Airborne electromagnetic geophysical surveying for mineral exploration

Airborne geophysical surveys utilise several different sensors to measure certain fields which can be related to physical properties of rocks such as density, magnetism and electrical conductivity. This in turn is translated into geological information that will guide exploration programs, assist in solving geotechnical issues or monitor environment problems. The fact that the measurements are done in the air results in more rapid coverage of ground, which in turn results in faster decision making, relatively cheap cost of acquisition and is totally non-intrusive by nature. Current survey aircrafts such as SPECTREM AIR offer a fully integrated multi-sensor platform.

Airborne geophysics, specifically airborne electromagnetic (AEM) technology, is one is one of the main tools used in in mineral exploration. The right application of airborne geophysics can reduce the footprint on the ground by focussing activities for follow up. This has important safety and environmental benefits to an exploration programme, whilst also speeding up the exploration process.

SPECTREM AIR has a competitive edge in the provision of airborne electromagnetic geophysical surveying solutions in Africa. The company provides a complete service, from project feasibility to detailed threedimensional geological modelling. In addition, the patented technology offers a unique mapping tool. Being a South

African based and developed technology, the company’s focus is very much on the African Continent, with its expertise in operating in this region also providing it with a strategic advantage.

Making use of the large capacity of its aircraft to increase the power that is transmitted by the sensors, SPECTREM AIR is the most powerful airborne system currently commercially available. Directly, this results in an increased depth of penetration and enhanced geological resolution, while still maintaining the high level of detail in the near-surface geology. The system is well suited to exploring and mapping geology under cover which is typical of most African environments, be that weathered regolith or thick sand covered regions.

In addition to many surveys in West Africa for gold exploration, SPECTREM AIR has deployed its proprietary SPECTREMPLUS airborne EM and magnetic system in Zambia and the DRC, on behalf of mining companies exploring for copper in the Central African Copperbelt. Further, Spectrem has a depth of experience in Botswana, Namibia and Angola, exploring for many commodities, including diamonds. Noticeably, the results of these surveys have been useful in geological and structural mapping, and particularly vectoring into areas of possible mineralization.

Spectrem has proven to generate useful information in the geohydrology realm, from mapping paleo-channels to providing essential additional information to map environmental impacts in the coal mining activities.

SPECTREM AIR maintains a high safety standard by ensuring that a strict approach to safety and environment are adhered to all times. All aspects of the survey, from data collection, processing and interpretation are governed by an in-house quality system which conforms to ISO standards, which together with our experience and knowledge ensures that data of the highest quality is collected, and that interpretation undertaken addresses client’s needs.

New technology is continuously being developed and the focus at the moment is on data processing and geological interpretation. In the coming years, a continuous improvement in hardware technology and better control on geometric information of the platforms will result in significantly better data interpretation, while the increase in computer power and software development will also result in better processing of the airborne geophysical data and the generation of 3D models that are now starting to closely resemble the true geology on the ground. These developments encompass no only the electromagnetic domain, but include improved processing and interpretation of tensor potential field data.