Secondary Minerals, Oxidation Potentials, Pressure and Temperature Gradients in the Pasco Basin of Washington State

摘要

Three subjects are addressed: pressure and temperature variations with depth in the Pasco Basin; problems associated with the measurement and interpretation of oxidation potentials; and a review of the secondary mineral phases present at depth in the Pasco Basin. It was found that clinoptilolite, smectite, and silica are the most common secondary minerals in basalts of the Pasco Basin. These materials will act as sorptive substrates for positively charged nuclear species when and if radionuclides enter the groundwater flow system. Any studies involving retention of radionuclides by sorption on geologic materials should, therefore, include the minerals clinoptilolite and smectite. Pressure and temperature profiles for the Pasco Basin show that the environment surrounding the Umtanum unit is characterized by a temperature near 60 exp 0 C and a lithostatic pressure near 0.10 kb. The measurement and interpretation of the oxidation potential of Pasco Basin waters may be difficult if not impossible. 6 figures, 1 table. (ERA citation 04:037605)