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Hydrothermal mineral deposits are accumulations of valuable minerals which formed from hot waters circulating in Earth's crust through fractures. They eventually produce metallic -rich fluids concentrated in a selected volume of rock, which become supersaturated and then precipitate ore minerals.
The Oubasi orogenic gold deposit in Southern Ghana is host to mineral resources of over 70 Moz Au at a grade of 7.39g/t or higher, with a past production of 32 Moz Au. [9] The deposit is located in the Birimian orogen, where gold mining is known to have taken place back to the 17th century, but modern industrial-scale mining began in 1897 by ...
Epithermal — mineral ore deposits formed at low temperatures (50–200 °C) near the Earth's surface (<1500 m), that fill veins, breccias, and stockworks. [2] Telethermal — mineral ore deposits formed at shallow depth and relatively low temperatures, with little or no wall-rock alteration, presumably far from the source of hydrothermal ...
Volcanogenic massive sulfide ore deposits, also known as VMS ore deposits, are a type of metal sulfide ore deposit, mainly copper-zinc which are associated with and produced by volcanic-associated hydrothermal vents in submarine environments. [2] [3] [4] These deposits are also sometimes called volcanic-hosted massive sulfide (VHMS) deposits.
Polymetallic or sulfide deposits form in active oceanic tectonic settings such as island arcs and back-arcs and mid ocean ridge environments. [29] These deposits are associated with hydrothermal activity and hydrothermal vents at sea depths mostly between 1 and 4 km (0.62 and 2.5 mi). These minerals are rich in copper, gold, lead, silver and ...
Veins formed in this way may exhibit a colloform, agate-like habit, of sequential selvages of minerals which radiate out from nucleation points on the vein walls and appear to fill up the available open space. Often evidence of fluid boiling is present. Vugs, cavities and geodes are all examples of open-space filling phenomena in hydrothermal ...
The ore fluids of MVT deposits are typically low temperature (100 °C–150 °C) and have the composition of basinal brines (10–30 wt.% NaCl equivalent) with pH's of 4.5–5 (buffered by host carbonates). This hydrothermal fluid may or may not carry the required sulfur to form sulfide minerals.
Phyllic alteration typically forms in the base-metal zone of a porphyry system. [2] Alteration assemblages vary with depth and with degree of fluid interaction. In deep environments, the most highly altered areas are veins and thin selvages, or halos, that surround them.