Geochemical Evolution of the Soufriere Hills Volcano, Montserrat, Lesser Antilles Volcanic Arc

The geochemical evolution of Montserrat provides an importantbackground to understanding the current activity of this islandarc volcano. Here we present major and trace element, and U-,Th- and O-isotope data for rocks generated in the last 300 kyrthat provide constraints on the magmatic processes occurringbeneath the volcano. Samples range from low- to medium-K calc-alkalinebasalts to dacites. Three suites can be distinguished on thebasis of major and trace element compositions: the South SoufrièreHills suite; the Soufrière Hills suite, including thelava from the current eruption; and the mafic inclusions. Magmaticdifferentiation of the magma that crystallized to form the maficinclusions appears to have been governed by closed-system processes,modelled by fractional crystallization (F     

Magma Emplacement and Remobilization Timescales Beneath Montserrat: Insights from Sr and Ba Zonation in Plagioclase Phenocrysts

Since 1995, the Soufrière Hills volcano on Montserrat,Lesser Antilles island arc, has erupted crystal-rich andesitemagma that is geochemically very similar to the volcanic productsof at least the last 174 ± 3 kyr (1     

Time Scales of Crystal Fractionation in Magma Chambers--Integrating Physical, Isotopic and Geochemical Perspectives

A simple heat balance model for an evolving magma chamber isused to make predictions of the time scales for magma differentiation,which are compared with geological and isotopic constraintson the rates of crystallization and differentiation. In a 10km³ magma chamber releasing thermal energy at a rate of 100MW, basalt and rhyolite magmas should reach 50% crystallizationafter