Polarization effects at grain-boundaries

部分熔融岩石的导电性主要取决于熔融相的连通性。不同的导电性机制在熔体和矿物中占主导地位。如果将电场施加到部分熔融的岩石上，由于熔体（离子）和晶体（电子）中的载流子不同，在熔融矿物界面上应该发生极化。这种极化将显著影响电导率实验的标度行为。在这个项目中，我们想测试以下假设：“部分熔融岩石的复杂导电性受到熔融矿物界面极化效应的显著影响”，并讨论熔融矿物界面极化的后果：a)实验室实验的解释，b)野外观测的反演和解释。对部分熔融体系电导率极化效应的定性和定量理解，将使我们更深入地了解在熔融矿物界面发生极化效应的体系的结垢行为。在低频率下（直流-直流实验），极化将显著影响观察到的总电阻率。在更高的频率下，例如在实验室实验中，这种极化通常由电极极化叠加。一个后果可能是，在忽略极化效应的情况下，用来解释观测到的电导率异常的推断熔体部分被低估了。因此，现有的安第斯山脉、西藏或比利牛斯山脉的大地电磁资料需要重新评估，同时考虑到熔融矿物界面的极化效应。

The electrical conductivity of partially molten rocks mainly depends on the interconnectivity of the melt phase. Different electrical conductivity mechanisms dominate in melts and minerals. If an electrical field is applied to a partially molten rock, polarizations should occur at meltmineral-interfaces due to different charge carriers in melts (ions) and crystals (electrons). This polarization will significantly influence the scaling behavior of electrical conductivity experiments. Within this project we want to test the following hypothesis: "The complex electrical conductivity of partially molten rock is significantly influenced by polarization effects at melt-mineral interfaces" and discuss the consequences of polarizations at the melt-mineral interface a) for the interpretation of laboratory experiments and b) for the inversion and interpretation of field observations. The qualitative and quantitative understanding of polarization effects on the electrical conductivity of partially molten systems should give us a deeper insight into the scaling behaviour of systems where polarization effects at meltmineral-interfaces occur. At low frequencies (direct current - DC experiments) the polarization will significantly contribute to the observed overall resistivity. At higher frequencies-such as in laboratory experiments - this polarization is usually overprinted by electrode polarizations. One consequence might be that the deduced melt portions to explain observed conductivity anomalies are underestimated while neglecting polarization effects. Therefore, a consequence, the existing magnetotelluric data for the Andes, in Tibet, or in the Pyrenees need to be re-evaluated while taking polarization effects at melt-mineral-interfaces into account.