MEGATEM

MEGATEM System Specifications

A time-domain airborne EM system to meet the challenge of exploration areas located at high altitude, in remote areas, or requiring deep target detection.

MEGATEM came into service in 1998 as the first new fixed-wing airborne electromagnetic (AEM) survey platform (aircraft) to be introduced in 15 years. The need for a new, larger, more powerful survey aircraft was required to meet the challenge of exploring areas at high altitudes and in remote frontier regions. These include the high priority exploration targets located in the high Andes of Argentina, Chile, Peru, Ecuador, and Bolivia. 

After detailed analysis by the operational, engineering, and electronics staff of Fugro Airborne Surveys, the DHC-7 (de Havilland Dash 7) has been chosen as the optimum survey aircraft to meet or exceed these challenges. The four- turbine-engine Dash 7 is capable of safe survey operation over exploration projects located at altitudes up to 15,000 feet (4575 metres). The Dash 7 also has a proven capability for short take off and landing (STOL), as well as the designed structural strength to carry the large AEM transmitter loop. 

The improved time-domain AEM system is based upon proven GEOTEM technology. The system can operate at waveform frequencies from 12.5 Hz to 90 Hz and can acquire both dB/dt and B-field data in three orthogonal directions (2 horizontal axes and 1 vertical axis). The transmitter dipole moment (transmitter power) is by far the largest of any operating AEM system, with a transmitter loop area of 406 square metres, four or five turns and a dipole moment of over one million ampere metres squared. These features combine to provide an exceptional effective depth of exploration as well as multiple EM parameters for precise target definition. Recent survey results have demonstrated the superior capability of MEGATEM to locate deep targets in all geological environments. 

In 1999, Noranda Inc. undertook a complete evaluation of existing AEM technology in order to determine the most effective AEM system to reevaluate the Abitibi Mining district in Quebec, Canada. This was achieved by systematically surveying, with each AEM system, a test grid which included three known deposits at different depths. The results indicated MEGATEM to be the most effective system and a MEGATEM survey was flown in late 1999 to reevaluate the Matagami mining camp. As follow up of this survey, the Perseverance Deposit was discovered in March 2000.

As a result of this success, Fugro Airborne Surveys, with strong support from Noranda Inc., initiated, in late 2000, a development program to further expand the capabilities of MEGATEM. The development focused on increasing the transmitter dipole moment to provide an even greater depth of effective exploration. This development program was completed in June 2001 with the commercial launch of MEGATEM^II having a dipole moment effectively twice that of MEGATEM. Successful surveys with MEGATEM^II have been completed in Canada and the USA.

The other geophysical systems routinely flown in conjunction with airborne EM on the Dash 7 include a sensitive towed-bird Cesium vapour magnetometer as well as a multichannel gamma-ray spectrometer. The Dash 7 has the capability to also include airborne gravity and hyper-spectral scanning systems on the aircraft.

Fugro Airborne Surveys continues to actively participate in and sponsor the UQAT research project on mineral exploration applications of the MEGATEM system in the Abitibi Region of Quebec. For details on this project also sponsored by the Government of Canada, the Government of Quebec and Noranda/Falconbridge, please click here. Actual MEGATEM data over the Iso New Insco VMS deposits in Hebecourt Township, Quebec are shown.