The production of Cu-Zn from volcanogenic massive sulfide (VMS) deposits in the eastern Pontides began in the early 1900s, with the exploitation of high-grade ores scattered across the district. The district still possesses economically important blind VMS and associated sulfide deposits. Careful descriptive documentation of the typical features of these VMS ores illustrated the geological characteristics that are important in identifying ore localities and can be used to define exploration targets.

Volcanogenic massive sulide (VMS) deposits, also known as volcanic-hosted massive sulide, volcanic-associated massive sulide, or sealoor massive sulide deposits, are important sources of copper, zinc, lead, gold, and silver (Cu, Zn, Pb, Au, and Ag). These deposits form at or near the sealoor where circulating hydrothermal luids driven by magmatic heat are quenched through mixing with bottom waters or porewaters in near-sealoor lithologies. Massive sulide lenses vary widely in shape and size and may be podlike or sheetlike. They are generally stratiform and may occur as multiple lenses.

Grade and tonnage models are useful in quantitative mineral-resource assessments. The models and database presented in this report are an update of earlier publications about volcanogenic massive sulfide (VMS) deposits (Mosier, Singer, and Salem, 1983; Cox, 1986; Singer, 1986a-c; Singer and Mosier, 1986a, b). These VMS deposits include what were formerly classified as kuroko, Cyprus, and Besshi deposits.

Simplified definition A lens of iron-, copper-, zinc- and lead-sulphides, with significant amounts of silver and gold, formed on or below the sea floor by hot springs on and around submarine volcanoes. Scientific definition Gold-rich volcanogenic massive sulphide deposits (Au-VMS) are a sub-type of both volcanogenic massive sulphide (VMS) and lode gold deposits (Poulsen and Hannington, 1996; Hannington et al., 1999; Huston, 2000; Poulsen et al., 2000) (Fig.1). Like most VMS deposits, they consist of semi-massive to massive, concordant sulphide lenses underlain by discordant stockwork feeder zones.

Volcanogenic massive sulphide (VMS) deposits are also known as volcanic-associated, volcanic-hosted, and volcano-sedimentary-hosted massive sulphide deposits. They typically occur as lenses of polymetallic massive sulphide that form at or near the seafloor in submarine volcanic environments. They form from metal-enriched fluids associated with seafloor hydrothermal convection. Their immediate host rocks can be either volcanic or sedimentary.