An Investigation into the Nature of the Magmatic Plumbing

The temporal evolution of erupted magma compositions at Paricutin Volcano (Mexico) is often cited as a classic example of assimila-tion^fractional crystallization processes with significant progressive changes in major element, trace element, and isotopic compositions occurring over the relatively short 9 year lifespan of the volcano. In this study, major and trace element compositions of olivine- and orthopyroxene-hosted melt inclusions are integrated with new trace element analyses of the erupted lavas and data for entrained xenoliths and xenolith glasses to provide a more comprehensive evaluation of the evolution of Paricutin Volcano that questions this view. Melt in-clusion compositions are bimodal with an undegassed, low-Si popu-lation (Type I) similar in composition to the whole-rock samples and a degassed, high-Si population (Type II) recording late-stage degassing and crystallization of the magma. Despite the rapid changes in lava composition, melt inclusions hosted in both olivin