Northern Territory Geology

Northern Territory Geology

Geological Summaries

Deformed and metamorphosed Palaeoproterozoic orogenic rocks older than 1800 million years crop out as major tectonic units surrounded by younger rocks and essentially form the recognisable and inferred basement to the North Australian Craton. These Palaeoproterozoic rocks form the Pine Creek Orogen, Tanami Region, northern Arunta Province, and Tennant, Murphy and Arnhem Inliers. They include remnants of Archaean rocks, which have been dated at 2500 million years.

Largely unmetamorphosed Palaeo- to Mesoproterozoic (1800-1400 million years) sedimentary platform covers include the McArthur, South Nicholson and Victoria-Birrindudu Basins and the Ashburton and Davenport Provinces of the Tennant Inlier. Apart from the Davenport Province the successions are generally not strongly deformed.

To the south, the rocks of the North Australian Craton pass into the Central Australian Mobile Belts where crustal deformation and metamorphism continued until about 300 million years ago. These intensely deformed rocks form the Musgrave Block and the Arunta Province. In the southern Arunta Province, episodic igneous activity took place between 1880-1050 million years and deformation included a series of major tectonic events in the Proterozoic and Palaeozoic. The Palaeozoic events also affected the Amadeus Basin succession. The Musgrave Block experienced igneous activity at intervals from 1550-800 million years and major orogenic events at 1200 and 550 million years.

In the Amadeus, Ngalia, Georgina, Wiso, Daly and Ord Basins, which cover a large part of the Northern Territory, sedimentation ceased by the Early Carboniferous (about 330 million years ago). In the Pedirka, Arafura and Bonaparte Basins sedimentation continued well into the Triassic (200 million years). During the Jurassic to Cainozoic period (the past 200 million years) sediments of the Eromanga, Browse, Bonaparte, Money Shoal, Dunmarra and Carpentaria Basins were deposited.