The effect of deformation on the crystallization kinetics of basalts

Crystals and bubbles nucleate and grow in a magma that experiences a range of temperatures, pressures and strain-rates. We have a good conceptual and sometimes quantitative understanding of how crystallization and bubble nucleation are controlled by decompression and cooling. However, the effect of strain rate on the crystallization kinetics of magmas is at present poorly constrained. In order to understand the interaction between deformation and crystallization, samples of basalt were deformed during their crystallization. We made measurements between 1080 and 1175°C and deformed samples in compression and in tension at strain rates varying from 3·10-5 to 2·10-2 s-1. We simultaneously imaged the samples using X-Ray micro-tomography at the Advanced Light Source, Lawrence Berkeley National Lab. We find that in general crystallization rates, both growth and nucleation rate, increase with increasing deformation rate.