Tanami Gold - what has been achieved and where to from now  

Authors / CoAuthors

Wygralak, A.S. | Mernagh, T.P.

Abstract

The Palaeoproterozoic Tanami Region is one of the most rapidly developing gold provinces in Australia. Its steadily growing gold resource currently stands at 12.5 Moz, including past production of 4.1 Moz. The entire Region contains some 60 gold occurrences. Most of these are concentrated in three goldfields ? Tanami, The Granites and Dead Bullock Soak (DBS). Mined deposits usually contain reserves of 0.01-0.1 Moz Au. Unique in size and a notable exception is the Callie deposit (DBS goldfield). Prior to 30 June 2001, this open cut and underground mine produced 1.7 Moz Au and there is a remaining underground resource of 4.3 Moz Au. Other significant deposits include Groundrush (0.5 Moz Au), Titania (0.3 Moz Au) and Minotaur (0.1 Moz Au). The Coyote deposit in Western Australia also appears to contain significant mineralisation, but its resource has not been announced as yet. In 1999, the Northern Territory Geological Survey commenced a major multidisciplinary project in the Tanami Province. This was designed to facilitate mineral exploration in the region by provision of a new generation of geological maps and the development of mineralisation models. Results of this work to date have been published in Hendrickx et al 2000, Dean 2001, Vandenberg et al 2001 and Wygralak and Mernagh 2001. Earlier reported metallogenic work (Wygralak and Mernagh 2001) concentrated on the delineation of physico-chemical characteristics, and the origin and evolution of hydrothermal fluids in the Tanami, The Granites and DBS goldfields. Pilot work has also been performed on the newly discovered Groundrush deposit. Mineralising fluids in each of the goldfields have a unique physico-chemical signature. Fluids in the Tanami goldfield have a temperature range of 120-220oC and contain almost no gases. Mineralisation occurred at shallow depths of 0.4-1.8 km. Gold was precipitated as a result of decreasing pressure and temperature. In The Granites goldfield, fluid temperature was in the range 260-312oC and the fluid contained significant amounts of CO2 mixed with minor CH4 and N2. Gold precipitated due to reaction of the fluid with host rocks containing magnetite, graphite and, in the case of the Bullakitchie deposit, carbonates. The depth of mineralisation is estimated at 3.8?7.5 km. In the Callie deposit (DBS goldfield), mineralising fluid had a temperature of 310-330oC and contained CO2 and N2, but no CH4. Gold precipitation occurred at a depth of 3.2?5.8 km as a result of the reaction of fluid with carbonaceous sediments. In the Groundrush deposit, fluid temperature was in the range 390-430oC. Fluid was dominated by CH4 and there was a minor amount of CO2. Mineralisation occurred at depths of 5.7-8.3 km and phase separation was the precipitation mechanism.

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nonGeographicDataset

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39433

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Keywords

• External PublicationAbstract

( Theme )

• mineral deposits

( Theme )

• economic geology

• AU-NT

Australian and New Zealand Standard Research Classification (ANZSRC)

• Earth Sciences

• Published_Internal

Publication Date

2002-01-01T00:00:00

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Australian Government Security ClassificationSystem    

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Creative Commons Attribution 4.0 International Licence    

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geoscientificInformation

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[-20.0, -19.5, 129.5, 130.0]

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