Late Hercynian and Alpine Deformation in Sidi Abdelaziz Area Small Kabylie—Algeria

Abstract

The region of Sidi Abdellaziz is located in the center of the massif of small Kabylie (Algeria), it is part of the basement of the internal domain of the Maghrebids chain. The petrographic study of metamorphic rocks in this region has made it possible to highlight the upper sets of the Kabyle basement constituted by metapelitic series intruded by deformed granite. Structural analysis has shown that this granite is syntectonic and has been emplaced in a strike-slip reverse fault toward the East. This granite was later affected by a second N–S directional deformation, responsible for the formation of shear bands. The statistical analysis of the poles of the schistosity planes and the lineation in the inclosing The statistical analysis of the poles of the schistosity planes and the lineation in the metapelitic rocks gives a ESE–WSW direction, parallel to the emplacement of the granite body. The statistical study of fold axes directions and fault planes in the granite body and its metapelitic inclosing rocks reveals the existence of at least two compression phases, the first is NW–SE direction and the second is E–W. The sigmoidal elements derived from the Djennah shales indicate the existence of a shear zone towards the NW compatible with the structural elements related to the emplacement of the granite body. The region recorded a reverse-thrust materialized by lying down folds and reverse thrusting faults toward the NW in the metapelites of Sidi Abdellaziz, this movement is confirmed by the folding of the abnormal contacts separating the various units dipping towards the South on the surface and to the north at depth. These structural elements suggest of a polyphase deformation of the basement, it records the Hercynian and Alpine movements. This type of structure was highlighted in the East and West of the basement of Small Kabylie (Peucat et al. 1994).