The Relationship Between Thermal Conductivity and Engineering Properties of Basalts with Increasing Serpentinization Degree

The thermal conductivity (TC) of rocks is an essential parameter for geothermal investigations and heat transport modeling under the ground. Although Turkey has a remarkable geothermal potential, investigation of rocks’ thermal conductivity has been very limited. The aim of this study is to investigate the relationships between TC and significant engineering parameters (uniaxial compressive strength (UCS), point load index (PLI), ultrasonic pulse velocity (UPV), indirect tensile strength (BTS), Schmidt hammer rebound number (R), Leeb hardness (H_L), density, and apparent porosity) of basalt samples. In addition to the engineering properties, TC correlated with the serpentinization of olivine and some chemical elements (O and Si). The study area was divided into three categories (A1, M2, and M3) according to the alteration zones with stratigraphically different levels. Petrographic thin section studies, SEM (scanning electron microscopy), and EDS (energy dispersive spectroscopy) analyses were also carried out to recognize the particles. This study demonstrated that the thermal conductivity values depend on the engineering properties of basalts due to the progressive serpentinization of olivine minerals. Serpentinization of olivine was found approximately 10% for A1 basalts, while this value was around 80% for M3. A strong relation was found between TC and serpentinization of olivine minerals for all samples and average A1, M2, and M3. The most significant factors affecting the serpentinization are proximity to the volcano cone and fault contact.