Effects of hydrogen on the electrical conductivity in upper mantle and transition zone minerals

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The influence of water (hydrogen) on electrical conductivity in mantleMinerals will be investigated through high-pressure, temperatureexperiments. Samples investigated include olivine, orthopyroxene and garnet.The AC impedance will be determined for a range of 1 KHz to 1 MHz. In mostcases, the investigators will determine the electrical conductivity inpolycrystalline samples with controlled grain-size. All the samples aresynthetic samples with controlled grain-size and water content. Thesynthesis will be made under controlled oxygen fugacity and oxide activity.In all runs, both grain-size and water content will bedetermined both before an after the experiment. The results will provide thefunctional relationships between electrical conductivity and temperature andwater content (+ grain-size, oxygen fugacity). The results can be usedto infer the water content in the Earth's upper mantle and transition zone.The PI will collaborate with Professor Utada's group at University of Tokyo,who investigates the three-dimensional distribution of electricalconductivity in Earth's upper mantle and transition zone in the westernPacific to infer the water distribution in this region of the Earth.