Geodynamic evolution of the Atlas system (Morocco) in post-palaeozoic times

Jacobshagen, Volker; Görler, Konrad; Giese, P.

doi:10.1007/bfb0011606

Cited by 51 publications

(32 citation statements)

References 24 publications

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“…These events are reflected in the sedimentary series by locally complex discontinuities related to overthrusting and the insertion Laville et al 1977, andJossen andFilali 1988) of klippen and other, commonly allochthonous structural units (Laville 1980;Errarhaoui 1998;Beauchamp 1999). This N±S compressive episode coincided with the convergence of the Iberian and North African plates (Jacobshagen et al 1988;Brede et al 1992; Giese and Jacobshagen 1992), and is thought to be at the origin of the warping and folding of the High Atlas.…”

Section: Subatlas Zone or Southern Atlas Marginal Zonementioning

confidence: 94%

“…These two geodynamic events were separated by a tectonically calm phase, materialized by palustro-lacustrine sedimentation ). Tectono-sedimentary analysis of the two megasequences shows that the basin structure and depositional processes were controlled by the compressive tectonic context generated by the collision of North Africa and Iberia in Tertiary times (Jacobshagen et al 1988). The Quaternary Formation was apparently controlled by a tectonic continuum and by climatic variations.…”

mentioning

confidence: 97%

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Cenozoic sedimentary dynamics of the Ouarzazate foreland basin (Central High Atlas Mountains, Morocco)

Harfi¹,

Lang

Salomon

et al. 2000

Int J Earth Sci

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Cenozoic continental sedimentary deposits of the Southern Atlas named ªImerhane Groupº crop out (a) in the Ouarzazate foreland basin between the Precambrian basement of the Anti Atlas and the uplifted limestone dominated High Atlas, and (b) in the Aït Kandoula and Aït Seddrat nappes where Jurassic strata detached from the basement have been thrust southwards over the Ouarzazate Basin. New biostratigraphic and geochronological data constraining the final Eocene marine regression, the characterization of the new ªAït Ouglif Detrital Formationº presumed to be of Oligocene age, and the new stratigraphic division proposed for the Continental Imerhane Group clarify the major tectonogenetic alpidic movements of the Central High Atlas Range. Four continental formations are identified at regional scale. Their emplacement was governed principally by tectonic but also by eustatic controls. The Hadida and Aït Arbi formations (Upper Eocene) record the major Paleogene regression. They are composed of marginolittoral facies (coastal sabkhas and fluviatile systems) and reflect incipient erosion of the underlying strata and renewed fluvial drainage. The Aït Ouglif Formation (presumed Oligocene) had not been characterized before. It frequently overlies all earlier formations with an angular unconformity. It includes siliciclastic alluvial deposits and is composed predominantly of numerous thin fining-upward cycles. The Aït Kandoula Formation (Miocene±Pliocene) is discordant, extensive, and represents a thick coarsening-upward megasequence. It is composed of palustro-lacustrine deposits in a context of alluvial plain with localized sabkhas, giving way to alluvial fans and fluviatile environments. The Upper Conglomeratic Formation (Quaternary) is the trace of a vast conglomeratic pediment, forming an alluvial plain and terraces. The second and third formations correspond to two megasequences engendered by the uplift of the Central High Atlas in two major compressive phases during late Oligocene and Miocene±Pliocene times. These two geodynamic events were separated by a tectonically calm phase, materialized by palustro-lacustrine sedimentation ). Tectono-sedimentary analysis of the two megasequences shows that the basin structure and depositional processes were controlled by the compressive tectonic context generated by the collision of North Africa and Iberia in Tertiary times (Jacobshagen et al. 1988). The Quaternary Formation was apparently controlled by a tectonic continuum and by climatic variations.

