Magma extraction pressures and the architecture of volcanic plumbing systems
Document Type
Article
Publication Date
9-15-2019
Department
Department of Geological and Mining Engineering and Sciences
Abstract
The deposits of large volcanic eruptions provide the sole record of the architecture of magmatic plumbing systems in the moments when large pools of crystal-poor, eruptible magma are present in the crust. It is widely accepted that silicic magmas form by segregation of melt-rich, crystal-poor magma from a crystal-rich source; however, the depths at which segregation takes place and the distribution of the magma within the crust are not well constrained. We present a new approach to calculate pressures at which crystal-poor, eruptible magma is extracted from a crystal-rich source (i.e. mush). We apply the approach to a sequence of large (>50 km3) eruptions from the Taupo Volcanic Zone (TVZ), New Zealand, which were part of a volcanic flare-up. We compare the calculated extraction pressures with pre-eruptive storage pressures for the same units. Our results show that storage and extraction pressures do not always coincide. Instead, eruptible magma can be completely segregated from the crystal-rich source, and stored at shallower levels in the crust prior to eruption. In the case of the TVZ flare-up, repeated input of material and heat – probably coupled with tectonic extension – gradually conditioned the crust and allowed extraction of eruptible magma over a growing range of pressures with time. Our approach has the potential to reveal important information on the structure and distribution of magmatic systems within the shallow crust.
Publication Title
Earth and Planetary Science Letters
Recommended Citation
Gualda, G.,
Gravley, D. M.,
Deering, C.,
&
Ghiorso, M.
(2019).
Magma extraction pressures and the architecture of volcanic plumbing systems.
Earth and Planetary Science Letters,
522, 118-124.
http://doi.org/10.1016/j.epsl.2019.06.020
Retrieved from: https://digitalcommons.mtu.edu/michigantech-p/578
Publisher's Statement
© 2019 Elsevier B.V. All rights reserved. Publisher’s version of record: https://doi.org/10.1016/j.epsl.2019.06.020