Dynamics and timescales of mafic–silicic magma interactions at Soufrière Hills Volcano, Montserrat

Abstract Mafic magma intrusions into silica-rich magmatic reservoirs are commonly proposed to drive the eruptions of andesitic hybrid magmas that characterise many arc volcanoes. However, interactions between contrasting involve large gradients physical and chemical properties change over time, details such processes have proven difficult constrain. In this paper we investigate dynamics mingling mixing using textural zoning patterns recorded in plagioclase crystals from February 2010 eruption at Soufrière Hills Volcano, Montserrat. This is considered a classic example andesite constitutes bulk erupted volume basaltic occurs as enclaves. We find characterised by two well-defined zones record mafic–silicic interaction: crystal interior, often identified patchy, dusty oscillatory zoning, an overgrowth zone (rim) different composition. use anorthite Mg contents track thermal compositional changes experienced time. Our results reveal rims formed few hours days prior eruption, during co-eruptive interactions. The interaction with rheology likely increased narrowing conduit geometry towards surface, which facilitates convection additional interface contact magmas. findings shed new light on nature timing driving final eruptive phase Volcano help propose interpretative framework monitoring signals.