Anharmonie vibration of the SiO4 tetrahedron in olivine at temperatures in the subduction zone: An infrared absorbance spectroscopic study

作者：Wang Fei^*; Liu Xi; Zheng HaiFei; Zhang LiFei

来源：Acta Petrologica Sinica, 2015, 31(7): 1891-1900.

• Anharmonic vibration
• Anharmonicity coefficient
• Olivine
• Infrared transmission spectroscopy
• Effect of temperature

Olivine is not only the dominant mineral in the upper mantle of the Earth, but also the major mineral in the subducted slab. It is generally accepted that the atom groups in olivine vibrate in an anharmonic manner at normal mantle temperatures. How they behave at the low temperatures typical in a subduction zone, however, is unclear. In this study, we systematically investigated the IR features of some doubly polished olivine thin sections with different thicknesses using infrared transmission spectroscopy, especially focusing on the overtone/combination bands in the 2100 similar to 1500cm(-1) region. With the IR data collected from room temperature to about 450 degrees C, we obtained the relationships between the anharmonicity coefficient (chi) and temperature for two characteristic IR bands of the SiO4 tetrahedra: the equations are chi(838) =6.37(2) x 10(-7) x T + 0. 0014(1) and chi(993) =7.86(3) x 10(-7) x T + 0. 0015(1), with T in degrees C. When extrapolated to 600 degrees C, these equations produce chi(838) = 0. 0018 (1) and chi(993) = 0. 0020 (2), which presumably indicate a negligible role of the anharmonic behavior for the SiO4 tetrahedra in olivine at the low temperatures in the subduction zone.

• 出版日期2015-7
• 单位北京大学