Original paper

Nucleation and growth rates of pyroxene, plagioclase, and Fe-Ti oxides in basalt under atmospheric conditions

Burkhard, Dorothee J.M.

Abstract

The crystal size distribution theory (CSD) is used to derive nucleation and growth rates (J, G) of pyroxene, plagioclase and Fe-Ti oxides in basalt glass during heat treatment under atmospheric conditions. The glass was sampled from active Pu'u O'o, Kilauea, Hawaii, by hammer-dipping and subsequent quenching. Temperature (T) and time (t) dependent heat treatment of the glass above temperatures of maximum nucleation (J) and growth (G), about 930 °C, allows one to derive the activation energy of J and G. J and G are linear with t on a logarithmic scale. The results are applied to estimate the crystallization temperature of cooling lava. Basalt textures defined by the order of crystallization, are explained with respect to thermal history based on the temperature-time relation between J and G.

Keywords

nucleation rategrowth ratekinetics of crystallizationcrystal size distribution theorypyroxeneplagioclasekilauea (hawaii)