Argon diffusion from biotite at high temperature and pressure

t The experiments of argon diffusion dynamics for biotite were carried out at 700 -1000℃ and 0.5 - 2,0 GPa and the diffusion coefficient and activation energy using different models have been calculated. The results indicate that the pressure does affect the argon diffusion and its effect is opposite to that of temperature. When p increases, the activation energy increases and diffusion coefficient decreases. The relation between pressure, closure temperature and cooling rate has been obtained. It is postulated that in low T and high p conditions, the argon diffusion from the environment to the system could occur and incur the appearance of the external argon in minerals.