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The copper history in the Anti Atlas belt, from Panafrican to Variscan orogeny, a persistence of tectonic controls: an overview of Bou Azzer-El Graara inlier

Abstract : The Anti-Atlas belt is well known for its numerous copper deposits. It displays also a complex geological, metallogenic and tectonic history which is challenging for mining companies in order to better understand and prospect these Cu-deposits. In the Bou Azzer-El Graara inlier, these deposits are hosted as well within the Precambrian basement as within the Neoproterozoic to Paleozoic cover. This study based on mapping, structural, mineralogy, textures and micro-textures observations present a synthesis of Cu-deposits at this inlier scale In this Neoproterozoic to Paleozoic sedimentary cover, two types of mineralizations are distinguished: one is related to local folds and faults and another one associated with a deformation localized in specific stratigraphic levels at the base of the cover. Geological and mineralogical studies showed that both Cu-ores types are controlled by the same hydrothermal event associated to the Variscan orogeny. In the Precambrian basement, massive copper sulfides lenses are present at the intersection between regional pyritic beds or black shales and brittle faults potentially associated with the late Panafrican deformation. Another kind of Cu-deposits is spatially associated with Panafrican shear zones, which showed ductile and brittle deformations. These mineralizations seem to be linked to the late brittle deformation that re-used the ductile shear zones inherited from the Panafrican orogeny. During the Variscan compression, the reactivation, of basement-inherited Panafrican structures controlled the deformation responsible of mineralization in the cover. In summary, copper mineralizations are closely associated with a brittle deformation, posterior to the ductile Panafrican deformation in the basement and synchronous with the Variscan orogeny in the cover. The metallogenic history of copper in the Bou Azer-El Graara inlier can be depicted through, at least, two models: (i) a two-stage model, with a first late Panafrican hydrothermal event, responsible for the basement-hosted Cu-bodies and a second Variscan event, yielding Cu-deposits hosted in the cover. (ii) A single metallogenic phase, during Variscan deformation, that mineralized both the basement and the cover. Works in progress try to assess the relevance of these models at the Anti-Atlas scale.
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Contributor : Isabelle Dubigeon Connect in order to contact the contributor
Submitted on : Wednesday, October 26, 2016 - 10:50:08 AM
Last modification on : Wednesday, August 3, 2022 - 4:03:46 AM


  • HAL Id : insu-01387813, version 1


Hugo Bourque, Luc Barbanson, Stanislas Sizaret, Yannick Branquet, Et Al.. The copper history in the Anti Atlas belt, from Panafrican to Variscan orogeny, a persistence of tectonic controls: an overview of Bou Azzer-El Graara inlier. 25 ème Réunion des sciences de la Terre (RST 2016), Société Géologique de France, Oct 2016, Caen, France. pp.60. ⟨insu-01387813⟩



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