An overview of vis-nir-swir field spectroscopy - Spectral International

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Boiling of liquid in the LS geothermal environment leads to precipitation of gold
in veins accompanied by a variety of features such as adularia and bladed
calcite cementing colloform and brecciated quartz. Silica sinters may be the
surface expression of such veins and may be accompanied by nearby zones of
surficial steam-heated acid alteration
These deposits form in both subaerial, predominantly felsic, volcanic fields in
extensional and strike-slip structural regimes and island arc or continental
andesitic stratovolcanoes above active subduction zones. Near-surface
hydrothermal systems, ranging from hot springs at surface to deeper, structurally
and permeability focused fluid flow zones are the sites of mineralization. The ore
fluids are relatively dilute and cool solutions that are mixtures of magmatic and
meteoric fluids. Mineral deposition takes place as the solutions undergo cooling
and degassing by fluid mixing, boiling, and decompression.
http://www.em.gov.bc.ca/mining/Geolsurv/MetallicMinerals/MineralDepositProfile
s/profiles/h05.htm Panteleyev (1996):
Model for Low Sulfidation Epithermal Vein Systems
Figure 20 - Figure shows a model for a low-sulfidation epithermal gold system. Note distribution
of alteration zoning and know deposits. (Corbett and Leach, 1998)
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