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| IOCG- Iron Oxide Copper Gold Deposits The difference in today's Base, Precious Metals and Uranium super cycle over previous ones is the focus on a relatively new type of deposit model -- the iron oxide-copper-gold (IOCG) deposit. Such systems have the potential for hosting copper, uranium, gold and silver, as well as numerous other metals. Although geologists were aware of such deposits in the past, they received very little attention up until the last 25 years or so, following the discovery, and more importantly the appreciation of, the Olympic Dam deposit in southern Australia. The mine owned and operated by WMC, a subsidiary of BHP Billiton [NYSE-BHP] is a true giant. The almighty Olympic Dam tips the scales at 2 billion tones grading 1.6% copper, 0.6 gram gold and 0.04% uranium oxide, making it the 6th largest copper deposit and the largest uranium resource in the world.
"The attraction is obvious," says Michael Porter, editor of Hydrothermal Iron Oxide Copper-Gold & Related Deposits, a recent report published by the Australian Mineral Foundation. "The prize is both large and high-grade and has not been the subject of concentrated exploration activity. IOCG Geology IOCG deposits are found throughout the globe, from the late Archean to the early Tertiary, though the majority are early to mid-Proterozoic (2.55 to 1.5 billion years old) in age. They occur as pods, veins and stockworks in various host rocks, extending both horizontally and vertically for kilometres with widths of metres to hundreds of metres. Their distinguishing characteristic is large concentrations of low-titanium, iron oxide minerals, mainly magnetite and hematite, as opposed to iron sulphides typical of porphyry copper-gold systems. The large amount of iron oxides can impart IOCG deposits with high magnetic and gravity signatures, making geophysical surveys an important facet of exploration. The high levels of iron oxides have led some researchers to speculate that IOCG systems and 'Kiruna-type' magnetite-apatite deposits are end-members of continuum, though the former are geologically more diverse. Unfortunately, outside of the abundance of copper and gold (and uranium in some IOCG deposits), there is no set of geologic features that distinguishes one deposit from the other. Whether this reflects a fundamental difference in these systems remains to be seen. Potassium feldspar, albite, sericite, biotite and chlorite, along with copper sulphides and pyrite, are generally present. Bulk rock analyses show varying enrichment in gold, silver, cobalt, bismuth, barium, fluorine, phosphorus, rare earth elements, uranium and thorium. Economic mineralization consists of copper sulphides (chalcopyrite, bornite, chalcoite) scattered throughout iron oxides; hematite at shallow depths, magnetite at deeper levels. Ores may be localized along both high- and low-angle faults that may be traced back to major crustal-scale structures. Brecciated rocks are common. Host rocks occur within hydrothermal alteration envelopes that can range from tens to hundreds of square kilometers in size. The exact alteration mineralogy depends on the host rocks and depth of formation, but there is a general trend from sodic alteration at deep levels to potassic alteration at more shallow levels. Both sericitic alteration and silicification are present at very shallow levels, though these zones are usually only a few kilometers in extent. Iron metasomatism may be locally pervasive. This time around, geologists have a much better idea of what to look for. Thanks to years of research, they now know that Olympic Dam is not unique but part of a class of deposits, including Kiruna in Sweden and the Great Bear magmatic zone in Canada's Northwest Territories that share common characteristics, such as high iron oxide content and intense alteration. Louise Corriveau --Geological Survey of Canada IOCG deposits in Canada Iron Oxide Copper-Gold (±Ag ±Nb ±P ±REE ±U) deposits form a particularly attractive target for mineral exploration in Canada as they can host significant resources in base, precious and strategic metals and are under-explored across the country.  Click to enlarge Canadian Environments for IOCG deposits:
 Click to enlarge The Great Bear Magmatic Zone The Eldorado Mineral Belt which is situated in the Great Bear Magmatic Zone, NT, has recently been recognized by geologists, as one of the most prospective iron oxide, copper, gold, silver and uranium regions in northern Canada. Alberta Star's Eldorado & Contact Lake claim blocks and surrounding area covers extensive alteration zones including large mineralized gossans that can be traced for over 1 kilometer in length and over 200 meters in width. The Contact Lake area is located in the Eldorado Mineral Belt and is host to two of Canada's three known IOCG deposits. This area has been under- explored and has lacked advanced 21st century exploration geophysics. The Contact Lake Mineral Belt is approximately 15 kilometers long. This is the northern extension of the same mineral belt that hosts Fortune Minerals NICO Gold-Cobalt-Bismuth deposit and the Sue-Dianne IOCG deposit. These large scale deposits are of a class that includes the 2 Billion Tonne Olympic Dam iron oxide, copper, gold, silver, REE and uranium (IOCG) deposit. Olympic Dam volcanic hosted hydrothermal iron-oxide copper, gold style of deposits are attractive targets for exploration and development due to their poly-metallic nature, high unit value and enormous size and grade potential. | |  | ||||||||||||||||||||||||||||||||||||||||||||||||||
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