Effect of T and P on the changes of the thermophysical properties of some rocks of the NW Ukrainian Shield
© T.S. Lebedev, V.I. Shapoval, I.N. Svyschuk
New experimental data on the change of the thermal parameters of samples of some rocks of the NW Ukrainian Shield under temperature (to +350°C) and pressure (to 0,7 GPa) have been obtained. The thermal and baric depedences of the thermal conductivity coefficient l and the character of the effect of pressure on the distribution of the thermal diffusivity coefficient l and specific heat capacity c of a representative collection of samples of chudnovo - berdychiv and korosten' granites, gabbro - norites and labradorites earlier taken from large outcrops quarries and some boreholes in the Korosten' Pluton area have been established. For baric experiments made by use of plane cylindric samples a modernized, measuring cell was formed. The results of the experiments confirm our known general conclusions that the temperature and pressure differently effect the thermal conductivity of rocks. It decreases or does not practically change with increasing temperature and increases to some extent with increasing pressure. It is shown that the main factor influencing the thermal conductivity of the rocks studied at atmospheric pressure and room temperature is their mineral composition. The structural features and every possible binary factors (grain boundaries, pores, microcracks, gas, water ets. are of minor importance slightly decreasing its values in general cases. The character of the temperature dependence of l of rocks is defined by mineral dominating their composition or their percentage of quartz as the most thermally conducting rock forming mineral. The higher the initial value of the thermal conductivity coefficient the higher is the temperature gradient of its decrease. The a, c and l values depending on pressure generally change according to the same law and may by approximated by the linear course of curves in different intervals of its effect. A clear differentiation of quartz - bearing and quartzless rock is observed as to their initial a and λ. The higher the latter the higher is the baric gradient of their increase.