EXAMINING THE ASSOCIATION OF SUPERVOLCANOES AND MASSIVE PEGMATITES

Massive complex pegmatites, such as Tanco, Bikita, and Greenbushes, are notable not only for their size, but also their complex chemistry and rare nature. Given relative rareness along with the high silica, high viscosity, and high volatile content of both these pegmatite melts and supervolcanoes, we are conducting a comparative analysis of the geochemistry of the magmas in order to build the argument for their association. In addition to the properties above, complex rare-element pegmatite melts are noted for the presence of REE, other rare-elements, and the flux components B, P and F, resulting in below-solidus crystallization. Previous work (e.g. Guiffre and Clark, 2014) has shown melts of various supervolcanoes to be consistent with pegmatite melts, containing flux components, REE and other rare elements including Li, Ta, Nb, Zr and U. In this study, we have examined melt inclusion data from the Toba Tuffs, Indonesia, and Yellowstone, USA. Melt inclusion studies allow for more accurate whole chemical analysis because they more closely reflect the chemistry of the original magma. These data further support a linkage between supervolcanoes and massive pegmatites. Both types of systems have shallow, H₂O-saturated magma chambers with similar chemical signatures, suggesting a clear link. Notable trends in data show the tectonic setting to play a major factor in aluminum content, phosphorous content and overall signature. In both pegmatites and supervolcanoes, those forming from subduction and/or continental collision yield peraluminous, S-type magmas with a high phosphorous content, while those forming from hot spots or rift zones yield subaluminous to metaluminous, A-type magmas with a low phosphorous content. Future work includes an analysis of elemental isotopes in zircon crystals with the hope of achieving a stronger, more definitive link between massive pegmatites and supervolcanoes.