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Pathline and Geochemical Evolution of Ground Water in a Regional Discharge Area, Red River Valley, North Dakota
Author(s) -
Gerla Philip J.
Publication year - 1992
Publication title -
groundwater
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.84
H-Index - 94
eISSN - 1745-6584
pISSN - 0017-467X
DOI - 10.1111/j.1745-6584.1992.tb01560.x
Subject(s) - groundwater recharge , geology , groundwater , surface water , hydrology (agriculture) , outwash plain , aquifer , geomorphology , geochemistry , glacial period , environmental science , geotechnical engineering , environmental engineering
Ground water in the Red River Valley region of North Dakota evolves from HCO 3 to SO 4 to Cl‐type water over a distance of less than 100 km. Pathline analysis of ground‐water flow in a transect across the valley combined with chemical equilibrium and mass balance relationships explain the processes responsible for the observed geochemical evolution. Prior geological studies have shown that the central Red River Valley is a discharge zone for regional ground‐water flow. Discharged waters are generated from different sources, processes, and pathlines. Closed surface drainage and small permeability provide Na‐HCO 3 water for bedrock recharge on the western side of the transect. In contrast, greater recharge in shale outwash is characterized by Ca‐Mg‐HCO 3 water. Both ultimately evolve to SO 4 water with similar proportions of major cations. Upward flow through Paleozoic sediments into the Lower Cretaceous Inyan Kara Group consists of Na‐Cl water modified by downward leakage of SO 4 water from Cretaceous shale and HCO 3 ‐SO 4 water from glacial sediments. Discharged ground water reveals chemical characteristics that suggest mixing of spatially varying proportions of local recharge and more evolved, deeper ground water. Mineral/ground‐water equilibria and estimation of mass transfer indicate that ground‐water composition is largely controlled by carbonate precipitation and dissolution, gypsum dissolution, and clay cation exchange.