Canadian Mining Journal


21st Century geophysics helps with exporation and discovery

There are tremendous changes taking place in the Canadian mining industry these days and the opportunity for a new mine discovery is both quite challenging and very exciting.

There are tremendous changes taking place in the Canadian mining industry these days and the opportunity for a new mine discovery is both quite challenging and very exciting.

 As companies large and small have come to recognize, most of the near-surface mineral deposits (especially copper) have already been discovered and that explorers have to go deeper to make rewarding discoveries.

Canadian-based companies account for more than half of the 2,400+ active mineral explorers worldwide, and those that are staying ahead of the game are creative and learning to adapt to the changing conditions.

The easy copper has been found and the world is left with mining copper that is either lower grade, or at greater depths, and the correlating higher cost to get it out of the ground has a real impact on the industry.

The world’s remaining copper deposits are increasingly found in locations that are difficult to reach and more difficult to explore and develop. This new reality puts copper mine explorers in a position where they are increasingly relying on high technology tools to identify and define new deposits.

21St Century Geophysics

In the past 10 years there have been major advances in the acquisition, processing and visualization of geophysical data. On the acquisition side, major improvements have been made in airborne systems, particularly airborne electromagnetic (EM) systems.

Since 2000, an entirely new class of exploration has emerged called the Helicopter Time-Domain Electro Magnetic system (HTEM).  Within this class, the time-domain electromagnetic system (VTEM) system developed by Ontario-based Geotech Ltd. has become the industry standard and is used extensively world-wide.

As with any commercial success, other entrepreneurs have followed Geotech’s success and there are now over five different HTEM systems in commercial service, the majority of which have been developed in Canada.

Today’s HTEM technology offers the exploration industry an approach that blends both the historic strengths of airborne EM systems, which dates back to the 1950s, with modern digital signal processing, highly efficient turbine helicopters and most importantly, the precise navigation information available with state-of-the-art GPS technology.

In many cases, ground programs are no longer required to follow-up airborne surveys. This saves both time and money in the target definition stage and leaves more funds for actual target testing.

The HTEM technology, with its improved signal to noise performance, is capable of detecting mineral deposits deeper in the earth than historic techniques. Earlier technologies could routinely reach depths of 50 to 75 metres investigation whereas systems such as VTEM can detect the same conductive target to a depth of 250 to 300 metres.

The performance of ground geophysics has improved significantly as well and many programs now employ a combination of surface and borehole EM to better define targets of interest to depths ranging from 500 metres to several kilometres underground. SQUID sensors, highly sensitive magnetometers used to measure extremely subtle magnetic fields, are now available as well to further enhance the capabilities of EM surveys, allowing the better detection of targets at depth or targets of very high conductance; such is typical with some nickel ores.

The modeling and analysis of geophysical data has advanced considerably as well. For many surveys, 3D modeling of the EM and magnetic data are produced, which allow explorers to better understand the location of potential ore deposits within the earth. The University of British Colombia Geophysical Inversion Facility in Vancouver, B.C., has been a pioneer in the development of the computer codes to perform this modeling. 

*Rick Mark is CEO of VMS Ventures, a Vancouver-based junior mining company that is developing a copper deposit in Northern Manitoba.

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