Evidence for transform motion along the South Balearic margin and implications for the kinematics of opening of the Algerian basin

Abstract

Two major types of kinematic models have been proposed to explain the opening of the western Mediterranean basins (Liguro-Provençal and Algerian basins, and Valencia trough). In one type of models, all continental blocks bounding the basins drift to the southeast, driven by the rollback of the Tethys subduction slab. In the other type of models, the Alboran domain drifts to the southwest, implying a westward rollback of the broken subducting slab and a NE-SW opening of the Algerian basin. In most models, however, the structure of the Balearic promontory was not taken into account, despite its key location at the boundary of the three major basins. We used the interpretation of a large seismic database coupled to gravity and magnetic anomaly analyses to characterize the nature and structure of the South Balearic margin. The constraints brought by the new analyses allow us to suggest a new scenario for the opening of the Algerian basin.Seismic profiles show that the South Balearic margin is composed of four segments with different morphologies and crustal structures. Two segments, the Mazarron and the Emile Baudot escarpments, are characterized by steep scarps and sharp crustal thinning. Two other segments, the South Ibiza and South Menorca margins, have a smoother bathymetry and crustal thinning. We interpret the former in terms of transform margins, and the latter as divergent margins. The distribution of faults on the passive margin segments suggests that they have recorded at least two phases of deformation. A first phase of opening, probably in a NW-SE direction, affected the south Balearic margin, and possibly created some oceanic floor. The existence of the transform margin segments and the prominent NW-SE orientation of the magnetic lineations in the eastern Algerian basin suggest that most of this basin opened in a NE-SW direction, in different oceanic corridors. The two eastern corridors formed by the southwestward drift of the Kabylies. The western corridor, bounded by the transform segments of the South Balearic margin and the Algerian margin, results from the southwestward drift of the Alboran domain, as suggested by previous studies.Résumé. -Deux grands types de modèles cinématiques ont été proposés pour expliquer l'ouverture des bassins de la Méditerranée occidentale (bassins Liguro-Provençal et Algérien et fossé de Valence). Dans un type de modèles, tous les blocs continentaux limitant les bassins dérivent vers le sud-est, tirés par le retrait de la subduction de la plaque téthysienne. Dans l'autre type de modèles, le domaine d'Alboran dérive vers le sud-ouest, impliquant un retrait vers l'ouest de la subduction d'une partie de la plaque téthysienne déchirée. Dans la plupart de ces modèles, cependant, le promontoire Baléares n'est pas pris en compte, et ce, malgré sa position clé à la frontière des bassins majeurs. Nous avons utilisé l'interprétation d'une large base de données sismiques couplée à une analyse des anomalies gravimétriques et magnétiques pour caractériser la nature et la structure de ...

Seismic imaging of Late Miocene (Messinian) evaporites from Western Mediterranean back-arc basins

“…Evidence for this is the identification of the north-south-trending Hannibal Ridge (HR), and associated magnetic anomalies, a relict and buried spreading centre with associated volcanic centres south of Menorca Island (Mauffret et al 2004). Such direction of the Algero-Balearic basin opening is supported by the interpretation of the northern margin of the basin, marked by the Emile Baudot Escarpment (EBE), as a right-lateral strike-slip fault system generated in response to the westward migration of the Gibraltar Arc (Mauffret et al 1992(Mauffret et al , 2004Acosta et al 2001;Camerlenghi et al 2009;Driussi et al 2015). Similarly the southern margin of the Algero-Balearic basin is defined by the North African continental margin, a rifted margin with dominance of left-lateral strike-slip deformation.…”

“…1), separated from the Sardo-Provençal basin by the NW-SE-trending Hamilcar magnetic anomaly (HMA) (Mauffret et al 2004;Driussi et al 2015). In this case there are alternative geodynamic interpretations.…”

“…According to some, rifting and seafloor spreading was triggered by the westward migration of the Gibraltar Arc from the Langhian (16 Ma) to the Tortonian (8 Ma) in an ENE-WSW direction (e.g. Driussi et al 2015). Evidence for this is the identification of the north-south-trending Hannibal Ridge (HR), and associated magnetic anomalies, a relict and buried spreading centre with associated volcanic centres south of Menorca Island (Mauffret et al 2004).…”

Heat flow in the Western Mediterranean: Thermal anomalies on the margins, the seafloor and the transfer zones

“…Recently, some hybrid models have been proposed (e.g. Van Hinsbergen et al, 2014;Driussi et al, 2015;Etheve et al, 2016), which equally predict large transform margins in the western part of the Algero-Balearic basin.…”

Extensional vs contractional Cenozoic deformation in Ibiza (Balearic Promontory, Spain): Integration in the West Mediterranean back-arc setting

“…12). This comprises not only the middle Miocene compressional deformation but also the late Miocene rifting event, which is poorly exposed in Ibiza but well known in Majorca (Majorca Central Depression) and along the Promontory's southern margin (Sàbat et al, 2011;Driussi et al, 2015).…”