ARGON DIFFUSION FROM BIOTITE AT HIGH-TEMPERATURE AND PRESSURE

The experiments of argon diffusion dynamics for biotite were carried o ut at 700-1000 degrees C and 0.5-2.0 GPa and the diffusion coefficient and activation energy using different models have been calculated. Th e results indicate that the pressure does affect the argon diffusion a nd its effect is opposite to that of temperature. When p increases, th e activation energy increases and diffusion coefficient decreases. The relation between pressure, closure temperature and cooling rate has b een obtained. It is postulated that in low T and high p conditions, th e argon diffusion from the environment to the system could occur and i ncur the appearance of the external argon in minerals.