TY - JOUR
T1 - Stability of majorite (Mg, Fe)SiO3 at high pressures and 1800°C
AU - Ohtani, Eiji
AU - Kagawa, Naohiro
AU - Fujino, Kiyoshi
N1 - Funding Information:
The authors appreciate Drs. I. Ohno and I. Kawabe of Ehime University and Dr. T. Kato and Prof. K. Onuma of Tohoku University for useful discussions on the manuscript. They also thank Prof. N. Yoshinaga and Dr. N. Matsueda of Ehime university for providing a chance to make a X-ray diffraction study of the run products. This work was partially supported by the grant-in-aid of the Ministry of Education, Science, and Culture, Japan, nos. 61840026, 63540654 and 01420013.
PY - 1991/2
Y1 - 1991/2
N2 - Phase relations in the system MgSiO3-FeSiO3 were studied experimentally up to a pressure of 24 GPa at 1800°C. Alumina-free tetragonal garnet exists in the pressure range from 16 to 23.5 GPa. The compositional range of the tetragonal garnet phase extends from pure MgSiO3 to (Mg0.76Fe0.24)SiO3 at 18.2 GPa and 1800°C. The sequence of the phase transitions in Mg-rich part of this system at 1800°C is: clinopyroxene → 17GPatetragonal garnet → 22.5GPailmenite → 23GPa Mg-perovskite. The lattice constants of tetragonal garnet increase with increasing iron content from a= 11.517 ± 0.002 A ̊ and c = 11.435 ± 0.003 A ̊ for MgSiO3 to a = 11.543 ± 0.002 A ̊ and c = 11.476 ± 0.003 A ̊ for (Mg0.76Fe0.24)SiO3. Cubic garnet was not observed in the pressure and temperature range studied in this work. The alumina-free tetragonal garnet observed in this study may exist in the harzbergite layer in the descending slab.
AB - Phase relations in the system MgSiO3-FeSiO3 were studied experimentally up to a pressure of 24 GPa at 1800°C. Alumina-free tetragonal garnet exists in the pressure range from 16 to 23.5 GPa. The compositional range of the tetragonal garnet phase extends from pure MgSiO3 to (Mg0.76Fe0.24)SiO3 at 18.2 GPa and 1800°C. The sequence of the phase transitions in Mg-rich part of this system at 1800°C is: clinopyroxene → 17GPatetragonal garnet → 22.5GPailmenite → 23GPa Mg-perovskite. The lattice constants of tetragonal garnet increase with increasing iron content from a= 11.517 ± 0.002 A ̊ and c = 11.435 ± 0.003 A ̊ for MgSiO3 to a = 11.543 ± 0.002 A ̊ and c = 11.476 ± 0.003 A ̊ for (Mg0.76Fe0.24)SiO3. Cubic garnet was not observed in the pressure and temperature range studied in this work. The alumina-free tetragonal garnet observed in this study may exist in the harzbergite layer in the descending slab.
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U2 - 10.1016/0012-821X(91)90005-3
DO - 10.1016/0012-821X(91)90005-3
M3 - Article
AN - SCOPUS:0026064818
VL - 102
SP - 158
EP - 166
JO - Earth and Planetary Sciences Letters
JF - Earth and Planetary Sciences Letters
SN - 0012-821X
IS - 2
ER -