Electric conductivity measurement of the Earth's materials

对日本北海道日高变质带麻粒岩的电导率进行了测量。根据实验结果，我们估计深度为10-30 km的高阻区温度为600℃。我们通过电导率测量的方法进行了实验，以估计铁-铁硫化物熔体在白云石和橄榄岩基质中的连通性。从这一系列的实验中，我们发现当铁-铁硫化物的体积比大于5%时，铁-铁硫化物熔体就会发生连接。因此，地核物质与地幔的分离应该很容易发生在地球的早期历史中。在压力为25、35和40 GPa，温度为500 ~ 1000 K的条件下，测量了SiO_3钛铁矿（Mg_<0.93>Fe_<0.07>）的电导率。我们发现指数前项在所有压强下都是常数3×10 S/m。活化体积和活化能分别为-0.90±0.10 cm^3/mol和0.69±0.04 eV。因此钛铁矿的压力依赖性很大。我们还测量了（Mg_<0.93>Fe_<0.07>）SiO_3钙钛矿在35和40 GPa压力和500 ~ 1100 K温度下的电导率。我们发现指数前项在两个压强下都是常数1×10 S/m。活化体积和活化能分别为-0.06±0.04 cm^3/mol和0.39±0.02 eV。因此，钙钛矿的压力依赖性比钛铁矿小一个数量级。

We measured electrical conductivity of granulite from Hidaka metramorphic belt, Hokkaido, Japan. From the experimental results, we estimated the temperature of the high resistance region at depth of 10-30 km to be 600℃.We conducted experiments to estimate connectivity of iron-iron sulfide melts in dunite and lherzolite matrixes by means of electrical conductivity measurement. From this series of experiments, we found that iron-iron sulfide melt connects if its volume proportion is more than 5 %. Therefore, segregation of core material from mantle should have easily occurred in the early history of the Earth.We measured electrical conductivity of (Mg_<0.93>Fe_<0.07>)SiO_3 ilmenite at pressures of 25, 35 and 40 GPa and temperature of 500 to 1000 K. We found the pre-exponential term is constant of 3×10 S/m at all of these pressures. The activation energy at 0 GPa and activation volume are 0.69±0.04 eV and -0.90±0.10 cm^3/mol. Thus pressure dependence of ilmenite is quite large.We also measured electrical conductivity of (Mg_<0.93>Fe_<0.07>)SiO_3 perovskite at pressures of 35 and 40 GPa and temperature of 500 to 1100 K. We found the pre-exponential term is constant of 1×10 S/m at both of these pressures. The activation energy at 0 GPa and activation volume are 0.39±0.02 eV and -0.06±0.04 cm^3/mol. Thus pressure dependence of pervoskite is one order of magnitude smaller than that of ilmenite.