GEOLOGICAL LINEAMENT MAPPING THROUGH SEMI-AUTOMATIC EXTRACTION FROM SATELLITE IMAGES OF SIBI AND SURROUNDING AREAS (MALI)

Geological lineament mapping represents an essential step in structural studies, mineral exploration, and natural resource management. However, its implementation remains challenging due to constraints related to field conditions, accessibility of outcrops, vegetation cover, and superficial formations that frequently obscure geological structures. In this context, remote sensing provides an effective alternative by enabling the identification and analysis of tectonic structures based on the spectral characteristics of satellite imagery. This study aims to develop a lineament map of the Sibi region and its surroundings using a semi-automatic extraction method applied to Landsat 7 ETM+ satellite images. The methodology is based on a sequence of digital processing techniques, including principal component analysis, band ratios, directional filtering, threshold-based binarization, mathematical morphology operations, and image algebra processing. These techniques enhanced structural contrasts and enabled the efficient extraction of linear features from satellite images. The results obtained allowed the identification and mapping of 10,058 geological lineaments, revealing a structural organization dominated by the NNE–SSW, NE–SW, and SE–NW directions, with a clear predominance of the NNE–SSW orientation. Validation based on field observations, existing geological data, and previous studies confirmed the reliability of the detected structures. The newly produced lineament map significantly improves the structural understanding of the region and highlights several previously unreported structures. These results demonstrate the relevance of the semi-automatic approach for updating geological maps and optimizing structural mapping activities in tropical environments.