Integration of Landsat 8 OLI and DEM for mapping lineaments and lithologies in the Ouanina basin, northern High Atlas, Morocco

Abstract

Dense vegetation cover in the Marrakech High Atlas region presents significant obstacles to conventional remote sensing based geological mapping. To address this challenge, we developed an integrated methodology combining Landsat 8 (OLI) multispectral data with (SRTM) Digital Elevation Model (DEM) derivatives for lithological and structural characterization of the Ouanina Basin. Our processing workflow incorporated a vegetation suppression algorithm achieving 56.3 % vegetation removal efficiency, as quantified through pre and post treatment (NDVI) pixel classification. Additional enhancement techniques included false color composites, Principal Component Analysis (PCA), directional filtering, Minimum Noise Fraction (MNF) transformation, spectral band ratios, and DEM derived shaded relief imagery. Integration of remote sensing products with field observations and historical geological data enabled construction of a detailed lithological map and identification of a complex structural network. Significantly, we identified a previously undocumented fault family oriented independently from established Moroccan orogenic trends (NNW-SSE, NW-SE, NNE-SSW). Our stratigraphic analysis revealed misclassification in previous mapping: formations attributed to the Cenomanian-Turonian are demonstrably Eocene in age. This revision derives from recognition of an overturned stratigraphic sequence generated by river transecting faults producing fault-drag geometries. These structural features exhibit genetic relationships with evaporitic diapirism and Atlas fault reactivation, culminating in dextral shear zone development north of the basin. The synthesis of these analyses produced a comprehensive litho-structural map integrating lithological units, facies variations, and major structural discontinuities.