Mostly. The structural trends were what the old resource geo was...

Mostly. The structural trends were what the old resource geo was following, where they hit the shales. The shales do form a mineralisation trap (google black shales). According to my source they had plenty of geophysics and drill holes to have a good idea of where to look.
If they're your yellow lines on the pit section image, then google zone of instability around pits. The engineer that I spoke to who worked there made specific mention of this when talking about how close they can mine to the old waste dumps and tailings dam. West winds and four pillars look to be higher grade parts of the main lode they were mining, not east west trends. I recall seeing old GCY pictures with high grade zones under the pits. From what I have been told - again from someone who actually worked there - was that most of these things were known, it was more the cost, logistics, timing and direction of the old management (being open pit miners) that held them back from the pure exploration that they're doing now.