Reitman, Nadine听1听;听Ge, Shemin听2听;听Mueller, Karl听3
1听University of Colorado at 麻豆影院, Department of Geological Sciences
2听University of Colorado at 麻豆影院, Department of Geological Sciences
3听University of Colorado at 麻豆影院, Department of Geological Sciences
Groundwater flow is an important control on subsurface salt dissolution. Natural evaporites are salt deposits that crack when dry or unloaded and flow ductilely when wet or loaded. These dynamics drive faulting and associated subsidence on the land surface. Dissolution of evaporites has increased salinity in groundwater and salt loading in river systems. A better understanding of the groundwater system is important for determining groundwater鈥檚 role in active fault slip, evaporite deformation, and salinity variations in freshwater resources. This study is conducted in the Gypsum Canyon watershed within the Paradox Basin in southeast Utah, south of Canyonlands National Park. The area comprises regional sedimentary formations underlain by evaporite cycles of the Paradox Formation. Active faults in the region slip at a rate of approximately 1 鈥� 2 mm/year (Furuya et al., 2007), possibly due to evaporite dissolution. This study characterizes the groundwater flow and solute transport system of the Gypsum Canyon watershed using a 3D finite element groundwater flow and solute transport model, SUTRA. The lack of prior data and instrumentation and remote location of the watershed led to the use of creative methods for constraining and validating the model. Methods include sampling and mapping groundwater seeps and springs, analyzing stable isotopes of water (未18O and 未D) and total dissolved solids (TDS) in springs samples, and collecting rock samples for conducting hydraulic conductivity tests. Modeling results suggest that there is not enough groundwater-driven salt dissolution to account for the observed rate of fault slip in the region, and this watershed contributes on the order of 0.5 ton of salt per year to the Colorado River.
Furuya, M., Mueller, K., and Wahr, J., 2007, Active salt tectonics in the Needles District, Canyonlands (Utah) as detected by interferometric synthetic aperture radar and point target analysis: 1992鈥�2002: Journal of Geophysical Research, v. 112, no. B6, p. 1鈥�18, doi: 10.1029/2006JB004302.