Geomorphic analysis and quaternary neotectonic deformation in the eastern Babors chain, Bejaia, Algeria

Abstract

The Eastern Babors are part of the Maghrebides chain formed by the alpine orogeny. This section of the Tellian Atlas is marked by a typical relief subjected to both tectonic and erosive activity observed in its rugged morphology and deep valleys. The paper highlights the link between external dynamics and neotectonic processes through the analysis of geomorphic factors and a morphostructural assessment. These factors are extracted from a series of processing using a Digital Elevation Model (DEM) in a GIS environment to quantitatively and qualitatively assess the response and evolution of the catchments in a morpho-tectonic context that characterizes the study area. Thus, we relied on hypsometric curve analysis, hypsometric integral distribution, elongation ratio and asymmetry. The indices were complemented by longitudinal profiles and the channel steepness index allowing a closer observation of the rivers' response to tectonic processes affecting the region by analyzing knickpoint and their relation with the fault zone that marks this region. Also, the uplift rate was estimated using the relative tectonic uplift index. The geomorphic factors reveal a young relief exposed to intense external dynamics in an active tectonic context. This is correlated with the hypsometric curves and longitudinal profiles confirming streams in equilibrium, while the breaking points highlight tectonic processes. The analysis of the relative uplift factor and the channel steepness index indicate an overall tectonic uplift in the region, with some areas uplifted more than others, particularly in the central region of the study area. Moreover, the channel steepness values reveal a tectonicly active zone around the Kherrata fault. In addition, this study is based on a morphostructural analysis in order to determine the different tectonic phases and, in particular, to highlight the influence of the current phase in the relief evolution. The different results obtained in this study reveal a rugged relief, young and strongly incised by a drainage system that undergoes tectonic and neotectonic activity that influences the evolution of the drainage system and the relief. This evolution is particularly observed in the center of the region and indicates that this region is marked by various tectonically uplifted blocks.