[S-MP23] Physics and Chemistry of Minerals

[SMP23-P05] Aluminium and iron effects on the electrical conductivity of the dense hydrous magnesium silicate phase-E

*ZHAO BIN¹, Takashi Yoshino¹ (1.Institute for Planetary Materials, Okayama University)

Keywords:dense hydrous magmesium silicates, high pressure, electrical conductivity

Subducted slabs containing dense hydrous magnesium silicates (DHMS) could carry considerable amount of water into the transition zone. In this study, we synthesized original and Al/Fe-bearing dense hydrous magnesium silicate phase-E using 14/8 cell assemblies in a Kawai-type multi-anvil press at 15 GPa and 1000 ℃. The electrical conductivity of the samples was measured up to 900 K at 15 GPa using a complex impedance analyzer (Solartron 1260). It is found that the electrical conductivity of original phase-E is comparable to that of phase-D, and a few orders of magnitude higher than that of phase-A and super-hydrous phase-B. On the other hand, the incorporation of Al and Fe in the phase-E would prominently increase its electrical conductivity by about one order of magnitude. The conduction mechanism of phase-E and the substitution mechanism of iron and aluminum have been discussed, respectively. The high electrical conductivity anomalies in the transition zone might be explained by the presence of iron and aluminum in DMHSs.