Laboratory derived constraints on electrical conductivity beneath Slave craton

The depth profile of the electrical conductivity, σ ( d ) , beneath the Central Slave craton (Canada) has been reconstructed with the help of laboratory measurements carried out on peridotite xenoliths. σ ( T ) of xenoliths was determined in the piston-cylinder apparatus at 1 and 2 GPa and from 600 to 1150  ° C. σ ( T ) of xenoliths follows the Arrhenius dependence with the activation energy, E a , varying from 2.10 to 1.44 eV depending on temperature range and the Mg-number. The calculated xenolith geotherm and the suggested lithology beneath the Central Slave have been used to constrain σ ( d ) as follows: σ ( d ) in the crust varies between 0.5 × 1 0 − 5 and 1 0 − 3  S/m; the lithospheric σ ( d ) sharply decreases below the Moho at 39.4 km to 0.5 × 1 0 − 8  S/m, which corresponds to 460  ° C, and then gradually increases with the depth d to 0.5 × 1 0 − 2  S/m. The modeled MT-response of the constrained σ ( d ) profile has been compared with MT-observations [Jones, A.G., Lezaeta, P., Ferguson, I.J., Chave, A.D., Evans, R.L., Garcia, X., Spratt J., 2003. The electrical structure of the Slave craton. Lithos, 71, 505–527]. The general trend of the calculated MT-response based on the σ ( d ) model mimics the MT-inversion of the field data from the Central Slave.