ABSTRACT

Hf-Zr interdiffusivity in zircon has been determined on hafnon-zircon double-layered crystals using back-scattered electron image contrast in a scanning electron microscope. The observed Hf-Zr interdiffusion coefficient at 1600°C and 1500°C in the direction perpendicular to the c-axis is 2×10^-15 and 3×10^-16 cm²/sec, respectively. The value observed at 1600°C perpendicular to the c-axis is about an order of magnitude higher compared with the value of ∼2×10^-16 cm²/sec along the c-axis. These observed low diffusivity values suggest that diffusivities of Th and U in zircon are expected to be similarly low.