Production from epithermal primary lode gold deposits along the Circum-Pacific rim exceeds one million ounces annually, from around 20 countries. Distribution of this important deposit type coincides with, and is genetically related to, convergent plate boundaries and the chain of associated volcanic-plutonic activity framing the ocean basin. Deposits are emplaced as clusters along two subparallel belts: the ocean margin transition zone and the zone within the continental framework boundary. Ocean margin deposits are associated with island arc-type intermediate to mafic igneous activity, active geothermal phenomena, and subduction-related regional fracture systems. Deposits inside the continental margin are associated with intermediate to felsic volcanic-plutonic belts an exhibit block faulting or volcano-tectonic fracture control. They feature strong Pb-Zn-Ag and local S-W metal associations. Within both belts, a continuum exists between near surface hot spring deposits, local disseminated replacement (Carlin-type) deposits, and deeper bonanza systems. Hot spring and replacement deposits feature relatively high Au:Ag ratios, contain micron-sized gold particles, are enriched in Hg-As-Sb-Ba, and are hosted by hydrofracted quartz-pyrite stockworks or fine-grained carbonaceous limestones. Bonanza deposits are characterized by polymetallic veins and stockworks. Economic concentrations require initial high gold solubility, unrestricted recharge of meteoric water into a region of steady high heat flow, fracture-controlled fluid focusing, and either host-rock r activity or episodic self-sealing, with explosive pressure release in the zone of deposition. Boiling, temperature decrease, solution oxidation and local ground-water mixing are the primary processes of ore deposition. Modern-day analogs of such ore forming systems exist in New Zealand, Japan, western USA, Indonesia, and the Philippines, among others.

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