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.

As the most enriched composition of the lower part of mantle transition zone, properties of bearing-Fe ringwoodite are important to deduce the composition and structure of the mantle. For understanding the properties of Fe-bearing ringwoodite under condition of the lower mantle transition zone, the density and seismic wave velocity (Vp and Vs) of ringwoodite with different Fe content (0, 12.5, 25, 50, and 100 at%) were calculated under 300-2000K and 0-26 GPa by forcefeild combined with molecular dynamic method. Changes of density, Vp and Vs of ringwoodite containing different Fe content with pressure and temperature were fitted by the binary linear equation. Density of ringwoodite linearly increases with increasing Fe content, however relationship between increase of Vp and Vs and increasing Fe content show quadratic. The calculated densities of ringwoodite show that the Fe content of ringwoodite shall be 55-64 at% to match the lower mantle transition zone’s density. Therefor existence of ringwoodite may result in a low-density zone or gravity anomaly in the lower part of the mantle transition zone. The Vp and Vs of ringwoodite along the Earth’s typical temperature and pressure profile are higher than the Earth’s wave velocity model at the lower mantle transition zone (510-660 km) and the Vp and Vs of ringwoodite with 12.5 at% Fe along the Earth’s typical temperature and pressure profile are 31.3-33.7%% and 22.9-27.7% higher. The calculated results provide new data to explore composition and structure of the mantle.

By using the combined ultrasonic interferometry and X-ray diffraction method, the elastic wave velocities of aragonite were measured for the first time at pressure and temperature up to 5.8 GPa and 1173 K by using a hot-pressed polycrystalline specimen. Aragonite has has extremely low compressional (Vp) and shear (Vs) wave velocities and VP, low VS and high VP/VS ratio than those of the major minerals of subduction slabs. According to the average content of CO2 in the subduction zones, the velocities of carbonated-eclogite and carbonated-peridotite in both cold and hot subduction zones were modeled. It was revealed that an increase of 2.5 wt% CO2 resulted in to 2% reduction in Vp and Vs and an increase of Vp/Vs. Our results show that the velocity effect of aragonite in subduction zone can’t be ignored and shed lights on the mechanism of low velocity layers (LVL) in the subduction zones.