Abstract
Al diffusion under anhydrous 1-atm conditions has been measured in natural zircon. Experiments used a source consisting of AlPO4-ZrSiO4 powder mixtures. Experiments were run in air in crimped Pt capsules. Al profiles were measured with Nuclear Reaction Analysis (NRA) using the reaction 27Al(p, γ)28Si. For diffusion parallel to c, the following Arrhenius relation is determined:D = 6.24 × 103 exp.(−774 ± 34 kJ mol−1 /RT) m2s−1Diffusivities normal and parallel to c are similar, indicating little anisotropy of diffusion of Al.Al diffuses more rapidly than tetravalent cations that substitute on the Si site in zircon, but more slowly than trivalent cations substituting on the Zr site. These slow diffusivities indicate that Al chemical signatures will be quite resistant to diffusional alteration. For example, Al compositions at the center of 50 μm radius zircon grains would be preserved over times greater than the age of the earth at temperatures in excess of 1000 °C.
Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
