Experimental studies of thermal grooving in the olivine and albite melt system

Abstract

Thermal grooving of low angle tilt boundary of San Carlos olivine in the albite melt were experimentally investigated at 1200–1300°C in mixed CO 2 and H 2 gases for 1–20 h. The depth, d, of the thermal groove on (010) of olivine along the (100) sub-boundaries is in the function of time and temperatures as follows; d 4 = k o · t · exp(− 190 000/ RT), in which R is the gas constant, and k o is the material constant. The melt shape changes due to the thermal grooving driven by surface tension and deformation of the upper mantle. Compared with the time scales of these two counteracting mechanisms, it is inferred that the melt shape is unstable in the high temperature and low stress conditions, and that the melt shape takes a stable form during progressive deformation in the low temperature and high stress conditions.