Geology of Australia

Australia lies within the fastest moving crustal plate. Long term geological stability has given the smallest continent its unusually deeply weathered and topographically subdued landscapes. The extensive blanket of weathered rocks and sediments the regolith has demanded the development of innovative approaches and technologies for mineral exploration and land and water management in Australia.

Australia is made up of 6 states (New South Wales, Queensland, South Australia, Tasmania, Victoria and Western Australia) and 2 territories (the Australian Capital Territory and the Northern Territory).

Western Australia

Western Australia, the largest state, is dominated by two Archaean cratons. It is home to the oldest identified life forms (in ~3.5 billion year old chert in the Pilbara region). It also has a remarkable mineral endowment, with world class gold and nickel provinces in the Yilgarn Craton, the vast Hamersley Iron Formations of the earliest Proterozoic, and major bauxite and mineral sand resources in the southwest. The fascinating Kimberley region in the northwest is underlain by Proterozoic and has a magnificently-exposed Devonian carbonate reef system on its southern margin. Major oil and gas fields occur off-shore on the Northwest Shelf, and pristine coral reefs, beautiful beaches, dolphin feeding grounds and Holocene stromatolites occur further south.

Northern Territory

The World Heritage listed Kakadu National Park is located in the “Top End” of the Northern Territory, where the Proterozoic geology is spectacularly scenic. In the east, the unmetamorphosed Palaeo- to Mesoproterozoic strata of the McArthur basin host a major zinc deposit and the oldest live oil. Further south and west, Proterozoic basement blocks are surrounded by Phanerozoic sedimentary basins containing major artesian water resources. The famous Uluru (Ayers Rock), Kata Tjuta (the Olgas), spectacular gorges and impact craters are geological attractions that draw tourists to the centre of Australia.

Tasmania

Tasmania, the island state is characterised by late Proterozoic to Mesozoic geology. Jurassic dolerites, with spectacular landforms, are related to those in Antarctica and South Africa. There has been a long history of base metal and gold mining in western Tasmania. Scenic wilderness areas abound, including glacially sculpted mountains, wild rivers, lakes and old forests.

South Australia

In South Australia, the picturesque Flinders Ranges include well preserved Ediacaran fauna and Neoproterozoic glacial horizons. These contrast starkly with the surrounding plains, where there are major salt lake systems and the Olympic Dam mine, a world-class copper-gold-uranium deposit in Proterozoic basement. In the southeast of the state is the well preserved crater lake of Mount Gambier, the most recent intraplate volcano in Australia, and a range of famous wine producing regions, each with its own distinctive geological features.

Queensland

Eastern Queensland is dominated by Palaeozoic fold belts, and large areas of the centre and west are covered by sedimentary basins that host vast coal resources, some petroleum fields, and well preserved fossils of dinosaurs and megafauna that are unique to Australia. The Palaeo- to Mesoproterozoic basement of western Queensland hosts a world class lead-zinc-silver province, with major mines at Mount Isa, Century, and Cannington. Spectacular coastal scenery abounds, and the World Heritage listed Great Barrier Reef is the largest coral reef system in the world.

New South Wales

New South Wales is dominated by a southern continuation of Palaeozoic fold belts, and volcanic units host some large porphyry style copper-gold deposits (e.g. Cadia-Ridgeway). Major coal measures occur in Permian and younger sedimentary basins. Fascinating insights into climatic changes and early human habitation have been found at Lake Mungo in the southwest of the state. In the west, the fabulous Broken Hill lead-zinc-silver mine is nearing the end of its life, which began in the 1880s, and the town has become a major centre for artists. The Murray Darling Basin hosts extensive heavy mineral sand resources and is the nation’s major agricultural region.

Victoria

The Palaeozoic fold belt geology continues south into Victoria, where there are many historic gold mining towns. Along the Great Ocean Road the younger sedimentary strata have been weathered and eroded to form fabulous coastal scenery from great beaches to rugged and colourful cliffs and islands that resulted in numerous shipwrecks in past times. Offshore is one of Australia’s main petroleum fields.

Geology of Oceania

New Zealand is a scenic wonderland. It separated from Australia in the Mesozoic and its geology reflects its location astride the boundary between the Australian and Pacific plates.

The North Island, lying on the overriding plate above the Hikurangi subduction zone, is noted for its volcanic and geothermal landscapes, and for active faulting. As examples of living with hazards, the city of Auckland is built on an active volcano field, and the city of Wellington is built on the active Wellington fault.

The South Island, formed largely from the continental fragment of the Chatham Rise indenting the Australian Plate, has spectacular alpine geology, permanent glaciers, and fiords. Its active faults include the 600 km long Alpine fault with a 25 mm/yr slip-rate.

Papua New Guinea also exhibits fascinating alpine and volcanic geology, in a tropical setting. It features major ophiolite belts, active tectonism, volcanism in arcs and back arc basins, uplifted coral terraces, and gold and copper mines.

The many smaller islands dotted through Oceania are characterised by volcanics, high level intrusives and coral reefs. Many international tourists are attracted to their tropical climate, beautiful scenery and beaches.

Fiji has a major epithermal gold deposit. New Caledonia, a little piece of France in the South Pacific, has some fascinating flora, including environments considered to resemble those of the Jurassic, and major lateritic nickel resources.

Vanuatu and the Solomons have interesting volcanic suites.

The geological features of countries to the northwest of Australia–Indonesia, Malaysia, the Philippines and Timor Leste–are dominated by island arcs and trenches, reflecting tectonic and volcanic activity during the long collision of the Australian, Eurasian and Pacific plates.

Hydrothermal copper and gold deposits occur in igneous complexes and thick marine sedimentary sequences host petroleum and coal accumulations. Again, beautiful coastal and mountain scenery abounds in tropical settings.

The geological features of Antarctica include Precambrian gneisses, modern volcanoes, dry valleys, volcanic activity, fossil mega fauna and the world’s largest land glacier.