The western termination of the Jebilet–High Atlas system (Offshore Essaouira Basin, Morocco)

Hafid, Mohamad; Salem, Abdallah Aı̈t; Bally, A. W.

doi:10.1016/s0264-8172(98)00082-8

Cited by 63 publications

(56 citation statements)

References 21 publications

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“…In the offshore Tarfaya basin, the recent studies of Abou Ali et al (2004Ali et al ( , 2005 only show NE-SW Mesozoic normal faults without any signs of inversion. Finally, the offshore/onshore studies of Hafid et al (2000Hafid et al ( , 2006 suggest that, in the oceanic area, the High Atlas folds rotate and terminate in a mainly thin-skin, salt-driven, westward-thrusting pattern, which we interpret as an escape pattern.…”

Section: Regional Extent Of the South Atlas Frontmentioning

confidence: 75%

Structure of the Kasbah fold zone (Agadir bay, Morocco). Implications on the chronology of the recent tectonics of the western High Atlas and on the seismic hazard of the Agadir area

Mridekh¹,

Medina²,

Mhammdi³

et al. 2009

Estud. geol.

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Detailed re-interpretation of the north-eastern segment of a profile realized across the Agadir bay along a NE-SW trend and crosscutting the main structures, together with analysis of available isochron maps, allowed us to retrace the geological history of the offshore western High Atlas. Two tectonostratigraphic sequences were distinguished: Unit II, which displays a simple structure, laying unconformably on Unit I, with a more complex structure dominated by a reverse fault (F1) striking E-W with a dip to the north. Correlation to boreholes Souss-1 and AGM-1 allowed us to assign Unit I to the Triassic – Palaeogene and Unit II to the Miocene – Present. The NE fault block shows a ramp-flat fault plane (F2) with an overlying SW-vergent fold that can be interpreted as a fault-bend fold. Three main stages were distinguished: (1) during the Cretaceous, F1 could have been a syndepositional normal fault with the NE block moving downwards; (2) towards the beginning of the Tertiary, the displacement of plane F2 induced the development of a fault-bend fold and erosion of the forelimb and hinge of the fold; displacement along F2 was transferred to fault F1; (3) afterwards, during the Miocene, reverse motion of F1 deformed and tilted the plane F2 and accentuated the folded structure. This evolution is typical for a frontal basin above a fault-related fold. Evaluation of the thickness and bed depth differences shows that the largest growth rate was recorded in Late Miocene times. Seismic activity recorded in the Agadir bay appears to be clearly related to this fault zone, as inferred from focal mechanisms. Seismic moment evaluation suggests that earthquakes of magnitude Mw≥6 are likely to occur, but could not be much larger because of the fault segmentation geometry of the High Atlas Front.<br><br>A partir de una detallada reinterpretación del segmento nororiental de un perfil que corta las principales estructuras de la bahía de Agadir a lo largo de una directriz NE-SW, y un análisis de los mapas de isocronas disponibles, se ha podido establecer la historia geológica de la costa del Alto Atlas occidental. En primer lugar, se han distinguido dos secuencias tectonoestratigráficas: la Unidad II, que muestra una estructura simple, y la Unidad I, de estructura más compleja dominada por una falla inversa (F1) de dirección E-W vergente al norte, sobre la que se dispone la Unidad II de forma discordante. La correlación con los sondeos Souss-1 y AGM-1 ha permitido asignar la Unidad I al Triásico-Paleógeno y la Unidad II al Mioceno-Presente. El bloque NE de la falla muestra un plano de falla de tipo rampa-rellano (F2) con un pliegue superpuesto vergente al SW que puede ser interpretado como un pliegue de flexión de falla. Respecto a su evolución temporal, se han distinguido tres estadios: 1) Durante el Cretácico, F1 pudo haber sido una falla normal sindeposicional, con el bloque NE desplazándose hacia abajo; 2) Al comienzo del Terciario, el desplazamiento del plano F2 indujo el desarrollo de un pliegue de flexión de falla y...

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Section: Regional Extent Of the South Atlas Frontmentioning

confidence: 75%

Structure of the Kasbah fold zone (Agadir bay, Morocco). Implications on the chronology of the recent tectonics of the western High Atlas and on the seismic hazard of the Agadir area

Mridekh¹,

Medina²,

Mhammdi³

et al. 2009

Estud. geol.

