During the Algerian-French SPIRAL survey aimed at investigating the deep structure of the Algerian margin and basin, two coincident wide-angle and reflection seismic profiles were acquired in central Algeria, offshore Greater Kabylia, together with gravimetric, bathymetric and magnetic data. This ~260 km-long offshore-onshore profile spans the Balearic basin, the central Algerian margin and the Greater Kabylia block up to the southward limit of the internal zones onshore. Results are obtained from modeling and interpretation of the combined data sets.Please note that this is an author-produced PDF of an article accepted for publication following peer review. The definitive publisher-authenticated version is available on the publisher Web site.slope. This disequilibrium is likely responsible for the peculiar asymmetrical shape of the crustal neck that may thus be a characteristic feature of inverted rifted margins.
Highlights► Modeling of deep seismic data images the deep structure of the Algerian margin. ► The Algerian margin offshore Greater Kabylia is a narrow, magma-poor rifted margin. ► Margin inversion may trigger lower crust seaward flow due to isostatic disequilibrium. ► A 3-layer thin oceanic crust reveals postaccretion volcanism in the Algerian basin. ► A two-step Miocene evolution of the West Algerian backarc basin is proposed.
Rédigé à l'invitation du Comité éditorial
RésuméEn Algérie, la tectonique active est localisée dans la région nord du pays, essentiellement dans le Tell. Dans cette région, frontière entre les plaques Africaine et Eurasiatique, la déformation tectonique est l'expression de la convergence actuelle des ces deux plaques et se traduit par la fermeture progressive des bassins néogènes et par la poursuite de
International audienceThe ∼60 km-long Sahel ridge west of Algiers (Tell Atlas, north Algeria) is considered as an ENE-WSW fault-propagation fold running along the Mediterranean coast and associated with a north-west dipping thrust. Its proximity with Algiers makes this structure a potential source of destructive earthquakes that could hit the capital city, as occurred in 1365 AD and 1716 AD. The first paleoseismologic investigation on the Sahel ridge was conducted in order to detect paleo-ruptures related to active faulting and to date them. From the first investigations in the area, a first trench was excavated across bending-moment normal faults induced by flexural slip folding in the hanging wall of the Sahel anticline thrust ramp. Paleoseismological analyses recognize eight rupture events affecting colluvial deposits. 14C dating indicates that these events are very young, six of them being younger than 778 AD. The first sedimentary record indicates two ruptures before 1211 AD, i.e. older than the first historical earthquake documented in the region. Three events have age ranges compatible with the 1365, 1673 and 1716 Algiers earthquakes, whereas three other ones depict very recent ages, i.e. younger than 1700 AD. Potential of these secondary extrados faults for determining paleoseismic events and thrust behaviour is discussed
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