Use of fractal analysis for discrimination of particles from primary and reworked jokulhlaup deposits in SE Iceland

The morphology of sideromelane particles from jokulhlaup deposits in southeastern Iceland has been studied by fractal analysis to assess post-depositional changes associated with reworking. Fractal dimensions of particle boundaries were calculated from data obtained by the caliper and dilation methods. Most particles exhibit multifractal relationships with a textural (D(1)) and structural (D(2)) fractal dimension, particles from primary jokulhlaup deposits have significantly greater textural and structural fractal dimensions compared to reworked deposits. Differences in the fractal dimensions indicate that reworking in the littoral zone has reduced both the amount of fine scale features on particle surfaces and the complexity of the overall particle shapes. The caliper and dilation methods yield similar values of textural fractal dimension for each particle. For the same particles, the dilation method yields higher values of structural fractal dimension. Reworked particles used in this study can be effectively discriminated from primary particles using a combination of D(1) and D(2) fractal dimensions. The results indicate that fractal analysis provides a useful quantitative characterization of complex volcanic particles and can be utilized to examine aspects of particle origin, transport and deposition. (C) 2000 Elsevier Science B.V. All rights reserved.