CHEMICAL AND ISOTOPIC INVESTIGATION OF GROUNDWATER SYSTEMS IN THE VICINITY OF THE NEW HARMONY BASIN, UTAH

The New Harmony basin is located between Cedar City and St. George Utah. The basin is bounded to the west and north-west by granitic rocks of the Pine Valley Mountains, to the south by Quaternary volcanic rocks and the Navajo Sandstone, and to the east by the Hurricane Cliffs uplifted along the Hurricane fault zone. Synclinally folded Tertiary to Mesozoic age sediments in the basin plunge gently into the Hurricane fault zone. The basin drains south along Ash Creek.

Based on solute and isotopic samples from 12 wells, 7 springs and 14 creeks in the vicinity of the New Harmony basin including the Toquerville area, Utah, several distinct groundwater systems have been identified by chemical isotopic differences. The systems include granitic rocks of the Pine Valley Mountains, basin fill sediments of the New Harmony Basin, volcanic rocks located south of New Harmony basin, and the Navajo Sandstone. Groundwater in the Pine Valley Mountains circulates shallowly and contains anthropogenic carbon-14. Shallow groundwater systems in the New Harmony basin also contain anthropogenic carbon-14 and have elevated tritium contents, whereas, deep groundwater systems in the basin have carbon-14 groundwater ages in excess of 11,000 years. Stable and unstable isotopic and chemical data indicate that New Harmony basin and granitic rock groundwater are not in hydraulic communication with the Navajo Sandstone and are not are not the source of the large discharge Toquerville spring, which issues from volcanic rocks down gradient of the New Harmony basin. Toquerville spring discharges modern water containing anthropogenic carbon-14 and appreciable tritium.