Zones of acid leaching in which all components of a rock have been removed except for silica
Typical list of modern geothermal features
Up-flow of acidic hydrothermal fluids break down rocks and form clays at Kerlingarfjoll Geothermal area, Iceland. Photo by Darren Atkins
Often associated with deposition of alunite and bordered by halos of Advanced Argillic Alteration. Leach Cappings are zones of acid leaching in which all components of a rock have been removed except for silica. Such zones are typically encountered near the surface at the zone of principle hydrothermal upflow, where volatile gases condense into shallow groundwater to produce acidic solutions.
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