U–Pb geochronology and Sr/Nd isotope compositions of groundmass perovskite from the newly discovered Jurassic Chidliak kimberlite field, Baffin Island, Canada

Abstract

We report the U–Pb age and Sr/Nd isotope composition for perovskite isolated from forty six kimberlite samples located in the newly discovered Chidliak field on Baffin Island, Canada. The minimum duration of kimberlite magmatism in this field was 17.9 m.y. from 157.0 to 139.1 Ma and represents a new Jurassic kimberlite field in NE Canada. The most prolific period of kimberlite magmatism occurred between 152 and 142 Ma (80% of dated kimberlites). Kimberlitic perovskite from these intrusions display a range in 87Sr/86Sr (0.7043 to 0.7030) and εNdT values (+3.9 to −0.4), overlapping the isotopic field previously defined for southern African Group I kimberlites.The ages and isotopic compositions obtained for Chidliak magmatism are identical to a number of Jurassic kimberlite fields in eastern North America and SW Greenland. Some of this Jurassic kimberlite magmatism has a link to one or more mantle plume hotspot tracks but the Chidliak kimberlites have an origin in the deep subcontinental lithospheric mantle and are part of a Jurassic magmatic province that erupted along both margins of Davis Strait; linked to upwelling asthenosphere, continental rifting, and Mesozoic–Cenozoic development of oceanic crust in the Labrador Sea basin. In contrast, the location of other eastern North American Jurassic kimberlites when plotted on a Jurassic continental reconstruction aligns closely to the northernmost projection of contours 2–4 of the African large low shearwave velocity province, consistent with a link to mantle plumes derived from the African mantle plume generating zone.