The Pan-African Belt

Gasquet, Dominique; Ennih, Nasser; Liégeois, Jean Paul; Soulaı̈mani, Abderrahmane; Michard, André

doi:10.1007/978-3-540-77076-3_2

Cited by 117 publications

(112 citation statements)

References 51 publications

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“…The main structural feature of the district is the N90°E Imini anticline (Figs. 1b and 2) that corresponds to the Variscan trend of the Anti-Atlas Major Fault further south (Choubert 1963;Ennih and Liégeois 2001;Gasquet et al 2008). The Imini anticline was exhumed again during a late Atlasic (late ore post-Miocene) phase, at the same time as the related N90°E Imini Fault that hosts massive vein-type barite deposits (Fig.…”

Section: Geological Settingmentioning

confidence: 94%

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: 94%

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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“…Syn-orogenic granitoids developed after 2050 Ma, associated with calc-alkaline and peraluminous magmas derived from a mafic source (with a small Archaean crustal component) in a plate-convergence back-arc setting (Gasquet et al, , 2004(Gasquet et al, , 2005(Gasquet et al, , 2008Mortaji et al, 2000;Mortaji, 2007). According to Benziane (2007), the Palaeoproterozoic in the Anti-Atlas is characterized by two distinguishable magmatic events both related to a subduction setting: the first at 2110-2080 Ma (trondhjemitic magmatism) and the second at 2050-2030 Ma (calc-alkaline magmatism).…”

Section: The Palaeoproterozoicmentioning

confidence: 93%

Lower Cryogenian calc-alkaline mafic rocks of the Western Anti-Atlas (Morocco): An example of orogenic-like magmatism in an extensional setting

Aouli

Gasquet

Cheilletz³

2010

Journal of African Earth Sciences

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“…According to geodynamic reconstructions (e.g., Thomas et al 2002Thomas et al , 2004Gasquet et al 2005Gasquet et al , 2008, this age of ca. 818 Ma might be related to ocean opening during the break-up of the Mesoproterozoic supercontinent Rodinia.…”

Section: Timing Of Magmatic/ Hydrothermal Events In the Zgounder Distmentioning

confidence: 99%

U/Pb Ages of Magmatism in the Zgounder Epithermal Ag–Hg Deposit, Sirwa Window, Anti-Atlas, Morocco

Pelleter¹,

Cheilletz²,

Gasquet³

et al. 2016

Mineral Deposits of North Africa

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The Zgounder epithermal Ag-Hg deposit (Jbel Sirwa inlier, Anti-Atlas, Morocco) is hosted in Neoproterozoic volcanosedimentary and magmatic rocks in a Pan-African belt. Strongly altered U-rich zircons were analyzed for in situ SIMS U-Pb ages of multiple rhyolitic intrusions spatially associated with the Ag-Hg mineralization. Morphological features, internal microstructures, and chemical characteristics allow the discrimination of two types of zircon, magmatic and hydrothermal. U/Pb data reveal four main geologic events: (1) ca. 815 Ma corresponding to inherited cores of zircons that reflect the reworking of Neoproterozoic crust during the Pan-African (*885-555 Ma) orogenic cycle; (2) 610 ± 7 Ma; (3) 578 ± 4 Ma corresponding to the emplacement-crystallization of multiple rhyolitic intrusions and the large magmatic input within the upper crust of the Pan-African chain during the late Neoproterozoic; and (4) 564 ± 15 Ma, a less-precise age obtained on hydrothermally altered domains that may be related to a dissolution-reprecipitation mechanism in U-rich magmatic zircons. Presently, this last age represents the best estimate for the timing of hydrothermal albitization/mineralization in the Zgounder epithermal Ag-Hg deposit.

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The Pan-African Belt

Cited by 117 publications

References 51 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

Lower Cryogenian calc-alkaline mafic rocks of the Western Anti-Atlas (Morocco): An example of orogenic-like magmatism in an extensional setting

U/Pb Ages of Magmatism in the Zgounder Epithermal Ag–Hg Deposit, Sirwa Window, Anti-Atlas, Morocco

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