Geology


Regional geology

The Carrapateena project is located within the Olympic Dam copper-gold province, a metallogenic belt along the eastern margin of the Gawler Craton in South Australia, which hosts the Prominent Hill mine, Olympic Dam mine and the Moonta-Wallaroo historic mining district. The Gawler Craton comprises variably deformed and metamorphosed sedimentary, volcanic and plutonic rock spread from the Late Archean to Mesoproterozoic, and it has been subdivided into a series of domains, the Carrapateena deposit being part of the Olympic Domain. The age of the iron oxide copper gold (IOCG) mineralisation in the Gawler Craton is uncertain although it is interpreted in the literature to be associated with Mesoproterozoic magmatism of the Hiltaba Suite and the Gawler Range Volcanics.


Mineralisation

The vast majority of copper and gold mineralisation within the deposit is hosted by hematite dominated breccias with moderate mineralisation occurring within hematite altered granite breccias (Eastern copper domain). Sulphides are the primary copper-bearing minerals in the Carrapateena Breccia Complex (CBC). Copper and gold mineralisation is structurally and chemically controlled, with subsequent alteration destroying mineralising structures. The most abundant sulphides are Chalcopyrite > Pyrite > Bornite, and constitute the vast majority of the sulphides at Carrapateena. The less common sulphides and their relative abundances are: Chalcocite ≈ Digenite ≈ Covellite >> Sphalerite ≈ Galena.

Gold mineralisation at Carrapateena is almost exclusively hosted by hematite altered breccias. Gold grains are usually very small (10 microns), and when seen in polished section, are often intimately associated with copper sulphides. Gold grains are commonly a combination of gold and minor silver (electrum).

 


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