Silicon diffusion in a natural quartz aggregate: constraints on solution-transfer diffusion creep

摘要: Abstract Silicon bulk diffusion rates were determined in a fine-grained (1.2 μm diameter) natural quartz aggregate (novaculite) from Hot Springs, AR. The experiments done at 600–800°C and 150 MPa confining pressure (hydrothermal) 800–1100°C 1 atm (in stream of dry N2). technique employed an isotopic tracer (30Si) standard step-scan analysis using ion microprobe (SIMS). temperature dependence silicon the novaculite is described by Arrhenius parameters: D0, bulk=3.7×10−10 m2/s Q=137 ±18 kJ/mol, bulk=6.2×10−9 m2/s Q=178 ±38 kJ/mol for hydrothermal experiments, respectively. At 800°C, rate 150 MPa, about factor 10 greater than 1 atm, dry. For assumed effective grain boundary width 2 nm, are two to three less oxygen similar conditions, more 12 orders magnitude anhydrous volume extrapolated these experiments. results this study provide valuable constraints on role diffusion-accommodated deformation quartz-rich rocks.