Chapter 9 Quaternary volcanicity

Abstract

The Quaternary volcanoes along the Sunda and Banda arcs of Indonesia are a well-known example of subduction-related volcanism. Subduction zones are the major sites of crustal recycling on the Earth, and it is the recycling of crustal material into the mantle that contributes to the continuing chemical differentiation of the planet Relatively primitive subduction-related magmas that might be melts of material beneath the volcanic arc, unmodified by postmelting processes, are rare, so that much attention has been dedicated in the last two decades to the study of the isotopic systematics of the most mafic volcanics as a means of identifying their source materials. These suggest that sediments-or fluids derived from the sediments-subducted along the Sunda Trench might have an effect on the composition of the Sunda-Banda arc volcanics. Gasparon & Varne (1998), however, argued that the isotopic signature of mafic volcanics in some sectors of the arc resembles that of Indian Ocean basalts, and that along-arc variations in magma types cannot be accounted for by crustal contamination in the mantle source. Indeed, Gasparon & Varne (1995, 1998) suggested that late-stage (post-melt generation) crustal contamination is the main process responsible for the wide array of volcanics in the Quaternary Sunda arc. The first detailed and comprehensive synthesis of the geology of Indonesia was published by van Bemmelen (1949), and an IAVCEI cataloque of the active volcanoes followed in 1951, compiled by Neumann van Padang (1951). This was later revised and updated by Kusumadinata (1979). These two fundamental publications, rich in information