Thanks for your post Boot. There may not be a textbook description of this type of gold deposit until Jim Tilsley actually writes the chapter.

My very simplistic understanding of the hydrothermal system that created our deposit is that during the collision of the continental plates that ultimately resulted in the formation of the Appalachians etc., some of the water from a great sea (the Iapetus Ocean), that was originally between the two plates, was driven deep into the earth where it was pressurized and heated to the point that it could collect silicates and gold from the surrounding rock. As it "searched" for a way to escape it seemed there were few faults (areas of low pressure where it could easily bubble up) so instead it opted for plan B, to use its hydraulic properties to fracture pre-existing diorite intrusions on a massive scale. Once the event began, it continued like a crack in a windshield until the pressure of the system dissipated to the point where no more fracturing was possible. The nature of the diorite rock apparently makes it particularly susceptible to this type of hydraulic fracturing and that is part of the reason why this model is favored at this time.

As for the formation of nuggets, I think the jury is still out there. Last time I spoke to Jim T I asked him for his impression of how the nuggets were formed and he simply stated he did not know but was learning more with each core he examined. In terms of the notion that there exist convergence zones containing much wider quartz veins at depth- I think we need to be careful what we wish for. My understanding is that at least for one massive quartz domain (pure quartz rather than quartz in diorite) sampled in the 2009 bulk sampling its average grade was lower than other quartz in diorite zones.

Best,

Scott