Greenstone belt

A greenstone belt is an elongated assemblage of metamorphosed volcanic and sedimentary rocks, especially common in Archean cratons. Many contain gold deposits.

Archean: The earliest eon of Earth history, spanning about 4.0 to 2.5 billion years ago. Many of the best-known greenstone belts formed during this eon.
Subduction: The descent of one tectonic plate beneath another into the mantle. Subduction can generate volcanic arcs and deform rocks later incorporated into belts.
Orogenic gold deposit: A gold deposit formed when mineralizing fluids moved through faults and fractures during mountain-building deformation. Many greenstone belts host this economically significant style of gold mineralization.
Barberton greenstone belt: An Archean geological belt in South Africa and Eswatini containing some of Earth's oldest well-preserved rocks. Its exceptionally old rocks provide a detailed record of early Earth environments.
Craton: An old, stable part of continental lithosphere that has resisted major deformation for billions of years. Greenstone belts are commonly preserved within these ancient continental cores.
Island arc: A curved chain of volcanic islands formed above a subduction zone in an ocean. Arc volcanism is one proposed source of some belt rocks.
Kalgoorlie: A Western Australian city near major gold deposits in the Archean Yilgarn Craton. Its goldfield lies within the Norseman–Wiluna greenstone belt.
Yilgarn Craton: An ancient continental block in Western Australia that contains extensive Archean greenstone belts. Its belts host major gold and nickel deposits.
Komatiite: An ultramafic volcanic rock formed from exceptionally hot, magnesium-rich lava. Komatiite is a distinctive volcanic rock found in some Archean belts.
Mantle plume: A rising column of unusually hot mantle that can produce extensive volcanism. Plume-related volcanism is another proposed origin for some Archean volcanic sequences.

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