Possible sequence of geological events1) Once upon a time, long ago, on some island out in Pacific ocean a porphyry intrusion came up from depth.
2) It created a stereotypical Copper porphyry deposit.
3) The passage of time dropped the erosion level down to the porphyry and supergene enrichment occurred.
4) The island was accreted to the western edge of the North American continent.
5) The accretion event generated heat which remobilized the Copper within the Porphyry copper deposit creating the hypogene Bornite-Chalcocite? blanket.
6) Before the blanket could significantly alter the Hercules rhyolite buried everything.
7) Another heat event of unknown origin remobilized some of the Silver into veins within the Hercules rhyolite.
8) The passage of time has dropped the erosion level back down to near the porphyry.
If this sequence is correct then the Porphyry is seriously depleted of mobile elements (Cu and Ag). If a good part of the Copper has been remobilized into a flat blanket on top BONUS!