High-silica magmas (≥68 weight % silicon dioxide) have produced some of the largest and most impactful volcanic eruptions in Earth’s history. Quartz-hosted melt inclusions can provide critical insights into the architecture, evolution, and eruption of silicic magmas; however, the reliability of mineral-hosted melt inclusion compositions has been questioned because of potential postentrapment modification of inclusions via diffusive exchange. We demonstrate that with careful sample selection, both naturally glassy and experimentally homogenized quartz-hosted melt inclusions can retain meaningful preeruptive signatures and provide useful insights into preeruptive magmatic conditions. We also show that hydrogen isotope measurements and detailed descriptions of melt inclusion geometries are particularly critical for identifying postentrapment diffusive exchange in melt inclusions, whether it is due to natural or experimental processes. Last, combining data from measurements of quartz-hosted melt inclusion hydrogen isotopes, trace elements, volatiles, and geometries, we fingerprint multiple discrete rhyolite magma reservoirs in the Highland Range volcanic sequence (NV, USA).
Hickernell et al. (Fri,) studied this question.