Crone’s Pulse EM borehole surveys (3D Borehole PEM) measure and orient 3-component data whether the borehole is on the surface, underground, down-dipping, up-dipping or flat. These surveys can be performed with two different types of sensors.
Induction sensors measure the rate of change of the B-field. This derivative value allows you to see targets, at depth exhibiting a large range of conductances including weakly conductive zinc mineralization.
Fluxgate sensors measure the absolute magnetic field. These highly sensitive sensors are better suited for high conductance targets and will record cleaner raw data for those conductances outside the suitable range of induction probes.