Abstract
Infrared spectroscopic (H 2 O and CO 2 ) and electron microprobe (Cl) analyses of glass inclusions in Plinian and ash-flow quartz phenocrysts from the Bishop Tuff reveal the preeruption concentrations of volatiles in separate parts of the body of magma. There is an inverse relation between H 2 O and CO 2 that can be explained 1) by closed-system, gas-saturated crystallization of parent magma to yield Plinian magma + (lost) crystals or 2) by the rise of CO 2 -rich bubbles through water-rich magma. Our estimated pressures of gas-saturation range from about 1.6kbar (Plinian) to 2.3kbar (ash flow) and accord with geologic evidence for 3km of magma withdrawal and caldera subsidence. -Authors
Original language | English (US) |
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Pages (from-to) | 221-225 |
Number of pages | 5 |
Journal | Geology |
Volume | 17 |
Issue number | 3 |
DOIs | |
State | Published - Jan 1 1989 |
ASJC Scopus subject areas
- Geology