Download - Hydrothermal mineral deposits
Hydrothermal mineral deposits
Hydrothermal ActivityHydrothermal Activity• The circulation of water through hot
volcanic rocks and magma• Forms fumarolesfumaroles – volcanic vents
emitting gases, some charged with dissolved minerals
• Forms geysersgeysers – heated hydrothermal waters under pressure, that intermittently erupts at the surface
• Provides the source for Geothermal Geothermal EnergyEnergy.
Hydrothermal Mineral DepositsHydrothermal Mineral Deposits
Most of the metallic minerals mined in the world, such as copper, gold, silver, lead, and zinc, are associated with volcanism
Magmas may get the metallic components from:
– Partial melting of the mantle at mid-ocean ridges and subduction zones
– From the subducted slab
– Melting of the crust as magma rises through it
Image from the article: The role of Magmas in the formation of Hydrothermal Ore Deposits, by Hendenquist and Lowenstern, Nature, Vol. 370, 1994
Rising magma does not always reach the surface to erupt; instead it may slowly solidify beneath the volcano
As the magma body cools, the metallic elements become concentrated in the residual fluids called HYDROTHERMAL SOLUTIONS
Groundwater or seawater can also come in contact with the magma body and form hydrothermal solutions
Hydrothermal Systems Hydrothermal Systems Water enters the ground by Water enters the ground by
infiltration infiltration
Hydrothermal Systems Hydrothermal Systems Water enters the ground by Water enters the ground by
infiltration infiltration
Heated water Heated water begins to rise begins to rise
Hydrothermal Systems Hydrothermal Systems Water enters the ground by Water enters the ground by
infiltration infiltration
Heated water Heated water begins to rise begins to rise
Hot Springs:Hot Springs: form when form when heated groundwater reaches the heated groundwater reaches the
surface surface
Hydrothermal Systems Hydrothermal Systems Water enters the ground by Water enters the ground by
infiltrationinfiltration
Heated water Heated water begins to risebegins to rise
Hot Springs:Hot Springs: form when form when heated groundwater reaches the heated groundwater reaches the
surfacesurface
Geysers:Geysers: form where a form where a complicated plumbing system complicated plumbing system
allows steam pressure to be built allows steam pressure to be built up, causing intermittent eruptions up, causing intermittent eruptions
The magma body heats and circulates the hydrothermal solutions carrying the metallic compounds
The metals become
concentrated by
circulating hot fluids
When the fluids become cooler (near surface or away from the magma body), the metallic minerals are deposited to form rich mineral veins
Oatman, AZGold bearing
hydrothermal vein deposit
Large quantities of sulfide deposits form at mid-ocean ridges and other undersea volcanoes in this manner
* Sulfides are the most common of the metallic ores* Sulfides are the most common of the metallic ores
Some Copper OresSome Copper Ores
Kennecott Open Pit Copper Mine, Utah