The role of variscan shortening in the control of mineralization deposition in Tadaout-Tizi N’rsas mining district (Eastern Anti-Atlas, Morocco)

Abstract

The abundance of the NE-SW direction veins mineralized in barite, copper, lead and zinc in theTadaout-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 anticlineduring the NE-SW Variscan shortening. Our work based on lineaments extraction using a Landsat 8OLI combined with some geological cross sections, shows a N130° major fold corresponding to TTRanticline. This big fold shows internal N130°, N95° and N20° minor folds. This structure indicatesthat the TTR area was formed in the hinge between the Anti-Atlas and the Ougarta belts. A numberof these folds are the consequence of the underlying Precambrian faults reactivation and alternationof competent and incompetent levels. Brittle tectonics is dominated by NE-SW normal faults whichresult 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