Iron Oxide Cu-Au Monograph - Volume 4, Abstract

Iron oxide copper-gold (IOCG) deposits challenge mineral explorationists by their extraordinary variety of styles, their extensive but typically unrecognised footprint, and at least in Canada, their geological, geographic and logistical environments. Canada's many prospective, but largely virgin orogenic terranes of all ages host some of the world's greatest field exposures of IOCG deposits. Their study better constrains the geotectonic settings, geological field characteristics, alteration zoning patterns and geophysical guides to exploration. Superb glaciallypolished cross-sectional exposures of polymetallic magnetite- to hematite-group IOCG and associated iron oxideapatite (IOA) deposits in the Great Bear Magmatic Zone, Northwest Territories, place the variety of volcanoplutonic associated IOCG deposits into a continuum that evolves to and is associated with porphyry and epithermal styles of mineralisation, broadening the potential impact of exploring Canada's remote territories.
As with global analogues, IOCG deposits in Canada cluster in mineral districts that populate entire belts. Commodities and mineralisation styles are most varied in the Port Radium-Echo Bay district at the northern end of the Great Bear Magmatic Zone, while production from the Au-Co-Bi NICO and Cu-Au-Ag Sue Dianne deposits in the south is planned for 2012 and large under-explored hydrothermal systems occur in between these districts. Extensive prograde and retrograde alteration and breccias show commonalities and systematic development of alteration patterns, brecciation and mineralisation that provide a useful framework for regional exploration and mapping. Crustal-scale fault control on the development of IOCG systems is common and exemplified, among others, by the Phanerozoic Cobequid-Chedabucto Fault Zone in the Appalachian orogen. Multi-stage development of IOCGs during orogenic processes is well illustrated by the Mesoproterozoic Manitou Lake district of the Grenville Province while the Archaean Shebandowan greenstone belt demonstrates that some of Canada's traditional VMS and Au mining districts hold potential for Archaean and Palaeoproterozoic IOCG deposits. Finally, the 3D high-mountain exposures of the Yukon's Wernecke Breccia is Canada's best contribution to case examples of IOCG settings with no outcropping coeval magmatic bodies. Collectively, Canadian IOCG settings with their regional-scale intense hydrothermal systems and great variety of deposit types provoke economic geologists to develop comprehensive IOCG deposit models that provide effective guides and methods for exploration.