New mineral province could hold another ‘Cadia’

By Paula Wallace

A new region of exploration in the northwest of the State has been advanced under the program, known as the Thomson Orogen, and the new geophysical data (seismic, gravity, airborne magnetics, radiometrics), geochemistry, age data and petrology, were presented at “Exploration in the House”.
Director of the Geological Survey of NSW, Lindsay Gilligan, told The Australian Journal of Mining, “Exploration Licences in the Thomson have gone from about five to about 120 in the last two or three years.
“We’ve identified that that Thomson region has similar rocks and thus similar possibilities and opportunities that exist in the Lachlan belt of NSW. Arguably there might be another Cadia up there for example.
“It’s prospective for copper, lead, zinc, gold and arguably nickel but it’s early days…a lot of the area’s under cover and it’s very hard to get a good handle on what’s going on,” he said.
Covering nearly 10 per cent of the geographic area of New South Wales, the Thomson Orogen requires substantial drilling to be carried out in order to get a clearer picture of the geology.
Whilst there are prospective areas under shallow cover (around 30 per cent by area less than 300 metres depth) “we need the exploration industry to drill and we can use those holes to further develop understanding,” said Gilligan.
But the effects of the global financial crisis have filtered through to mineral exploration investment and New South Wales’, despite sustaining the lowest drop in spending from the December to March quarters, has been slowly dropping off a peak since March last year. At this peak it received $52.3 million in exploration investment, and in the last quarter registered $40.2 million.
However, exploration does not equal mining, a point that Ian Macdonald, NSW Minister for Primary Industries and Mineral Resources, made in his opening address at the “Exploration in the House” event.
But the Government does see it as a fundamental part of the future success of the mining industry, which has an export value of $11 billion in NSW.
“New mineral discoveries have provided an economic and employment boost to many regional areas including Orange, Parkes and Mudgee and mines coming on-line near Dubbo should assist economic activity in that region,” said Minister Macdonald.
This is a subject close to home for the Minister, originally from Orange, who has seen the community there benefit, particularly in a time of drought, from the Cadia Valley Operations. A point often lost on “latte sipping, inner city types” according to the Minister, and other such detractors to the mining industry who fail to see the fundamental function of mining to “society and its prosperity”.
Cadia Valley Operations is the largest gold and copper producer in New South Wales and one of Australia's largest gold producers. Cadia Valley is located in central western NSW, 20 kilometres southwest of Orange, and 250 kilometres west of Sydney.
Lindsay Gilligan believes the chances of finding a deposit similar to the massive resource at Cadia Valley are “very good”.
“At last count we’ve identified something like 22, or 24 porphyry systems in NSW so far and some of those require a lot more exploration. Some of them are productive now like Northparkes, so it’s really exploration investment, putting money into the ground, putting money into holes.”
Gilligan describes Cadia as essentially a “big three dimensional problem”, that involves exploring a block of rock in three dimensions - a task that has taken Newcrest Mining the best part of 20 years’ to accomplish.
“Now they’ve got this massive system at Cadia East that really has moved the Cadia deposit into a massive system,” said Gilligan.
“So I think that exploration is a high cost, difficult scientific process…there is so much out there to be done, so much opportunity out there.
“In the Thomson we’re looking at cover varying between 70 and a couple of hundred metres and the challenge there is actually getting enough material to get a really good handle on the chemistry and the origin of these rocks.”
Even amidst a global economic crisis Gilligan is optimistic of a recovery in exploration investment in New South Wales.
“There’s a lot of enthusiasm out there in the industry,” he said, “I mean gold exploration really is undiminished.
“We’ve still got big markets up to our north and when the situation recovers in China I think we’re going to be back into it. I’m very optimistic…in fact you can’t be in the game if you’re not optimistic,” said Gilligan.
For more information visit: www.dpi.nsw.gov.au/minerals