (Bagas et al., 2020). The Aillik and Cape Harrison domains are now considered as one domain, termed the Adlavik Domain (Hinchey, 2021a; Figure 3).…”