KAT Exploration Inc (KATX)

[geo_newfie]

Relikwie,

I may have to start charging a consulting fee... ;^)

A mafic dyke already has a lot of Fe, which is part of the definition of mafic: Mg and Fe.

Some mafic igneous rocks have a natural low magnetic field due to the amount of Fe in them... in fact ultramafic rocks are extremely hard to get structural information from because the compass needle goes crazy when you are standing on one.

So the magnetism might be just related to the Fe content (not enough to be Fe ore) or, as you suggest, it could be related to alteration. Without seeing the rocks that is as far as I can go.

Hydrothermal processes are related to dykes, but not all the time. If it is just a feeder dyke, then chances are lower as it is not a hydrothermal process. What you need are late stage melts from an intrusion or deep circulating meteroic (groundwater) or ocean water that will crystallize or precipitate minerals enriched in incompatible elements.

This relates to your next question regarding the location of the hole #1 in regard to the anomaly. Deposits are typically associated with the edges of intrusions, that is true. However, in this case they did not mention any intrusion, except for the dyke. The conglomerate records a period of quiescence, if it is sandwiched between volcanic flows. It also records large amounts of water and a high energy environment, which is needed to round the cobbles, etc that make up the conglomerate. So going only by the limited information offered in the PR, it would seem that water was nearby and subsequent volcanic flows covered the area several times. The water would then get heated and probably mobilize Fe, etc that then passed through the permeable and porous conglomerate, which is the origin of the hematite alteration. And could also explain the magnetism in the dyke(s).

The REEs appear to be related to peralkaline, felsic volcanism in the area and not the mafic volcanism, so I have my doubts that REEs would also be within the hematite altered conglomerates.

Again, this is my interpretations based on limited data, but I have done a LOT of mapping in ancient volcanic terranes.