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TS6.3/GD5.5/GMPV34/SM4.4

The subduction interface: cross-disciplinary views from Geodynamics-Geochemistry-Seismology (co-organized)
Convener: Philippe Agard  | Co-Conveners: Bradley Hacker , Aral Okay , Taras Gerya , José Alberto Padrón-Navarta , Frederik Tilmann , Nina Kukowski , Vicente López Sánchez-Vizcaíno 
Oral Programme
 / Tue, 05 Apr, 10:30–12:00  / 13:30–17:00  / Room 26
Poster Programme
 / Attendance Tue, 05 Apr, 17:30–19:00  / Display Tue, 05 Apr, 08:00–19:30  / Hall XL
Subduction zones are crucial areas for understanding lithospheric-scale coupling between plates, risk assessment, or vertical movements and material recycling on Earth. In recent years a wealth of geophysical and petrological data have been gathered on the plate-slab interface, envisioned by many as a 'subduction channel'. Geophysical imaging supports the existence of 2-8 km thick low-velocity layers on top of most subducting slabs and confirms the presence of a hydrated (30-40 vol%), serpentinized mantle wedge tip. Petrological studies now provide detailed T-depth-time-fluid evolutions with a km-scale spatial resolution, and thermomechanical models yield insightful views on subduction dynamics and exhumation models.

Yet, in detail, the nature and structure of the subduction channel are still poorly constrained. Crustal ± mantle slices likely migrate upwards along some sort of a channel, but the following questions remain: how and at what depths do these rocks detach from the sinking slab, and how do they circulate in a melange zone or rise as large-scale slices? To what extent are slab- or mantle wedge-derived serpentinites (or sediments) present in the channel? What is the amount of underplated material deep in the subduction channel? What is the dynamic behaviour of this "channel": is there single-pass upward flow at restricted times or continuous, extreme mixing? How does element recycling take place and what are the fluid fluxes into and out of the mantle wedge? What is the rheological behaviour of the mantle wedge?

The time has come to further combine data to get a more refined view of the physical conditions and processes at work along the subduction interface. We welcome contributions from all disciplines, with a special focus on high-resolution lithospheric and crustal-scale constraints from geophysics and geochemistry, high-precision thermobarometry and P-T-t paths, fully coupled thermodynamic and mechanical numerical modelling. This session also aims at fostering joint collaboration and research and at bridging the gap between the various communities.