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Adularia-Sericite Model
e.g. Tonopah (USA), Creede (USA)

Adapted from Evans 1997: Ore Geology and Industrial Minerals


Also known as low sulphidation deposits because of the near neutral sulphide bearing fluids. Located in calderas or other complex volcanic environments and hosted by rhyolite to andesite volcanics with associated intrusions and sediments. The ore has high gold and silver values with variable copper and is situated outside of the heat source. Mineralisation also tends to post date that of the host rock >1 Ma. Alteration is sercitic to intermediate argillic with abundant adularia.

As the meteoric fluid descends it develops a varied elemental composition from the surrounding lithologies, as it is heated by the intrusion it joins a convective cell and rises to the surface, moving within the plane of major fracture system it cools, causing precipitation of its metals and the formation of a deposit.


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