Porphyry and Hydrothermal Cu-Au Deposits: A Global Perspective

The Mankayan Mineral District in northern Luzon, Philippines hosts three world class copper and gold orebodies, all of which lie within Lepanto Consolidated property. These are the Enargite-Gold deposit, the Far Southeast Porphyry Copper deposit (FSE) and the newly discovered Victoria Gold deposit. There are other copper and gold prospects identified in the district making the area attractive for potential exploration.
The enargite-luzonite-gold deposit is a high sulphidation vein and unconformity replacement type of mineralisation. It is hosted by andesites and dacitic rocks. The principal ore minerals are enargite and luzonite, with significant presence of tennantite-tetrahedrite, base metals electrum and gold.
The FSE porphyry copper deposit is a deep seated bell-shaped deposit hosted by volcanoclastics. It has strong zonation features both in alteration and sulphide mineralisation. It is centred on a quartz diorite intrusive complex characterised by the presence of a mineralised dark coloured and a relatively barren light coloured facies. The deposit is truncated by a north trending hydrothermal breccia pipe, which in itself is also mineralised with copper and gold. The resource at FSE is of the order of 140 Mt @ 0.85% Cu, 1.9 g/t Au.
The newly discovered Victoria gold deposit has the signature of a low sulphidation, quartz-gold vein deposit, hosted by dacitic rocks and volcaniclastics. About 80% of the ore minerals are made up of sphalerite, galena and chalcopyrite. Steeply dipping 2 to 8 metre wide vein systems with up to 600 metre strike lengths have been developed so far. It has an overall potential for 150 to 300 t (i.e., 5 to 10 Moz) of gold. The gold deposit could have some genetic associations with the Enargite deposit and probably indirectly with the FSE porphyry system. It is relatively apparent that the Victoria quartz-gold-base metal veins could have occurred similarly as the quartz-gold roots overprinting the enargite mineralisation. This overprinting signifies the waning stages of the entire hydrothermal system.