geothermal resource potential of the safford-san simon basin, arizona

Artesia in D-8-26-32 and 33 have estimated temperature gradients over lOOoC!km
(Figure 21). No well data is available south of this area. This area may
have potential for geothermal resources exceeding 1000C at reasonably drillable
depths (1 to 2 km).
The high-temperature gradients may indicate a convective
geothermal system beneath confining clays.
Mercury Soil Survey
A mercury soil survey was conducted in the area with high estimated temperature
gradients.
Because mercury soil sampling has been shown to be a
useful exploration technique to define geothermal anomalies with no surface
expression, it is used herein to help define the southern closure of the
anomalous temperature gradient anomaly at Artesia. Matlick and Buseck (1975)
have used the technique in Long Valley, California, Summer Lake and Klamath
Falls, Oregon, with success.
In this survey, two soil samples at each location, five to ten feet apart
and from five to ten cm depth, were collected in 3x5-inch ziplock plastic
bags, sealed and placed in a styrofoam cooler.
Consequently, back in the lab,
the samples were dried and screened through a -80 stainless steel mesh sieve.
Mercury analysis of the sieved fines was done by atomic absorption.
No apparent correlation exists between lithologic units and different
surficial deposits in the area surveyed.
The background mercury concentration
is 225 parts per billion (ppb) mercury (Hg) ± 99 ppb.
This is a relatively
high background concentration, which may reflect the geologic setting
of the surveyed area.
Unusually high soil mercury contents are defined by values exceeding
303 ppb, which is the statistical mean plus one standard deviation.
High concentrations of soil mercury exist south of Artesia and adjacent
to the area of high estimated temperature gradients. Two east-northeast-
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