The Cu–Pb–Zn-bearing veins of the Bou Skour deposit (Eastern Anti-Atlas, Morocco): structural control and tectonic evolution
Ayoub Aabi, Lahssen Baïdder, Younes Hejja, Mohammed El Azmi, Abdellah Nait Bba, Khadija Otmane
Abstract
In the central Saghro massif of the Moroccan Anti-Atlas belt, the Bou Skour polymetallic deposit is hosted within mafic to felsic rocks of the Ediacaran Saghro Group and the lower Ouarzazate Group together with Pan-African plutons and dykes. The mineralizations occur in a brittle-ductile shear zone as a vein-type system recently dated at <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mrow> <mml:mn>574</mml:mn> <mml:mo>.</mml:mo> <mml:mn>9</mml:mn> <mml:mo>±</mml:mo> <mml:mn>2</mml:mn> <mml:mo>.</mml:mo> <mml:mn>4</mml:mn> <mml:mspace width="3.33333pt"/> <mml:mi mathvariant="normal">Ma</mml:mi> </mml:mrow> </mml:math> . In this contribution, a new multi-scale structural mapping and vein system analysis have been integrated to understand structural control and tectonic evolution of the Bou Skour deposit. The most important mineralized structures are known as “ Filon Principal ”, “ Filon 1 ”, and “ Filon 2 ” and are mainly hosted within NNW to NW transcrustal faults. They are represented as en-echelon tension gashes occasionally associated with horsetail satellite structures pointing to left-lateral strike-slip movement. The age and tectonic patterns are coherent with the NW–SE shortening of the last stage of the Pan-African orogeny rather than with post Pan-African events. Subsequent collapses and tilted blocks were accommodated by NE- to ENE normal and strike-slip faults in response to the Late Ediacaran–Cambrian extension events. Much later, probably during the Variscan or even Atlasic shortening, conjugated strike-slip reverse faults and related folds occurred, disrupting most of the rhyolitic dykes as well as the major mineralized structures.