If there is one exploration technology that is viewed as critical to the success of companies looking to strike it rich in Western Australia’s remote Paterson Province, it is airborne electromagnetics, or AEM.
While the richest deposit discovered in the Paterson to date, Telfer, was found outcropping at surface in the 1970s, most of the region is covered by a layer of sandy material that ranges in depth from a few metres to more than a kilometre.
This is one of the key reasons the Paterson had remained a relatively unfashionable exploration address until a few months ago.
But AEM, which is a geophysical surveying method that allows explorers to “see” through the layers of cover and better identify drilling targets, is helping to change that.
Indeed, Rio Tinto’s much-hyped Winu discovery was made after the company flew an AEM survey over its ground neighbouring Antipa’s (ASX:AVY) in late 2017 and identified a large anomaly.
AEM was also used by AIM-listed Greatland Gold in identifying drill targets at its Havieron discovery, where drilling in November returned a stunning intercept of 275 metres at 4.77 g/t gold and 0.61 per cent copper.
The intercept came from a depth of 459 metres, emphasising the effect that cover can have in making exploration in the Paterson more challenging.
AEM has also figured in other Paterson discoveries including Newcrest’s O’Callaghan’s tungsten deposit and the Calibre gold-copper deposit, which is located within Antipa’s Citadel Project, the area Rio is currently farming into.
The technology works by transmitting an electromagnetic signal from a system attached to a plane or helicopter (see picture) into the ground below.
The signal induces eddy currents in the ground which are detected by receiver coils towed below and behind the aircraft in a device called a bird.
Depending on the system used and the subsurface conditions, AEM techniques can detect variations in the conductivity of the ground to a depth of several hundred metres.
The conductivity response in the ground is commonly caused by the presence of electrically conductive materials such as salt or saline water, graphite, clays and sulphide minerals.
In 2018, Antipa Minerals (ASX:AZY) flew an AEM survey over a structure that runs through its Paterson tenements that it refers to as the El Paso Corridor.
This AEM survey identified 11 priority gold-copper targets that will be drill tested in the first half of 2019, providing the opportunity for a game-changing discovery.
Late last year the company also advised that Rio had opted to fly an additional AEM survey over the Citadel Project, in another sign that the major is excited about what it is onto in the Paterson.
This content is produced by Star Investing in commercial partnership with Antipa Minerals. This article does not constitute financial product advice. You should consider obtaining independent advice before making any financial decisions.
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