Extraction and analysis of geological lineaments by combining ASTER-GDEM and Landsat 8 image data in the central high atlas of Morocco

The present work focuses on using remote sensing techniques and geographical information system (GIS) to automatically extract lineaments in the southeast of Morocco, which is one of the most important segments of the Moroccan Atlas system, especially between the southern border of the Central High Atlas and the northern part of the Anti-Atlas. For this purpose, we used Landsat 8 OLI multispectral image processing and the mosaic of two ASTER GDEM images covering the field of study. To achieve this objective, basic pre-processing was applied to our satellite images for the automatic extraction of lineaments, by applying the mathematical algorithm Line Module of the software Geomatica 2016 of PCI. The processing used included principal component analysis (PCA), shading at different angles of the GDEM, and 7 × 7 matrix directional filters, followed by the extraction of the lineament steps. The lineament extraction obtained results from the PC1 image, derived from the panchromatic band satellite image and the GDEM, proving that each produced map had a strong similarity in terms of concentration and orientation in two major directions: WSW-ENE and SW-NE, with a concentration of these lineaments in the northeastern part of the southern part of the Central High Atlas. This concentration was also clearly observed in the southeastern part at the Precambrian bedrock of Saghro. The results obtained from the automatic extraction of the lineaments revealed 18,450 lineaments, with sizes varying from a few meters to 7.5 km, with an average length of 902 m. The lineaments of small extensions were the most numerous, having intervals included between 458 and 2972 m. The projection of these lineaments on a directional diagram revealed a predominance of the NE-SW direction. To improve our results, multisource data such as the mosaic of two geological maps at a scale of 1:100,000, covering the complete study area, as well as a calibrated high-resolution field imagery backgrounds from the environmental systems research institute (ESRI) were used to validate our automatic lineament mapping results. As a conclusion of this investigation, we discovered that the automatic extraction provides a more accurate means of mapping structural lineaments, showing a good accordance with and more information than previous geological data, and confirming the efficiency of the techniques applied in geological studies.