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Presented by Mal Cattach, Gap Geophysics and Bill Peters, Southern Geoscience Consultants.
Drinks from 5:30pm sponsored by Gap Geophysics and Southern Geoscience Consultants. Talk starts at 6pm.
Airborne EM (AEM) is routinely used as a primary exploration technique for the detection of conductive orebodies. AEM has the benefit of rapid acquisition and is a relatively cost-effective technique for covering large areas. However the depth penetration of AEM will always be limited by relatively high transmit frequencies, minimal stacking time and small dipole moments.
Ground level EM (GEM) surveys are commonly used as either a primary exploration tool or to follow up AEM anomalies. They can achieve much greater depth penetration than AEM due to the ability to employ low Tx frequencies, long station occupation time, large dipole moments and very stable B-field sensors. However, the requirement to establish large loops and have stationary readings means that they are consequently slow and expensive. Budget constraints usually dictate wide line spacing and station intervals. GEM surveys are therefore generally spatially under-sampled as a result.
As exploration extends to greater depths and budgets tighten, it is clear that the industry requires techniques capable of significantly improving the cost-effectiveness of deep search EM surveys. Recent advances in Sub-Audio Magnetics and High Power Transmitter technologies have meant that dynamic acquisition of high quality, Deep Penetrating ElectroMagnetics (DPEM) is now a commercial reality. Examples are presented from trials conducted at the Forrestania EM Test Range and the Fraser Range in Western Australia. Also presented are the results of a recent HeliSAM Fixed Loop EM trial over the Lalor VMS Deposit in Manitoba.
Malcolm Cattach received BSc, MSc and PhD degrees from the University of New England (UNE). Mal was one of the founders of the Geophysical Research Institute (GRI) which developed some of the world’s first rapid sampling, digitally recording Cs vapour magnetometers. These instruments led to the refinement of high-resolution field acquisition techniques for mineral exploration, archaeological and environmental mapping as well as the detection of unexploded ordnance.
Mal’s PhD focussed on the development of the Sub-Audio Magnetics (SAM) technique. SAM was conceived as a method by which the rapid sampling methodologies developed for High Definition Magnetic surveying could be utilised to improve the effectiveness and efficiency of electrical and electromagnetic surveying techniques.
Mal is Chief Geophysicist and Managing Director of Gap Geophysics Australia Pty Ltd which was formed in 2005 to commercialise and further refine the SAM technique. Collaboration with Andrew Duncan from EMIT in 2007 led to the development of the SAMSON Deep Search EM method and the formation of Absolute Geophysics. Mal is also a founder and Managing Director of Gap GeoPak Pty Ltd which was formed in 2007 and has pioneered the development of a new generation of high powered geophysical transmitters.
Mal is an Active Member of the ASEG and the SEG. He is the recipient of several Research Awards from the ASEG including three Graham Sands Awards for “Innovation in Applied Geoscience”. His career has been committed to the development, commercialisation and promotion of unique Australian geophysical survey technologies.
Bill Peters graduated with a BSc (Hons) from the University of Western Australia in 1972. The next year was spent as a field geophysicist with McPhar Geophysics in Western Australia doing electrical surveys. In 1974, he moved to South Africa and joined Anglo American Corporation working as a field geophysicist responsible for airborne and ground geophysical projects directed at uranium, diamonds and base metals in Botswana, Namibia and Zimbabwe, for the Anglo American-De Beers group. Later, he was responsible for geophysical exploration in the Western Cape Province. In 1980, Bill moved to Perth, Western Australia to join BHP with responsibility for diamond exploration geophysics. This responsibility later included iron ore, gold and base metal exploration projects. Bill moved to Sydney in 1982 as a consultant to the Canadian companies Teck Exploration Ltd. and DIGHEM Ltd. working mainly on helicopter and ground EM surveys for base metals in Australia and Canada.
In 1983, he returned to Perth continuing consulting and in 1985 co-founded Southern Geoscience Consultants. Subsequently he has consulted to hundreds of clients in many different geological environments throughout the world.
Bill is an active member of the AIG, ASEG, SEG, SAGA, and a Fellow and Chartered Professional of the AusIMM.
