The electrical conductivity of eclogite in Tibet and its geophysical implications

The electrical conductivity of Tibetan eclogite was investigated at pressures of 1.5–3.5 GPa and temperatures of 500–803 K using impedance spectroscopy within a frequency range of 10−1–106 Hz. The electrical conductivity of eclogite increases with increasing temperature (which can be approximated by the Arrhenius equation), and is weakly affected by pressure. At each tested pressure, the electrical conductivity is weakly temperature dependent below ∼650 K and more strongly temperature dependent above ∼650 K. The calculated activation energies and volumes are 44±1 kJ/mol and −0.6±0.1 cm3/mol for low temperatures and 97±3 kJ/mol and −1.2±0.2 cm3/mol for high temperatures, respectively. When applied to the depth range of 45–100 km in Tibet, the laboratory data give conductivities on the order of 10−1.5–10−4.5 S/m, within the range of geophysical conductivity profiles.