Orals

Transform faults form major active plate boundaries and are intrinsic features of plate tectonics and plate accretion. Submarine transforms are likely to be fundamental pathways for fluid circulation in depth, thus significantly contributing to the exchange between the lithosphere and the hydrosphere. This implies serpentinization and weathering that affect the mechanical properties in the deformation zone. An open question is the influence of the elemental exchange between the crust and ocean water on these processes, as well as the interactions with the biosphere, both at the surface and at depth. Continental transforms and strike-slip faults are often a site of major earthquakes, representing major hazards for the population. Here too, the role of weathering in the deformation zone is still unconstrained. Both types of faults are still poorly known in terms of structure, rheology and deformation. These features are seismically active zones, with large earthquakes often being recorded on the largest faults. Yet, little is known about the rupture process, seismic cyclicity and active deformation of transform faults. Recent works have shown that fracture zones, supposedly inactive features, can be reactivated and be the site of large earthquakes and deformation. Additional open questions are the way transform faults deform under far-field stresses, such as plate kinematic changes, and under more local stresses, what are the time constants of the processes and what are the primary controls of the tectonic and magmatic styles of the response. The tectonic and magmatic response of large offset transforms, particularly, is still largely unknown.

This session aims to present recent results on studies of these large features, especially on the rheology, deformation patterns, rupture processes, fluid circulation and physical properties of transform faults. We welcome observational studies on strike-slip and transform faults, both continental and oceanic, on fracture zones and on transform continental margins (structural geology and tectonics, geophysical imaging of the crust and lithosphere, petrology and geochemistry, seismology, fluid circulation and rock alteration, geodesy) as well as modelling studies, both analogue and numerical. Cross-disciplinary approaches are encouraged. The submission of abstracts divulging on-going international projects (drilling sites, seismic reflection imaging along strike-slip faults) are also welcome. This session is promoted by the Oceanic Transform Faults working group of InterRidge.