Rapid Rates of Magma Generation at Contemporaneous Magma Systems, Taupo Volcano, New Zealand: Insights from U–Th Model-age Spectra in Zircons

Fine-scale temporal recovery, reconstruction and evolution of a post-supereruption magmatic system

“…pyroclastic material (see Miller and Wark 2008 for overview), and are often interpreted to result from a unique set of circumstances that lead to the accumulation and mobilisation of large amounts of magma (Caricchi et al 2014;Malfait et al 2014). It is now widely regarded that significant volumes of partly molten crystal-rich mush are required to generate the huge volumes of melt(s) required for supereruptions Bergantz 2004, 2008;Hildreth 2004;Glazner et al 2004;Wilson et al 2006;Hildreth and Wilson 2007;Lipman 2007;Girard and Stix 2009;Wilson and Charlier 2009;Allan 2013;Lipman and Bachmann 2015). Such studies often highlight the crucial interplay of this evolved crystal mush with a deeper-seated feeder system of less evolved mafic melts and their crystalline products (Hildreth 1981).…”

“…1). U-Th disequilibrium model-age contrasts between zircons extracted from the precursor 'Oruanui-type' magmas and those from the Oruanui magma itself (Wilson and Charlier 2009) and element diffusion modelling indicate that although the broader Oruanui mush source likely developed over tens of thousands of years, the eruptible melt-dominant magma body was accumulated in 3000 years or less. The Oruanui juvenile material was >99 % rhyolite, with a minor (<1 %) component of mafic magmas (Sutton et al 1995;Wilson et al 2006).…”

The temporal evolution of chemical and physical properties of magmatic systems

“…These data have been interpreted to result from the long-term storage of zircons in highly crystallized or solidified magma bodies, which are rapidly remobilized before eruption (Wilson & Charlier 2009;Charlier & Wilson 2010;Storm et al 2011). Interestingly, zircons from the same rock sample crystallized over different periods of time, which suggests that zircons from different portions of the subvolcanic reservoir are assembled before eruption (Davidson et al 2007;Storm et al 2014).…”

“…First, thermal models of crustal magmatism reveal the difficulty in generating and then sustaining large bodies of true magma (.40% melt) in the shallow crust Annen et al 2008;Annen 2009;Schöpa & Annen 2013). Volcanic eruptions of relatively crystal-poor magma testify to the existence of such bodies, but thermal models together with geochronological and geochemical data require that this is a relatively transitory physical state (Wilson & Charlier 2009;Cooper & Kent 2014;Wotzlaw et al 2014). Second, petrological studies of igneous rocks reveal a level of geochemical and textural complexity that cannot be reconciled with simple precipitation from a melt, instead suggesting physical and chemical interaction of crystal residues with melts over long periods of time in a thermally fluctuating mush environment (Paterson et al 2011;Humphreys et al 2012;Thomson & Maclennan 2012;.…”

Great challenges in volcanology: how does the volcano factory work?

“…Modeling has reached a relatively sophisticated stage, allowing understanding otherwise inaccessible and/or long-lasting 2D and, to a lesser extent, 3D processes. Similarly crucial to understand the mean to longerterm behavior of volcanoes are many field and petrological-geochemical studies, supported by dating techniques (e.g., Gravley et al, 2007;Thordarson and Larsen, 2007;Collins et al, 2009;Wilson and Charlier, 2009;Corsaro et al, 2013). In particular, field studies prove fundamental in reconstructing the eruptive history of a volcano, including the eruption location, type, size and frequency; petrological and geochemical studies provide an invaluable amount of information on the processes and times characterizing the formation of the magma, its rise and emplacement within the crust, including mixing, mingling, crustal assimilation, and fractionation.…”