A transient AMT (TAMT) survey was conducted over body 140/141 of the Fort a la Corne cluster to assess the method's utility for mapping the kimberlite body at depth and ideally, vents located within the large mostly flat lying bodies. Three-dimensional inversion of the TAMT data indicates that the bodies can be mapped at depth with TAMT data and that some, but not all, of the feeder vents are imaged in some capacity. This is believed to be due to the differing phases of kimberlite intrusion, some of which are more conductive than others. Note that in the Fort a la Corne case, the kimberlite is resistive relative to surrounding marine Cretaceous shales, with a resistivity contrast of ten to one at most, this makes for a challenging target.
Courtesy of Shore Gold, please click here (4.5 MBytes) to download the 3D TAMT inverted results over Body 122. Kimberlite intersections are indicated by white vertical lines. Note the good correlation with the known extent of the north-western edge of Body 122, seen in the TAMT data at approximately station located at +600.