Airborne Magnetic Surveys Are an Essential Tool for Mineral Exploration in the Mining Industry

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Airborne Magnetic Surveys Airborne magnetic geophysical surveys or aeromagnetic surveys are one of the most commonly employed geophysical survey methods being practiced today.  Aeromagnetic surveys are considered the primary and essential survey technology which are typically flown in conjunction with other survey technologies.
 
An airborne magnetic survey is able to measure the earth's magnetic fields from the air. Variations in magnetic fields are detected by the geophysical equipment enabling the detection of concentration levels of magnetic minable commodities.
 
When choosing an airborne geophysical survey company, take the time to consider the equipment offered. A typical modern system includes; a data acquisition system, one to three cesium magnetometers plus a variety of secondary geophysical sensors, and a specially modified aircraft equipped with stingers and pods to isolate the sensors from the noise of the aircraft.  The aircraft are periodically degaussed to remove any magnetic noise buildup.

 

Reliable data acquisition systems are the cornerstone of any airborne magnetic survey. The basic function of the data acquisitions system (DAS) for airborne geophysical surveying is to digitally record all geophysical, navigation, altitude, temperature and pressure data. Two commercial DAS are readily available, from Picodas and RMS Instruments DAARC C500.  Consider the following when selecting an advanced geophysical acquisition system:
  • Reall TIme Graphical Display – Is the data viewable in real time?
  • Magnetometers – How many are there?
  • Is the system capable of real time correction, or is post flight correction necessary?
  • Is the navigation interface available to all GPS instrumentation?
  • Is detailed flight path planning available?
  • How many channels of analog recording are there?
  • Multiple magnetometer inputs
  • Adjustable vertical and horizontal scales
  • Data is recorded during aircraft turns

Airborne Surveys are normally flown along a series of equally spaced parallel flight lines. Fore general reconnaissance mapping purpose the flight line direction is usually oriented north-south or east-west depending on the predominant strike of the known geology. For more specific surveys, such as the definition of mineral exploration targets, the flight-line direction will be oriented across the strike to maximize the magnetic signature. (Source; ASO Journal of Australian Geology and Geophysics.)

 

The quality of data acquired will vary depending on whether the airborne magnetic survey is a regional or detailed survey. Regional surveys provide data that is typically of a lower resolution, as the traverse line spacing is usually more than 250 meters and the area covered is at least 5000 square kilometers.  Detailed surveys have a lower traverse line spacing of less than 250 meters. The data resolution is higher. Detailed surveys are used as a means of mineral prospecting for magnetic ores such as kimberlites, asbestos-bearing ultramafic rocks, and magnetic iron ores. Detailed surveys are also capable of discriminating between non-metallic and metallic conductors as well as locating specific basement targets.

 

 
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