THE ROLE OF VARISCAN SHORTENING IN THE CONTROL OF MINERALIZATION DEPOSITION IN TADAOUT-TIZI N’RSAS MINING DISTRICT (EASTERN ANTI-ATLAS, MOROCCO)

Received Date: 19.07.2018 Accepted Date: 16.01.2019 ABSTRACT The abundance of the NE-SW direction veins mineralized in barite, copper, lead and zinc in the Tadaout-Tizi n’Rsas (TTR) anticline make this area one of the principal vein fields in Tafilalet (easternmost border of the Eastern Anti-Atlas). Reactivation of faults and alternation of competent (thicks Ordovician series, Silurian limestone and Devonian limestone) and incompetent levels (Silurian shales and Devonian marls) have an important role in the deformation of the TTR anticline during the NE-SW Variscan shortening. Our work based on lineaments extraction using a Landsat 8 OLI combined with some geological cross sections, shows a N130° major fold corresponding to TTR anticline. This big fold shows internal N130°, N95° and N20° minor folds. This structure indicates that the TTR area was formed in the hinge between the Anti-Atlas and the Ougarta belts. A number of these folds are the consequence of the underlying Precambrian faults reactivation and alternation of competent and incompetent levels. Brittle tectonics is dominated by NE-SW normal faults which result from the NE-SW shortening consequence of the Gondwana and Eurasia continents collision. Consequently, the mineralization of TTR is necessarily related to late or post-Variscan orogeny.

[1]  J. Bardintzeff,et al.  Devonian to Early Carboniferous magmatic alkaline activity in the Tafilalt Province, Eastearn Morocco: An Eovariscan episode in the Gondwana margin, north of the West African Craton , 2017 .

[2]  Abderrahmane Soulaimani,et al.  Fold interference pattern in thick-skinned tectonics; a case study from the external Variscan belt of Eastern Anti-Atlas, Morocco , 2016 .

[3]  O. Saddiqi,et al.  Late Ediacaran–Cambrian structures and their reactivation during the Variscan and Alpine cycles in the Anti-Atlas (Morocco) , 2014 .

[4]  N. Youbi,et al.  The Late Triassic‐Early Jurassic Volcanism of Morocco and Portugal in the Framework of the Central Atlantic Magmatic Province: An Overview , 2013 .

[5]  G. Walsh,et al.  Neoproterozoic tectonic evolution of the Jebel Saghro and Bou Azzer—El Graara inliers, eastern and central Anti-Atlas, Morocco , 2012 .

[6]  Moulley Charaf Chabou,et al.  Geochemistry of the Central Atlantic Magmatic Province (CAMP) in south-western Algeria , 2010 .

[7]  C. Robert-Charrue,et al.  Inversion tectonics, interference pattern and extensional fault-related folding in the Eastern Anti-Atlas, Morocco , 2008 .

[8]  A. Michard,et al.  Devonian extension of the Pan-African crust north of the West African craton, and its bearing on the Variscan foreland deformation: evidence from eastern Anti-Atlas (Morocco) , 2008 .

[9]  O. Saddiqi,et al.  Continental Evolution: The Geology of Morocco , 2008 .

[10]  M. Malusà,et al.  Post‐Variscan tectonics in eastern Anti‐Atlas (Morocco) , 2007 .

[11]  A. Michard,et al.  Variscan deformation at the northern border of the West African Craton, eastern Anti-Atlas, Morocco: compression of a mosaic of tilted blocks , 2007 .

[12]  C. Vérati,et al.  40Ar/39Ar ages and duration of the Central Atlantic Magmatic Province volcanism in Morocco and Portugal and its relation to the Triassic–Jurassic boundary , 2007 .

[13]  G. Levresse,et al.  Contribution to a geodynamic reconstruction of the Anti-Atlas (Morocco) during Pan-African times with the emphasis on inversion tectonics and metallogenic activity at the Precambrian–Cambrian transition , 2005 .

[14]  R. Thomas,et al.  A new lithostratigraphic framework for the Anti-Atlas Orogen, Morocco , 2004 .

[15]  Abderrahmane Soulaimani,et al.  The Tasrirt structure (Kerdous inlier, Western Anti-Atlas, Morocco): a late Pan-African transtensive dome , 2004 .

