Lithostratigraphic framework and correlation of the Neoproterozoic northern West African Craton passive margin sequence (Siroua–Zenaga–Bouazzer Elgraara Inliers, Central Anti-Atlas, Morocco): an integrated approach

Bouougri, El Hafid; Saquaque, Ali

doi:10.1016/j.jafrearsci.2004.07.045

Cited by 59 publications

(28 citation statements)

References 21 publications

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“…1), is a Neoproterozoic basement massif located in the central part of the larger Saghro massif. The inlier consists of a succession of Cryogenian (middle Neoproterozoic; 850-630 Ma) to Ediacaran (late Neoproterozoic; 630-542 Ma) deformed and metamorphosed volcanic-sedimentary, volcanic, and intrusive rocks interpreted to have been emplaced either in a back-arc environment (Saquaque et al 1992;Leblanc and Moussine-Pouchkine 1994;Bouougri and Saquaque 2004) or in an intracontinental basin synchronous with Pre-African rifting (Fekkak et al 2003).…”

Section: District Scale Geologymentioning

confidence: 99%

Re/Os Age Determination, Lead and Sulphur Isotope Constraints on the Origin of the Bouskour Cu–Pb–Zn Vein-Type Deposit (Eastern Anti-Atlas, Morocco) and Its Relationship to Neoproterozoic Granitic Magmatism

Bouabdellah

Maacha²,

Jébrak³

et al. 2016

Mineral Deposits of North Africa

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The newly re-evaluated Bouskour deposit is a large, polymetallic vein-type system in the Precambrian Sidi Flah-Bouskour inlier of the eastern Anti-Atlas orogen. Resources are >53 Mt at 0.8 % Cu, of which 21 Mt has a higher grade of 1.3 % Cu and 9 g/t Ag. Host rocks are assigned to the Ediacaran Ouarzazate Group, and consist of a succession of mafic-ultramafic to felsic igneous rocks, both intrusive and extrusive, with ages ranging from 570 ± 5 to 557 ± 5 Ma, partly intruding Cryogenian basalt and andesite. Among these igneous bodies, intrusive felsic rocks are by far the most abundant lithologies, consisting of three elongate, NW-SE-trending, calc-alkaline intrusions referred to as: (1) Bouskour Granodiorite, (2) Bouskour Granite dated at 570 ± 5 Ma, and (3) system of red to white aphanitic rhyolite locally known as the "Bouskour rhyolitic dike swarm" intruded all older units at 564 ± 7 to 562 ± 5 Ma. Cu-Pb-Zn sulphide mineralization produced an array of five transtensional, N-S and ENE-to NNW-trending vein systems referred to as "Filon Principal," "Filon Ouest," "Filon I," "Filon II," and "Filon Camra." The veins are up to 20 m wide and extend laterally from a few hundred meters to more than 10 km, spaced 50 to >1000 m apart, striking predominantly N160°E with steep dips (70°to *90°). Characteristic are comb, cockade, laminated, breccia, and crack and seal textures, suggesting that episodic mechanisms were important in vein formation. Sulphide minerals consist predominantly of various proportions of chalcopyrite, bornite, galena, sphalerite, pyrite, and arsenopyrite, with subordinate tetrahedritetennantite, magnetite, cassiterite, and rutile. The hydrothermal alteration assemblage comprises sericite, epidote, chlorite, quartz, and carbonates (calcite, dolomite). Three successive stages of ore deposition are recognized. The earliest stage (I) is referred to as "Cu-Zn-(Fe-As-CoBi-Sn) stage" is followed by the main Cu-Pb-Zn sulphide stage (II), which accounts for most of the exploited sulphide ore at Bouskour. The latest stage (III) forms late fillings in calcite or quartz veins or within older stage I and II assemblages, and includes Au-Ag-Cu-(Zn-Pb) mineralization. New 187 Re/ 188 Os age dating of a single molybdenite crystal from stage II yields an age of 574.9 ± 2.4 Ma. This age coincides, within analytical uncertainty, with a SHRIMP U-Pb age on zircon from the Bouskour Granite. The age correspondence suggests a foremost role of granite-derived hydrothermal fluids in the genesis of this polymetallic vein system, consistent with sulphur and lead isotopic data. This timing of mineralization relates to the final, post-collision extensional stage of the Pan-African orogeny.

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Section: District Scale Geologymentioning

confidence: 99%

Re/Os Age Determination, Lead and Sulphur Isotope Constraints on the Origin of the Bouskour Cu–Pb–Zn Vein-Type Deposit (Eastern Anti-Atlas, Morocco) and Its Relationship to Neoproterozoic Granitic Magmatism

Bouabdellah

Maacha²,

Jébrak³

et al. 2016

Mineral Deposits of North Africa

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“…5) is a depression of about 500 km 2 containing mainly Paleoproterozoic gneisses and granitoids unconformably overlain by the late Neoproterozoic Ouarzazate volcanic Group or, in places, directly covered by the Cambrian Tata Group (Thomas et al, 2004). Neoproterozoic rocks, also present within the inlier, are represented by passive margin sedimentary rocks (Taghdout Group; Bouougri and Saquaque, 2004;Fig. 5), pre-Pan-African doleritic dykes and sills, and a late Pan-African alkaline ring-complex (red dot in Zenaga; Fig.…”

Section: Magmatic Metacratonization Of a Craton Margin: The Pan-africmentioning

confidence: 99%

Metacraton: Nature, genesis and behavior

et al. 2013

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“…At the beginning of the Neoproterozoic, the WAC was affected by several extensional events associated with continental breakup. The most important event was the formation of the Gourma aulacogen in Mali (MoussinePouchkine & Bertrand-Sarfati 1978) but also the deposition of passive margin sediments on its northern boundary in the Anti-Atlas (Bouougri & Saquaque 2004) and to the SE in the Voltas basin (Ako & Wellman 1985;Nédélec et al 2007). The formation of the huge Taoudeni cratonic subcircular basin also began during that period (Bronner et al 1980).…”

