Thermal Decomposition Kinetics of Clinochlore at High Temperature and Its Implications

Abstract

Abstract The dehydration kinetics of clinochlore were performed using a non-isothermal thermogravimetric analysis under a dynamic nitrogen atmosphere at ambient pressure. Clinochlore, with a grain size of 5–10 μm, was analyzed using heating rates of 2, 5, 10, 20, and 40 K/min at temperatures of up to 1260 K. Thermogravimetric data of clinochlore at different heating rates were modeled using the Kissinger method, Flynn-Wall-Ozawa method, and Coats-Redfern method. The dehydration of clinochlore is ascribed to the decomposition of brucite and talc layers. The dehydration temperature of the brucite layer is 730–920 K, which corresponds to a two-dimensional phase boundary model (R2) with an activation energy of 214.94 ± 7.79 kJ/mol and a pre-exponential factor of 12.52 ± 0.62 min−1. The dehydration temperature of the talc-like layer is 960–1140 K, which follows a two-dimensional diffusion model with an apparent activation energy of 419.49 ± 23.62 kJ/mol and a pre-exponential factor of 19.97 ± 1.76 min−1. Combined with the parameters obtained in this study, the fast dehydration of clinochlore can trigger earthquakes in the subduction zone.