Mineral Exploration

Geological fracture and fault zones may influence local and regional groundwater passages and flows, which makes these important features to understand and locate. The geological material surrounding the fault contact may generally be more porous and contain a higher water content than the denser, less porous basement material either side of the fault. This type of geological setting is well suited for electrical and electromagnetic methods. The geological material surrounding the fault contact may generally be more fractured and contain material of a different material to that either side of the fault. This type of geological setting is also well suited for seismic and potential field (gravity and magnetic) methods.

• Gravity can be an effective technique for detecting faults. This method measures changes in the density of the subsurface. If a fault is present a difference in the measured gravity data may be observed due to a shift in basement material causing the basement to be higher/lower to the surface either side of the fault. Also, geological material surrounding a fault may be of a different density in comparison to the geological material either side of the fault. If this density contrast Is large enough a feature will be observed in the gravity dataset. Gravity tends to be used in conjunction with electrical and electromagnetic methods, as these methods target the contrasts in electrical properties in and around the fault zones.
• Magnetic methods, similar to gravity methods, can be an effective technique for detecting faults. This method measures changes in the magnetic properties of the geological subsurface. If the geology is magnetic in nature, if a fault is present a difference in the measured magnetic field may be observed due to a shift in basement material. Also, geological material surrounding a fault may be of a different magnetic property in comparison to the geological material either side of the fault. If this magnetic contrast Is large enough a feature will be observed in the magnetic dataset. Magnetic methods tend to be used in conjunction with gravity methods, as this method targets contrasts in geological density in and around the fault zones.
• Electromagnetic (EM) methods are quick and effective at highlighting regions of faulting. The geological material surrounding the fault contact may generally be more porous and contain a higher water content than the denser, less porous basement material either side of the fault. Where a strong electrical contrast exists between the higher electrically conductive fault gauge material and lower electrically conductive basement material, the general depth and extent of the fault may be mapped.
• Seismic Reflection is a geophysical technology which is directly related to the acoustic impedance between geological materials; the greater the acoustic impedance the greater seismic reflection. This technology is most useful where the density contrast between geological materials is large, such as in and around fault zones and where a fault is present large features can be observed in the interpreted seismic layers.