Precambrian Greenstone Belts of North Baffin Island, Canadian Arctic: Geochronological Constraints on Magmatism and Stratigraphy in the Rae Craton

Supracrustal greenstone belts of the Rae craton of north Baffin Island have been historically attributed to the Mary River Group (MRG), a key tectonostratigraphic unit of economic significance. Best‐preserved exposures of supracrustal rocks occur within the Eqe Bay Greenstone Belt. New mapping and U‐Pb zircon dating of samples from Eqe Bay, combined with previous geochronological work, reveal that greenstone belts hitherto known as MRG consist of two temporally and spatially distinct episodes of volcanism: a ca. 2863–2830 Ma Mesoarchean pulse, to which we assign the name “Tuktuliarvik Group”, and a ca. 2759–2718 Ma Neoarchean pulse, which retains the designation “MRG.” High‐purity Fe‐ores of the world‐class Mary River deposit occur exclusively within the Neoarchean‐age MRG. Detrital zircon U‐Pb dates from quartzite and psammite (e.g., Pond Inlet) constrain a transition within the MRG, from magmatism to clastic sedimentation, at ca. 2720 Ma. An extensive tract of turbiditic siliciclastic rocks of the Eqe Bay Greenstone Belt, originally thought to represent the upper succession of the MRG, yields a Paleoproterozoic maximum depositional age. This suggests that turbiditic rocks instead form part of the younger, ca. <2.19–2.16 to >1.88 Ga Piling Group, and that the MRG lacks a turbiditic sequence typical of the upper stratigraphy of many greenstone belts. An updated chronostratigraphy of the greenstone belts of north Baffin Island has implications for stratigraphic links with Greenland and mainland Canada, Archean geodynamics within the northeastern Rae craton and the footprint of Precambrian basins during the amalgamation of the Nuna supercontinent.