Neoproterozoic tectonic evolution of the Jebel Saghro and Bou Azzer—El Graara inliers, eastern and central Anti-Atlas, Morocco

Walsh, Gregory J.; Benziane, Fouad; Aleinikoff, John N.; Harrison, Richard W.; Yazidi, Abdelaziz; Burton, William C.; Quick, James E.; Saadane, Abderrahim

doi:10.1016/j.precamres.2012.06.010

Cited by 137 publications

(175 citation statements)

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“…The geology of the Bouskour district has been summarized by Tixeront (1971), Clavel and Tixeront (1971), Ezzouhairi (1989Ezzouhairi ( , 1997Ezzouhairi ( , 2001), Ezzouhairi et al (2008), and Walsh et al (2008). The following description summarizes work by these authors supplemented by our own observations.…”

Section: District Scale Geologymentioning

confidence: 99%

“…The following description summarizes work by these authors supplemented by our own observations. Exposed rock types are stratigraphically assigned to the middle to late Neoproterozoic Ouarzazate Supergroup, and are geodynamically related to the post-collision extensional stage of the Pan-African orogeny (Thomas et al 2002;Walsh et al 2012). The oldest rocks (Fig.…”

Section: District Scale Geologymentioning

confidence: 99%

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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%

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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“…615-548 Ma; Gasquet et al 2005;Pouclet et al 2007;Walsh et al 2012;Álvaro et al 2014a), the Malcocinado Group of the OssaMorena Zone in SW Iberia (587-540 Ma; Sánchez-García et al 2003, some reworked clasts lining the Narcea/ Herrería contact in the Cantabrian Zone (ca. 575-560 Ma; Rubio-Ordóñez et al 2015), and the Sériès Tuffs of the Axial Zone and the Rivernous Formation of the northern Montagne Noire in the Occitan Domain (ca.…”

Section: Cadomian Arc-related Events In West Gondwanamentioning

confidence: 99%

Cadomian volcanosedimentary complexes across the Ediacaran–Cambrian transition of the Eastern Pyrenees, southwestern Europe

Padel

Álvaro

Casas

et al. 2017

Int J Earth Sci (Geol Rundsch)

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International audienceThe volcanism hosted by the Ediacaran–Terreneuvian Canaveilles Group of the Eastern Pyrenees displays two distinct geochemical affinities: (1) metabasites of the Nyer and Olette formations reflect the emplacement of a tholeiitic magmatism linked to extensional conditions, whereas (2) subsequent felsic and calc-alkaline magmatic rocks marking the top of the Olette Formation and forming the overlying Fabert and Finestrelles members represent Cadomian magmatic events. Based on U–Pb zircon dating constraints, palaeotopographic relationships linked to onlap geometries and distance from vent sources, three volcanosedimentary edifices can be distinguished, the so-called Tregurà (ca. 565–552 Ma), Cap de Creus (ca. 558 Ma) and Coll d’Ares (ca. 542–532 Ma) edifices. The top of their palaeoreliefs recorded locally the nucleation of centres of microbial carbonate productivity (Puig Sec Member) linked to synsedimentary tilting and karstification. Throughout West Gondwana, the presence of carbonate production across the Ediacaran–Cambrian transition is exclusively located in back-arc settings (Central-Iberian Zone) and areas far from the Cadomian subduction trench and devoid of significant terrigenous input, such as those reported in the Eastern Pyrenees and the neighbouring Montagne Noire

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“…690 ± 57 Ma Ikniwn Granite that hosts the gold mineralization and the ca. 563 Ma (Walsh et al 2008) rhyolitic dike swarm that cuts the mineralized structures (Fig. 3).…”

Section: Discussionmentioning

confidence: 99%

“…The aim of the present contribution is to update the geological setting of the deposit and reexamine previously published geochemical data (Alansari 1997;Alansari and Sagon 1997;Chaker 1997;Jettane et al 1999;Jettane 2001;Benchekroun and Jettane 2004;Alansari et al 2011), in the context of improved geologic understanding (Walsh et al 2012) since publication of these earlier studies.…”

Section: Introductionmentioning

confidence: 87%

The Granitoid-Related Tiouit Gold Deposit, Saghro Inlier, Eastern Anti-Atlas (Morocco): Neoproterozoic Mineralization by a Polyphase Late-Magmatic to Hydrothermal System

Bouabdellah

Chekroun²,

Alansari

et al. 2016

Mineral Resource Reviews

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The Tiouit gold deposit occurs in the central part of the Precambrian Saghro inlier in the eastern Anti-Atlas orogen. It is the second-largest gold producer in Morocco with a total production of ca. 1 Mt of ore at an average grade of 7.9 g/t Au, 67 g/t Ag, and 0.45 % Cu. Host rocks consist of metamorphosed sedimentary, volcanic, and volcaniclastic rocks of the Neoproterozoic Ouarzazate Supergroup locally intruded by the synto post-tectonic, I-type, calc-alkaline Ikniwn Granodiorite and Isk-n-Alla Granite. Auriferous mineralization is restricted to the southwestern part of the hydrothermally altered 690 ± 57 Ma Tiouit granodiorite, forming discontinuous sulphide veins and disseminations that trend N-S to N10°E and dip 10°-30°E to SE. Four mineralized zones are recognized, referred to as North, Central, South, and Northeast. The veins are up to 6 m wide, averaging 1.5-2 m, and extend along strike 40-300 m. Silicified halos containing up to 2-3 % disseminated pyrite are common near the veins; the highest gold and sulphide concentrations are confined to veins that exhibit the largest pyrititic halos. Primary mineral assemblages consist of varying amounts of intergrown galena, sphalerite, chalcopyrite, pyrite, electrum, and native gold, with subordinate arsenopyrite, argentite, sulphosalts (tetrahedrite-tennantite), and iron oxides plus quartz. Native gold occurs either as: (1) inclusions disseminated in sulphide grains, typically at boundaries between pyrite-chalcopyrite and arsenopyrite-galena-sphalerite-aikinite, interpreted to constitute the first generation of gold (Au-1); (2) anhedral fillings in pyrite, where gold (Au-2) is commonly accompanied by chalcopyrite; and (3) fillings of fractures in quartz ± chlorite ± hematite ± muscovite ± K-feldspar. Owing to the absence of radiometric age constraints, the inferred age for gold mineralization is attributed to emplacement and subsequent crystallization of the Ikniwn Granite. Mineralogical, textural, and geochemical data together with fluid inclusion measurements are consistent with phase separation of an H 2 O-rich fluid containing dissolved CO 2 , which ultimately exsolved an early high-salinity aqueous fluid from the Tiouit granitic magma. This early, high-salinity and CO 2 -rich fluid progressively evolved and mixed with larger volumes of colder, oxygenated, and more acidic solutions resulting in the precipitation of the Tiouit auriferous and base-metal mineralization.

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Neoproterozoic tectonic evolution of the Jebel Saghro and Bou Azzer—El Graara inliers, eastern and central Anti-Atlas, Morocco

Cited by 137 publications

References 64 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

Cadomian volcanosedimentary complexes across the Ediacaran–Cambrian transition of the Eastern Pyrenees, southwestern Europe

The Granitoid-Related Tiouit Gold Deposit, Saghro Inlier, Eastern Anti-Atlas (Morocco): Neoproterozoic Mineralization by a Polyphase Late-Magmatic to Hydrothermal System

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