THERMAL-CONDUCTIVITY OF A VOLCANIC ROCK MATERIAL (OLIVINE-MELILITITE)IN THE TEMPERATURE-RANGE BETWEEN 288 AND 1470 K

Experimental studies have been performed on the thermal properties of an olivine-melilitite in solid and partly molten states in a temperatu re range between 288 and 1470 K. Densities (rho), heat capacities (C-r ho), and thermal diffusivities (alpha) were measured by dilatometry, h eat flux differential scanning calorimetry, and laser flash analysis a nd used to calculate the thermal conductivities (lambda). In the solid state (288 to 1220 K) rho decreased from 3091 to 2993 kg/m(3), C-rho, increased from 0.76 to 1.41 J g(-1) K-1, alpha varied between 5.1 and 8.7 10(-3) cm(2)/s, and lambda varied between 1.75 and 2.54 W m(-1) K -1. In the partly molten state (1300 to 1470 K) C-rho increased from 1 .56 to 1.70 J g(-1) K-1, alpha decreased from 2.5 to 2.2 10(-3) cm(2)/ s, and lambda decreased from 1.16 to 1.09 W m(-1) K-1. The importance of these data for the physical description of processes acting during explosive volcanic eruptions is discussed. (C) 1998 Elsevier Science B .V.