Evolution and present state of the hydrothermal system in Long Valley Caldera

摘要: Evidence for previous periods of hydrothermal activity in Long Valley caldera exists the form extensive deposits alteration products at several locations within and saline Searles Lake which contain mineral assemblages contributed by hot spring discharge from Valley. Hydrothermal was more intense past probably involved fluid circulation to depths kilometers or with heat supplied magma chamber. During 40,000 years source may have shifted Inyo-Mono magmatic system beneath west moat, where deep water shallower zones lateral flow Bishop Tuff resurgent dome. The present-day appears consist two principal flows laterally east less than 1 km around Maximum measured temperatures these are near 170°C, but estimates chemical geothermometers extrapolation a high-temperature gradient recent drill hole indicate that reservoir 240° exist greater moat. Regions possibly containing silicic melt detected shear wave attenuation 4–5 dome not been place long enough influence sensibly overlying thermal regime upper 2 fill.