Strong Neotectonic Block Rotations, Related to the Africa‐Eurasia Convergence in Northern Algeria: Paleomagnetic Evidence From the Mitidja Basin

Abstract

Significant tectonic clockwise rotations were evidenced in the Tell Atlas (Neogene Algerian Cheliff basin) by previous paleomagnetic studies. For northwestern Africa and in the context of the Africa-Eurasia convergence, they provided a new argument validating a kinematic model, based on transpression with shortening accommodated by clockwise block rotations. To corroborate this deformation pattern at a larger scale, new paleomagnetic studies were performed on 349 cores in the Mitidja basin, of Mio-Plio-Quaternary age, in the Algerian Tell Atlas. This intramontaneous basin is structured by two regional major E-W to WNW-ESE dextral shear zones. Primary magnetization data were obtained in 43 out of the 49 sampled sites. This magnetization is carried by Ti-poor titanomagnetite. Its direction shows that significant tectonic block rotations affected this basin since 16 Ma. Zones located between the E-W and WNW-ESE major structures are affected by coherent clockwise rotations (average magnitude of 48°) of large blocks, compartmented by presently associated sinistral NE-SW faults. Along the shearing structures, smaller blocks, resulting from the fragmentation of the large blocks, show various rotations, many of which are of large magnitude. These rotations, similar to those highlighted previously in the Cheliff basin, are interpreted as resulting from bookshelf, consequence of the Africa-Eurasia plates convergence in the Tell Atlas.

Ongoing Inversion of a Passive Margin: Spatial Variability of Strain Markers Along the Algerian Margin and Basin (Mediterranean Sea) and Seismotectonic Implications

“…North Africa accommodates the convergence of Eurasian and African plates since Late Cretaceous times. Since the closure of the Tethyan oceanic lithosphere and the docking of the Kabylian blocks with Africa ∼19 Myr ago, the transpression induced by the relative plate convergence has been likely accommodated by a combination of shortening along large thrust fault systems onland and clockwise block rotations (book-shelf faulting) in the Tell-Atlas fold-and-thrust belts (Frizon de Lamotte et al, 2000Roure et al, 2012;Derder et al, 2019). The relative importance of each process has long been debated (e.g., Frizon de Lamotte, 2005).…”

Multi‐temporal InSAR analysis to monitor landslides using the small baseline subset (SBAS) approach in the Mila Basin, Algeria

“…Location of Algeria in the Mediterranean region between the Eurasia-Africa plate boundary (a) (Boulahia et al, 2021;Derder et al, 2019) technique has proven efficient for monitoring ground surface movement, we could evaluate the impacts of seismic shaking in causing damage together with other environmental factors affecting stability within the Mila Basin. The MT-InSAR method is costeffective compared to conventional geodetic techniques or the ground truth data (boreholes) with a complete understanding of its limitation.…”

“…The Mila Basin is a Mio‐Plio‐Quaternary sedimentary basin located in northeast Algeria (Boulahia, Abacha, Yelles‐Chaouche, et al, 2021; Derder, Djellit, Henry, et al, 2019; Mezerreg, Kessasra, Bouftouha, et al, 2019) (Figure 1). In the last 10 years, various slope failures resulting in many casualties have occurred in the Mila Basin, but no studies to investigate the subsurface instability or monitor the ongoing land subsidence have been conducted until now.…”

“…Location of Algeria in the Mediterranean region between the Eurasia‐Africa plate boundary (a) (Boulahia et al, 2021; Derder et al, 2019) and the location of Mila city in the northeastern Algeria surrounded by low‐dense vegetation area (b). (b) Sentinel‐1 A/B data coverage indicates the ascending track 161 (red rectangle) and the descending track 66 (blue rectangle), respectively.…”

Introduction to the Special Section in “Geodynamics, Crustal and Lithospheric Tectonics, and Active Deformation in the Mediterranean Regions” (A Tribute to Prof. Renato Funiciello)

“…As an addition and important input, the analysis of paleomagnetic data documents faulting processes and block rotations from the Moroccan and Algerian Atlas (Derder et al., 2019; Torres‐López et al., 2018), through Sicily (Speranza et al., 2018), to the central Taurides (Koç et al., 2018).…”