Services
Magnetics
Airborne magnetics is probably the cheapest, fastest and most effective way to get a 'first look' at an exploration area without the need for camps, line cutting or other infrastructure. For this reason it has long been a standard exploration tool, particularly in the early stages of an exploration program.
The earth's magnetic field interacts with the magnetic materials in the near surface rocks creating easily measurable features representing changes in magnetic susceptibility. These changes most often reflect changes in rock type, which means that when we map the magnetic field we are also mapping geologic structure.
Modern high resolution airborne magnetic systems are sufficiently precise to allow measurements not only of the total magnetic field, but also of the magnetic gradients in the horizontal and vertical plane. Magnetic gradients are very useful when applying a quantitative interpretation of the magnetic field as they help to constrain the number of possible solutions, which is otherwise infinite.
The simplest example of automated interpretation is the process of gridding, which produces a 2 dimensional picture (or grid) of the measured quantity from a series of 1 dimensional survey lines. The measured horizontal gradients can be used within the gridding algorithm to guide and constrain the between line interpolations, improving the look and interpretability. Click here to read more about gradient enhanced gridding.
Since gradients are directional, much care must be taken when collecting gradient data to remove the effects of aircraft attitude as the pilot reacts to cross winds and terrain. Goldak has developed a multi-GPS based Attitude Determination System (ADS) to capture the actual attitude of the aircraft for every sample and 'derotate' the gradients to the ideal measurement plane parallel to the line direction.
Radiometrics
Airborne radiometrics (or spectrometry) is the practice of measuring the natural radiation emitted from the surface rocks. In constrast to magnetics it only represents the top few inches of cover and so represents the surficial geology. In natural landscapes only 3 elements are directly detectable: Potassium (K), Uranium (U) and Thorium (Th).
The use of radiometrics in uranium exploration is well known and obvious, but there are many more potential uses that depend on the method's ability to highlight local changes in geochemistry. For example, potassic alteration zones associated with shear hosted gold or massive sulphide deposits can be detected radiometrically. Read more here.
All of Goldak's spectrometers are state of the art RS-500 series detectors from Radiation Solutions. These 1024 channel systems are highly robust and reliable. We have sufficient detectors to equip 3 aircraft with 12 downward crystals (48 liters or 3,000 cubic inches) or all 4 of our aircraft with 8 downward crystals (32 liters / 2,000 cubic inches), along with a suitable number of upward crystals.
The secret to capturing good quality radiometric data is proper calibration. To that end Goldak has established it's own radiometric calibration range near Saskatoon and acquired a set of concrete calibration pads. The Geological Survey of Canada, which operates the only other calibration facility in Canada, has assisted us in this endeavour and approved our setup for use. To our knowledge no other N American survey provider is as well equipped.
VLF-EM
Airborne VLF is a passive electromagnetic method that depends on high power marine communication transmitters as the energy source. An anomaly is produced when the large electrical field interacts with local conductors or by a significant change in the resistivity. The VLF field may also concentrate itself along planar features which are parallel to the transmitter, which results in a strong directional bias in the VLF response. To alleviate this effect 2 orthogonal stations are typically monitored.
VLF is generally collected along with magnetic data on a 'best efforts' basis. Frequent maintenance of the transmitters and variable signal strength means that stations may have to be substituted and signal outages may occur. For these reasons interpretation is more qualitative than quantitative, but may still yield useful information at very low cost. The total field map tends to show variations in conductivity, while the quadrature measurement is more responsive to planar features such as faults and contacts.