Andersen

Aspinall

Barclay

Blank

Devine

Gardner

J. Barclay

J. D. Devine

J. E. Gardner

Johnson

M. D. Murphy

M. J. Rutherford

M. R. Carroll

Murphy

Nakamura

Pallister

R. S. J. Sparks

Robertson

Rutherford

S. R. Young

Silver

Sparks

Tait

Venezky

Wadge

English

Crossref

Petrologic evidence for pre-eruptive pressure-temperature conditions, and recent reheating, of andesitic magma erupting at the Soufriere Hills Volcano, Montserrat, W.I.

The recent eruption of the Soufriere Hills Volcano in Montserrat (July, 1995, to present; September, 1997) has produced an andesitic dome (SiO2 ∼ 59–61 wt.%). The eruption has been caused by invasion of mafic magma into a preexisting andesitic magma storage region (P ∼ 130 MPa; ≥5 km depth). The composition of the andesite has remained essentially constant throughout the eruption, but heating by the mafic magma increased the andesite temperature from ≤830°C to ≤880°C. Prior to being heated, the stable mineral assemblage in the andesite was plagioclase + amphibole + orthopyroxene + titanomagnetite + ilmenite + quartz. The rise in temperature from ≤830°C to ≤880°C (fO2 ∼ 1 log unit above NNO) has caused quartz to become unstable, and has also caused changes in silicate and Fe-Ti oxide mineral compositions. The andesitic magma is likely saturated with an H2O-rich vapor phase in the upper part of the magma storage region. Melt H2O content is ∼4.7 wt.%

Devine, J. D.

Murphy, M. D.

Rutherford, M.

Barclay, J.

Sparks, R. S. J.

Carroll, M. R.

Young, S. R.

Gardner, J. E.

University of East Anglia digital repository

Petrologic evidence for pressure-temperature conditions and recent reheating of andesitic magma erupting at Soufriere Hills Volcano, Montserrat, WI

Petrologic evidence for pressure-temperature conditions and recent reheating of andesitic magma erupting at Soufriere Hills Volcano, Montserrat, WI

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University of East Anglia digital repository