Relationship between geo-structural evolution and development of karstic systems in the culminating area of Ouarsenis (West Algeria)

• Published in: Arabian journal of geosciences 2016-09, Vol.9 (14), p.1-17, Article 638
• Main Authors: Mansour, Zaagane, Soraya, Refas, Abdelkader, Khaldi, Donzé, Frédéric, Abderahmane, Hamimed, Aissa, Safa, Kacem, Moussa, Abbes, Sebbane, Habib, Azzaz, Souad, Mouassa
• Format: Article
• Language: English
• Subjects: Area; Basins; Cenozoic; Civil Engineering; Construction hydraulique; Drinking water; Earth and Environmental Science; Earth science; Earth Sciences; Engineering Sciences; Géotechnique; Identification; Joints (timber); Jurassic; Karst; Limestone; Nappes; Original Paper; Phase transitions; Risques; Shear stress; Shearing; Slip; Stress history
• ISSN: 1866-7511; 1866-7538
• DOI: 10.1007/s12517-016-2662-9

The Ouarsenis area is one of the most developed karstic systems of Algeria. It is a karst reservoir drinking water with a population of more than 50,000 people taking fully benefit from it. To understand the development of this karstic system, the local tectonic history of the four main mountain ranges of this culminating area (Ouarsenis) has been analyzed. Although previously identified primarily Cenozoic tectonic activities have been observed, a set of NW-SE joints intersecting the Jurassic limestone has been associated to a post-nappes tectonic events. Moreover, numerous joint sets oriented NNE/SSW have been identified almost over the entire culminating area. These joints are the direct consequence of the following stress history: (i) a NW/SE shortening responsible for a major overlap and the first fold (P1) phase, (ii) a second NNE/SSW shortening stage responsible for the second folding (P2) phase associated with 70° N sinistral strike-slip trend, (iii) a WNW/ESE extension phase resulting from the change of σ 3 stress vertical axis, and (iv) a shearing stress creating a 120° N sinistral strike-slip fault. Only the late phases are responsible of the development of joints, which have been karstified later on. Indeed, significant families of karstified joints, i.e., 20° and 70° N have been found. These joints are related to the extensional and shearing modes, respectively, and linked to a particular in situ karstogenesis. Moreover, this study suggests an ancient establishment of the karstic systems in the Ouarsenis region in at least two stages: pre-figured and activated behaviors during the Cenozoic.