Volume 4 Article informations Automatic extraction of lineaments from Landsat Etm+ images and their structural interpretation: Case Study in Nefza region (North West of Tunisia) Slimen Sedrette a,*, Noamen Rebaï b Abstract The lineaments are linear or curvilinear discontinuities in direct connection with the faults and the composite fractures. Lineament analysis constitutes an interesting approach in the geological mapping and mineral exploration. In our study, various types of techniques to extract lineaments were applied to a panchromatic band of Landsat 7 ETM + image covering the Nefza mining district in the North West of Tunisia. In the first step, four derived images were generated from four Sobel directional filters in all possible directions (N-S, E-W, NE-SW and NW-SE). These filters increase contrast in the image and allowed mapping a larger number of lineaments. In the second step, the lineaments mapping was performed by using the Line module of PCI Geomatica. This will allow us an automatic extraction of lineaments. The next step is the superposition of the lineaments maps obtained in different directions to create a synthesis lineaments map. The result of this study show a positive correlation between structural geology (faulting, lineament, warping) and the dominant extracted lineament orientations. The highest densities obtained are oriented NE-SW, N-S and E-W, with the predominance of the first direction. Key words: Lineaments extraction, Satellite images, Nefza, Tunisia.