Moderately low-T Hydrothermal Deposit
Low-T Hydrothermal Deposit + Moderate-T Hydrothermal Deposit
Required Geological Setting
Occurrence
Combined vein-type deposit formed by overlapping two types of hydrothermal deposits: Low-T hydrothermal deposit by 100-250 degree hydrothermal fluid and Moderate-T hydrothermal deposit by 200-300 hydrothermal fluid. Both types of hydrothermal fluid are originated from Acidic (Rhyolite) to Neutral (Dacite, Andesite) magmatic activities by volcanoes such as caldera complexes in volcanic island arc. Moderate-T hydrothermal deposit is usually formed at the early stage, and it is followed by Low-T hydrothermal deposit along with cooling of the heat source. Rare minerals such as sulfosalt minerals may be formed at the Low-T hydrothermal deposit formation stage as low-T hydrothermal fluid reacts with minerals of Moderate-T hydrothermal deposit. High-T hydrothermal deposit may be also overlapped to be Xenothermal deposit.
Distribution of Moderately low-T Hydrothermal Deposits described in this site. Green dots are moderately low-T hydrothermal deposits, and red dots are those combined with skarn. Yellow lines are volcanic fronts.
Mineral Assemblages (Characteristic minerals)
Boulangerite, Jamesonite, Bournonite, Lillianite, Chalcostibite
Localities
- Suzukura Mine (Granite, Fe-Pb-As)
- Nakamaru Mine (Dacite, Cu-Sb-As)
- Tsugu Mine (Andesite, Cu-Sb)