Genesis of copper-precious metal sulfide deposits in the Port Coldwell alkalic complex, Ontario

Abstract

<p>Two gabbro-hosted sulfide deposits in the Port Coldwell alkalic complex were studied to determine the most probable mode of Cu-precious metal sulfide deposition. The deposits examined are the Marathon deposit (Fleck Resources Ltd.) in the Two Duck Lake gabbro on the eastern margin of the complex, and the MacRae occurrence in the Geordie Lake gabbro located well within the complex. A magmatic origin for sulfides in the Marathon deposit is consistent with geochemical and petrographic evidence, but is inconsistent with experimental studies for equilibration of sulfide liquids with olivine and/or silicate melts. In general, the proposed sulfide liquid contains too little Ni and Ir, and possibly too much Cu. In addition, metals in the sulfide liquid are fractionated such that their geochemical behaviour becomes increasingly like that of Pd in the order Ni = Ir<</p>