Low-Wave-Velocity and High-Electrical-Conductivity Layer of Serpentine: A Compilation

Serpentine is formed by hydrothermal metasomatism and may penetrate into the deep crust or mantle of the Earth. It is considered to be the water resource of the mantle owing to its high water content and high-temperature decomposition (600-900 degrees C). In some geological settings, it has low wave velocity (lower than that of the surrounding rocks) and high electrical conductivity (higher than that of the surrounding rocks), which are the universal physical and geological properties of serpentine found across continents on Earth. Studying the properties of this layer, in particular the wave velocity and electrical conductivity, contributes to a more in-depth understanding of the mid-lower crust or mantle of the Earth. It is also helpful for exploring the mechanism of seismicity owing to the relationship of this layer with the earthquake center location. In subduction zones, the stability of serpentine is a factor affecting seismicity. In this study, the wave velocity and electrical conductivity data for serpentine, together with temperature and pressure, have been collated from previous studies. Some of these studies provide more comprehensive results and others provide new conclusions. Overall, the findings showed that a low-wave-velocity and high-electrical-conductivity layer can be found in serpentine under suitable geological settings. Details of the driving mechanism behind seismicity in subduction zones are also shown.