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“…The geology of this large area is relatively well studied, but its salt tectonics has been analyzed only in a few previous publications (Heyman, 1989;Hafid, 2000Hafid, , 2006Mridek, 2000;Hafid et al, 2000Hafid et al, , 2005bTari et al, 2000Tari et al, , 2001Tari et al, , 2003. Here, it will show be shown that salt tectonics strongly controlled the geological evolution of the area.…”

Section: Introductionmentioning

confidence: 84%

Salt tectonics and structural styles of the western High Atlas and the intersecting Essaouira‐Cap Tafelney segments of the Moroccan Atlantic margin

Hafid¹,

Bally

Salem

et al. 2010

Quaternary Carbonate and Evaporite Sedimentary Facies and Their Ancient Analogues

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The Safi-Agadir Moroccan coastal region is the only area where the Moroccan Atlantic salt province makes an inland incursion. It is also an area where the High Atlas alpine fold-belt intersects at right angles the Atlantic passive margin. Regional reflection seismic transects have been constructed across this area and its offshore extension. These are used here to analyze the effects of the post-sedimentary mobility of salt on sedimentation and on structural styles, and to link these effects to the main stages of the geodynamic evolution of the Atlas and the Atlantic systems. Salt was deposited in Late Triassic-Early Jurassic times during the last stage of rifting prior to continental breakup. It played an important role in the genesis of most of the structures presently encountered in the area. A great variety of salt structures have been identified, including: gentle salt-cored folds and pillows; compressional diapirs; and salt withdrawal synclines. Completely allochthonous pluri-kilometric salt sheets and canopies are bounded to the west by toe-thrust salt structures that overlie oceanic crust in the deep offshore basin. This offers a great variety of favourable settings for possible hydrocarbon traps.

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“…De nombreux travaux ont étudié les systèmes réservoirs du Bassin d'Essaouira (Hafid, 2000;Hafid et al, 2000). Les études par sismique-réflexion ont contribué à l'identification des structures profondes et à la compréhension hydrogéologique des aquifères (Zouhri et al, 2003;Laroque & Dupuy, 2004).…”

Section: Profil Sismique Et Discussionunclassified

Une approche multicritères pour l'implantation de forages dans les zones productives des systèmes fissurés / A multicriteria approach for well drilling in productive zones of fissured systems

Hanich

Zouhri

Vachard³

et al. 2008

Hydrological Sciences Journal

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Résumé Le réservoir hydrogéologique du bassin d'Essaouira (Maroc) est examiné selon une approche multicritères. Les forages hydrogéologiques et les profils sismiques, ainsi que l'étude de la fracturation et les observations de terrain, fournissent les outils d'investigation conduisant conjointement à établir une représentation tridimensionnelle. Celle-ci traduit à la fois l'écoulement souterrain et la structure du système aquifère crétacé du bassin d'Essaouira, dont les formations hydrogéologiques hétérogènes renferment d'importantes ressources en eau pour le domaine côtier marocain. Le découpage de l'aquifère d'Essaouira (Crétacé) et de son imperméable (marnes cénomaniennes) répond à une tectonique en horsts et grabens résultant de la réactivation de structures hercyniennes. L'identification d'un faisceau de failles verticales permet de montrer l'influence de la géologie structurale sur l'individualisation des aquifères côtiers, sur l'écoulement des eaux souterraines, sur les variations piézométriques et sur la productivité des forages.Mots clefs fissuration; sismique; écoulement souterrain; productivité des puits; zone transmissive; transfert de pression A multicriteria approach for well drilling in productive zones of fissured systems Abstract The multicriteria approach used in this paper aims to examine the aquifer of the Essaouira basin (Morocco). Investigation methods such as interpretation of hydrogeological wells and seismic sections, as well as the analysis of in situ fissuration measurements and field observations are used together in this study. The established hydrostructural models reveal the groundwater flow and the structure of the coastal aquifer system, whose heterogeneous hydrogeological formations contain very important water resources for the Moroccan coastal area. The partition of the Cretaceous Essaouira aquifer, and of its impermeable basement (Cenomanian marls) corresponds to a tectonic structure (horsts and grabens) resulting from reactivation of Hercynian structures. The identification of the normal faulting network demonstrates an influence of the structural geology on the specificity of coastal aquifers, on the groundwater flow, on the piezometric variation and the productivity of wells, depending on their location.

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The western termination of the Jebilet–High Atlas system (Offshore Essaouira Basin, Morocco)

Cited by 63 publications

References 21 publications

Structure of the Kasbah fold zone (Agadir bay, Morocco). Implications on the chronology of the recent tectonics of the western High Atlas and on the seismic hazard of the Agadir area

Structure of the Kasbah fold zone (Agadir bay, Morocco). Implications on the chronology of the recent tectonics of the western High Atlas and on the seismic hazard of the Agadir area

Salt tectonics and structural styles of the western High Atlas and the intersecting Essaouira‐Cap Tafelney segments of the Moroccan Atlantic margin

Une approche multicritères pour l'implantation de forages dans les zones productives des systèmes fissurés / A multicriteria approach for well drilling in productive zones of fissured systems

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