Réinterprétation des conditions de dépôt des calcaires fluviatiles, lacustres et palustres du bassin plio-quaternaire du Saïss de Fès (Maroc)

The Eastern Saïss limestones, until then regarded as lacustrine Pliocene, have been referred to two main environment types : palustrine carbonates in the middle of the basin, and fluviatile carbonates (oncolitic sands, travertine dam, réservoir muddy limestones) on the N and S edges. The threefold paleogeographic evolution (Late Pliocene, Pleistocene, Holocene) is related to tectonics morphogenesis and climatic evolution, influencing the development of specific fluviatile carbonates on the Northern edge of the Moyen Atlas.L'étude des calcaires du Saïss oriental, réputés pliocènes et lacustres, a conduit à distinguer deux grandes types d'environnements de dépôt : des carbonates palustres au centre et des carbonates fluviatiles (sables oncolithiques, barrages travertineux, calcaires boueux de biefs) sur les bordures N et S. L'organisation paléogéographique se modifie en trois étapes (Pliocène supérieur, Pléistocène et Holocène) mises en relation avec la tectonique, la morphogenèse et une évolution climatique, qui rythment en particulier le développement des dépôts fluviatiles originaux sur le versant N du Moyen Atlas.Ahmamou M., Conrad Georges, Plaziat J.-Cl. Réinterprétation des conditions de dépôt des calcaires fluviatiles, lacustres et palustres du bassin plio-quaternaire du Saïss de Fès (Maroc). In: Méditerranée, troisième série, tome 68, 2-3-1989. Carbonates continentaux et paléoenvironnements dans le domaine méditerranéen, sous la direction de P. Freytet, J. Vaudour et E. Verrecchia. pp. 41-49

Kinematics and paleostresses in the Jebha-Chrafate transcurrent fault (northern Rif, Morocco)

4 páginas, 3 figuras.-- Trabajo presentado en la 38ª Sesión Científica, Teruel, 2005.The Jebha-Chrafate is an ENE-WSW sinistral major transcurrent fault of the Rif Cordillera, formed during the southwestwards emplacement of the Internal Zones on the Flysch units and the External Zones. The analysis of minor structures along the Jebha area indicates the activity of top to the SW low and high angle normal faults during the tectonic wedge emplacement. In addition, most of the kinematic indicators along the transcurrent fault zone point to a reactivation as dextral fault during the recent NW-SE Eurasia-Africa convergence and a final overprinting of normal faults during the late stages of relief uplift.Este trabajo se ha realizado gracias a la beca postdoctoral concedida al primer firmante por parte de la Agencia Española de la Cooperación Internacional (AECI) 2004-2005. El trabajo ha sido financiado por proyectos de la Consejería de Presidencia (Junta de Andalucia), AECI y BTE 2003-01699 (CICyT).Peer reviewe

Tectonic wedge escape in the southwestern front of the Rif Cordillera (Morocco)

18 páginas, 12 figuras.-- Editores: G. Moratti y A. Chalouan.The Rif Cordillera is a part of the Alpine orogenic arc in the Western Mediterranean, which was developed by the interaction of the westward motion of the Alboran Domain between the converging Eurasian and African plates. The Prerif Ridges, located along the southwestern front of the Rif, are south-vergent folds that are in places associated with faults affecting Jurassic to Quaternary sedimentary rocks and slope breccias that evidence the deformations that were active over the Neogene-Quaternary period. The different southward or southwestward displacement of each Prerif Ridge is related to the development of frontal and lateral ramps, which may or may not reach the surface. Oblique shortening may be explained by southwestward escape of large tectonic wedges, bounded by large strike-slip faults: the North-Middle Atlas fault which extends northward into the Alboran Sea, the Fez-Tissa-Taïneste fault, the Bou Draa-Sidi Fili fault, the Jebha fault and the Fahies fault. The relative displacement of these tectonic wedges toward the SW may explain the NNE-SSW to ENE-WSW compression observed in the Rif front and in the northern part of its Meseta-Atlas foreland.The research has been financed by collaborative Spanish-Moroccan projects of the Junta de Andalucfa, the AECI and CICYT project BTE2003-01699.Peer reviewe

Interactions between tectonic and sedimentation related to the Rides Prérifaines in the Volubilis basin (Rif front, Morocco)

4 páginas, 4 figuras.-- Trabajo presentado en la 47ª Sesión Científica, Santander, 2009.The Volubilis Neogene basin (Morocco) was part of the South Rif Corridor that connected the Atlantic Ocean with the Mediterranean. This basin recorded the tectonic - sedimentary interactions of a foreland basin subjected to the progressive advance of the Rif mountain range front. Since the Miocene, the displacement of the Prerif to the WSW, caused the detachment of the Mesozoic and Cenozoic cover from the Variscan basement and the compartimentation of Saïss Basin. Simultaneously, the upper Neogene sedimentation continued, developing several types of syntectonic sedimentary structures and Volubilis basin finally becomes a piggy-back basin.Esta investigación ha sido financiada gracias al proyecto CGL 2006.06001, CSD 2006-00041 del MICIN, grupo RNM148 Junta de Andalucía y al proyecto de la AECID: A/018425/08.Peer reviewe

Recent deformations in the front of the Rif Cordillera (Prerif, Morocco)

