GROWTH RATE OF OLIVINE IN A BASALTIC MELT FROM THE KILAUEA VOLCANO IN HAWAII USING CRYSTAL SIZE DISTRIBUTION THEORY

Quantitative evaluation of crystal growth and nucleation rates is important for understanding magmatic processes. Crystal Size Distribution Theory suggests that in a plot of the ln(n) vs. L, slope of the line is equal to -1/Gt where G is the crystal growth rate and t is the magma residence time. Therefore, if t is known then G can be calculated. In a basaltic rock from the Kilauea volcano in Hawaii where both plagioclase and olivine are present, we plotted ln(n) vs. L for the plagioclase as well as for the olivine. Using the known growth rate of plagioclase (10^-10 cm/sec) we first calculated the magma residence time (t), and assuming that it is the same for the olivine we used the slope of the ln(n) vs. L line and solved for the growth rate (G) for the olivine. We calculated a value of 10^-8.5 cm/sec for the olivine growth rate in a basaltic melt, which is comparable to < 10^-10 to 10^-7 cm/sec given by Donaldson and Jambon et al. ( 1992 ).