Geological mapping of the Adrar Souttouf mafic complex in the Northern West African Craton using remote sensing and geophysical data

Haous EHE, Fekkak A, Houali Y, Haidatte S, Bouasria A, Boumehdi M, Achkouch L, Genske F, Haissen F, Jouhari A, Berrada I, Berkat NE, Errami A, Sadki O, Shebl A

Zusammenfassung

Geological mapping of the Adrar Souttouf Mafic Complex (ASMC) is constrained by its remote arid mountainous setting, where logistical limitations hinder traditional field surveys; however, advances in satellite data have provided powerful, cost-effective tools for high-resolution lithological and structural mapping. This research presents the first synergistic use of Sentinel-1 radar, Sentinel-2 and Landsat-8 optical imagery, and airborne gamma-ray spectrometry data to decipher the main structural and lithological characteristics of the Adrar Souttouf mafic complex within Morocco’s Oulad Dlim Massif. To achieve this, image processing—including color composites, band ratios, Principal Component Analysis (PCA), and radiometric terrain correction (RTC) —was employed for lithological mapping at regional and local scales. These spectral results were integrated with airborne gamma-ray spectrometry (K\%, Th ppm, U ppm), providing the geochemical constraints necessary to differentiate lithological units and update existing geological maps. The study revealed that the highly complex geology with a variety of facies. These facies can be classified into three main categories: (i) (minor) ultramafic cumulates (ii) massive isotropic gabbros that represent magmatic intrusions that correspond to interconnected laccolites through a network of feeding dykes, and (iii) evolved silica-rich facies corresponding to charnockites, that are found either in undeformed massifs, or in elliptical bodies. The latter are situated under the broad gneissified massif of Hassi Bougaffa. All these magmatic facies were emplaced within a strongly deformed gabbroic body and are structurally controlled by fault systems. The most significant faults are oriented E-W and NNE-SSW. The result validation by fieldwork aided by remote sensing and gamma-ray spectrometry maps have clearly helped in better distinguishing between the various lithological units. This led to update the litho-structural map of the study area.