TY - JOUR
T1 - Effects of Fe-enrichment on the equation of state and stability of (Mg,Fe)SiO3 perovskite
AU - Dorfman, Susannah M.
AU - Meng, Yue
AU - Prakapenka, Vitali B.
AU - Duffy, Thomas S.
N1 - Funding Information:
This work was supported by the NSF and the Carnegie-DOE Alliance Center . C.M. Holl assisted with beamline measurements. J. Delaney assisted with chemical analyses at the Rutgers University microprobe facility. S. Tkachev provided support for high-pressure gas loading. High-pressure gas loading was supported by COMPRES and GeoSoilEnviroCARS. P. Dera, K. Zhuravlev and I. Kantor assisted with beamline operations. Experiments were performed at GeoSoilEnviroCARS (Sector 13) and High Pressure Collaborative Access Team (HPCAT, Sector 16) at the APS. GeoSoil EnviroCARS is supported by the NSF – Earth Sciences ( EAR-1128799 ) and DOE – Geosciences ( DE-FG02-94ER14466 ). HPCAT is supported by CIW, CDAC, UNLV and LLNL through funding from DOE-NNSA and DOE-BES, with partial instrumentation funding by NSF. Use of the APS was supported by the U.S. Department of Energy, Office of Basic Energy Sciences, under Contract No. DE-AC02-06CH11357. Appendix A
PY - 2013/1/1
Y1 - 2013/1/1
N2 - Fe-rich natural orthopyroxenes with compositions of (Mg0.61Fe0.38Ca0.01)SiO3 (Fe#38) and (Mg0.25Fe0.74Ca0.01)SiO3 (Fe#74) were studied at pressures up to 155GPa and temperatures up to 3000K. Single-phase orthorhombic GdFeO3-type perovskite was synthesized by heating to ~2000 K at 63GPa for the Fe#38 composition and at 72GPa for the Fe#74 composition. At lower pressures, heating both compositions resulted in a mixture of perovskite, SiO2 and (Mg,Fe)O. These measurements provide new constraints on the dependence of (Mg,Fe)SiO3 perovskite stability on pressure and composition. Upon further compression and heating at 89 and 99GPa, Fe#38 and Fe#74 perovskites transformed to two-phase mixtures of perovskite and post-perovskite, consistent with previous findings that increasing Fe content lowers the transition pressure. The volume of (Mg,Fe)SiO3 perovskites increases linearly with Fe-content. Volume data were fit to the Birch-Murnaghan equation of state. The bulk modulus at 80GPa is 550-560GPa for both Fe-rich perovskites, comparable to or slightly higher than the values measured for MgSiO3 perovskite at this pressure, indicating that the bulk modulus of perovskite is not strongly sensitive to Fe content.
AB - Fe-rich natural orthopyroxenes with compositions of (Mg0.61Fe0.38Ca0.01)SiO3 (Fe#38) and (Mg0.25Fe0.74Ca0.01)SiO3 (Fe#74) were studied at pressures up to 155GPa and temperatures up to 3000K. Single-phase orthorhombic GdFeO3-type perovskite was synthesized by heating to ~2000 K at 63GPa for the Fe#38 composition and at 72GPa for the Fe#74 composition. At lower pressures, heating both compositions resulted in a mixture of perovskite, SiO2 and (Mg,Fe)O. These measurements provide new constraints on the dependence of (Mg,Fe)SiO3 perovskite stability on pressure and composition. Upon further compression and heating at 89 and 99GPa, Fe#38 and Fe#74 perovskites transformed to two-phase mixtures of perovskite and post-perovskite, consistent with previous findings that increasing Fe content lowers the transition pressure. The volume of (Mg,Fe)SiO3 perovskites increases linearly with Fe-content. Volume data were fit to the Birch-Murnaghan equation of state. The bulk modulus at 80GPa is 550-560GPa for both Fe-rich perovskites, comparable to or slightly higher than the values measured for MgSiO3 perovskite at this pressure, indicating that the bulk modulus of perovskite is not strongly sensitive to Fe content.
KW - D ″ region
KW - Lower mantle
KW - Perovskite
KW - Post-perovskite
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U2 - 10.1016/j.epsl.2012.10.033
DO - 10.1016/j.epsl.2012.10.033
M3 - Article
AN - SCOPUS:84872363232
SN - 0012-821X
VL - 361
SP - 249
EP - 257
JO - Earth and Planetary Science Letters
JF - Earth and Planetary Science Letters
ER -