Geochemistry of selected rock samples: Colado geothermal area, Nevada

The results of the chemical analysis of 30 surface rock samples from the Colado geothermal area are presented. The samples represent a variety of materials affected by several hydrothermal events which have formed Au, Sb and clay deposits within the area. The active geothermal system is currently being evaluated for electrical power production. The elements As, Sb, Au, Ag, Li and Hg have been concentrated during more than one of the hydrothermal events which have affected the Colado area. Distinct chemical signatures do not exist for any particular event, instead, it appears that this suite of elements has been repeatedly remobilized, probably in response to similar physical and chemical conditions and processes. Delineation of geochemical zoning related to the active geothermal system is possible only because it is spatially separated from the older hydrothermal deposits. The chemical similarity between the older hydrothermal events and the present hydrothermal system suggest that the Sb and Au mineralization formed at shallow depths in a boiling geothermal environment. It is suggested that new ore zones may be discovered in the Willard mining district if the geothermal model is applied to exploration.