Earth-Science Reviews Diverse Magma Storage and Major and Volatile Magma Composition: What are the implications on the Eruptive Style Across a Volcanic Arc? An Example of the Lesser Antilles Arc

co-auteur étrangerInternational audienceUnderstanding variations in eruptive style and defining the processes and controls on different eruption styles is particularly important at arc volcanoes. This is due to the range of eruption styles which vary from phreatic behaviour to effusive magma extrusion and large explosive Plinian eruptions. Such eruptions can have wide-ranging and long-term impacts on vulnerable communities living near volcanoes. Magma storage and chemistry are key to understanding the origins of such variations along-arc. The Lesser Antilles Arc provides a perfect setting to investigate magma storage, magma composition and eruptive style variations associated with arc volcanism. This arc is comprised of eleven volcanically active islands. Since 1900, there have been 24 eruptions. Many eruptions have resulted in thousands of deaths, large scale and long-term displacements and severe economic impacts, which have had profound impacts on the people living in this region. Through this review we highlight the variations observed in magma storage, which is described as a vertically extensive trans crustal mush system. We hypothesise that across the arc there are generally three levels of the mush storage system. First, a deep system at 25 km (ca. >400 MPa). This system is poorly constrained and contains the most primitive magmas which fractionate to produce magmas which ascend into the second mid-crustal system at 10–18 km (ca. 320–400 MPa). The mid-crust stores basalt to basaltic andesite which supplies and remobilises the third and last shallow system at <10 km (ca.