1301.0 - Year Book Australia, 2002  
ARCHIVED ISSUE Released at 11:30 AM (CANBERRA TIME) 25/01/2002   
   Page tools: Print Print Page  
Contents >> Mining >> Mineral resources and geology

Australia has the world's largest EDR (economic demonstrated resources) of lead, mineral sands (ilmenite, rutile and zircon), nickel, tantalum, uranium and zinc. In addition, its EDR is in the top six worldwide for bauxite, black and brown coal, cobalt, copper, diamond (gem/near gem), gold, iron ore, manganese ore and rare earth oxides.

The diversity of Australian geology provides the basis for its wide range of economically important minerals and variety of deposit types. Its classified geological settings range from major Precambrian Shields composed of Archaean (older than 2.5 billion years) granite greenstone terrains, through to extensive Proterozoic (2.5 to 0.5 billion years) basins and metamorphic belts, to the younger Palaeozoic fold belts (0.5 to 0.25 billion years). Most significant mineral deposits discovered in the past two decades were hidden beneath cover and this is likely to be the pattern in the future, because prospective rocks in some 80% of the continent are concealed by a veneer of deeply weathered rocks or sedimentary strata. The weathering occurred particularly during the Mesozoic and Cainozoic periods (0.25 billion years to the present) and weathered rocks also host important mineral deposits.

The Archaean and Proterozoic basement rocks, underlying most of the western two-thirds of Australia, have been the source of much of the country's mineral wealth to date. Large deposits such as the gold and nickel mines of the Kalgoorlie region and iron ore deposits of the Pilbara region (Western Australia); base metal deposits at Broken Hill (New South Wales), Mount Isa (Queensland), McArthur River (Northern Territory); copper-uranium-gold deposit at Olympic Dam (South Australia); Argyle diamond deposit (Western Australia), and the uranium deposits of the Alligator Rivers area of the Northern Territory all occur in the Precambrian rocks. In eastern Australia, the major deposits are of Palaeozoic age and include the base metal deposits at Elura, Cobar (New South Wales); Hellyer and Rosebery, the Mount Lyell copper-gold deposit, and the Renison tin deposit (Tasmania); and Kidston, Mount Leyshon (Queensland) and most other gold deposits. The large black coal deposits of New South Wales and Queensland are of upper Palaeozoic and Mesozoic age. Deposits formed in Tertiary times include the brown coal of Victoria; the oil shales of eastern Queensland; the bauxite of Weipa (Queensland), Gove (Northern Territory) and the Darling Ranges (Western Australia); the lateritic nickel deposits of Queensland and Western Australia; and the mineral sands deposits of the Murray Basin (Victoria and New South Wales) and Eneabba (Western Australia).

The continuing discovery of world class deposits in both the established and new mineral provinces confirms Australia's high mineral potential. Major discoveries since 1990 include the Century (zinc), Cannington (lead, zinc, silver) and Ernest Henry (copper-gold) deposits in the major Carpentaria--Mount Isa base metal province; the Cadia and Ridgeway (gold-copper) deposit in central western New South Wales; and the Bronzewing (gold), Wallaby (gold) and Silver Swan (nickel) deposits in the Eastern Goldfields of Western Australia. Exploration in the Murray Basin is continuing to increase the level of heavy mineral resources and underline the world-class significance of this heavy mineral province.

It is important to note that although the resources for many of Australia's mineral commodities have more than kept pace with production, the number of discoveries of large mineral deposits has been declining over the past decade. This is partly a reflection of the fact that mineral deposits are becoming harder to find because of the surficial cover. Future discoveries will depend increasingly upon the application of advanced and predictive geoscientific exploration concepts and upon the development of new exploration technologies designed to explore the extensive prospective areas under the shallow cover. The continuing global trend for mineral production to be consolidated and increasingly confined to large tonnage, high grade deposits means that there is an additional challenge for Australia to come up with discoveries of large world class deposits, if it is to maintain its status as a major supplier of mineral commodities.

Australia's most important petroleum basins are off north-western Australia and under Bass Strait. These sedimentary basins, located around the margin of Australia, were formed as the super-continent of Gondwana broke apart in the Mesozoic age, mostly between 150 and 60 million years ago. The oil, condensate and gas are contained in sandstone reservoirs, while organic matter from both land plants and marine organisms sourced the hydrocarbons.

Currently most of the production is from the Carnarvon Basin, offshore from Onslow and Dampier in Western Australia. Oil, condensate and gas are produced, including from the giant North West Shelf LNG project, which exports liquefied gas primarily to Japan. Further to the north, large reserves of gas and condensate have been identified in the Browse Basin, offshore from Derby in Western Australia. Oil is produced from the Timor Sea area and plans are well advanced for the production of gas and condensate from the Joint Petroleum Development Area with East Timor.

The Gippsland Basin, underlying eastern Bass Strait, has been in the past Australia's major hydrocarbon producing area, but is now in decline. However, recent discoveries of gas and condensate have been made in the offshore Otway Basin, at the western end of Bass Strait.

Some of Australia's onshore basins also contain hydrocarbons, and again sandstone reservoirs predominate. The main onshore petroleum accumulations are in sedimentary strata of middle Palaeozoic and Mesozoic age and include the Bowen/Surat Basin straddling Queensland and New South Wales, the Copper/Eromanga Basin of South Australia and Queensland, the Otway Basin of South Australia and Victoria, the Adavale Basin in Queensland and the Perth Basin.

Previous PageNext Page