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Moderately high-T Hydrothermal Deposit

Chemical Process (Liquid-phase Growth) - Open system under ground


Mesothermal Deposit, Moderately high-T Hydrothermal Vein Deposit, Moderately high-T Hydrothermal Ore Deposit

Index Minerals

Chalcopyrite, Galena, Sphalerite, Pyrrhotite

Required Geological Setting

Caldera complexes

Associated metasomatic zones

Pyrophyllite zone, High-T silicified zone, Epidote-Actinolite zone


Vein-type deposit formed by 300-350 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, meteoric water, and/or seawater. Meteoric water and seawter are circulated by heat of magma. Typical elements concentrated are Cu, Pb, Zn, and/or As. Host of deposits are volcanic products or basements of volcanoes. Mineral assemblages depends on geological settings of deposits; terrestrial volcano, sumarine volcano, and host rock types in which hydrothermal fluid circulated. The deposit may shift to H-T hydrothermal deposit in the deeper level, and to Moderate-T hydrothermal deposit in the shallower level.

Moderately high-T Hydrothermal Deposit

Distribution of Moderately high-T Hydrothermal Deposits described in this site. Green dots are As-free deposits, and red dots are As-bearing deposits. Yellow lines are volcanic fronts.

Mineral Assemblages (Ore)

Chalcopyrite, Pyrrhotite, Pyrite, Galena, Sphalerite, Arsenopyrite

Mineral Assemblages (Gangue)

Quartz, Rhodochrosite, Calcite, Dolomite, Siderite, Barite, Kaolinite

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