Geochemistry of water in the Fort Union formation of the northern Powder River basin, southeastern Montana
Water Supply Paper
2076
By: Roger W. Lee
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Abstract
Shallow water in the coal-bearing Paleocene Fort Union Formation of southeastern Montana was investigated to provide a better understanding of its geochemistry. Springs, wells less than 200 feet deep, and wells greater than 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, waters containing sodium and bicarbonate 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.
Suggested Citation
Lee, R.W., 1981, Geochemistry of water in the Fort Union formation of the northern Powder River basin, southeastern Montana: U.S. Geological Survey Water Supply Paper 2076, iv, 17 p. :ill., maps ;23 cm., https://doi.org/10.3133/wsp2076.
| 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 | Water Supply Paper |
| Series number | 2076 |
| DOI | 10.3133/wsp2076 |
| Year Published | 1981 |
| Language | ENGLISH |
| Publisher | U.S. G.P.O. : for sale by the Supt. of Docs., |
| Description | iv, 17 p. :ill., maps ;23 cm. |