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Soutenance de thèse Manar ALSAIF

Soutenance de thèse Manar ALSAIF

Vendredi 20 septembre 2019 à 10h30 sc23.01, bât. 23, campus Triolet, Université de Montpellier
Manar ALSAIF soutiendra publiquement ses travaux de thèse Upper Plate deformation in retreating Subduction Zones

Subduction trenches are mobile plate boundaries, and are observed to retreat towards the subducting plate or advance towards the upper plate over geological time. We explore upper plate deformation in retreating subduction systems. Three techniques are used : large-scale numerical models addressing physical processes ; seismic profiles in the Central Aegean addressing basin-scale fault patterns ; and field-scale observations clarifying fault kinematics in the Central Aegean.
The large-scale thermo-mechanical models deal with viscous deformation of the upper plate, and investigate the relationship between slab pull, slab rollback, trench retreat and upper plate deformation. They show that asthenosphere flows below the plates can control both trench retreat and upper plate deformation.
The type of deformation in the upper plate also depends on the plate’s far-field conditions. The Aegean region is used as a case study for an upper plate exhibiting extension above a narrow, retreating subduction zone. Related extensional structures in the central Aegean have been analysed from seismic and field data, revealing co-existing normal, oblique and strike slip faults. These features reflect a combination of rollback-related extension and extrusion-related strike slip activity. Resulting block rotation and trench retreat have re-activated inherited normal faults in oblique-normal slip, while new pure-normal faults are created. Additionally, accelerated trench retreat and upper plate extension are the cause of the Aegean’s high surface heat flow, which makes it potentially suitable for geothermal energy production. We use this to asses the role of tectonic research in predicting geothermal energy potential as a final perspective on the application of geodynamic research.

Composition du Jury :

- Muriel GERBAULT Géosciences Environnement Toulouse, Rapportrice
- Olivier VAN DER HAEGHE Géosciences Environnement Toulouse, Rapporteur
- Christel TIBERI Géosciences Montpellier, Examinatrice
- Frédéric GUEYDAN Géosciences Montpellier, Directeur de thèse
- Fanny GAREL Géosciences Montpellier, Co-Directrice de thèse
- Serge LALLEMAND Géosciences Montpellier, Invité