QUANTIFICATION OF EXPERIMENTALLY PRODUCED IGNEOUS TEXTURES USING CLUSTER ANALYSIS

One-atmosphere melting experiments were conducted at the QFM buffer on a sample of tholeiite from Mole Hill, Virginia. A new technique developed by the author to induce vibrations in crystallizing magmas was used to determine the effects of vibrational frequencies on crystallization of plagioclase and olivine in this sample. Textures of vibrated and static experiments were compared qualitatively by visual inspection and quantitatively using crystal size distribution (CSD) analysis. There was a clear effect on plagioclase crystallization, with minimal, if any, effect on olivine crystallization. Plagioclase crystals in static experiments were more euhedral and had higher aspect ratios compared to plagioclase in vibrated experiments. In addition, the CSDs for plagioclase showed a higher population density for small crystal sizes in the vibrated experiments. Olivine crystals in all experiments were subhedral and nearly equant; CSDs were identical, within uncertainties, except perhaps for slight differences in population density at the smallest crystal sizes. As in the case for plagioclase, vibrated samples appear to have a slightly higher population density for small crystal sizes of olivine when compared to static experiment. To compliment textural analysis by visual inspection and CSD, cluster analysis is being undertaken to quantify the size and characteristics of clusters of plagioclase crystals in these experiments. Specifically, the complete linkage hierarchical cluster analysis technique is being used. Cluster analyses of experiments are normalized to cluster analyses of random distributions with the same population density as the experiments. Preliminary results indicate clustering is more pronounced in static experiments.