@pintohoo I can see why the presence of Lamprophyre might excite...

@pintohoo

I can see why the presence of Lamprophyre might excite you. I notice this was also present in BRB and that you guys were onto that in the very early stages as a possibly indicator

Lamprophyre

"These are relatively rare, deeply-sourced ultra-potassic intrusive rocks with a common spatial association with large Archean gold deposits (eg. Golden Mile, Darlot, Superior
Province in Canada)"

The average gold abundance in lamprophyres seems to be at least an order of magnitude higher than in 'common' igneous rocks, and many individual values are 100-1,000 times higher. This high gold content may reflect two factors:

(1) lamprophyres tap exceptionally deep regions of the Earth - regions not only where diamond is stable, but also where gold may be more enriched than in the source regions for other igneous rocks;

(2) lamprophyre magmas are suitable carriers of gold from depth because, in their high CO2, H2O, F, K, Rb and Ba but moderate S contents, they closely mirror fluids actually known to deposit gold veins in the crust. Most types of lamprophyre rise rapidly enough from great depths to retain any diamond and gold, along with rich mantle-xenolith suites. Calc-alkaline lamprophyres, on the other hand, undergo extensive crustal interactions which cause them to pick up crustal xenoliths, and to lose any diamond and mantle xenoliths along with at least some of their gold; this last may account for their association with mesothermal (for example, Archaean) gold deposits.

http://www.nature.com/nature/journal/v332/n6161/abs/332253a0.html
https://www.geologyforinvestors.com/gold-archean-greenstone-belts/