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Geochemistry of water in the Fort Union Formation of the northern Powder River basin, southeastern Montana

Open-File Report 80-336

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Abstract

Shallow water in the coal-bearing Fort Union Formation of southeastern Montana was investigated to provide a better understanding of the geochemistry. Springs, wells less than 200 feet deep, and wells greater then 200 feet deep were observed to have different water qualities. Overall, the ground water exists as two systems: a mosaic of shallow, chemically dynamic, and localized recharge-discharge cells superimposed on a deeper, chemically static regional system. Water chemistry is highly variable in the shallow system, whereas sodium and bicarbonate waters characterize the deeper system. Within the shallow system , springs, and wells less than 200 feet deep show predominantly sodium and sulfate enrichment processes from recharge to discharge. These processes are consistent with the observed aquifer mineralogy and aqueous chemistry. However, intermittent mixing with downward moving recharge waters or upward moving deeper waters, and bacterially catalyzed sulfate reduction, may cause apparent reversals in these processes. (USGS)

Additional Publication Details

Publication type:
Report
Publication Subtype:
USGS Numbered Series
Title:
Geochemistry of water in the Fort Union Formation of the northern Powder River basin, southeastern Montana
Series title:
Open-File Report
Series number:
80-336
Edition:
-
Year Published:
1980
Language:
ENGLISH
Publisher:
U.S. Geological Survey,
Description:
iv, 21 p. ill., maps ;26 cm.