EGU 2020 session – “The spectrum of obliquity: A multidisciplinary approach from orthogonal rifts to transform tectonics”

Please consider submitting an abstract to our session on transform margins and oblique rifting at EGU 2020: There will also be a dedicated special issue of EGUs Solid Earth to accompany the session, and we can also confirm that Prof. Laetitia Le Pourhiet from ISTeParis, Sorbonne Université, France will give an invited talk in the EGU session

Session abstract:

It is becoming increasingly apparent that the majority of rifts contain a component of obliquity. As such, a spectrum of obliquity can be recognised from orthogonal rifts through to pure strike-slip tectonics. This is in contrast with more conventional conceptual models of rifting and rifted margin formation, which often assume that the rift velocity is oriented perpendicular to the plate boundary. The cause of rift obliquity has been attributed to a range of driving mechanisms, including: oblique crustal and mantle inheritance, a reduced force required for plastic yielding, changes in far-field forces, asthenospheric dynamics, and grain size changes in the lower crust and mantle. The effects of obliquity on rift and transform evolution are extensive, often leading to unique structural settings dominated by transtensional and transpressional processes. The spatio-temporal overlap of distinctive rifting events (governed by transtensional, transpressional or orthogonal kinematics) can result in strongly segmented 3D rift architectures that may influence subsequent reactivation. In addition, rift obliquity and transforms have been linked to a diverse array of phenomena including: rift and breakup-related magmatism, subduction initiation, supercontinent dispersal, microcontinent cleaving, structural inheritance, relative plate motion, hydrocarbon systems, geothermal energy potential, lithosphere-hydrosphere interaction, and hazardous seismic activity.
In this session, we will explore the formation, evolution, extinction and reactivation of orthogonal, oblique and transform extensional systems. In addition, the wealth of new understanding and ideas concerning the control of such systems on, or their interaction with other Earth processes will be discussed. We seek contributions that address these topics from all geoscience disciplines using both geological and geophysical data, numerical and analogue modelling, and/or direct rock studies from different settings and natural examples, from global, basin, and outcrop scales. Special emphasis will be given to multidisciplinary studies, and submissions from early career researchers, including students, are particularly encouraged.