U–Pb geochronology of the eastern Hall Peninsula, southern Baffin Island, Canada: a northern link between the Archean of West Greenland and the Paleoproterozoic Torngat Orogen of northern Labrador

Abstract

A corridor east of Iqaluit that crosses several regionally significant lithologic boundaries has been mapped and sampled for geochronology. Zircon, monazite and titanite were analysed by the isotope dilution U–Pb method to characterize igneous and metamorphic events, and Pb–Pb ages of detrital zircons were determined by laser ablation microprobe ICP-MS. Tonalitic gneisses at the eastern end of the corridor are Archean, with emplacement ages of 2920+8/−6, 2848±3, 2844+6/−5 and 2797+27/−15 Ma; these samples record variable tectonothermal overprints at ca 2.77 Ga, and between 1844 and 1736 Ma, and may be related to similar rocks in West Greenland. A sequence of quartzites and semipelites associated with the Archean gneisses contains exclusively Archean detrital zircons, and was metamorphosed at 1.88 Ga. In the central part of the corridor, semipelitic and psammitic rocks contain almost exclusively Paleoproterozoic detritus deposited after 1.93±0.05 Ga, and are interpreted as the northern continuation of the Tasiuyak gneiss of the Torngat Orogen. At the western end of the corridor, monzogranites of the Cumberland batholith intruded at 1869+9/−3, 1857+5/−3 and 1850+3/−2 Ma. The present data suggest that the north–south Nagssugtoqidian collision (<1.89 Ga) in West Greenland may predate the east–west Torngat collision (<1.87 Ga) in northern Labrador.