Dynamics of Cooling and Plagioclase Crystallization in a Feeder Dike of the Columbia River Flood Basalt Group
Abstract (Summary)Image analysis of crystal sizes for plagioclases from a basaltic trachy-andesite feeder dike of the Columbia River Flood Basalt Province yields a linear relation when the natural log of the number of plagioclase crystals of a given size interval per volume is plotted against L (cm). The slope of this line, ?(1/G?), is related to the plagioclase growth rate, G (cm/sec), and the magma residence time, ? (seconds). For one sample, an observed slope of ?5.0329 corresponds to values of ? of 1.9 years, determined using conductive cooling equations. The derived value for G is 1?10?8.9 cm/sec, in good agreement with previously published results for the plagioclase growth rates found for larger basaltic magma bodies.
School:University of Cincinnati
School Location:USA - Ohio
Source Type:Master's Thesis
Date of Publication:01/01/2008