R7: Petrology, Mineralogy and Economic geology (Joint session with SRG)

[R7P-04] A pseudo-temperature distribution in the oceanic lithosphere caused by cooling rate responsiveness of pyroxene geothermometry

*Koshi Nishimura¹, Junji Yamamoto², Hidemi Ishibashi³ (1. Toyo Univ., 2. Hokkaido Univ., 3. Shizuoka Univ.)

Keywords:two-pyroxene thermometer, oceanic lithosphere, mantle, cooling-rate responsiveness, Project Mohole

We calculated a pseudo-temperature distribution in the oceanic lithosphere caused by cooling rate responsiveness of pyroxene geothermometry. Calcium diffusion in clinopyroxene adjacent to orthopyroxene is estimated under P-T conditions of a cooling oceanic lithosphere. The compositions of two pyroxenes at a contact surface are determined based on a thermodynamic model assuming instantaneous interfacial equilibrium.