Solute Chemistry and Isotopic Investigation of the Groundwater Flow Paths in Honey Lake Basin, Lassen County, California and Washoe County, Nevada Solute Chemistry and Isotopic Investigation of the Groundwater Flow Paths in Honey Lake Basin, Lassen County, California and Washoe County, Nevada
Temperature data reveal that thermal waters circulate to 1.6-3.0 km and 2.8-3.8 km along two major fault zones. Shallow groundwaters above 17Â°C are determined to have a component of thermal water and mixing ratios are presented. Î´18O and Î´D data show that deep groundwater was recharged by cooler, more humid precipitation from the last ice age, whereas shallow groundwaters reflect current meteoric conditions and show extensive evaporation trends. The two thermal flow paths show exchange with silicate minerals at high temperatures (>100Â°C). Î´13C data show interaction with carbonate minerals in basin fill lacustrine sediments. 3H concentrations and 14C ages show that deep groundwaters throughout the Basin and shallower groundwaters in the center of the basin are not greatly affected by post-1952 recharge. Mean 14C ages range from modern to 23,500 years old.
NETPATH was used to model geochemical evolution along the flow paths. Groundwater on the west side of the basin (granitic terrain) is typically low TDS (~150 mg/L) calcium-bicarbonate water and evolves into higher TDS (~300 mg/L) sodium-bicarbonate groundwater as it interacts with granitic rocks and then lacustrine sediments. Groundwater on the east side of the basin (mafic terrain) is typically low TDS (~200 mg/L) sodium-bicarbonate water and evolves into high TDS (~300 mg/L) sodium-bicarbonate water groundwater as it interacts with mafic rocks and then lacustrine sediments. Dissolution of silicate minerals and calcite, and ion exchange with clays is responsible for major chemistry changes. As both of these types of groundwaters come into contact with lacustrine sediments with evaporite minerals on the playas, dissolution of halite and gypsum dominate and the groundwater becomes extremely high in TDS (~ 1100 mg/L on the Honey Lake Playa and ~ 43,000 mg/L on the Fish Spring Playa) and strongly sodium-chloride in character.
School:Brigham Young University
School Location:USA - Utah
Source Type:Master's Thesis
Keywords:honey lake groundwater solute chemistry isotopes oxygen 18 deuterium tritium carbon 13 14 geochemical evolution closed basin playa
Date of Publication:03/02/2007