Proterozoic zircon growth in Archean lower crustal xenoliths, southern superior craton - a consequence of Matachewan ocean opening

The U-Pb zircon ages for four granulite-facies xenoliths discovered from a Jurassic kimberlite pipe in the south-central Superior craton of the Canadian Shield are studied. Results show that granulite facies anorthositic to mafic xenoliths in a Jurassoc kimberlite pipe have Neoarchean protolith ages. Xenoliths also witnessed Paleoproterozoic metamorphic activity marked by zircon growth at 2416 +/- 30 Ma and 2497 +/- 25 Ma.