Temperature Dependence of the Low-Frequency Electrical Properties of Partially Frozen Rocks

The spectral induced polarization (SIP) method is increasingly used for ice-content quantification and thermal characterization of permafrost sites. To improve interpretation, we must understand how low-frequency conduction and polarization in rocks vary with temperature, ice content, textures, and mineralogies under partially frozen conditions. This study investigates SIP signatures of six solid rock and two loose sediment samples from Alpine permafrost sites with different texture and mineralogy in a frequency range between 10 mHz and 45 kHz during controlled freeze-thaw cycles down to $-40$$°$C. All samples exhibit resistivity magnitude increases with decreasing temperature, freezing-point depression, and thermal hysteresis. Spectral phase responses reflect the well-known temperature-dependent relaxation behavior of ice at higher frequencies, with variations in shape and strength. These are linked to rock and pore water properties, such as texture, mineralogy, and salinity. The presented findings reveal that the investigated electrical properties are predominantly controlled by the presence of ice and its temperature-dependent conduction and polarization mechanisms. The results provide novel insights into the electrical behavior of partially frozen rocks, underline the importance of hysteresis effects, and show potential challenges in SIP-based ice content and temperature estimation. The presented data set also makes a significant addition to existing data facilitating future model development.