H 2 O, CO 2 , Cl, and gas in Plinian and ash-flow Bishop rhyolite

A. T. Anderson, S. Newman, S. N. Williams, T. H. Druitt, C. Skirius, E. Stolper

Research output: Contribution to journalArticlepeer-review

221 Scopus citations


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 languageEnglish (US)
Pages (from-to)221-225
Number of pages5
Issue number3
StatePublished - Jan 1 1989

ASJC Scopus subject areas

  • Geology


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