Towards subduction inception along the inverted North African margin of Algeria? Insights from thermo-mechanical models

Tectonic Inversion and Geomorphic Evolution of the Algerian Margin Since Messinian Times: Insights From New Onshore/Offshore Analog Modeling Experiments

“…Leprêtre et al, 2013). Recent 2D thermo-mechanical models suggest that in the central Algerian margin, both the thinned continental crust and the high geothermal gradient favor strain localization and underthrusting of the oceanic lithosphere at the margin toe (Hamai et al, 2018). Therefore, the rheology of the Algerian margin is likely weak owing to the propagation of the Tethyan slab tear and the Miocene (17-11 Ma) plutonic and volcanic activity emplaced in the Kabylies posterior to the collision (Chazot et al, 2017, and references therein).…”

“…From recent wide‐angle seismic data, the Moho is found at 20–25 km depth beneath the continental domain, evidencing a relatively thin continental crust over ∼60 km across strike, while toward the Algerian basin, the Moho rises to a depth of about 10 km and the crust is of oceanic type (Aïdi et al., 2018; Bouyahiaoui et al., 2015; A. Leprêtre et al., 2013). Recent 2D thermo‐mechanical models suggest that in the central Algerian margin, both the thinned continental crust and the high geothermal gradient favor strain localization and underthrusting of the oceanic lithosphere at the margin toe (Hamai et al., 2018). Therefore, the rheology of the Algerian margin is likely weak owing to the propagation of the Tethyan slab tear and the Miocene (17–11 Ma) plutonic and volcanic activity emplaced in the Kabylies posterior to the collision (Chazot et al., 2017, and references therein).…”

“…The area has received special attention over the last 20 years, especially after the occurrence of the Boumerdès earthquake ( M w = 6.9, 2003; Ayadi et al., 2003). Geophysical studies since then have evidenced that the Algerian margin is experiencing crustal shortening and a generalized tectonic inversion possibly leading to subduction inception (Hamai et al., 2015, 2018; Strzerzynski et al., 2010; Yelles et al., 2009). In Lesser Kabylia, a first cooling episode between 17 and 15 Ma was followed by a kilometer‐scale exhumation between 9 and 7 Ma, interpreted as a consequence of slab breakoff and the formation of imbricated thrust sheets in the upper margin, respectively (Recanati et al., 2019).…”

“…Recent geodetic results in Algeria demonstrate that the offshore fault system, running along the toe of the central Algerian margin, possibly accommodates 1.5 mm/year of shortening, in contrast with the coastal domain of the Tell and Kabylies where strain rates are very low (Bougrine et al., 2019). Thermo‐dynamical modeling suggests that the relatively high geothermal gradient and the deep inherited structures of the stretched continental margin contribute to weaken the margin and to focus compressional deformation at the margin toe (Hamai et al., 2018).…”

Kinematics and extent of the Piemont-Liguria Basin – implications for subduction processes in the Alps

“…Interestingly, Dannowski et al (2020b) re-evaluated the nature of basement beneath the Liguro-Provencal Basin to be hyperextended continental crust (only a few km thick) and exhumed mantle, rather than oceanic crust. Moreover, compressional earthquakes and inverted structures have been observed within the Liguro-Provencal Basin and along the northern African margin, which suggest that those hyper-extended margins and OCT zones may represent incipient subduction zones accommodating the present-day Africa-Europe convergence (Billi et al, 2011;Hamai et al, 2018;Dannowski et al, 2020b).…”