Combine INTRUSIVE(S) with SHEAR ZONE with those kinds of rock types layered on top of more layered. In a few hundred years they will be mining at depths like Sudbury only because it will take them that long to get the stuff nearer the surface out of the ground at tonnes per day that will make Sudbury seem like a training century getting ready for the real thing. NAMELY "The EAGLES" in Mc Fauld's "Ring of Fire". Old Joe PS: Just a little real perspective on this place in the James Bay Lowlands of Ontario, Canada.