INTERNAL MELT FIGURES IN ICE BY RAPID ADIABATIC-COMPRESSION

Single crystals and bicrystals of water-ice have been adiabatically pr essurized to produce, and clearly illustrate, two types of internal me lt figures: (1) dendritic figures that grow from nucleation imperfecti ons on the specimen's surface, or from air bubbles at grain boundaries , into the ice as pressure is elevated; and (2) compression melt fract ures, flat liquid-filled disks, that nucleate at imperfections in the crystal and grow with the application of pressure eventually to sprout dendritic fingers at the periphery. The transparency of the ice permi tted visualization of the growth and behavior of the figures, and this could be an important tool in understanding the role of phase transfo rmations in deep-focus earthquakes. Correlation between figure size an d pressure is noted for the first time.