Origin and tectonometamorphic history of the Repulse Bay block, Melville Peninsula, Nunavut: exotic terrane or deeper level of the Rae craton?

The Rae craton on Melville Peninsula, Nunavut, comprises several lithotectonic domains, including a structurally and lithologically distinct yet poorly known crustal terrane, the Repulse Bay block (RBb). This study presents new lithological and petrographic observations, combined with U–Pb zircon data, to better understand the Archean and Paleoproterozoic crustal evolution of the RBb. The new data demonstrate that the central-eastern RBb consists of the following: (i) upper amphibolite- to granulite-facies, ca. 2.73–2.71 Ga intermediate granitoid gneisses and gabbroic sheets; (ii) ca. 2.69 Ga two-pyroxene charnockite to enderbite intrusions; and (iii) thin slivers of both Archean and Paleoproterozoic supracrustal rocks. Inherited zircon also attests to the presence of a Mesoarchean to Paleoarchean substrate. A semi-pelitic gneiss from one of the Paleoproterozoic supracrustal panels was deposited sometime after ca. 1.89 Ga and shows a similar detrital zircon age profile to a <1.92 Ga semi-pelitic gneiss from the Lyon Inlet boundary zone at the northern extent of the RBb. Zircon in most rocks analyzed record metamorphism related to the Trans-Hudson orogeny between ca. 1.84 and 1.82 Ga. Results from this study are most consistent with the RBb, representing a piece of lower to middle crustal level of the Rae craton, rather than a distinct and separate crustal entity (i.e., an exotic block).