Low-T Hydrothermal Deposit

Synonym

Epithermal deposit, Low-T Hydrothermal Vein Deposit, Low-T Hydrothermal Ore Deposit

Index Minerals

Stibnite, Gold, Realgar, Marcasite

Required Geological Setting

Caldera complexes

Associated metasomatic zones

Kaolinite zone, Low-T silicified zone, Interstratified mineral zone

Occurrence

Vein-type deposit formed by 100-250 degree hydrothermal fluid originated from Acidic (Rhyolite) to Neutral (Dacite, Andesite) magmatic activities by volcanoes such as caldera complexes in volcanic island arc. Origin of hydrothermal fluid is magmatic water from magma and/or meteoric water. Meteoric water is circulated by heat of magma. Typical elements concentrated are Au, Sb, and/or As. Host of deposits are volcanic products or basements of volcanoes. The deposit may shift to Moderate-T hydrothermal deposit in the deeper level, and to Hydrothermal Au-Ag deposit in the shallower level.

Mineral Assemblages (Ore)

Stibnite, Gold, Realgar, Pyrite, Marcasite, Tetrahedrite

Mineral Assemblages (Gangue)

Quartz, Baryte