UPb zircon ages for the Missanabie-Renabie area and their relation to the rest of the Michipicoten greenstone belt, Superior Province, Ontario, Canada

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The Missanabie-Renabie area is the eastern portion of the Michipicoten greenstone belt. Ten new UPb zircon ages confirm and extend the chronostratigraphy established previously for the Michipicoten and the adjoining Mishibishu and Gamitagama greenstone belts in northern Ontario. The Michipicoten belt evolved between 2661 and 2889 Ma. The igneous activity was episodic. The bimodal cyclic volcanism occurred at ∼2700, 2750, 2900 Ma. Extensive plutonic activity occurred at 2670 Ma and synchronously with the three volcanic cycles. The pattern of ages in the Michipicoten belt is significantly different from that in the Abitibi belt. The felsic volcanism in this area is dated by the Renabie crystal tuff at 2740 Ma and by the Cradle Lakes porphyry at 2736 Ma. These ages are typical of cycle 2 volcanism in the Michipicoten belt. A deformed quartz-feldspar porphyry at Conboy Lake has an age of 2675 Ma, which correlates with a well-documented regional plutonic event. It is possible that this rock unit is synvolcanic with a hitherto unrecognized volcanic episode in this belt. The Conboy Lake tonalite, a pluton in the Wabatongushi Lake granitoid complex which lies to the north of the supracrustal rocks, has an age of 2688 Ma. The Nudulama tonalite of the Missanaibi Lake batholith to the east of the supracrustal rocks has an age of 2741 Ma. The southern flank of the greenstone belt is bordered by the Ogasiwi Lake granitoid complex; the Hand Lake tonalite in this complex has an age of 2723 Ma. Four plutons internal to the belt are dated as follows: Ruby Lake stock, 2661 Ma; Lochalsh Bay stock, 2670 Ma; Ash Lake pluton, 2679 Ma; and Rennie Lake stock, ∼2668 Ma. The four internal plutons dated here together with previously dated eight similar post-tectonic to syntectonic plutons were emplaced between 2661 and 2679 Ma along the northern margin of the greenstone belt. Most of the deformation in the supracrustal rocks developed between 2661 and 2741 Ma, but a period of late deformation related to the gold mineralization can be bracketed more precisely between 2661 and 2679 Ma.