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Chemical characteristics of the major thermal springs of Montana

Open-File Report 76-480
By: , , and 
https://doi.org/10.3133/ofr76480

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Abstract

Twenty-one thermal springs in western Montana were sampled for chemical, isotope, and gas compositions. Most of the springs issue dilute to slightly saline sodium-bicarbonate waters of neutral to slightly alkaline pH. A few of the springs issue sodium-mixed anion waters of near neutral pH. Fluoride concentrations are high in most of the thermal waters, up to 18 milligramsper litre, while F/Cl ratios range from 3/1 in the dilute waters to 1/10 in the slightly saline waters. Most of the springs are theoretically in thermodynamic equilibrium with respect to calcite and fluorite. Nitrogen is the major gas escaping from most of the hot springs; however, Hunters Hot Springs issue principally methane. The deuterium content of the hot spring waters is typical of meteoric water in western Montana. Geothermal calculations based on silica concentrations and Na-K-Ca ratios indicate that most of the springs are associated with low temperature aquifers (less than 100?C). Chalcedony may be controlling the silica concentrations in these low temperature aquifers even in 'granitic' terranes.

Suggested Citation

Mariner, R.H., Presser, T.S., and Evans, W.C., 1976, Chemical characteristics of the major thermal springs of Montana: U.S. Geological Survey Open-File Report 76-480, iii, 31 leaves :ill. ;28 cm.; (38 p. - PGS), https://doi.org/10.3133/ofr76480.

ISSN: 2331-1258 (online)

Publication type Report
Publication Subtype USGS Numbered Series
Title Chemical characteristics of the major thermal springs of Montana
Series title Open-File Report
Series number 76-480
DOI 10.3133/ofr76480
Year Published 1976
Language ENGLISH
Publisher U.S. Geological Survey,
Description iii, 31 leaves :ill. ;28 cm.; (38 p. - PGS)
Additional publication details