Section: The West African Cratonmentioning

confidence: 99%

“…High temperature/low pressure grade metamorphism occurred with large movements of fluids causing mineralization in several areas Kolb et al;Belkabir et al). Although partially buried by younger deposits, rock exposures contain excellent preservation of the early Neoproterozoic events such as the passive margin sediments (Bouougri & Saquaque 2004), the early thrust oceanic terranes Bousquet et al) and Pan-African magmatism (Touil et al; Ezzouhairi et al ). The Pan-African orogeny generated large sediment influx, for example outside the WAC, within the PeriGondwanan terranes whose sedimentary sequences are marked by the WAC-typical signature, a bimodal set of zircon ages at c. 1.8-2.2 Ga and at 0.55 -0.75 Ga (Nance et al).…”

Section: The Boundaries Of the West African Cratonmentioning

confidence: 99%

“…Portions of this unit have been metamorphosed to greenschist facies. The Taghdout Group contains well-preserved sedimentary features, such as ripple marks, desiccation cracks or oblique stratification (Bouougri & Saquaque 2004). The Taghdout Group is a 2 km-thick succession deposited during three stages of an extensional event (Bouougri & Saquaque 2004): (1) a shallowwater and gently dipping mixed siliciclasticcarbonate ramp facing north and attached to braided alluvial plain in the south, indicating a relatively stable margin; (2) tholeiitic sills and dykes of the Ifzwane Group that cut the sedimentary sequence and the basement of the Zenaga inlier (particularly to the NW; Fig.…”

Section: The Zenaga Inliermentioning

confidence: 99%

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The boundaries of the West African craton, with special reference to the basement of the Moroccan metacratonic Anti-Atlas belt

Ennih

Liégeois

2008

172

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The West African craton (WAC) was constructed during the Archaean and the c. 2 Ga Palaeoproterozoic Eburnian orogeny. Mesoproterozoic quiescence at c. 1.7-1.0 Ga allowed cratonization. In the absence of Mesoproterozoic activity, there are no known WAC palaeogeographical positions for that time. At the beginning of the Neoproterozoic, the WAC was affected by several extensional events suggesting that it was subjected to continental breakup. The most important event is the formation of the Gourma aulacogen in Mali, and the Taoudeni cratonic subcircular basin and deposition of platform sediments in the Anti-Atlas. At the end of the Neoproterozoic, the WAC was subjected to convergence on all its boundaries, from the north in the Anti-Atlas, to the east along the Trans-Saharan belt, to the south along the Rockelides and the Bassarides and to the east along the Mauritanides. This led to a partial remobilization of its cratonic boundaries giving rise to a metacratonic evolution. The WAC boundaries experienced Pan-African Neoproterozoic to Early Cambrian transpression and transtension, intrusion of granitoids and extrusion of huge volcanic sequences in such as in the Anti-Atlas (Ouarzazate Supergroup). Pan-African tectonism generated large sediment influxes around the WAC within the Peri-Gondwanan terranes whose sedimentary sequences are marked by distinctive zircon ages of 1.8-2.2 Ga and 0.55-0.75 Ga.WAC rocks experienced Pan-African low grade metamorphism and large movements of mineralizing fluids. In the Anti-Atlas, this Pan-African metacratonic evolution led to remobilization of REE in the Eburnian granitoids due to the activity of F-rich fluids linked to extrusion of the Ouarzazate Supergroup. During the Phanerozoic, the western WAC boundary was subjected to the Variscan orogeny, for which it constituted the foreland and was, therefore moderately affected, showing typical thick-skin tectonics in the basement and thin-skin tectonics in the cover. During the Mesozoic, the eastern and southern boundaries of the WAC were subjected to the Atlantic opening including Jurassic dolerite intrusion and capture of its extreme southern tip by South America. The Jurassic is also marked by the development of rifts on its eastern and northern sides (future Atlas belt). Finally, the Cenozoic period was marked by the convergence of the African and European continents, generating the High Atlas range and Cenozoic volcanism encircling the northern part of the WAC. The northern metacratonic boundary of the WAC is currently uplifted, forming the Anti-Atlas Mountains.The boundaries of the WAC, metacratonized during the Pan-African orogeny have been periodically rejuvenated. This is a defining characteristic of the metacratonic areas: rigid, stable cratonic regions that can be periodically cut by faults and affected by magmatism and hydrothermal alteration -making these areas important for mineralization.

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Lithostratigraphic framework and correlation of the Neoproterozoic northern West African Craton passive margin sequence (Siroua–Zenaga–Bouazzer Elgraara Inliers, Central Anti-Atlas, Morocco): an integrated approach

Cited by 59 publications

References 21 publications

Re/Os Age Determination, Lead and Sulphur Isotope Constraints on the Origin of the Bouskour Cu–Pb–Zn Vein-Type Deposit (Eastern Anti-Atlas, Morocco) and Its Relationship to Neoproterozoic Granitic Magmatism

Re/Os Age Determination, Lead and Sulphur Isotope Constraints on the Origin of the Bouskour Cu–Pb–Zn Vein-Type Deposit (Eastern Anti-Atlas, Morocco) and Its Relationship to Neoproterozoic Granitic Magmatism

Metacraton: Nature, genesis and behavior

The boundaries of the West African craton, with special reference to the basement of the Moroccan metacratonic Anti-Atlas belt

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