The Northern Territory has a long and continuous history of gold mining, from three main goldfields – Pine Creek, Tennant Creek and the Tanami. Total gold production to June 2015 in the Northern Territory is estimated to have been 521 tonnes, or 18.3 million ounces. Gold production in 2014/15 was 14.57 tonnes, or 514,000 ounces, with most gold produced from two underground mines: Newmont’s Tanami operations (Callie mine) and Newmarket Gold’s Pine Creek operations (Cosmo Deeps mine). A third mine, ABM Resources’ Old Pirate open cut mine in the Tanami Region, commenced operation in 2015 and ceased in 2016 after producing 29,376 ounces.
Gold continues to be one of the leading commodities for both exploration and mining in the NT. Gold mineralisation is present in a number of deposit styles including orogenic Au (quartz veins), intrusion-related Au, iron oxide Au±Cu, Homestake-style Au (veins in iron-rich metasediments), and unconformity-related U-Au. Most of these deposits are concentrated into three Palaeoproterozoic geological provinces; Pine Creek Orogen, Tanami Region and the Warramunga Province. Quartz vein (orogenic-style) gold deposits are most common in the Pine Creek Orogen and Tanami Region. Ironstone-hosted Au±Cu style deposits are dominant in the Tennant Creek field in the Warramunga Province. Significant undeveloped gold resources occur in all three provinces.
The Callie gold mine, operated by Newmont Mining Corporation was discovered in 1991 and mining commenced in 1995. Mineralisation at Callie consists of high-grade Au-quartz veins occur in folded Palaeoproterozoic carbonaceous siltstone. As of 31 December 2014, Ore Reserves at Newmont’s Tanami operations were 17.7 Mt at 5.80 g/t Au containing 3.01 Moz of gold, with a further 2.33 Moz in additional resources. In October 2015 Newmont announced plans for an expansion of their Tanami operation by building a second decline and increasing plant capacity to increase production to 425,000-475,000 oz per annum. Also in the Tanami Region, Northern Star Ltd have farmed into Tanami Gold’s Central Tanami project, which has a total resource of 25.5 Mt at 3.2 g/t Au, for 2.63 Moz Au. The flagship Groundrush deposit, which is hosted within a thick fractionated dolerite unit and a secondary discrete high-grade quartz vein and has a resource of 6.72 Mt at 4.8 g/t Au.
Newmarket Gold’s Pine Creek operations in the Pine Creek Orogen include the Cosmo Deeps underground gold mine which at the end of 2014 had Measured and Indicated Mineral Resources of 4.53 Mt at 3.43 g/t Au and an Inferred Mineral Resource of 1.11 Mt at 2.9 g/t Au, for a total contained mineral resource of 0.61 Moz of gold. Numerous other orogenic gold deposits occur throughout the Pine Creek Orogen, including Mount Todd, Maud Creek and Toms Gully.
In the Tennant Creek region, over 5 Moz of gold has been historically produced from high-grade ironstone-hosted gold-copper deposits. A similar field occurs undercover in the Rover field, 70 km to the southwest, where Metals X Ltd have defined a gold and copper resource at the Rover 1 deposit.
The Arunta Region hosts a number of significant auriferous quartz vein prospects and potential for iron oxide (Au-Cu), intrusion related polymetallic (gold-bearing) veins and gold skarns. The Murphy Province has potential for orogenic- and intrusion-related auriferous quartz veins and unconformity-related U-Au (±PGE).