Abstract
Shallow epithermal stockworks hosted by maar eruption craters contain over ninety percent of the bulk minable gold identified to date in the Circum-Caribbean region. Pueblo Viejo (Dominican Republic) and Santa Rosa (Panama) contains combined gold reserves of over 600 tonnes. Bulk mineable gold deposits are also being discovered in and around veins that were formely mined underground. Bellavista, El Recio and San Martin (Costa Rica) contain combined announced gold reserves of over 50 tonnes.
Two hundred ninety one representative samples collected at 8 bulk mineable gold deposits were analyzed for Au, Ag, As, Hg and Sb and include veins, vein stockworks, hydrothermal eruption breccias, sinter, variably altered host, unaltered host, nearby intrusive rocks, and basement. Analyses completed to date show that Circum-Caribbean epithermal ores are enriched in arsenic, mercury and antimony as well as gold and silver.
Exploration efforts in the region naturally focus on districts with past prodution. However, an order of magnitude more bulk mineable gold has been discovered in maar-hosted shallow epithermal stockworks outside of the old bonanza vein camps. Explorations guides include basal island arc volcanic sequences, hydrothermal and hydrovolcanic (maar) eruption breccias, thinly-bedded carbonaceous maar sediments, and hot spring-related silicification and argillic alteration