Melt inclusions as a 'window' through the crust: What drives the most productive region of silicic volcanism on Earth?
Abstract
The Taupo Volcanic Zone (TVZ) is globally unique in the intensity of its magmatic-volcanic-geothermal flux. However, the causes of this anomaly are not yet understood, as primary magmas (basalts) are extensively modified in the TVZ during their ascent to the surface, overprinting the geochemical features required to infer conditions under which they formed. Moreover, the small amounts of basalt that do erupt are likely buried or destroyed by explosive and voluminous rhyolitic (super)eruptions. Our novel study addresses this issue by applying forensic geochemical techniques to glassy melt inclusions trapped within olivine crystals, separated from volcanic rocks throughout the TVZ, ranging in age from 0 to 350 ka. Our approach is motivated by the recent identification of high-Mg olivine xenocrysts inherited from primitive basalts in large-volume TVZ rhyolites, which contain trapped basaltic melt inclusions with the most primitive magma compositions ever recorded in the TVZ. These inclusions provide a novel and unique "window" into mantle processes driving voluminous rhyolitic volcanism. Here we present major and trace element data from olivine melt inclusions from across and along the arc and, for the first time, quantify the spatial and temporal compositional variability of magmas feeding the TVZ. Our data reveals the unique subduction and rifting processes behind the extreme, globally unique heat flow and eruptive rate of this end member continental arc.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2016
- Bibcode:
- 2016AGUFM.V31A3088B
- Keywords:
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- 3612 Reactions and phase equilibria;
- MINERALOGY AND PETROLOGYDE: 3618 Magma chamber processes;
- MINERALOGY AND PETROLOGYDE: 8408 Volcano/climate interactions;
- VOLCANOLOGYDE: 8430 Volcanic gases;
- VOLCANOLOGY