256 Recent Advances in Igneous Petrology and Geochemistry (Posters)

Tuesday, 27 September 2016
9:00 AM - 6:30 PM
Exhibit Hall E/F

EXAMINING THE ASSOCIATION OF SUPERVOLCANOES AND MASSIVE PEGMATITES

Paper number: 256-3
Program: Technical Sessions
Time: 9:00 AM – 6:30 PM

Authors

Abstract

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.

Geological Society of America Abstracts with Programs. Vol. 48, No. 7

doi: 10.1130/abs/2016AM-285298

© Copyright 2016 The Geological Society of America (GSA), all rights reserved. Permission is hereby granted to the author(s) of this abstract to reproduce and distribute it freely, for noncommercial purposes. Permission is hereby granted to any individual scientist to download a single copy of this electronic file and reproduce up to 20 paper copies for noncommercial purposes advancing science and education, including classroom use, providing all reproductions include the complete content shown here, including the author information. All other forms of reproduction and/or transmittal are prohibited without written permission from GSA Copyright Permissions.