Energetics of melts from thermal diffusion studies. FY 1993 progress report

This research program characterizes diffusional mass transport in geological fluids in response to thermal, solubility and chemical gradients using tools of experimental petrology. Quantitative information is obtained on the thermodynamic and kinetic properties of multicomponent systems that are the basis for predictive models of chemical diffusion, mineral dissolution, and complexing in synthetic and natural silicate systems. Among the technical accomplishments related to establishing the UCD experimental petrology laboratory in the last year has been the design and construction of two compact piston-cylinder devices capable of achieving 40 kb using 1/2-in. pressure vessels (also capable of accommodating 3/4-in. vessels). These machines are now on-line and performing thermal diffusion experiments. In addition to establishing the new laboratory at UCD, the PI began studies of molecular diffusion in the absence of a thermal gradient with results published on the chemical and self diffusion of Sr and Nd in naturally-occurring silicate liquids, and self diffusivities of Si and O in basaltic liquid