Géochimie et signification géotectonique des volcanites du Cryogénien inférieur du Saghro (Anti-Atlas oriental, Maroc) Geochemistry and geotectonic significance of Early Cryogenian volcanics of Saghro (Eastern Anti-Atlas, Morocco).

Les groupes du Cryogénien inférieur de Sidi Flah, Kelaat Mgouna et Boumalne (Saghro, Anti-Atlas, Maroc) sont formés de dépôts turbiditiques et de laves interstratifiées, accumulés dans des bassins tectoniques. A Sidi Flah, les volcanites correspondent à des basaltes transitionnels à composition de tholéiites de rift initial (IRT) et à des basaltes alcalins de type basalte dmodifier letter vertical lineîles océaniques (OIB). A Kelaat Mgouna, il smodifier letter vertical lineagit de tholéiites continentales pauvres en Nb. A Boumalne, les basaltes ont une signature d'IRT. Ces formations volcaniques et sédimentaires constituent les éléments dmodifier letter vertical lineun rift naissant à lmodifier letter vertical lineaplomb de dômes thermiques, le long dmodifier letter vertical lineun axe SW-NE, le rift du Saghro. La déchirure continentale a eu lieu au début du Néoprotérozoïque lors de la dislocation du supercontinent Rodinia, dans un continent « ibéro-saharien » qui occupait une position frontale par rapport au craton ouest-africain alors situé au voisinage du pôle sud. La formation du rift du Saghro est contemporaine de lmodifier letter vertical lineouverture dmodifier letter vertical lineun domaine océanique représenté par les ophiolites de lmodifier letter vertical lineAnti-Atlas central et correspondant à l'extension de lmodifier letter vertical lineocéan Braziliano. The Early Cryogenian groups of Sidi Flah, Kelaat Mgouna and Boumalne (Saghro, Anti-Atlas, Morocco) are constituted by turbiditic deposits and interbedded lavas, accumulated in tectonic basins. At Sidi Flah, volcanics are transitional showing initial rift tholeiites (IRT) fingerprint and alkali basalts of oceanic island basalt (OIB) compositions. At Kelaat Mgouna, volcanics consist of low-Nb continental tholeiites. At Boumalne, basalts are of IRT composition. The volcanic and sedimentary formations belong to a nascent rift caused by thermal doming along a SW-NE axis, the Saghro rift. The continental break-up occurred in the early Neoproterozoic and during the Rodinia supercontinent dislocation, within a continent called “Ibero-saharian Craton” which was in front of the West-African Craton located near the South Pole. The Saghro rift is contemporaneous to the opening of an oceanic domain represented by Central Anti-Atlas ophiolites and related to the extension of the Brazialiano Ocean

Analyse sedimentologique, structurale et lithogeochimique de la serie du Proteorozoique superieur (PII) de l'environnement de la mine d'argent d'Imiter (Anti-Atlas oriental, Maroc): implications geodynamiques

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The Açdif Gold-Bearing Shear Zone (Zenaga Inlier, Central Anti-Atlas, Morocco): New Petro-Structural and Geochemical Data

The Açdif gold deposit is located in the Zenaga Inlier (central Anti-Atlas), approximately 120 km southwest of the city of Ouarzazate. It hosts gold mineralization associated with a shear zone affecting the metamorphic and magmatic formations of the Eburnean basement. It mainly consists of alternating micaschists, augen gneisses, and orthogneiss. These crystalline rock assemblages are intruded by a variety of granitoids. These are the Azguemerzi granitoids, which are locally affected by Eburnean deformation. Subsequently, these facies are intersected by a swarm of mafic dykes, which show a variety of rocks ranging from microgabbro-dolerite to quartz diorite. Detailed mapping, petro-mineralogical investigations, and geochemistry of the major and trace elements of these magmatic intrusions suggests the following: (i) for the granodiorite rocks (deposited before the basic dykes), a calc-alkaline affinity, with a chemical signature similar to a syn-collisional context; (ii) for mafic dykes, a contemporaneous emplacement of these mafic intrusions with an evolutionary process controlled by fractional crystallization of the same magma of continental tholeiites, whose chemical composition is comparable to that of enriched MORBs (EMORBs). These continental tholeiites are related to a distensive tectonic context that would have affected the Zenaga inlier prior to the Pan-African orogeny