Exploring the sub-surface with airborne transient electromagnetic (TEM) systems such as GEOTEM, HOISTEM, TEMPEST and VTEM is gaining more popularity as explorers seek to target mineral deposits by mapping the electrical conductivity of the sub-surface. However, airborne TEM is characterised by very large volumes of complex multi-channel data that are difficult and enormously time-consuming to analyse in terms of mineral targets. A number of mathematical techniques are available to transform the multi-channel TEM data into conductivity-depth images showing the absolute conductivity of the subsurface at particular depths. But these algorithms assume that the electrical structure of the ground is horizontally layered, although this is usually not the case in mineral provinces and hence they provide only limited resolution of the underlying geology. They also fail to resolve small and subtle conductive and resistive features which are often important exploration targets.
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