Australia Yearbook - 2001

684 Year Book Australia 2001
Mineral resources and
geology
Australia has the world’s largest EDR of lead,
mineral sands (ilmenite, rutile and zircon),
tantalum, uranium, silver and zinc. It claims a
place also in the top six countries in the world
for EDR of black and brown coal, cobalt, copper,
diamonds, gold, iron ore, manganese ore and
nickel.
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 the iron ore deposits of the
Pilbara region (Western Australia); the base metal
deposits at Broken Hill (New South Wales),
Mount Isa (Queensland), McArthur River
(Northern Territory); the copper-uranium-gold
deposit at Olympic Dam (South Australia); the
Argyle diamond deposit, and the uranium
deposits of the Alligator Rivers area of the
Northern Territory all occur in the Precambrian
rock. 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) and Silver Swan (nickel)
deposits in the Eastern Goldfields of Western
Australia.
Australia’s most important petroleum basins are
under Bass Strait and off north-western Australia.
Petroleum has been identified in Australian
sediments as old as middle Proterozoic, but the
main onshore petroleum accumulations are in
sedimentary strata of middle Palaeozoic and
younger ages and include the Bowen/Surat,
Cooper/Eromanga, Otway and Perth Basins.
Mineral exploration
Exploration involves the search for new ore
occurrences or undiscovered oil or gas, and/or
appraisal intended to delineate or greatly extend
the limits of known deposits of minerals or oil or
gas reservoirs by geological, geophysical,
geochemical, drilling or other methods. This
includes construction of shafts and adits primarily
for exploration purposes, but excludes activity of
a developmental or production nature.
Exploration for water is excluded.
Mineral exploration expenditure
Expenditure in Australia during the last five years
on private mineral exploration other than for
petroleum is summarised in table 17.6.
Exploration expenditure in 1998–99 was 6% lower
than in 1994–95, and much lower than in recent
years. Queensland, with expenditure lower by
$83m (47%) than in 1994–95, was the main
contributor to the fall over that period. Despite
a fall of 21% in expenditure from 1997–98 to
1998–99, Western Australia continued to account
for the majority of exploration expenditure,
remaining at 62% of the national total.