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Section: Subatlas Zone or Southern Atlas Marginal Zonementioning

confidence: 94%

mentioning

confidence: 97%

Cenozoic sedimentary dynamics of the Ouarzazate foreland basin (Central High Atlas Mountains, Morocco)

Harfi¹,

Lang

Salomon

et al. 2000

Int J Earth Sci

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“…1977). These mountain belts together with the Rif collectively evolved in response to the convergence of the African and Eurasian plates (e.g., Jacobshagen et al 1988;Brede et al 1992) which resulted in a complex collisional plate boundary separating Africa from continental Europe.…”

mentioning

confidence: 99%

Active tectonism in the intracontinental Middle Atlas Mountains of Morocco: synchronous crustal shortening and extension

Gomez

Barazangi

Bensaid

1996

JGS

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Geological field observations are integrated with digital topography, LANDSAT imagery, and earthquake focal mechanisms to investigate the Middle and Late Quaternary tectonism in the intracontinental Middle Atlas mountain belt in northern Morocco. The NE-SW-trending Middle Atlas Mountains, approximately 80 km in width and about 200 km long, are part of the Atlas system of northwestern Africa and represent an inverted rift that developed into an intracratonic mountain system in the foreland of the Alpine collisional zone. The Middle Atlas is composed of two provinces, the Folded and Tabular Middle Atlas, representing the palaeo-rift and a flank of the palaeo-rift, respectively. Evidence for Late Quaternary tectonism is provided by the analysis of stream morphology in addition to geological relations. Kinematic analysis of fault-slip data and earthquake focal mechanisms demonstrate the coexistence of both extensional and compressional deformation in different areas of the Middle Atlas with a common sinistral component of slip along NE-SW-striking fault zones. Compressional features dominate the Folded Middle Atlas, whereas extension predominates in the Tabular Middle Atlas. Extension is also manifested by widespread Middle to Late Quaternary alkali volcanism. The observed kinematic variations appear to correlate with the Mesozoic palaeogeography; one possible model may involve tectonic escape. This suggests that differences in the structures inherited from the Mesozoic and Palaeozoic may influence the responses of the different regions to the Cenozoic Alpine collision between Europe and northwest Africa.

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“…1) is attributed to the inversion of Jurassic rift or transtensional basins as a consequence of continental convergence between Africa and Europe during Cenozoic time (Jacobshagen et al 1988;Beauchamp et al 1996;Frizon de Lamotte et al 2009). According to Leach et al (2010), this interval of time included microplate assimilation that affected the western margin of North America and Africa-Eurasia and constitutes a favorable period worldwide during which approximately 36 % of dated MVT deposits formed.…”

Section: Introductionmentioning

confidence: 96%

Geology, Geochemistry, and Current Genetic Models for Major Mississippi Valley-Type Pb–Zn Deposits of Morocco

Bouabdellah¹,

Sangster²

2016

Mineral Resource Reviews

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Morocco has been for the past two centuries one of the top ten Pb-Zn producers with two thirds of base-metal production derived from three major Mississippi Valley-type districts (Touissit-Bou Beker, Upper Moulouya, and Jbel Bou Dahar). Collectively, these districts have produced more than 100 Mt of ore at an average grade of *3 wt% Zn and 4 wt% Pb. At the present time, none of the three districts is active. favorable fluid channels for metal-bearing brines into permeable host rocks and dissolution structures. The geometry of the orebodies that parallel the major alpine faults, coupled with lead isotopic constraints, suggest that the MVT mineralizing event occurred during midle Tertiary time (i.e., Cretaceous to Miocene) coincident with closing stages of the Alpine orogeny in the Atlasic orogenic belt. Alpine mineralization is thought to have been promoted by the mixing of older, high-temperature, rock-buffered, dense brines stored within the Paleozoic basement, and a downwelling, cooler fluid probably of meteoric origin. The resulting mixed brines were centered mainly on the basement high structure and its flanks, then flowed laterally away from the basement high and giving rise to the lower grade mineralization of the distal prospects. Fluid migration towards the ore districts could have been achieved either by a gravity-driven system (Touissit-Bou Beker, Mibladen, and Jbel Bou Dahar) or sediment compaction in the foredeep (Jbel Bou Dahar), or a combination of both. An alternative buoyancy-driven fluid convection model is proposed for the Touissit-Bou Beker MVT mineralization.

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Geodynamic evolution of the Atlas system (Morocco) in post-palaeozoic times

Cited by 51 publications

References 24 publications

Cenozoic sedimentary dynamics of the Ouarzazate foreland basin (Central High Atlas Mountains, Morocco)

Cenozoic sedimentary dynamics of the Ouarzazate foreland basin (Central High Atlas Mountains, Morocco)

Active tectonism in the intracontinental Middle Atlas Mountains of Morocco: synchronous crustal shortening and extension

Geology, Geochemistry, and Current Genetic Models for Major Mississippi Valley-Type Pb–Zn Deposits of Morocco

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