摘要：

It has been proposed that the shape of plagioclase crystals is controlled by the environment of crystallisation [9, 10]. Higgins & Chandrasekharam [11] concluded that tabular crystals form in a magmatic environment where advection dominates over diffusion. The almost equidimensional form of the plagioclase crystals hence suggest that they formed in an almost static magma, where diffusive transport dominated. Perhaps the static environment encouraged the formation of plagioclase crystal clusters.ConclusionsThe textures of the Taapaca dacites were produced by textural coarsening, probably related to reheating by injections of mafic magma into a magma chamber. Sanidine nucleated during a deeper thermal cycle and may have been preserved and grown during subsequent cycles.Acknowledgements: I would like to thank Jorge Clavaro, Judit Ozoray, and the Departamento de Geologia, Universidad de Chile.

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