15:30 〜 16:30
[S22-P-02] Thermomechanical modeling of tectonic inversion at the ocean-continent boundary of the North African margin (Algeria): possible initiation of subduction
While ocean subduction is one of the most important processes of plate tectonics, the understanding of
how and where it begins is still being debated (eg. Gerya, 2011). Northern Algeria is currently undergoing a
slow compression deformation due to the ongoing African-Eurasian convergence, as evidenced by active
seismic activity recorded both on land and at sea (Yelles et al., 2006). The Algerian margin can thus
represent a transitional step between the parameters of active and passive margin (Jolivet et al., 2006).
Wide-angle seismic profiles data and The isostatic anomaly models show signs of active or recent
compressive deformation along this margin in isostatic desequilibrium. (Hamai et al., 2015). From these
observations, two questions: I) What rheological and thermal parameters control the location of
compressive deformation at the margin toe? II) Are these parameters suitable for long-term evolution of
this margin into a mature subduction zone?
we use the thermo-mechanical code pTatin (May et al., 2014) to test the effect of thermal and rheological
parameters on the tectonic inversion of a passive margin characterized by a hot young oceanic area
adjacent to a colder continental zone. We consider olso a transition zone (OCT) of 20 km wide between
oceanic lithosphere and continental lithosphere, which can be either of oceanic or continental affinity. This
OCT can be either vertical or diving towards the continent. Finally, we test the effect of a smooth thermal
gradient between the ocean and the continent and a clear vertical line between oceanic and continental
geotherms.
Our results indicate that tectonic inversion may evolve towards subduction, when the transition zone
plunges towards the continent or towards an indentation of the lower continental crust by the oceanic
lithosphere when the transition zone is vertical. In both cases, the strain localization in the margin toe
occurs only when it is sufficiently heated by the adjacent ocean area.
how and where it begins is still being debated (eg. Gerya, 2011). Northern Algeria is currently undergoing a
slow compression deformation due to the ongoing African-Eurasian convergence, as evidenced by active
seismic activity recorded both on land and at sea (Yelles et al., 2006). The Algerian margin can thus
represent a transitional step between the parameters of active and passive margin (Jolivet et al., 2006).
Wide-angle seismic profiles data and The isostatic anomaly models show signs of active or recent
compressive deformation along this margin in isostatic desequilibrium. (Hamai et al., 2015). From these
observations, two questions: I) What rheological and thermal parameters control the location of
compressive deformation at the margin toe? II) Are these parameters suitable for long-term evolution of
this margin into a mature subduction zone?
we use the thermo-mechanical code pTatin (May et al., 2014) to test the effect of thermal and rheological
parameters on the tectonic inversion of a passive margin characterized by a hot young oceanic area
adjacent to a colder continental zone. We consider olso a transition zone (OCT) of 20 km wide between
oceanic lithosphere and continental lithosphere, which can be either of oceanic or continental affinity. This
OCT can be either vertical or diving towards the continent. Finally, we test the effect of a smooth thermal
gradient between the ocean and the continent and a clear vertical line between oceanic and continental
geotherms.
Our results indicate that tectonic inversion may evolve towards subduction, when the transition zone
plunges towards the continent or towards an indentation of the lower continental crust by the oceanic
lithosphere when the transition zone is vertical. In both cases, the strain localization in the margin toe
occurs only when it is sufficiently heated by the adjacent ocean area.