The zone 1440 AD eruption of the soufriere of Guadeloupe (Lesser Antilles) : an experimental determination of the pre-eruptive consitions of the andesitic magma body.
Abstract
The 1440 AD eruption of the Soufriere of Guadeloupe (Lesser Antilles arc) is characterized by a dramatic change of the chemical composition of erupted products, from andesitic (clear pumices, 61-62 wt% SiO2) to basaltic andesite (dark scoria, 55-56 wt% SiO2). This compositional sequence is interpreted to reflect the tapping of a silicic magma body remobilised following the arrival of a mafic magma batch. The conditions of equilibrium ( T, P, fO2, melt H2O content) within the andesite body prior to the mixing event were determined from a coupled ineralogical/petrological and experimental approach.