Fig 7. Summary of estimates of the duration of crystallization for the Bishop Tuff.

Zircon crystallization times are typically on the order of tens of thousands of years. Quartz interiors reveal crystallization timescales on the order of centuries to a few millennia. Quartz and orthopyroxene (Opx) rims have been previously inferred to have crystallized on decadal to centennial timescales. We show in this study that quartz rims mostly crystallized within a year of eruption, with most growth taking place in the days to weeks prior to eruption. Much of the discrepancy between the timescales results from different minerals, or different zones within the same mineral, recording different processes. Zircon records the evolution of the entire magmatic system, including long stages characterized by high crystal contents; quartz interiors and much of zircon crystallized within centuries to millennia of eruption, revealing the lifespan of crystal-poor, eruptible magma bodies; quartz rims reveal the onset of eruptive decompression. SIMS: secondary ionization mass spectrometry; TIMS: thermal ionization mass spectrometry.