VISCOSITY OF THE ALBITE MELT TO 7 GPA AT 2000 K

Abstract

Viscosity of melt at high pressure provides an important clue to understanding the dynamics of magmas in the Earth's deep interior. We measured viscosity of the albite melt to 7 GPa at 2000 K by the falling sphere method using a single crystalline diamond as a density marker. Viscosity of the melt decreases significantly from 5.28+/-1.78 Pa s at 3 GPa to 0.90+/-0.34 Pa s at 5 GPa and 0.99+/-0.27 Pa s at 6 GPa. We observed a further decrease in viscosity of the melt to 0.28+/-0.06 Pa s at 7 GPa. The change in viscosity with pressure may suggest existence of some structural change in the albite melt at high pressure.