Airborne Magnetic SurveysIn the past several decades, airborne magnetic surveys have become a common means of acquiring data required for mineral expeditions and hydrocarbon exploration. The information uncovered during a magnetic survey is often the first phase of an exploration program to detect valuable minable magnetic ores such as kimberlites, chrome, and magnetic iron ores, as well as hyrdrocarbons, precious metals, uranium and water.
 
The exploration process usually commences with a regional airborne magnetic survey producing relatively low-resolution data, to be followed up with a detailed survey.  Detailed surveys tend to be smaller in scale, with closer line spacing producing higher resolution, more detailed data, and are typically flown with secondary geophysical technologies such as gravity and VLF-EM, which may lead to further mineral exploration such as exploratory drilling.
 
In an airborne magnetic survey, a magnetometer or series of magnetometers are attached to an aircraft measuring variations in the earth's magnetic fields from the air. These fields may detect anomalies that may indicate where minerals are present.
 
While mining companies uses airborne magnetic surveys in the prospecting stages of mineral exploration, governments also rely on these methods as a means of uncovering concentrations of non-metallic commodities such as petroleum and coal.
 
Airborne magnetic surveys provide sufficient data for mapping lithologies and structure.
 
Types of airborne magnetometer setups include;
  1. Single sensor (typically a tail stinger, or heli boom, which generally gets the best data due to greater separation)
  2. Horizontal magnetic gradiometry (data acquired from two wingtip pod magnetometer sensors)
  3. Vertical gradiometer (two tail stinger mags mounted in a vertical orientation)
  4. Total magnetic intensity surveys (A combination of several magnetic sensors, typically three, but potentially four)
Airborne magnetic surveys work by identifying the frequencies and disturbances of the ambient magnetic fields existent as a result of the concentration of magnetic minerals present in the Earth's crust.
 
Typically magnetic minerals that can be detected using an airborne magnetic survey are:
  • Magnetite
  • Maghemite
  • Titanomagnetites
  • Titanomaghemites
  • Pyrrhotite
When it comes to economics of airborne magnetic surveys, carefully executed surveys are vital as the costs of executing remote airborne operations are high. Delays can be costly. The costs of airborne surveys are affected by inclement weather, permitting delays, and scheduled and unscheduled aircraft maintenance. Further, as airborne surveys are the first stage of the exploration process, they are highly speculative.
 
Important factors in the cost of an airborne survey are;
  1. Location of Survey – remote surveys typically increase costs substantially
  2. Fuel costs (highest in remote regions requiring airborne fuel lifts, and drummed fuel)
  3. The size of Survey (large surveys have a lower cost per km)
  4. Time of year, weather conditions
  5. Price variations in the type of data acquisition system used
  6. Delivery products (optional deliverables, map products etc.)
An experienced survey crew and a high quality geophysical aircraft and system are important factors in the success of an airborne magnetic survey. If the data acquired is questionable, it can lead to re-flights, complications during data processing and ultimately further exploration costs.
 
Look for the following characteristics when sourcing a data acquisition system:
  • Adaptive signal processing techniques
  • Immediate quality control
  • Flight planning
  • Navigation interface for a wide range of GPS instrumentation
  • No need for post flight corrections
  • Multi-channels of analog recording
In summary, when surveys are completed with an experienced crew and a high quality geophysical system, an airborne magnetic survey can result in highly useful data that is integral to the exploration program of a mining exploration company.
 
gravity survey
The world’s gravity field varies from spot to spot due to subsurface density variations. Gravity surveying measures these variations and creates a map which helps geologists determine where light and dense rocks are located.
airborne geophysics
Airborne geophysics and aeromagnetic surveys are employed by governments and mining companies to map and prospect specific terrains. Advanced data acquisition systems enable companies to acquire data that is highly accurate to be used to form an overall geological picture of a target area.
airborne survey
Airborne Surveying – Airborne Geophysical Surveying is an Industry with Strong Demand and a Bright Future
airborne geophysical surveys
Airborne geophysical surveys are advanced means of collecting accurate geophysical data remotely. This information is applied to the development of geophysical maps and as a part of the initial stage of mining prospecting.
airborne magnetic surveys
Airborne magnetic surveys provide highly relevant data for mapping lithology and mineral prospecting. The two types of airborne magnetic surveys are regional and detailed and are categorized by the resolution of the data acquired.
airborne magnetic surveys
Airborne magnetic surveys are commonly used by mining companies and governments as a means of sourcing out minable commodities present in the Earth’s crust. Success is dependent upon accurate data acquisition systems and strategic planning.
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Terraquest Ltd.        |        9054772800        |        sb@terraquest.ca        |        www.terraquest.ca
2-2800 John Street,   Markham,   ON,   L3R 0E2,   Canada