An IP survey (Induced Polarization) was used at Mulligan as it...

An IP survey (Induced Polarization) was used at Mulligan as it was a smaller sized tenement...From a MEI announcement:
The target of interest is cobalt bearing polymetallic vein structures within the subsurface. Cobalt is a ferromagnetic transition metal, thus has strong magnetic properties. In the environment, it is generally found in the form of cobaltite, erythrite, glaucodot, or skutterudite ores (Lenntech B.V., 2018). These
disseminated sulphides are highly chargeable and due to these properties, it was determined that induced polarisation and magnetic surveys are preferred to provide detailed information on the location and strength of the veins. The survey lines were planned in a perpendicular direction to the historically known vein structure orientation, thus providing optimal data acquisition for the targeted
veins.

MEI's acquistion of Joyce River included a previously done airborne TEM survey so they went with a 3D model of that since Joyce River includes a very large area which is mostly all prospective for cobalt...

The airborne VTEM survey is a more recent time domain electromagnetic survey that penetrates deeper and with higher resolution than a TEM survey...

From an MEI announcement:
We have found that the cost of flying airborne VTEM surveys in Canada is extremely cheap when compared to other locations globally and given Iron Mask, Mulligan East and Beauchamp cover over 60 km2 of ground prospective for cobalt mineralisation, flying the chopper survey as a first pass is a very cost-effective method for generating targets.”
“In quick time the airborne survey will provide us detailed results on the potential for mineralisation in
the sub-surface and allow our field crews to continue to complete our target generation for advanced
exploration activities, including drilling at our other projects.”