From what I could glean, Archean actually refers to the age of the rock, not the type of rock, or of the way the deposit was formed. I can see how there might not be a history of rich deposits in rock created in a certain time period, in a certain area. But I see being frightened of the term as a red herring.

For instance, granite and magmatic intrusions could be (and have been) formed at all ages in the Earth's development, and may or may not have deposits. You could just as easily pick another time period in the Earth's development, and discover it has about the same, or worse, development potential. And maybe there are no known Archean deposits in one part of Canada, but tons of them in another.

MR