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Rabat, Morocco

Elabidi A.,Institute National dHygiene | Fekhaoui M.,Institute scientifique | Ghouli A.,Ministere de lEducation National | Piervittori R.,University of Turin | Yahyaoui A.,Universite Ibn Tofail
Avocetta | Year: 2010

Adult Columba livia pigeons were used as bioindicators of atmospheric pollution by heavy metals, from different sources (road traffic, earthenware workshops). Concentrations in pigeon tissues varied according to metals. Lead and cadmium showed higher accumulation in kidneys, while zinc was the found in whole organs. Except for Oulja, where lead is commonly used in earthenware production, lead and cadmium were accumulated according to the density of road traffic, thus the highest lead concentrations were found in the town centre, followed by Kamra where car traffic is moderate, and with the lowest concentrations of lead in rural areas. On average, high concentrations of cadmium were observed in the kidneys of pigeons in the town centre, and a lower content ratio (25 times) was found in rural areas (Allal Behraoui). The low metal concentrations in the pigeons blood and organs was due to the limited presence of industry in Rabat-Salé. © 2010 CISO - Centro Italiano Studi Ornitologici. Source

El Hadi H.,Hassan II University Mohammedia - Casablanca | Tahiri A.,Institute scientifique | Simancas J.F.,University of Granada | Gonzalez-Lodeiro F.,University of Granada | And 2 more authors.
Geoheritage | Year: 2011

The Bou Azzer ophiolitic complex (Anti-Atlas, southern Morocco) marks the suture of the Pan-African orogenic belt. This fragment of old oceanic crust (697 ± 8 Ma) obducted onto the continental margin of the West African Craton during a collisional event that occurred between 650 and 580 Ma. Very well exposed desert outcrops display serpentinites associated with chromite pods and clinopyroxenolites, ultrabasic and basic cumulates, quartz diorite, a sheeted-dyke complex, basaltic pillow lavas, and red cherts, i.e., the set of lithologies composing an ophiolitic sequence. Other geological units cropping out in the area are: (1) the underlying continental margin of the West African Craton; (2) a volcanic arc next to the oceanic crust represented by the ophiolite; (3) overlying unconformable volcanic and sedimentary rocks. The unusual character of this Neoproterozoic magmatic and tectonic geoheritage site, together with the excellent quality of the outcrops and the relatively easy access to the area, make this complex attractive from both a scientific and a geotouristic perspective. Its declaration as a geoheritage site will serve as a stimulus for the preservation of this singular area. © 2011 Springer-Verlag. Source

Tahiri A.,Institute scientifique | Montero P.,University of Granada | El Hadi H.,British Petroleum | Martinez Poyatos D.,University of Granada | And 4 more authors.
Journal of African Earth Sciences | Year: 2010

The northern border of the Variscan Moroccan Meseta is characterized by the presence of Cambrian rocks affected by pre-Variscan deformation (the Sehoul block) thrust to the south onto Ordovician, Silurian and Devonian sediments and volcanics of the Bou Regreg corridor. A correct appraisal of the significance of this tectonic contact in the framework of the Variscan orogen needs new data on the age, geochemical features and field relationships of granitoids cropping out in the Sehoul block (Rabat granitoids) and the Bou Regreg corridor (Tiflet granitoids). Accordingly, we provide here with new geochemical data and accurate U-Pb geochronology of these granitoids, which lead us to conclude that: (i) the Rabat granitoids are Late Devonian in age (367. Ma); (ii) the Tiflet granitoids are Late Proterozoic in age (605-609. Ma) and display Andean-arc features, thus being genetically linked to the Cadomian/Pan-African subduction and forming part of the Variscan basement during the Palaeozoic; (iii) the previously accepted 430. Ma Rb-Sr age, common for the Rabat and Tiflet granitoids, which would imply a trivial Carboniferous displacement of the Sehoul thrust, must be rejected; and (iv) the Sehoul thrust might be a major Variscan boundary, perhaps hiding the Rheic Ocean suture. © 2009 Elsevier Ltd. Source

El Hadi H.,Science Faculty | Simancas J.F.,University of Granada | Martinez-Poyatos D.,University of Granada | Azor A.,University of Granada | And 5 more authors.
Precambrian Research | Year: 2010

