Thermal conductivity variations with temperature for various rock types: Estimation of lattice and radiative conduction

The temperature is a very important parameter, which mainly controls the physical and chemical state in different layers of the Earth. The thermal properties of layers of the Earth depend on the type of rock present in it and the thermal properties of rock depend on its mineral composition. The main task of our work was to investigate the variation of thermal conductivity with temperature from the available datasets for the different group of rocks such as granitic, amphibolitic, granulitic and ultramafic rocks. Thermal conductivity consists of two components i.e. lattice and radiative. From our analysis, we found that rate of decrease of thermal conductivity depends on rock type as well as their thermal conductivity at room temperature. For crustal rocks, lattice conduction is dominant below 600 to 800-degree Celsius, whereas the maximum temperatures that exist in the earth’s crust range between 400 to 600-degree Celsius and for ultramafic rocks, lattice conduction is dominant below 300-degree Celsius. Consequently, lattice conduction dominates in the crust and radiative conduction dominates in the mantle. Thus, lattice and radiative conduction are dependent on rock type and because of these characteristics, thermal conductivity decreases with temperature within the earth’s crust and increases in the mantle.