SOLUTE AND ISOTOPIC GEOCHEMISTRY AND GROUND-WATER FLOW IN THE CENTRALWASATCH RANGE, UTAH

Ground water flow systems in the rugged central Wasatch Range, Utah, w ere investigated by solute and isotopic methods. Six types of ground w ater systems were identified on the basis of rock type and structure. The systems are broadly grouped into four categories: (1) granitic sys tems; (2) non-granitic systems: (a) unconsolidated alluvial systems, ( b) consolidated sedimentary rock systems, and (c) fault controlled sys tems; (3) thermal systems; (4) mine drainage systems, These ground wat er systems have distinctive solute and isotopic chemistries, Based on an analysis of H-3 and C-14 data, all of the ground waters have a comp onent of post-1952 recharge water, and most of the ground waters are c omposed almost entirely of post-1952 recharge water. A few of the grou nd water systems contain some water which is hundreds to perhaps thous ands of years old. The delta(18)O and delta(2)H data plot on a local m eteoric water line, and none of the data exhibit a positive delta(18)O shift. The absence of a positive delta(18)O shift suggests maximum aq uifer temperatures are approximately 100 degrees C. Granitic terrains are dominated by fracture controlled, local ground water flow systems which respond rapidly to recharge events. The granitic ground water sy stems have estimated maximum circulation depths of about 160 m below l and surface. All the alluvial, most of the consolidated sedimentary be drock, and some of the fault controlled ground water systems are shall ow circulating, local flow systems with short travel times. Ground wat er circulation of most of the local flow systems is within 200 m of la nd surface and is bedding plane controlled. Some of the consolidated b edrock and many of the fault controlled ground water systems are of th e intermediate type and have circulation depths to 500 m. Four thermal ground water systems have been identified. The thermal systems are he ated by the geothermal gradient and have not circulated deeper than 2- 2.5 km. The thermal systems are of the intermediate and regional type.