Cumberland batholith, Trans-Hudson Orogen, Canada: Petrogenesis and implications for Paleoproterozoic crustal and orogenic processes

Large volume, plutonic belts, such as the ∼ 221,000 km2, ca. 1.865–1.845 Ga Cumberland batholith (CB) of the Trans-Hudson Orogen in Canada, are major components of Paleoproterozoic orogenic belts. In many cases, they have been interpreted as continental arc batholiths. The petrogenesis and tectonic context of the CB and implications for crustal growth and recycling are interpreted herein based on a 900 km geochemical-isotopic (Nd–O) transect across it and into granitoid plutons within bounding Archean cratons in central and southern Baffin Island. The mainly granulite grade CB, emplaced over an age span of between 14 and 24 Ma, consists mainly of high-K to shoshonitic monzogranite and granodiorite, but also includes low- and medium-K granitoid rocks. Metaluminous to slightly peraluminous compositions and δ18O (VSMOW) values (+ 6 to + 10‰) indicate derivation from infracrustal (I-type) sources. εNd 1.85 Ga signatures (− 12 to − 2) of both mafic and felsic units suggest a dominance of evolved sources. Isotopic signatures in the interior of the CB (− 2 to − 7) are more radiogenic than those within Archean domains in central (− 8 to − 15) and southern (− 5 to − 19) Baffin Island. The isotopic transect is interpreted as ‘imaging’ an accreted microcontinental block (Meta Incognita) and bounding Archean cratons. The CB includes granites of arc, within-plate (A-type) and post-collisional affinity and volumetrically minor mafic rocks with both arc and non-arc features. (La/Yb)CN and Sr/Y values range from  60 km), as evidenced by adakitic granites.