Structural styles and Neogene petroleum system around the Yusuf-Habibas Ridge (Alboran Basin, Mediterranean Sea)

International audienceThe Algerian offshore is part of the southern margin of the western Mediterranean Sea. The western part of this offshore area represents the transitional margin between the South Algero-Balearic Basin and the Alboran Basin. The study area includes the southern and eastern parts of the Alboran Basin and the northwestern part of the Algerian margin and is in the western part of the plate boundary between Eurasia and Africa (Figure 1). The Yusuf-Habibas Ridge is a major EW-striking structure of this complex plate boundary, separating the eastern and southern parts of the Alboran Basin from the South Algero-Balearic Basin (Martinez-Garcia et al., 2011, and references therein). The ridge played an important role during the Neogene Alboran westward block migration between the Africa and Iberia plates, while the Kabylies blocks migrated southward and accreted to Africa. Furthermore, the ongoing NW-SE convergence between Africa and Iberia has induced a new stress field, since 7 Ma ago, replacing an earlier stress field (Fernandez-Ibañez et al., 2007) and leading to reactivation and polyphased deformation on the main structures in the basin, including the Yusuf-Habibas Ridge

Post-Cretaceous kinematics of the Atlas and Tell systems in central Algeria : Early forlenad folding and subduction-related deformation

Available surface and industrial subsurface data provide the basis for a general balanced cross-section from the Sahara platform to the Mediterranean Sea in central Algeria. This section gives an overview of the whole Maghrebian orogen comprising from south to north the following structural domains: the intra-continental Atlas system; the External Tell system, deriving from the African palaeo-margin; the Flyschs domain, representing the cover of the former oceanic domain and, finally, the Kabylides domain of European affinities. Restoration of the southern segment of the section, comprising the Atlas and External Tell systems, yields a minimum value of 40 km (20%) of horizontal shortening. For this part of the section, a four-step kinematic scenario, built using the THRUSTPACK software, illustrates the main stages of the deformation history: (1) Late Eocene 'Atlas' deformation pulse, (2) Early Miocene deposition of a thick flexural sequence, (3) Middle-Late Miocene emplacement of the Tell nappes and (4) Late Miocene to present out-of-sequence thrusting. On this basis, a conceptual geodynamic model is proposed for the whole Maghrebian orogen. After the Atlas event, which just preceded the roll-back of the Tethyan slab, the model emphasises the role of subduction responsible for: (1) flexuration of the subducting plate (slab pull effect), (2) development of both accretionary prism and back-arc basin, and (3) late uplift linked to slab break-off. © 2005 Académie des sciences. Published by Elsevier SAS. All rights reserved

Seismic imaging of the eastern Algerian margin off Jijel: integrating wide-angle seismic modelling and multichannel seismic pre-stack depth migration

This study presents the results of a deep seismic survey across the north Algerian margin, based on the combination of 2-D multichannel and wide-angle seismic data simultaneously recorded by 41 ocean bottom seismometers deployed along a north-south line extending 180 km off Jijel into the Algerian offshore basin, and 25 land stations deployed along a 100-km-long line, cutting through the Lesser Kabylia and the Tellian thrust-belt. The final model obtained using forward modelling of the wide-angle data and pre-stack depth migration of the seismic reflection data provides an unprecedented view of the sedimentary and crustal structure of the margin. The sedimentary layers in the Algerian basin are 3.75 km thick to the north and up to 4.5-5 km thick at the foot of the margin. They are characterized by seismic velocities from 1.9 to 3.8 km s(-1). Messinian salt formations are about 1 km thick in the study area, and are modelled and imaged using a velocity between 3.7 and 3.8 km s(-1). The crust in the deep sea basin is about 4.5 km thick and of oceanic origin, presenting two distinct layers with a high gradient upper crust (4.7-6.1 km s(-1)) and a low gradient lower crust (6.2-7.1 km s(-1)). The upper-mantle velocity is constrained to 7.9 km s(-1). The ocean-continent transition zone is very narrow between 15 and 20 km wide. The continental crust reaches 25 km thickness as imaged from the most landward station and thins to 5 km over a less than 70 km distance. The continental crust presents steep and asymmetric upper- and lower-crustal geometry, possibly due to either asymmetric rifting of the margin, an underplated body, or flow of lower crustal material towards the ocean basin. Present-time deformation, as imaged from three additional seismic profiles, is characterized by an interplay of gravity-driven mobile-salt creep and active thrusting at the foot of the tectonically inverted Algerian margin

The Algerian Margin : A Case Study of Interaction between Plio-Quaternary Sedimentation and Tectonics

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