Zircon-scale insights into the history of a Supervolcano, Bishop Tuff, Long Valley, California, with implications for the Ti-in-zircon geothermometer

Assimilation of preexisting Pleistocene intrusions at Long Valley by periodic magma recharge accelerates rhyolite generation: rethinking the remelting model

“…Ghiorso and Gualda (2012) therefore suggested that the FeTi oxide temperature estimates for the Bishop Tuff likely do not record preeruptive conditions (i.e., near-eruption temperatures), but rather may imply reequilibration. In addition, Reid et al (2011) find that the apparent Ti-in-zircon crystallization temperatures determined for the Bishop Tuff are more restricted (DT *30-40°C) and more similar (\720°C) to the recalibrated zircon saturation temperature estimates. The similarity between a majority of the zircon saturation temperatures and the Ti-in-zircon crystallization temperatures is increased if realistic pressure corrections are included in the Ti-in-zircon calculations.…”

“…The similarity between a majority of the zircon saturation temperatures and the Ti-in-zircon crystallization temperatures is increased if realistic pressure corrections are included in the Ti-in-zircon calculations. Moreover, because of recent evidence for enhanced solubility of Ti in quartz at upper crustal pressures (Thomas et al 2010), the reported Ti-in-quartz temperature estimates may also be too high (Reid et al 2011). Collectively, a limited range of zircon temperatures is more consistent with the idea that the Bishop Tuff was derived primarily from remelted subvolcanic intrusions by the recharge of hotter magmas rather than from a long-lived, cooling, and evolving magma body.…”

“…For this reason, individual zircon crystals are often zoned (both compositionally and with respect to age). In fact, zoning in Bishop Tuff zircon is well established by various analytical approaches (e.g., Crowley et al 2007;Reid and Coath 2000;Reid et al 2011;Simon and Reid 2005). Simon et al (2008b) considered the effect of unrecognized heterogeneity (i.e., older cores) when dating individual zircon grains.…”

Timescales of mixing and mobilisation in the Bishop Tuff magma body: perspectives from diffusion chronometry

“…These thermometry calculations have utilised Fe-Ti oxides (Hildreth, 1977(Hildreth, , 1979Hildreth and Wilson 2007;Evans and Bachmann 2013), Ti concentrations in quartz Thomas et al 2010;Thomas and Watson 2012;Wilson et al 2012), Ti concentrations in zircon (Reid et al 2011;Chamberlain et al 2014), 18 O fractionation between crystal phases (Bindeman and Valley 2002), and 2-pyroxene compositions (Hildreth 1979;Frost and Lindsley 1992) all of which yield ~100 °C temperature difference between upper and lower regions in the magma chamber. In contrast, thermodynamic modelling of the Bishop Tuff system has been used to propose a very uniform temperature range (Gualda et al 2012b).…”

Zircon geochronology and geochemistry to constrain the youngest eruption events and magma evolution of the Mid-Miocene ignimbrite flare-up in the Pannonian Basin, eastern central Europe

“…Reconstructing the chronology of large explosive eruptions fed by silicic magmas and constraining the lifetime of magmatic systems are fundamental challenges in volcanic petrology (Reid and Coath 2000;Vazquez and Reid 2004;Charlier et al 2005;Bachmann and Bergantz 2008;Wilson and Charlier 2009;Schmitt et al 2011;Danišík et al 2012;Gelman et al 2013;Wotzlaw et al 2013;2015 Cooper andKent 2014;Cooper et al 2014a;Frazer et al 2014;Simon et al 2014). The origin and evolution of such silicic magma bodies, which either feed large volcanic eruptions or end up crystallizing as plutonic masses, still generates much debate.…”