HYDROTHERMAL ALTERATION AND MINERALIZATION AT THE CUKARU PEKI CU-AU DEPOSIT, TIMOK CU-AU METALLOGENIC BELT, SERBIA

Cukaru Peki discovered in 2012 by Freeport-McMoRan Exploration Corporation (a subsidiary of FreePort-McMoRan Copper & Gold), is a concealed high-grade, bulk tonnage Cu-Au deposit in the historic Bor Cu-Au mining district, Serbia. The deposit is located within the Timok Cu-Au metallogenic belt, which contains historical production plus reserves and resources of over 20M tonnes of copper and 1000 tonnes gold. Cukaru Peki is a zoned high-sulfidation Cu-Au deposit, which telescopes into a significantly larger porphyry system at depth. Mineralization is predominantly hosted in Upper Cretaceous (89-85 Ma) andesitic rocks intruded by intermediate-composition porphyry dikes. The Upper Zone high sulfidation mineralization consists of brecciated to massive, high-grade, pyrite-covellite-enargite±digenite mineralization enveloped in an associated advanced argillic (pyrophyllite-alunite-kaolinite-quartz) alteration halo. The roots of the Upper Zone mineralization and associated alteration styles partially overprint the underlying sericitic (quartz-sericite-illite-anatase/rutile) and potassic (secondary biotite-K-feldspar-anhydrite-rutile) alteration styles. The Lower Zone mineralization style is typical of many Cu-Au porphyry deposits, with highest grades occurring in areas of stockwork quartz + sulfide veining, disseminated, and veinlet-controlled chalcopyrite-bornite ± molybdenite mineralization. The Upper and Lower Zone mineralization are believed to be roughly coeval, with the Upper Zone high-sulfidation style of mineralization continuing after the end of the “classic” porphyry style mineralization of the Lower Zone, resulting in widespread and deep overprinting of porphyry mineralization by high-sulfidation style mineralization and related alteration. The use of detailed core logs, petrography, and geochemical sampling, is the basis of a preliminary deposit model including the distribution of alteration and mineralization, petrogenesis, and an overall time-space evolution of the magmatic-hydrothermal system.