It appears to me that in this paragraph, SLI is referring to the general area of the Tesoro property, when they say the source has never been located. As far as the "belt" goes, there are most likely many individual sources right along the chain, one source did not create this 300km belt, IMO. One major event years ago,for example earthquake, was the start of a series of events after, each one causing new fractures, new deposits.

I agree 100% with Hogs perspective on the geology of this area, it was well written and explained. One very important point he made, IMO, is that geologists are still trying to better understand mesothermal systems, like ours.