Initiatives by Australia’s State Government of Victoria to develop its untapped gold potential are bearing fruit with proponents saying at least three of newly discovered orefields are expected to contain more than 1 Moz of gold. Addressing the second day in Melbourne of the Paydirt 2008 Victoria Resources Conference, Geoscience Victoria Director, Ms Kathy Hill, said the State’s A$9 million gold undercover assessment had now completed two of its three planned stages.
“The results in the Bendigo zone for example, have provided the geoscience data pointing to a potential 30 Moz of gold in mesozonal orogenic deposits only, awaiting exploration and potential development,” Ms Hill said. “Our analysis has also delivered a confidence level of around 80% that the actual range could be as high as 50 Moz. Within this range, there are possibly 15 to 32 significant undiscovered ore fields each pointing to hosting around 250,000 oz of gold.
“The work north of Bendigo has unlocked several basement highs, with the regional gravity data now intensified from 1500 m spacing to as close as 500 m spacing. Some initial drilling has already been initiated over these opportunities. Leviathan Resources announced last November, for example, gold intercepts in bedrock at 70 m depth, including intercepts of 1 m grading 160 g/t Au – so the value of the Geoscience Victoria work is setting the groundwork for future discoveries.”
A new gold assessment over the Stawell region will be released at the Conference’s Technical Forum on August 27.
Latest technologies are being used in Victoria’s work, including one that mimics bats’ night navigation technique, which has been used for the first time to image structures beneath the earth’s surface that played an important role in forming Victoria’s gold deposits. Speaking as he opened the conference, Energy and Resources Minister Peter Batchelor said the innovative approach being presented at the conference would produce deep seismic data that could help explorers better pinpoint new gold deposits.
“Previously geologists have been able to map the land surface in Victoria and estimate what might be below, but this is the first time they have been able to directly image how faults behave deep in the earth’s crust,” Batchelor said. “The deep seismic study focused on an area nearly 400 km long, spanning western and central Victoria from Stawell to Cobram and has for the first time imaged the earth’s crust at depths of up to 40 km below the surface. Analysis of this seismic data has provided crucial evidence which supports the long held theory that Victoria’s gold came from faults deep below the surface.”
The presentation at the conference, Tectonic Evolution of Western and Central Victoria: New Interpretations from the Deep Seismic Transect, showcases the results of one of a number of new geological studies that are either completed or currently being undertaken by GeoScience Victoria.
Several projects are being released at the three-day conference to help industry better pinpoint resources in Victoria with the potential to be explored and exploited. GeoScience Victoria Senior Geologist Ross Cayley said the seismic survey used controlled energy waves to identify objects, a technology based on the same technique used by bats to navigate in darkness.
“Bats direct controlled bursts of energy waves at objects and by listening to reflections of this energy bats can interpret their shape, distance and geometry,” Cayley said. “Using an advanced version of this technique used by bats, geologists can image objects deep beneath the surface of the earth, even when they may lie buried as is the case for this survey, at depths of up to 40 km. In the past these types of seismic surveys have mostly been used for offshore gas and oil exploration.
“While there have been two small surveys carried out near Stawell previously, this is the first time geologists have been able to carry out a large-scale onshore seismic survey designed specifically to look into Victoria’s oldest rocks .” Cayley said to carry out the survey three specially constructed 15 t trucks were used. Each truck as a number of steel plates attached which send vibrations at various frequencies into the ground. Geophones, are then placed in the ground around the area to listen to reflections of the energy pulses.
“This survey has proven that geologists have been on the right track about how gold deposits were formed in Victoria and it will now help us model the ancient fluid flow from the faults, which should help us better understand known minerals deposits, and perhaps more accurately locate new ones.”
“It’s all about reducing exploration risk for mineral explorers,” Batchelor said. “The more information we make available to explorers, then potentially the lower the financial risks, which makes Victoria a better prospect for resources investment. The data collected will also feed into the 3D geological model of Victoria currently being developed by GeoScience Victoria. There are also plans to use the model to look at the last 500 million years of Victoria’s history and create detailed ‘snapshots’ of critical moments of mountain building and movement of mineral rich fluids from great depths within the earth beneath Victorians’ feet.”