Climbing the crustal ladder: Magma storage-depth evolution during a volcanic flare-up

Abstract

Very large eruptions in the TVZ (New Zealand) reveal rapid magma assembly and eruption and progressive magma shallowing with time.

Coexisting Discrete Bodies of Rhyolite and Punctuated Volcanism Characterize Yellowstone's Post‐Lava Creek Tuff Caldera Evolution

“…When used with the Rhyolite‐MELTS geobarometer, the LCT‐A bulk composition returns pressures of 260–300 MPa, whereas the LCT‐A glasses suggest pressures of ~180 MPa. Differences in these estimates suggest a two‐stage storage history (i.e., crystallization at ~300 MPa, followed by shallower glass re‐equilibration at ~180 MPa), as has been inferred for Taupo volcanic zone rhyolites (e.g., Gualda et al, ) or the presence of a disequilibrium mineral assemblage such that the bulk composition yields inaccurate estimates (Ganne et al, ). The LCT‐B bulk compositions suggest pressures of ~150 MPa, whereas the glasses suggest pressures of ~110 MPa.…”

Hydrothermal Cooling as a Requirement for Short Storage of Silicic Magmas

“…Geobarometry results in Gualda et al (2018Gualda et al ( , 2019 would be much different if crystallization primarily took place during ascent. Pumice textures and mineral zoning would also reflect this behavior.…”

“…Crystal growth times inferred from geochronometry and geochronology suggest that magma bodies are typically not stored for longer than centuries to a few millennia (Allan et al., 2013; Charlier et al., 2008; K. M. Cooper & Kent, 2014; Druitt et al., 2012; Gualda & Sutton, 2016; Gualda et al., 2018; Gualda, Pamukcu, et al., 2012; Pamukcu, Gualda, Bégué, & Gravley, 2015; Shamloo & Till, 2019). In the Taupō Volcanic Zone (TVZ), New Zealand, crystallization may be even shorter, spanning only decades to a few centuries, as demonstrated by Ti‐in‐quartz geochronometry (Gualda et al., 2018). This suggests that eruptible magma bodies in this region are only stored for decades to centuries, at relatively constant pressures, prior to catastrophic, caldera‐forming eruptions (Gualda et al., 2018; Pamukcu, Gualda, Bégué, & Gravley, 2015).…”

“…In the Taupō Volcanic Zone (TVZ), New Zealand, crystallization may be even shorter, spanning only decades to a few centuries, as demonstrated by Ti‐in‐quartz geochronometry (Gualda et al., 2018). This suggests that eruptible magma bodies in this region are only stored for decades to centuries, at relatively constant pressures, prior to catastrophic, caldera‐forming eruptions (Gualda et al., 2018; Pamukcu, Gualda, Bégué, & Gravley, 2015). While Ti diffusivities in quartz have been recently questioned (Jollands et al., 2020a, 2020b; see also Audétat et al., 2021), other sources of evidence suggest that these slow diffusivities do not prevail under magmatic conditions (Gualda & Pamukçu, 2020; Pamukcu, Gualda, Bégué, & Gravley, 2015).…”

“…Mamaku pumice is high‐silica rhyolite with a mineralogy of primarily plagioclase, quartz, and orthopyroxene, and crystal contents of pumice are <10 wt% crystals (Bégué et al., 2014). Storage pressures for the Mamaku ignimbrite range between 50 and 160 MPa (∼1.8–5.5 km depth) (Bégué et al., 2014; Gualda et al., 2018).…”