The Northern Territory (NT) has a long history of uranium mining and has some of Australia’s most significant and highest grade uranium deposits. It currently contains around 30% of Australia’s low-cost uranium resources. The first mining of uranium in the NT commenced in 1953 in the Rum Jungle and South Alligator fields, and a second phase of mining in the Alligator Rivers uranium field near Jabiru commenced in 1980 and is ongoing. In total, over 135,000t of uranium oxide has been produced to June 2015. Production from the one currently operating mine (Ranger) in 2014/15 was 2,015t of uranium oxide.
Ranger mine is a world-class uranium deposit hosted in the lower Cahill Formation in the Pine Creek Orogen, close to the structural contact with the underlying Archaean Nanambu Complex. At the end of 2014 Ore Reserves at Ranger (entirely within stockpiles from Ranger 3 pit) are 5.05Mt at 0.123% U3O8 for 6206 t U3O8, and Mineral Resources (in stockpiles and in Ranger 3 Deeps) are 50.87Mt at 0.10% U3O8 for 52,711 t U3O8. The nearby Jabiluka deposit has a resource of 29.24Mt at 0.48% U3O8.
Ranger and Jabiluka form part of the Alligator Rivers Uranium Field, a unconformity-related uranium field in which deposits vary in size from a few tonnes to more than 100 000 t contained U3O8, with grades generally in the range 0.2-2% U3O8. These deposits are typically hosted at tectonised lithological contacts within the Palaeoproterozoic basement of the Cahill Formation, with the largest deposits occurring proximal to tectonised contacts with Neoarchean basement, close to the unconformity with the overlying Kombolgie Subgroup (basal MacArthur Basin). Large deposits in this field account for 96% of past production and 95% of known resources in the NT. As well as uranium, these deposits may contain economic quantities of gold, platinum and palladium. Elsewhere in the Pine Creek Orogen, smaller but locally high-grade vein-style and other basement-hosted uranium deposits occur in the South Alligator, Rum Jungle and Hayes Creek uranium fields
The largest known uranium deposits in the NT outside of the Alligator Rivers Uranium Field are sandstone-type deposits in Palaeozoic sediments in the Ngalia and Amadeus basins in central Australia. The largest of these deposits are the roll-front Angela deposit in the Amadeus Basin (10.7Mt at 0.13% U3O8, for 13 980 t U3O8 ) and the stratiform Bigrlyi deposit in the Ngalia Basin (7.5Mt at 0.13% U3O8 and 0.12% V2O5 for 9600 t U3O8). Cenozoic palaeochannel-hosted uranium has also been identified in the Ngalia Basin area, and has the potential to become an important exploration target in central Australia
Westmoreland- type deposits predominantly occur within conglomerate, sandstone and mafic and felsic volcanics of the basal southern McArthur Basin, close to the northern margin of the Murphy Province. Small deposits also occur within the Murphy Province, beneath the exhumed unconformity with the McArthur Basin, are also included in this group. They have some features in common with sandstone-hosted, vein-type and unconformity-related deposits, and are all associated with redox boundaries near the contacts between different lithologies, in a variety of geological settings. The largest deposit (Westmoreland) is located in adjacent regions of Queensland, where mineralisation occurs as sub-horizontal and sub-vertical lenses in the Westmoreland Conglomerate, adjacent to altered, sub-vertical dolerite dykes.