Spatial association between orogenic gold deposits and crustal-scale faults in the Bendigo Zone, central Victoria - Implications for gold mineralisation

A spatial analysis of the distribution of orogenic gold deposits in relation to crustal-scale faults has been conducted for the Bendigo Zone in central Victoria. Orogenic gold deposits are located at various distances from recognised crustal-scale faults (mostly from several hundred metres to 10 km). However, most productive parts of major goldfields (>10 t Au) tend to be confined between adjacent crustal-scale faults, separated from the nearest crustal-scale fault to the east and to the west by 3 km to 7 km-wide poorly mineralised zones. Barren zones to the east of major goldfields often coincide with higher-strain zones in the hangingwalls of west-dipping crustal-scale faults. This spatial association is consistent with previous suggestions that gold mineralising fluids were channelled in the upper crust through multiple interconnected fold-related fractures and low-displacement faults, away from crustal-scale faults, during regional folding. This type of fold-related fluid flow was probably most favourable for the formation of major goldfields. Fluid flow along crustal-scale faults in the upper crust was less effective and resulted in the formation of generally smaller goldfields adjacent to the faults.