Polyphasic Tectonic on the Deformation Zone in the Northern Foothill of the Blida Atlas, the Cross Section of Hammam Melouane, Algeria

Abstract

The Mitidja Basin is considered as an extensional tectonic structure created in the early Miocene, located in the north of Algeria. It covers an old transition zone in the tertiary collision between the “Internal and External Domain” of the central Maghreb. The Mitidja—Tell Atlas limit is a major geological contact that coincides with a slope and trench break separating the Cretaceous Tell Atlas, from the Neogene and Quaternary Mitidja plain. Hammam Melouane is one of the best sites that summarize the structural geology of this contrasting area Mitidja-Tell. Our observations on this site, supported by a detailed cartography, as well as a study of the kilometric folds and fractures that we interpret as deformations induced by a dextral compression sliding phase having participated in the uplift of the Atlas and in the collapse-subsidence of the Mitidjian basin during the Miocene. The structural analysis revealed a polyphasic tectonic beginning with an extensional phase appropriate to the upper Burdigalian, with a north-south direction and a post-Burdigalian tectonic inversion phase, expressed by a combination of a strike-slip and thrust movements (transpressive), a feature that marks a certain degree in the intensity of the deformations in the “post-nappe” tectonic.