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Ali, Nazir; Chellaie, E. H.; Nahim, Mohamed

doi:10.3989/egeol.04603-683

Cited by 4 publications

(2 citation statements)

References 17 publications

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“…It does not exclude a contribution from the Proterozoic basement in the western Reguibat Shield. Two huge deltas developed in the TLDB during the Early Cretaceous, at the latitude of TanTan and Boujdour [AUXINI, 1969;Mitchum and Vail, 1977;Ranke et al, 1982;Abou Ali et al, 2004]. They show a prograding trend bypassing the edge of the Jurassic paleoshelf, with a typical forced regression prism in the TanTan delta [Mitchum and Vail, 1977].…”

Section: Discussionmentioning

confidence: 99%

Postrift history of the eastern central Atlantic passive margin: Insights from the Saharan region of South Morocco

et al. 2015

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The passive margin of South Morocco is a low-elevated passive margin. It constitutes one of the oldest margins of the Atlantic Ocean, with an Early Jurassic breakup, and little geological data are available concerning its postrift reactivation so far. We investigated the postrift thermal history of the onshore part of the margin with low-temperature thermochronology on apatite crystals. Fission track and (U-Th-Sm)/He ages we obtained are significantly younger than the breakup (~190 Ma). Fission track ages range from 107 ± 8 to 175 ± 16 Ma, with mean track lengths from 10.7 ± 0.3 to 12.5 ± 0.2 μm. (U-Th-Sm)/He ages range from 14 ± 1 to 185 ± 15 Ma. Using inverse modeling of low-temperature thermochronological data, we demonstrate that the South Moroccan continental margin underwent a complex postrift history with at least two burial and exhumation phases. The first exhumation event occurred during Late Jurassic/Early Cretaceous, and we attribute this to mantle dynamics rather than to intrinsic rifting-related processes such as flexural rebound. The second event, from Late Cretaceous to early Paleogene, might record the onset of Africa/Europe convergence. We show a remarkably common behavior of the whole Moroccan passive margin during its early postrift evolution. The present-day differences result from a segmentation of the margin domains due to the Africa/Europe convergence. Finally we propose that varying retained strengths during rifting and also the specific crustal/lithospheric geometry of stretching explain the difference between the topographical expressions on the continental African margin compared to its American counterpart.

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Section: Discussionmentioning

confidence: 99%

Postrift history of the eastern central Atlantic passive margin: Insights from the Saharan region of South Morocco

et al. 2015

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“…At a larger scale, Sahabi et al (2004, their figure 6) also suggested continuity between the Atlas Front and the eastern boundary of the Tarfaya basin, at least during the Triassic. 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: 99%

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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Constraining Mesozoic early post-rift depositional systems evolution along the eastern Central Atlantic margin

Arantegui

Jerrett

Schröder

et al. 2019

Sedimentary Geology

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Extensive Mesozoic outcrops exposed in the Aaiun-Tarfaya Basin, in the Atlantic margin of Morocco, have been overlooked for decades. Original subdivisions and dating of rocks, performed more than five decades ago, have survived until today virtually without any update. In the north eastern margin of the basin, key Mesozoic sections have been revisited. Its coastal position next to the Variscan Anti-Atlas Orogen allows insight into the interplay between local tectonics and eustasy during deposition of sedimentary sequences on passive margins. High-resolution stratigraphy and sedimentology have allowed for an improved understanding of the depositional systems and evolution during the early opening of the Atlantic and provided a valuable control point recording the syn-and early post-rift evolution of the basin. Three formations are described: (i) a basal continental red bed unit unconformably overlying the Palaezoic Variscan basement of the Ifni Inlier; (ii) a unit dominated by intertidal clastics and microbial carbonates, and (iii) a shallow marine unit comprising mixed siliciclastic-carbonates. Despite the sedimentological affinity of these outcrops to Triassic or Lower Jurassic deposits elsewhere in Morocco, these units had previously been assigned an Early Cretaceous age, based on limited non-conclusive fossil fauna and basinscale lithostratigraphic correlation. New collections of macrofauna have yielded a Bathonian age for the upper part of the succession and a possible Triassic/Early Jurassic for the lower part. The whole succession displays an overall transgressive trend not consistent with the eustatic Bathonian sea-level fall. Local postrift tectonic pulses exhuming the Western Anti-Atlas coupled with eustasy are responsible for increased sediment supply at this time. Enhanced tectonic subsidence, overcoming sea-level fall, is interpreted to be the main driver for creation of accommodation and preservation of this sequence. Resumed sedimentation on structural heights offshore suggests exhumation of the Western Anti-Atlas ceased by the early Callovian, reducing clastic input to the region and allowing the development of a carbonate platform. Variable regional exhumation and local tectonics along the Moroccan margin during the early post-rift stage 2 influenced the highly variable nature of clastic vs carbonate deposition, thickness distribution and depositional environments at this time.

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Untitled

Cited by 4 publications

References 17 publications

Postrift history of the eastern central Atlantic passive margin: Insights from the Saharan region of South Morocco

Postrift history of the eastern central Atlantic passive margin: Insights from the Saharan region of South Morocco

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

Constraining Mesozoic early post-rift depositional systems evolution along the eastern Central Atlantic margin

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