TS1.2/GD7.9Transpressional/Transtensional deformation at oblique tectonic settings (co-organized)
|Co-Convener: Karen Leever|
In plate tectonics, the rotational relative displacements of lithospheric plates imply that oblique plate boundaries must be the norm, rather than the exception. Oblique displacement includes a lateral and an orthogonal component, which can be convergent (Transpression) or divergent (Transtension). Therefore, a better understanding on the kinematics and the mechanics involved in transpressional and transtensional deformation is crucial to the knowledge of the processes that take place at plate tectonic boundaries. Transpression was first modeled by Sanderson and Marchini in what has become one of the most cited papers in Structural Geology. Now, thirty years after its publication, their proposal is still current, and many Structural Geology and Tectonic studies are partly based on it. Subsequent kinematic models have become progressively more complex, including transtension (kinematically equivalent to transpression but with a divergent, rather than a convergent orthogonal strain component), triclinic symmetries arising from oblique simple shear and/or coaxial extrusion, general coaxial strain, deformation zones with migrating limits, etc. These have helped to understand many natural deformation zones, at different tectonic settings, that could not be explained by more simple models. Still, there are several aspects, some of them currently ongoing, that will improve our knowledge of deformation at oblique tectonic settings, such as heterogeneous deformation, non-steady strain rates or the consideration of mechanical aspects. We pretend to acknowledge Sanderson and Marchini’s contribution, by proposing a broad session covering different topics related to oblique tectonics: studies on natural cases of deformation at oblique tectonic settings, including oblique convergent orogens, lateral branches of orogenic arcs, strike-slip settings or transtensional tectonics; as well as innovative approaches on numerical (kinematical and mechanical) and analogue modeling of transpressional/transtensional deformation. Our aim is provoke wide discussion that would include (1) heterogeneous distribution of simple shear and coaxial components of deformation, (2) transpressional/transtensional zones showing strain partitioning at multiple scales, (3) upper crustal heterogeneous transpression/transtension or (4) tectonic uplift and basin development related to transpression/transtension.