[16]  Mohammed Benssaou,et al.  Le graben de l'Anti-Atlas occidental (Maroc) : contrôle tectonique de la paléogéographie et des séquences au Cambrien inférieur , 2003 .

[17]  A. Piqué,et al.  L’extension continentale au Néo-Protérozoïque supérieur-Cambrien inférieur dans l’Anti-Atlas (Maroc) , 2003 .

[18]  G. Stampfli,et al.  A plate tectonic model for the Paleozoic and Mesozoic constrained by dynamic plate boundaries and restored synthetic oceanic isochrons , 2002 .

[19]  J. Liégeois,et al.  The Moroccan Anti-Atlas: the West African craton passive margin with limited Pan-African activity. Implications for the northern limit of the craton , 2001 .

[20]  R. Guiraud,et al.  Hercynian compressional deformations of the Ahnet–Mouydir Basin, Algerian Saharan Platform: far‐field stress effects of the Late Palaeozoic orogeny , 2001 .

[21]  B. Chbani,et al.  Sedimentation et volcanisme synsédimentaire de la série de base de l'adoudounien infra-cambrien à travers deux exemples de l'Anti-Atlas du Maroc , 2001 .

[22]  H. Djellit,et al.  Juxtaposed and superimposed paleomagnetic primary and secondary components from the folded middle carboniferous sediments in the Reggane Basin (Saharan craton, Algeria) , 2001 .

[23]  B. Chbani,et al.  Un enregistrement sédimentaire éocambrien dans un bassin intracontinental en distension: le cycle « conglomérats de base — unité calcaire — grès de Tikirtde Bou-Azzer El Graara (Anti-Atlas central, Maroc) , 1999 .

[24]  M. Joachimski,et al.  Hydrothermal origin of Devonian conical mounds (kess-kess) of Hamar Lakhdad Ridge, Anti-Atlas, Morocco: Comment and Reply , 1999 .

[25]  M. Savard,et al.  Hydrothermal origin of Devonian conical mounds (kess-kess) of Hamar Lakhdad Ridge, Anti-Atlas, Morocco , 1998 .

[26]  Z. Belka.  Early Devonian Kess-Kess carbonate mud mounds of the eastern Anti-Atlas (Morocco), and their relation to submarine hydrothermal venting , 1998 .

[27]  F. Boulvain,et al.  Comparaison des Kess-Kess de Hmar Lakhdad (Emsien, Maroc) et des monticules micritiques de l'anticlinorium de Philippeville (Frasnien, Belgique) , 1998 .

[28]  A. Piqué.  Géologie du Maroc : les domaines régionaux et leur évolution structurale , 1994 .

[29]  M. Joachimski,et al.  Controls of mud mound formation: The Early Devonian Kess-Kess carbonates of the Hamar Laghdad, Antiatlas, Morocco , 1992 .

[30]  J. Wendt,et al.  Age and depositional environment of upper devonian (early Frasnian to early famennian) black shales and limestones (Kellwasser facies) in the eastern Anti-Atlas, Morocco , 1991 .

[31]  H. Bertrand,et al.  40Ar/39Ar dating and geochemistry of tholeiitic magmatism related to the early opening of the Central Atlantic rift , 1991 .

[32]  A. Michard,et al.  Moroccan Hercynides; a Synopsis; the Paleozoic Sedimentary and Tectonic Evolution at the Northern Margin of West Africa , 1989, American Journal of Science.

[33]  W. Buggisch,et al.  Paleogeography and facies of the ‘gres terminaux’ (uppermost Lower Cambrian, Anti-Atlas/Morocco) , 1988 .

[34]  J. Wendt.  Disintegration of the continental margin of northwestern Gondwana: Late Devonian of the eastern Anti-Atlas (Morocco) , 1985 .

[35]  A. Michard,et al.  Foreland thrusts and olistromes on the pre-Sahara margin of the Variscan orogen, Morocco , 1982 .

[36]  J. G. Mitchell,et al.  Palaeomagnetic and Radiometric Dating Results from Jurassic Intrusions in South Morocco , 1971 .

[37]  H. Hollard.  Le Devonien du Maroc et du Sahara Nord-Occidental , 1967 .

[38]  J. Destombes.  Le Cambrien et la base de l'Ordovicien dans la partie orientale et meridionale du Tafilalt (Maroc) , 1963 .