Anomalous gold, antimony, arsenic, and tungsten in ground water and alluvium around disseminated gold deposits along the Getchell Trend, Humboldt County, Nevada

Journal of Geochemical Exploration
By: , and 

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Abstract

Ground-water, alluvium, and bedrock samples were collected from drill holes near the Chimney Creek, Preble, Summer Camp, and Rabbit Creek disseminated gold deposits in northern Nevada to determine if Au and ore-related metals, such as As, Sb, and W, are being hydromorphically mobilized from buried mineralized rock, and, if they are, to determine whether the metal-enriched ground water is reacting with the alluvial material to produce a geochemical anomaly within the overburden.

Results of chemical analyses of drill-hole water samples show the presence of hydromorphic dispersion anomalies of Au, As, Sb, and W in the local ground-water systems associated with these deposits. Background concentrations for Au in the ground water up-gradient from the buried deposits was less than 1 nanogram per liter (ng/L), near the deposits the Au values ranged from 1 to 140 ng/ L, and in drill holes penetrating mineralized rock, concentrations of Au in the ground water were as high as 4700 ng/L. Highest concentrations of Au were found in ground-water samples where the measured Eh and the distribution of arsenic species, arsenite [As(III)] and arsenate [As(V)], indicated oxidizing redox potentials. Similarly, As, Sb, and W concentrations in the ground water near the deposits were significantly enriched relative to concentrations in the ground water up-gradient from the deposits. In general, however, the highest concentrations of As, Sb, and W occurred in ground-water samples where the measured Eh and the distribution of arsenic species indicated reducing conditions. Arsenic concentrations ranged from 9 to 710 micrograms per liter (μg/L); Sb, from less than 0.1 to 250 μg/L; and W, from 1 to 260 μg/L.

In addition, analysis of sequential dissolution and extraction solutions of drill cuttings of alluvium and bedrock indicate geochemical anomalies of gold and ore-related metals in the overburden at depths corresponding to the location of the present-day water table. This relationship suggests that water-rock reactions around these buried deposits are active and that this information could be very useful in exploration programs for concealed disseminated gold deposits.

Publication type Article
Publication Subtype Journal Article
Title Anomalous gold, antimony, arsenic, and tungsten in ground water and alluvium around disseminated gold deposits along the Getchell Trend, Humboldt County, Nevada
Series title Journal of Geochemical Exploration
DOI 10.1016/0375-6742(94)00023-5
Volume 52
Issue 3
Year Published 1995
Language English
Publisher Elsevier
Description 21 p.
First page 351
Last page 371
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