The three main steps of the Marrakech High Atlas building in Morocco: Structural evidences from the southern foreland, Imini area

Leprêtre, Rémi; Missenard, Yves; Saint-Bézar, Bertrand; Barbarand, Jocelyn; Delpech, Guillaume; Yans, Johan; Dekoninck, Augustin; Saddiqi, Omar

doi:10.1016/j.jafrearsci.2015.05.013

Cited by 37 publications

(36 citation statements)

References 68 publications

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“…Ore deposits are aligned along a N70°E direction, reflecting small-scale deformation and large folds. This direction is related to the first Eocene constructional phase of the Atlas Mountains, leading to strong deformation focused in a narrow Eocene Atlas belt with minor deformation on the borders (Leprêtre et al 2015).…”

Section: Geological Settingmentioning

confidence: 96%

“…Cenomanian to Eocene sequence forms broad plateaus more or less titled and mildly folded, in contrast to the nearby South Atlas Front (SAF, Fig. 1a; Leprêtre et al 2015). Paleozoic basement is exposed typically in valleys underlain by former anticlinal cores (Fig.…”

Section: Geological Settingmentioning

confidence: 99%

“…Deposition of these terrestrial sediments, sourced from the Anti-Atlas Mountains, continued into the Paleocene (Rhalmi 1992;Saddiqi et al 2011 and references therein). Sedimentation resumed during Eocene time with the deposition of fossiliferous shallow marine carbonate and clays, coeval with quiescent periods between the three main constructional stages of the High Atlas Mountains (Leprêtre et al 2015): Late Eocene, Middle to Late Miocene, and post-Miocene. Cenomanian to Eocene sequence forms broad plateaus more or less titled and mildly folded, in contrast to the nearby South Atlas Front (SAF, Fig.…”

Section: Geological Settingmentioning

confidence: 99%

“…Strata of the Imini district are affected by numerous faults mainly inherited from the Triassic-Jurassic rift system (Missenard et al 2007) and reactivated during the Cenozoic inversion of the Atlas Mountains (Frizon de Lamotte et al 2000). Structures that trend N90°E to N130°E, as well as N20-30°E to N45°E, are well represented in the Precambrian Anti-Atlas basement, and were reactivated during the Cenozoic (Leprêtre et al 2015). The main structural feature of the district is the N90°E Imini anticline (Figs.…”

Section: Geological Settingmentioning

confidence: 99%

“…Mineralogical associations indicate that ore formation is clearly polyphase, following the first epigenetic mineralizing event in the karstic system. Cenozoic tectonic activity, due to the exhumation of the Atlas belt further north, probably remobilized and/or reworked the Mn ore (Leprêtre et al 2015). The present chapter aims to provide an overview of the ore-forming processes, from host-rock deposition to manganese mineralization, based on field observations and petrography.…”

Section: Introductionmentioning

confidence: 99%

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The High-Grade Imini Manganese District—Karst-Hosted Deposits of Mn Oxides and Oxyhydroxides

Dekoninck

Leprêtre

Saddiqi³

et al. 2016

Mineral Deposits of North Africa

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For more than 80 years of mining the economically important Imini district has been the main producer of manganese in Morocco. Three stratabound manganiferous orebodies in the district are hosted in a 10-m-thick Cenomanian-Turonian dolostone that records the effects of laterally extensive dissolution and epigenetic processes. The predominance of pyrolusite, accompanied by minor amounts of hollandite group minerals (cryptomelane, hollandite s.s., coronadite), lithiophorite, and romanechite, provide a high grade ore having more than 70 wt% MnO and low contents of SiO 2 , Fe 2 O 3 , and P 2 O 5 . One metallogenic model suggests the main mineralization stage was related to a period of terrestrial exposure and weathering, leading to formation of an extensive karst system, following host rock deposition and dolomitization. This model envisages Mn mineralization prior to the deposition of ConiacianMaastrichitan (Senonian) red beds, carbonates, and evaporites. A variety of data shows that the ore beds formed by epigenetic processes, in which Mn precipitation occurred with increasing pH and Eh. These physicochemical conditions are linked to dolomite dissolution and the influx of oxygenated meteoric waters, probably in contact with deeper O 2 -depleted meteoric groundwaters, and to surficial saline solutions and/or microbial

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Section: Geological Settingmentioning

confidence: 96%

Section: Geological Settingmentioning

confidence: 99%

Section: Geological Settingmentioning

confidence: 99%

Section: Geological Settingmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

The High-Grade Imini Manganese District—Karst-Hosted Deposits of Mn Oxides and Oxyhydroxides

Dekoninck

Leprêtre

Saddiqi³

et al. 2016

Mineral Deposits of North Africa

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Polyphased Inversions of an Intracontinental Rift: Case Study of the Marrakech High Atlas, Morocco

et al. 2018

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The High and Middle Atlas intraplate belts in Morocco correspond to Mesozoic rifted basins inverted during the Cenozoic during Africa/Eurasia convergence. The Marrakech High Atlas lies at a key location between Atlantic and Tethyan influences during the Mesozoic rifting phase but represents today high reliefs. Age and style of deformation and the mechanisms underlying the Cenozoic inversion are nevertheless still debated. To solve this issue, we produced new low‐temperature thermochronology data (fission track and [U‐Th]/He on apatite). Two cross sections were investigated in the western and eastern Marrakech High Atlas. Results of inverse modeling allow recognizing five cooling events attributed to erosion since Early Jurassic. Apart from a first erosional event from Middle/Late Jurassic to Early Cretaceous, four stages can be related to the convergence processes between Africa and Europe since the Late Cretaceous. Our data and thermal modeling results suggest that the inversion processes are guided at first order by the fault network inherited from the rifting episodes. The sedimentary cover and the Neogene lithospheric thinning produced a significant thermal weakening that facilitated the inversion of this ancient rift. Our data show that the Marrakech High Atlas has been behaving as a giant pop‐up since the beginning of Cenozoic inversion stages.

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Mineralogical and geochemical characterization of supergene Cu–Pb–Zn–V ores in the Oriental High Atlas, Morocco

et al. 2017

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The three main steps of the Marrakech High Atlas building in Morocco: Structural evidences from the southern foreland, Imini area

Cited by 37 publications

References 68 publications

The High-Grade Imini Manganese District—Karst-Hosted Deposits of Mn Oxides and Oxyhydroxides

The High-Grade Imini Manganese District—Karst-Hosted Deposits of Mn Oxides and Oxyhydroxides

Polyphased Inversions of an Intracontinental Rift: Case Study of the Marrakech High Atlas, Morocco

Mineralogical and geochemical characterization of supergene Cu–Pb–Zn–V ores in the Oriental High Atlas, Morocco

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