Extent of salt dissolution and brine flushing to the Dolores River in the Paradox Valley, Colorado

Ambria P. Dell'Oro, Jihyun Kim, Grant Ferguson1, and Jennifer McIntosh

Hydrology and Atmospheric Sciences
The University of Arizona

The Dolores River is a tributary to the Colorado River located in Paradox Valley, CO and is widely known for it’s high salt loads. The Paradox Valley is an anticlinal salt valley, underlain by a salt wall of the Pennsylvanian Hermosa Formation. The valley began forming when mountain uplifts caused lateral stresses on the sedimentary formation. The weight from the overlying strata followed by stress relaxation forced salt from deep underground to flow up and create a diapiric anticline. Discharge of shallow brines (up to 43,300 tons/yr TDS) in the alluvial aquifer into the Dolores River is responsible for the significant increase in the salinity load. Prior research concluded the dissolution of halite and gypsum is the main contributor of salinity in shallow aquifers and the Dolores River. Our research aims to determine the volume of salt that has been dissolved and the amount of chloride that has been discharged to the Colorado River over geologic time. Results from this study will help further constrain mechanisms of salt valley formation in the Colorado Plateau. In addition, by investigating other world rivers underlain by salt deposits, we can estimate global riverine chloride fluxes from geologic sources.

1Department of Civil and Geological Engineering, University of Saskatchewan, Saskatoon, Canada

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