The Bou Azzer ophiolite in the Moroccan Anti-Atlas represents the suture of the Neoproterozoic Pan-African orogen. The Bou Azzer inlier includes, from NE to SW, three main geological units: a volcanic-arc, an ophiolite and a continental platform. Several subduction-related plutons intrude the ophiolite and the volcanic-arc, and syn-to-late orogenic deposits unconformably cover the three terranes. The Eburnean (≈2. Ga) continental basement observed in other inliers of the Anti-Atlas appears not to crop out at Bou Azzer, where rocks traditionally attributed to that old basement are in fact Neoproterozoic rocks, either metagranitoids of the continental margin or ophiolitic metagabbros.The age of a metagabbro of the ophiolite is reported here for the first time, as 697 ± 8. Ma (SHRIMP U-Pb on zircons). U-Pb geochronological data are also presented for two syn-kinematic subduction-related plutons which, together with previous data, establish a time-span of ca. 655-635. Ma for these arc-type rocks. Moreover, the Oumlill granite, previously attributed to the Eburnean basement, has been dated as 741 ± 9. Ma.The earliest tectonometamorphic event affecting the ophiolite is recorded as a relic foliation and a garnet-rutile metamorphic assemblage, which might attest to an early peak-pressure exceeding the 5-6. kbar medium pressure reported so far. Thus, we suggest a first stage of ophiolite underthrusting below a volcanic-arc, followed by ophiolite exhumation and the concomitant development of the main low-grade planar-linear tectonic fabric. The ages of the calc-alkaline, syn-kinematic subduction-related plutons (655-635. Ma) might be taken as the end of subduction and the beginning of the ophiolite exhumation-obduction.The author's work in the Bou Azzer region supports the ophiolite-continental platform interpretation of Leblanc (1975) and Leblanc and Moussine-Pouchkine (1994), rather than the tectonic mélange interpretation proposed by Saquaque et al. (1989b) and others. A recumbent anticlinal and the basal thrust of the ophiolitic terrane are the main macrostructures formed during the obduction stage, characterized by top-to-the-W/SW kinematics. This deformational event is also recorded in the rocks of the underlying continental platform. A syn-orogenic unit, namely the Tiddiline Formation, unconformably overlies the arc volcanics, the ophiolite and the continental platform. Further collisional deformation affected the Tiddiline sediments, giving way to ESE-WSW striking upright folds and oblique reverse faults. The latest structures in this Neoproterozoic suture were left-lateral strike-slip faults, pointing to an increase in the left-lateral component of the continental collision. © 2010 Elsevier B.V. Source

Le Roy P.,CNRS Oceanic Domains Laboratory | Sahabi M.,Laboratoire geosciences marines | Maad N.,Laboratoire geosciences marines | Rabineau M.,CNRS Oceanic Domains Laboratory | And 8 more authors.
Marine and Petroleum Geology | Year: 2014

This study focuses on the evolution of the Atlantic NW Moroccan Rharb continental shelf during the Neogene and Quaternary. This region is part of a foreland basin bounded by the Rif mountain belt and thus provides an interesting geological setting to study the interactions between eustasy and tectonics and the driving mechanisms controlling stratigraphic patterns. The results are supported by an interpretation of new data including high-resolution seismic lines coupled with an interpretation of industrial seismic lines and detailed logs of industrial wells completed by micropaleontologic analysis of cuttings. The stratigraphy reveals a succession of three mega sequences related to the transition from an underfilled to an overfilled stage reflecting the long-term evolution of the foreland system. Moreover, evidence of cyclical sea-level changes are visible in the upper megasequence composed of three depositional sequences assumed to be fourth-order sequences generated in response to the most recent 100-ka glacio-eustatic cycles. This study also shows the peripheral deformation of the Rharb shelf responsible for changes in the geometry of the deposits and thicknesses of the sedimentary fill during the Pliocene and Pleistocene. The most important change was triggered by the uplift of the Lallah Zahra Ridge corresponding to a major Quaternary kinematic boundary and the broad uplift of the southern shelf interpreted as a flexural uplift of the forebulge domain. The deformation-controlled sediment dispersal pattern consists of a progressive growth of the shelf accompanied with a progressive shift of depocenters from the North East to the South West and a general progradation to the North West along the southern border. This progressive filling has led to the confinement of the Rharb paleo-valley across the continental shelf. The complete filling of the palaeo-valley was followed by the development of a more than 70-m thick prodeltaic lobe at the front of the Oued Sebou river mouth during the Holocene. © 2013 Elsevier Ltd. Source

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