Pressure-driven conductivity of lizardite-implication to the high conductive layers in craton lithosphere

The electrical transport behavior of lizardite was investigated by in-situ impedance measurements up to 22.6 GPa in a diamond anvil cell with comparation to its dehydrated counterpart. The conductivity of lizardite is found to increase one order of magnitude with increasing pressures from 0.2 to 1.9 GPa, due to pressure-activated ionic and electronic transportation. The proton hopping and hopping-created vacancy accounts for the conduction mechanisms. Compression initially promotes proton hopping at lower pressures and then impedes it at elevates pressure to make conduction purely electronic. Compared to the dehydrated specimen, the hydroxyl in lizardite enhances conductivity 4-7 times. The electronic resistivity at higher pressures gradually increases at a constant rate, except in the pressure range where pressure minimized the misfit structural disordering. The pressure-activated proton hopping in the lizardite and other phyllosilicates may ascribe the high conductive layer in the craton lithosphere and geoelectric anomalies related to earthquakes.