Evidence for surface uplift of the Atlas Mountains and the surrounding peripheral plateaux: Combining apatite fission-track results and geomorphic indicators in the Western Moroccan Meseta (coastal Variscan Paleozoic basement)

Barbero, L.; Jabaloy, A.; Gómez-Ortíz, David; Pérez-Peña, Jose Vicente; Peces, Martín Jesús Rodríguez; Tejero, Rosa; Estupiñán, J.; Azdimousa, Ali; Vázquez, M.; Asebriy, L.

doi:10.1016/j.tecto.2010.01.005

Cited by 44 publications

(28 citation statements)

References 40 publications

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“…Structural constraints based on geometry of the mineralized vein systems led Clavel and Tixeront (1971) to favor an Hercynian age for the Cu-Pb-Zn sulphide mineralization. This inferred age is in accord with the time span of mineralizing hydrothermal events dated at 250 to 210 ± 10 Ma (Ghorbal et al 2008;Sebti et al 2009;Barbero et al 2011) that affected most Hercynide domains of North Africa (Valenza et al 2000;Cheilletz et al 2010) and Western Europe (Sánchez et al 2006). However, crosscutting relationships indicate that the mineralized structures cut the 570 ± 5 Bouskour Granite but in turn do not transgress overlying 558 ± 4 Ma upper Neoproterozoic strata, thereby bracketing the mineralization between 570 ± 5 and 558 ± 4 Ma.…”

Section: Discussionsupporting

confidence: 76%

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: Discussionsupporting

confidence: 76%

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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“…1). Interestingly, the inferred deposition of this type of mineralization fits within the time span of hydrothermal events dated at 250-210 Ma (Ghorbal et al 2008;Saddiqi et al 2009;Barbero et al 2011) that affected most Hercynide domains of North Africa (Valenza et al 2000;Cheilletz et al 2010) and Western Europe (Johnson et al 1996;Sánchez et al 2006). …”

Section: Age Of Mineralizationsupporting

confidence: 65%

The Bou Azzer Co–Ni–Fe–As(±Au ± Ag) District of Central Anti-Atlas (Morocco): A Long-Lived Late Hercynian to Triassic Magmatic-Hydrothermal to Low-Sulphidation Epithermal System

Bouabdellah

Maacha²,

Levresse

et al. 2016

Mineral Resource Reviews

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The Neoproterozoic Bou Azzer Co-Ni-Fe-As(±Au ± Ag) district in the Central Anti-Atlas Mountains of southern Morocco hosts the only mine in the world where Co is produced as a primary commodity directly from Coand As-bearing arsenide minerals. The district has a mean annual production of 100,000 t of ore at an average grade of *1 % Co, 1 % Ni, 3-42 g/t Ag, and 3-4 g/t Au. Major orebodies are developed either within serpentinite or more importantly along the contact between serpentinite and quartz-diorite rocks. Field and textural relationships record three hydrothermal stages characterized by mineral assemblages of pre-arsenide auriferous stage I, (Co, Ni, Fe)-arsenide and sulpharsenide stage II, and sulphide-sulphosalt ± Au ± Ag epithermal stage III; one postore supergene stage IV is characterized by secondary Co minerals (erythrine, roselite,

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“…Indeed, Mesozoic ages and t-T paths comparable to the ones discussed above have been obtained from rocks from the Jebilet Hills N of Marrakech to the Rabat area (e.g., Ghorbal et al 2008;Saddiqi et al 2009;Barbero et al 2011). Subsidence along the Central Atlantic margin to the N of the EssaouiraAgadir basin has been quantified and modeled by Gouiza et al (2010) Early Cretaceous (100Ma) Fig.…”

Section: The Region N Of the High Atlasmentioning

confidence: 82%

“…The recent discovery of Late Triassic to Early Cretaceous km-scale vertical movements, subsidence and then exhumation, affecting substantial parts of Morocco which had hitherto been considered as stable (Ghorbal et al 2008;Saddiqi et al 2009;Barbero et al 2011;Ruiz et al 2011) represents a major development in Moroccan geology, opening new horizons for understanding the Mesozoic tectonic evolution of NW Africa. The exhumation component of these movements, in particular, is remarkable as it took place after the appearance of oceanic crust in the Central Atlantic, that is, during its passive margin development (e.g., Sahabi et al 2004;Gouiza et al 2010).…”

Section: Introductionmentioning

confidence: 99%

“…In the recent past, a number of studies by different groups (e.g., Ghorbal et al 2008;Saddiqi et al 2009;Ghorbal 2009;Barbero et al 2011;Ruiz et al 2011) have concluded that rocks of the Meseta of N Morocco, the High Atlas and parts of the Anti-Atlas, have experienced [1 km of exhumation during Middle Jurassic to Early Cretaceous times. More low-temperature geochronology (low-T) work is ongoing on samples from the Anti-Atlas and areas of southern Morocco ) and will undoubtedly result in new relevant information.…”

Section: Introductionmentioning

confidence: 99%

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Post-rift vertical movements and horizontal deformations in the eastern margin of the Central Atlantic: Middle Jurassic to Early Cretaceous evolution of Morocco

Bertotti

Gouiza

2012

Int J Earth Sci (Geol Rundsch)

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Wide regions of Morocco, from the Meseta to the High Atlas, have experienced km-scale upward vertical movements during Middle Jurassic to Early Cretaceous times following the appearance of oceanic crust in the Central Atlantic. The area experiencing exhumation was flanked to the W by a domain of continuous subsidence, part of which is named the Essaouira-Agadir basin. Comparison with vertical movement curves predicted by lithospheric thinning models shows that only 50-60 % of the subsidence documented in the Essaouira basin can be explained by postrift thermal relaxation and that \30-40 % of the observed exhumation can be explained by processes (in)directly related to the evolution of the Central Atlantic rifted margin. Syn-sedimentary structures in Middle Jurassic to Lower Cretaceous formations of the Eassouira-Agadir basin are common and range from m-scale folds and thrusts to km-scale sedimentary wedges. These structures systematically document coeval shortening generally oriented at high angle to the present margin. As a working hypothesis, it is suggested that regional shortening can explain the structural observations and the enigmatic vertical movements.

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Evidence for surface uplift of the Atlas Mountains and the surrounding peripheral plateaux: Combining apatite fission-track results and geomorphic indicators in the Western Moroccan Meseta (coastal Variscan Paleozoic basement)

Abstract: a b s t r a c t a r t i c l e i n f o

Cited by 44 publications

References 40 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

The Bou Azzer Co–Ni–Fe–As(±Au ± Ag) District of Central Anti-Atlas (Morocco): A Long-Lived Late Hercynian to Triassic Magmatic-Hydrothermal to Low-Sulphidation Epithermal System

Post-rift vertical movements and horizontal deformations in the eastern margin of the Central Atlantic: Middle Jurassic to Early Cretaceous evolution of Morocco

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