Porphyry Copper Gold Deposit Model

Porphyry deposits are the world's most important source of Cu and Mo, and are major sources of Au, Ag, and Sn. They account for about 50 to 60% of world Cu production and more than 95% of world Mo production.  Porphyry deposits are large, low- to medium-grade deposits in which primary ore minerals are dominantly structurally controlled and which are spatially and genetically related to felsic to intermediate porphyritic intrusions. They are distinguished from other granite-related deposits such as skarns and mantos by their large size and structural control, mainly stockworks, veins, vein sets, fractures, and breccias. Porphyry deposits typically contain hundreds of millions of tonnes of ore.   In porphyry Cu deposits, for example, Cu grades range from 0.2% to more than 1% Cu while in porphyry Au and Cu-Au deposits, Au grades range from 0.2 to 2 g/t Au. Associated igneous rocks vary in composition from diorite-granodiorite to high-silica granite; they are typically porphyritic epizonal and mesozonal intrusions, commonly subvolcanic. 

Known deposits within the Lachlan Fold Belt include the world class Cadia/Ridgeway copper-gold system and the Northparkes copper deposits, associated with Silurian alkaline and calc-alkaline intrusions. 

Thomson Resources has two areas considered prospective for the porphyry copper-gold style in the north-east part of the tenement package – at Warraweena and Tringadee, where alteration and mineralisation have been intersected in drilling. Prospective features encountered in exploration work include arc-type volcanic rocks, copper mineralisation up to 1% and albite/pyrite alteration.


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(after Sinclair, W.D. 2007 Porphyry Deposits. in Goodfellow, W.D., ed., Mineral deposits of Canada: A synthesis of major deposit types, district metallogeny, the evolution of geological provinces, and exploration methods: Geological Association of Canada, Mineral Deposits Division, Special Publication 5)