Figure I Generalized map of the Wilbur Mining ... - University of Utah

This method of calculation assumes the following:
1. Depth is a vertical distance from ground surface.
2. Correction for mean annual temperature is independent
of discharge rate.
3. Water is not mixing between aquifers.
4. Temperature equilibrium is maintained in well.
5. Mean annual temperature influences water temperature
at surface and influences critical
depth as defined above.
CHEMICAL COMPOSITION
The results of standard mineral analyses were
plotted on multiple tri-linear diagr'ams after
Piper (1944). Ground waters were classified as
either sodium chloride-calcium sulfate type, calcium
sulfate type, or calcium-magnesium bicarbonate
type. The bicarbonate waters were generally
found in wells and springs near recharge areas,
and the calcium sulfate waters were found with
either increasing distance from recharge areas
or in ground waters which were known to be mixing
between aquifers. The sodium chloride-calcium
sulfate type water was found only in Madison
ground watiers in the Edgemont geothennal area.
The standard mineral composition of these ground
waters was found to be significantly different
from that of all other sampled ground waters.
Of all the trace elements analyzed, only lithium
and cobalt have higher concentrations in Edgemont
area waters than in waters at all other sites.
Strontium concentrations in Edgemont area waters
ranged from 1,8 to 3,4 mg/l. Although cesium and
rubidium were detected in Edgemont ground waters,
it was not determined whether this is significant
as there is no data from other sampled sites.
Aluminum, copper, lead, manganese, silver, and
zinc were not detected in Edgemont waters, and
additional analyses supplied by the U.S. Geological
Survey indicated that only trace amounts of
these elements, if any at all, occur in ground
waters at other sites in the study area.
GEOTHERMOMETRY
Temperatures were calculated using the quartz and
chalcedony geothermometers defined by Truesdell
(1975) and the Na-K-Ca geothermometer defined by
Fournier and Truesdell (1973). Water temperatures
calculated using the quartz geothermometer ranged
from 9.70c to 46.IOC above observed temperatures,
whereas temperatures calculated using the chalcedony
geothermometer ranged from 24.50C below to
14.0OC above observed temperatures. Water temperature
calculated using the Na-K-Ca geothermometer
ranged from 41.30C below to 41.50C above observed
temperatures.
Table 3 lists the results of selected geothermometer
calculations. The chalcedony geothermometer
yielded the best correlation between observed temperatures
and calculated temperatures. This is in
agreerent with Fournier (1973) who found that
chalcedony, rather than quartz, controls the dissolved
silica content of waters below lOOOC.
167
Knirsch
Most work with geothermometers has been done for
high-temperature geothermal systems. The highest
observed temperature in this study was 560C. No
correlations exist between the results of geothermometer
calculations and temperature-depth gradients.
ACKNOWLEDGEMENTS
We wish to thank the U.S. Department of Energy and
the U.S. Geological Survey for their assistance
with this study.
REFERENCES
Fournier, R. 0., 1973, Silica in thermal waters:
Laboratory and Field Investigations, 2£ Proceedings
of the International Symposium on Hydrogeochemistry
and Biogeochemistry, Japan, 1970, v.
I, Hydrogeochemistry: Washington, DC, The Clark
Co., p. 122-139.
Fournier, R, 0., and Truesdell, A. H., 1973, An
empirical Na-K-Ca geothermometer for natural
waters: Geochim. et Cosmochim. Acta, v. 37,
n. 5, p. 1255-1276.
Gries, J. P., 1977, Geothennal applications on the
Madison (Pahasapa) aquifer system in South Dakota:
Final Report, Contract No. EY-76-S-07-1625,
South Dakota School of Mines and Technology,
100 pp.
Iszler, J., Carda, D,, Skillman, D., Dunham, G.,
and Reuter, W., 1979, Western South Dakota usage
of geothermal energy from the Madison Formation
--final report, ET-78-S-07-1707: Department of
Energy, Division of Geothermal Energy, Washington,
D.C., 153 pp.
Piper, A. M., 1944, A graphic procedure in the
geochemical interpretation of water analyses:
Trans., Am. Geophys. Union, 25th annual meeting,
p. 914-923.
Schoon, R. A., and McGregor, D. J., 1974, Geothermal
potentials in South Dakota: S.O. Geol.
Survey Rept. Inv. 110, 76 pp.
Truesdell, A. H., 1975, Summary of Section III:
Geochemical techniques in exploration Ui Proceedings,
United Nations Symposium on the Development
and Use of Geothermal Resources, 2nd,
San Francisco: Washington, D.C, U.S. Govt.
Printing Office, p. LIII-LXXIX.