Subduction drives plate tectonics, generating the major proportion of subaerial volcanism, releasing >90% seismic moment magnitude, forming continents, and recycling lithosphere. Therefore, it is the most important geodynamical phenomenon on Earth and the major driver of global geochemical cycles. Seismological data show a fascinating range in shapes of subducting slabs. Arc volcanism illustrates the complexity of geochemical and petrological phenomena associated with subduction.

Numerical and laboratory modelling studies have successfully built our understanding of many aspects of the geodynamics of subduction zones. Detailed geochemical studies, investigating compositional variation within and between volcanic arcs, provide further insights into systematic chemical processes at the slab surface and within the mantle wedge, providing constraints on thermal structures and material transport within subduction zones. However, with different technical and methodological approaches, model set-ups, inputs and material properties, and in some cases conflicting conclusions between chemical and physical models, a consistent picture of the controlling parameters of subduction-zone processes has so far not emerged.

This session aims to follow subducting lithosphere on its journey from the surface down into the Earth's mantle, and to understand the driving processes for deformation and magmatism in the over-riding plate. We aim to address topics such as: subduction initiation and dynamics; changes in mineral breakdown processes at the slab surface; the formation and migration of fluids and melts at the slab surface; primary melt generation in the wedge; subduction-related magmatism; controls on the position and width of the volcanic arc; subduction-induced seismicity; mantle wedge processes; the fate of subducted crust, sediments and volatiles; the importance of subducting seamounts, LIPs, and ridges; links between near-surface processes and slab dynamics and with regional tectonic evolution; slab delamination and break-off; the effect of subduction on mantle flow; and imaging subduction zone processes.

With this session, we aim to form an integrated picture of the subduction process, and invite contributions from a wide range of disciplines, such as geodynamics, modelling, geochemistry, petrology, volcanology and seismology, to discuss subduction zone dynamics at all scales from the surface to the lower mantle, or in applications to natural laboratories.

Subduction zones are arguably the most important geological features of our planet, where plates plunge into the deep, metamorphic reactions take place, large earthquakes happen and melting induces volcanism and creation of continental crust. None of these processes would be possible without the cycling of volatiles, and this session aims to explore their role in convergent margins. Questions to address include the following. Do Atlantic and Pacific subduction zones cycle volatiles in different ways? What dynamic or chemical roles are played by subducted fracture zones and plate bending faults? How do fluids and melts interact with the mantle wedge and overlying lithosphere? Why do some of the Earth’s largest mineral resources form in subduction settings? We aim to bring together geodynamicists, geochemists, petrologists, seismologists, mineral and rock physicists, and structural geologists to understand how plate hydration/slab dynamics/dehydration, and subsequent mantle wedge melting/fluid percolation, and ultimately melt segregation/accumulation lead to the diverse range of phenomena observed at convergence zones around the globe.

Includes Augustus Love Medal by Harro Schmeling
Invited Speaker: Nestor Cerpa (University of Montpellier, France)

Subduction zones are one of the key players in driving plate tectonics. They are also the locus of most mineral and rock transformations, mass/fluid transfer and seismicity. Understanding initiation, development and closure of subduction zones -including their evolution into collisional systems- is therefore a challenge facing Earth sciences. This session aims at covering the tectonic and metamorphic evolution from nascent to mature convergent systems in both space and time as well as studying the complex feedbacks of processes related to the thermo-mechanical history of subducted and exhumed rocks. This includes studies focusing on tectonic processes in oceanic and continental subduction setting over space and timescales (e.g. mechanical (de)coupling, rock accretion and exhumation...) in active and ancient convergent settings. We welcome contributions from a wide range of disciplines such as structural geology, tectonics, petrology, geophysics, experimental deformation and numerical modelling, with particular emphasis on the rock record.

Orogenic plateaus and their margins are integral parts of modern mountain ranges and offer unique opportunities to study the feedback between tectonics and climate through the Earth’s surface. Complex interactions and feedbacks occur among a wide range of parameters, including crustal and deep-seated deformation, basin growth, uplift, precipitation and erosion, landscape and biological change; and lead to (i) the growth, recycling, and destruction of the lithosphere; (ii) shifts in surface elevation; and (iii) high topography that can affect atmospheric circulation. These controlling factors result in plateau lateral growth and its characteristic morpho-climatic domains: humid, high-relief margins that contrast with (semi-)arid, low-relief plateau interiors.

This session aims at creating a discussion forum on the complex interactions and feedbacks among climatic, surficial and geodynamic processes that challenge the notion of a comprehensive mechanism for surface uplift and topographic growth in orogenic plateaus and their margins. To fuel the exchange, we welcome studies of orogenic plateaus worldwide at various scales, from the Earth’s mantle and crust to its surface and atmosphere. We particularly encourage contributions that aim at bridging temporal and spatial gaps between datasets using an interdisciplinary approach or novel techniques.

Foreland basins archive the evolution of mountain belts, and fold-thrust belts are the linking elements between orogens and their forelands. One of the major challenges for understanding the dynamics of mountain belts is untangling the different driving mechanisms that can be responsible for exhumation of mountain belts and foreland basin deformation. In particular, the signals of plate convergence (i.e. tectonic processes), deep seated (mantle-related) processes, or climate differ with respect to their timing and spatial extent. Ensuing foreland deformation is also influenced by heterogeneity of the deforming material. For instance, stratigraphic variations of the foreland basin fill or its substrate or inherited structures add complexity to the system.

In this session we invite contributions focusing on linking mantle and crustal tectonic processes with foreland basin dynamics. This includes addressing the interplay between plate boundary forces and of inherited structures, sediment production, transport and deposition (source to sink studies), and studies constraining timing of orogen processes at different scales (ranging from short term deformation rates to longer term rates based on cosmogenic nuclides or thermochronometry). We particularly invite contributions linking geophysical with geological data including 3-D models and addressing their respective uncertainties. We encourage the presentation of field-based studies as well as analog and numerical models highlighting the link between foreland basin deformation and mountain building processes including deformation of fold-thrust belts.