Quantifying the P–T–X-M conditions recorded in high- and ultrahigh-pressure rocks — where X encompasses phase composition, including fluid/melt and redox state and M encompasses phase amount including fluid/melt — requires a methodological toolkit that has expanded well beyond classical geothermobarometry. This session welcomes contributions that estimate model or experimental constrains of these dimensions, whether through phase equilibrium modelling, elastic barometry, Raman spectroscopy of mineral inclusions, or quantitative compositional and mineral/crystallographic mapping using EPMA, XRF, LA-ICP-MS, EBSD, or synchrotron-based techniques, including the development of data processing and interpretation tools for such datasets. Both methodological advances and applications to natural examples are welcome.

How fast do rocks subduct, reach peak conditions, and return to the surface? This session explores the geochronological methods (e.g., U-Pb, Lu-Hf, Sm-Nd, Rb-Sr in garnet, zircon, rutile, monazite, epidote and phengite, but not only) that allow quantifying the timescales of subduction metamorphism and exhumation. Contributions integrating multi-system geochronology with petrological context, diffusion modelling, and rate-sensitive approaches are especially welcome.

Fluids and melts are the principal agents of mass transfer in subduction zones, driving metasomatism, volatile cycling, arc magmatism, and rheological weakening. This session invites contributions on the sources, compositions, and pathways of fluids and melts at all depths of the subduction zone — from high-pressure dehydration reactions to melt generation and element recycling. Approaches combining fluid inclusions, stable and radiogenic isotopes, experimental petrology, and thermodynamic modelling are welcome.

Intermediate-depth seismicity and episodic tremor and slip at subduction plate interfaces and within the slab remain incompletely understood. This session focuses on the role of metamorphic fluid production, pore-fluid overpressure, reaction-induced embrittlement, and stress transfer in controlling rock failure and seismicity. Contributions bridging observations from exhumed high-pressure terranes, active seismic records, experimental rock mechanics, and numerical modelling are welcome.

What geodynamic processes drive rocks to extreme depths and return them to the surface? Can we reproduce them numerically? This session bridges observations from exhumed high-pressure terranes with geodynamic models and numerical simulations. Topics include subduction initiation and termination, slab dynamics and rollback, exhumation mechanisms, collisional tectonics, and the thermal evolution of subduction zones. Thermomechanical numerical modelling including 2D and 3D viscoplastic models of subduction, tectonic erosion, melt generation, and mantle flow are welcome alongside petrological and structural constraints from natural examples.

The Variscan orogen records a protracted history of high-pressure and ultrahigh-pressure metamorphism spanning much of the Devonian and Carboniferous, resulting from the complex accretionary assembly of Pangaea. World-class eclogite complexes are exposed along the Iberian, Armorican, French Massif Central, and Bohemian massifs, as well as in the Alpine and Corsica-Sardinia basements. Multiple high-pressure belts with contrasting P-T conditions and ages record successive subduction events in perhaps more than one subduction zones. The host region of IEC16 exposes some of the most complete and accessible sections through this nappe system, including the Cabo Ortegal and Malpica-Tui complexes. This session invites contributions on all aspects of high-pressure and ultrahigh-pressure metamorphism, tectonics, and geodynamics of the Variscan orogen and its correlatives worldwide.