Arcs are key-geological actors of plate tectonics. They are viewed as major factories contributing to crust generation, continental growth, explosive volcanism and the geochemical cycles through the solid Earth, via magma production, differentiation and crustal foundering. Few accreted arcs sections expose a complete crustal and upper mantle section emphasizing the crucial role of arc preservation during subduction and continental collision. Active arc settings, in turn, allow direct investigation of the upper crustal and volcanic dynamics while, apart for indirect imaging or discrete sampling (xenoliths), very little is known about their deeper crustal section. Recent studies and results acquired on fossil and active arc systems have boosted our comprehension of subduction initiation, arc growth and accretion as well as their ultimate participation in crust production.

The study of arc construction and accretion processes through Earth's history - from Archean to modern case studies - requires bringing together multidisciplinary communities across a wide range of disciplines and methods encompassing, among others, (i) igneous, structural, petrological, geochemical, geochronological studies in exhumed arc sections and active arcs, (ii) new insights from recent advances in analogue and numerical modeling, (iii) geophysical studies of active arcs, and (iv) deep drilling of active oceanic arcs as such recently accomplished by IODP expeditions in the western Pacific.

This session invites wide-ranging multidisciplinary contributions aimed at constraining growth, structure, accretion and preservation processes of oceanic and continental arcs; going from melting processes in the sub-arc mantle, mass transfer in the subduction zone and igneous, tectonic and metamorphic processes in the arc crust.