Capricorn Copper Geology


The copper deposits of the Capricorn Copper Mine (CCM) are situated within the Western Fold Belt of the Mount Isa Inlier. The Mount Isa Inlier consists of Early to Middle Proterozoic rocks, which are endowed with a variety of ore deposits, including the Mount Isa Pb– Zn –Ag and copper (Cu) deposits, Century Zn – Pb –Ag deposit, Cannington Ag– Pb– Zn deposit, and the Osborne and Ernest Henry iron oxide Cu–Au deposits.

The Mount Isa Inlier is divided into three tectonic units - the Western Fold Belt, the Kalkadoon - Leichhardt Belt and the Eastern Fold Belt. The Western Fold Belt is sub-divided into the Lawn Hill Platform, Leichhardt River Fault Trough (LRFT), Ewen Block and the Myally Shelf. The Eastern Fold Belt is divided into the Mary Kathleen, Quamby-Malbon and Cloncurry-Selwyn zones.

The Capricorn Copper Project occurs within the western-most part of the Leichhardt River Fault Trough, associated with the Mount Gordon Fault Zone (MGFZ), a regional scale northeast-trending, transpressional dextral strike slip system (Hespe, 2001).

The CCM project includes five deposits with Mineral Resource Estimates (MRE’s) in compliance with the Joint Ore Reserves Committee (JORC) 2012 Code, named Mammoth (MAM), Mammoth North (MAM_N), Esperanza-Pluto (ESP), Esperanza South (ESS) and Greenstone (GST).

The Proterozoic Mount Isa Inlier showing the location of the Capricorn Copper Project and Mount Isa deposit. Tectonic units after Blake (1987)
 

The Capricorn Copper Project deposits (MAM, MAM_N, ESP, ESS and GST) are each at different stages of definition, development or mining. Copper mineralisation is related to a set of interconnected east to northeast-trending faults and fault splays associated with the regional scale, north-trending MGFZ. Mineralisation occurs as stockwork veins, breccias and as adjacent replacement of host rocks within and close to the faults.

Capricorn Copper Mine local geology