An overview of the Fe oxide-Cu-Au deposits and related deposit types

CIM Montreal 2003
Abstract Iron oxide-rich deposits genetically related to continental, intermediate to felsic volcano-plutonic complexes comprise a wide range in deposit characteristics. The classic Kiruna magnetite-apatite-actinolite deposit of Sweden and the recently developed Olympic Dam breccia-hosted Cu-Au-U-REE deposit in South Australia, each containing 2 billion tonnes of ore, are world class examples of these deposits. Since the discovery of Olympic Dam deposit in 1975, intensive exploration for economically attractive polymetallic deposits of this type has led to discovery of several new deposits, and to reclassification of many known deposits previously classed as other deposit types. This, in turn, has broadened the deposit spectrum, which now includes deposits formed by hydrothermal imprint on pre-existing iron oxide concentrations, referred to as the Cloncurry-type after an important district in Australia. The broader term 'Fe oxide-Cu-Au deposits' includes the Olympic Dam and Cloncurry types. More recently the deposits hosted by alkaline intrusives e.g., the Phalaborwa deposit in South Africa and the Kovdor deposit in Russia, have been regarded by some workers as another related deposit type.

A digital database for deposits of this broad group is in preparation by the author as part of the World Minerals Geoscience Database Project, which is an industry-supported project undertaken by the Geological Survey of Canada. The database presently lists more than 750 deposits and occurrences. Kiruna-type deposits are the most numerous, and aggregate resources of iron ore in them is in the order of several billion tonnes. Larger deposits are tabular or pipe-like in form, and the smaller ones are commonly veins or stockwork of veins. The major districts are: Kiruna, Sweden; St. Francois Mountains, Missouri, and Adirondack Mountains, New York, USA; Cerro de Mercado, Mexico; Chilean Iron Belt and its extension in Peru; Bafq, Iran; Avnik, Turkey; and Lower Yangtze Valley, China. Fe oxide-Cu-Au deposits include several major economic deposits in addition to the giant Olympic Dam deposit. Important productive districts are: Stuart Shelf, Cloncurry and Tennant Creek, Australia; Carajás, Brazil; the Chilean Iron Belt; and Bayan Obo, China. In addition, there are several deposits and prospects in the Great Bear-Great Slave Lakes and Wernecke Mountains regions in Canada. The Olympic Dam-type Sue-Dianne deposit and the Cloncurry-type Lou Lake deposit in the Great Bear magmatic zone provide incentive for further exploration in this and other Proterozoic terranes of the Canadian Shield.
Keywords: Fe oxide-Cu-Au deposits, Olympic Dam-type, Alkaline intrusion-related, digital database, world-class deposits, Iron Ore, Kiruna-type, polymetallic deposits, Cloncurry-type, World Minerals
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