3 páginas, 2 figuras.-- Trabajo presentado en la 29ª Sesión Científica, Salamanca 2000.The Prerif ridges form part of the foreland of the Rif Mountains. They are formed by superposed slices, withi folds and faults, originated during the late Miocene WSWwards displacement of the Prerif units. At present, they thrust over the Plio-Quaternary formations of the Saïs and Gharb basins. The analysis of the deformations in the Prerif ridges and the Plio-Quaternary lacustrine formations of the Saïs basin, as well as the thrust structures, indicates a recent tectonics with a N-S to NW-SE compression, subparallel to the trend of the present Iberian-Africa convergence.Este trabajo se ha realizado en el marco del proyecto 'Deformaciones tectónicas recientes y actuales en una transversal de la Cordillera Rifeña' cofinanciado por la A.E.C.I.Peer reviewe

Tectónica reciente y activa en la Cordillera del Rif (Alhucemas, Marruecos): Implicaciones en la peligrosidad sísmica

11 páginas, 9 figuras.La determinación de la actividad tectónica reciente y actual en la Cordillera del Rif tiene gran interés, ya que está asociada a la actividad de las fallas que determinan la peligrosidad sísmica de la región. El objetivo de este trabajo es describir las características de la actividad tectónica sismogenética en la región de Alhucemas situada en el interior de la Cordillera del Rif, para discutir algunos factores geológicos que no suelen tenerse en cuenta habitualmente en los estudios de peligrosidad sísmica, desarrollados con técnicas aplicables a zonas frontales de cordilleras.Este trabajo ha sido posible gracias a proyectos de colaboración internacional financiados por el MEC, la Agencia Española de Cooperación Internacional y la Agencia Andaluza de Cooperación Internacional.Peer reviewe

Recent Tectonic Deformations and Stresses in the Frontal Part of the Rif Cordillera and the Saïss Basin (Fes and Rabat Regions, Morocco)

20 páginas, 10 figuras.Prerif Ridges are located at the frontal part of the Rif Cordillera, which develops at the Eurasian-African plate boundary. The ridges are formed by recent tectonic structures that also deform foreland basins (Saïss and Gharb basins) and the foreland (Moroccan Meseta). The position of the ridges is the consequence of inversion tectonics undergone in the area. The ENE-WSW trend of the northern edge of the Neogene Saïss basin is determined by the location of Mesozoic basins. Although Prerif ridges probably started to develop since the Early Miocene, the most active deformation phase affecting Pliocene rocks consisted of N-S to NW-SE oriented compression. Striated pebbles show that this compression has prolate stress ellipsoids. The deformation produces southwards vergent folds and NNW-SSE striae on reverse faults at the base of the ridges. The flexure of the Paleozoic basement by the emplacement of the Ridges produced extensional deformation and the development of the Saïss foreland basin. The extension in this basin is oblate and features a well determined NNE-SSW trend near the Ridges, whereas it becomes prolate and pluridirectional near the foreland edge represented by the Rabat region. This part of the Moroccan Meseta, commonly considered to be stable, is deformed by sets of orthogonal joints and faults with short slip that affect up to Quaternary sediments. Southwestward, the Meseta rocks are also deformed by transcurrent faults, which indicate NW-SE and N-S trends of compression. The NW-SE approximation of Eurasia and Africa determines a regional stress field with the same trend of compression. Regional stresses are notably disturbed by the development of the active structures in the Rif, which exhibit alternating trends of compression and extension. The clearest evidence of the relationship between the local deformation and the general plate motion is found at the deformation front of the Cordillera, that is, the Prerif Ridges.This research was supported by project BTE-2000-1490-C02-01 and the Spanish-Moroccan Inter-Universities Cooperation Programs 29/PRO/99 of the A.E.C.I. and the Junta de Andalucía.Peer reviewe

Recent deformations in the front of the Rif Cordillera (Prerif, Morocco)

The Prerif ridges form pari of the foreland of the Rif Mountains. They are formed by superposed slices, with folds and faults, originated during the late Miocene WSWwards displacement of the Prerif units. At present, they thrust over the Plio-Quaternary formations of the Sa/'s and Charb basins. The analysis of the deformations in the Prerif ridges and the Plio-Quaternary lacustrine formations of the Sai'ss basin, as well as the thrust structures, indicates a recent tectonics with a N-S to NW-SE compression, subparallel to the trend of the present Iberian-Africa convergenc

Eustatic and tectonic controls on Quaternary Ras Leona marine terraces (Strait of Gibraltar, northern Morocco)

12 páginas, 9 figuras, 2 tablas.Well-preserved Quaternary staircased marine terraces appear on Ras Leona limestone relief. This is a peculiar sector of the Betic-Rif Cordillera, lying in the four-way junction between the Atlantic and the Mediterranean, and Europe and Africa. The age and altitude correlation of the Ras Leona terraces with travertine-covered lateral equivalent terraces fashioned in the neighbouring Beni Younech area, and comparison with those along the Moroccan Atlantic coasts, would suggest that the Ras Leona terraces were mainly formed by eustatic factors. The importance of the eustasy is supported by further comparisons with Spanish and Moroccan Mediterranean terraces and with different marine terraces developed on passive-margin coasts around the world. A tectonic event occurred mainly during the period between the formation of the Maarifian and the Ouljian terraces (i.e., between 370 and 150 ka). The moderate Quaternary tectonic uplift deduced from the marine terraces and its comparison with uplifted marine terraces developed in active subduction setting disagrees with the model of an active eastwards subduction below the Gibraltar tectonic arc.This paper forms part of the projects A/024878/ 09 (AECID, CGL2007-60535, CGL2009-07721 and CSD2006-00041 (MEC), P06RNM-01521, RNM-024 and 148 (Junta de Andalucía).Peer reviewe