Mapping and analysis of structural lineaments using SRTM radar data and Landsat 8-OLI images in Telouet-Tighza area, Marrakech High Atlas - Morocco.

Abstract

Certainly, remote sensing data more specifically Landsat 8 Operational Land Imager and SRTM images can be used as a powerful tool for lineament mapping. Lineament extraction method and statistical studies are attractive an alternative analysis techniques which resolve lineament mapping problems in the region and allow exceeding the usual classical method. The present study deals with the estimation of the potential of both Landsat 8 Operational Land Imager sensor images and SRTM Digital Elevation Model data for automatic lineament extraction in the south side of Marrakech High Atlas (Telouet-Tighza area). After image corrections, enhancement methods such as principal component analysis (PCA), Band Composite and Directional Filter were adopted in order to create new images with high visibility of linear structures. A Principal Component Analysis (PCA) has been realized on the Landsat 8- OLI bands in order to reduce the redundancy information in highly correlated bands. Validating the use of the new Landsat band composite image relied on calculating statistical optimum index factor (OIF), Correlation Index and matching interpreted linear structures to previously published geologic maps. Therefore, the SRTM Digital Elevation Model is used in this study to generate shaded relief images as well as three-dimensional representation of the terrain and slope. Shaded relief images allowed to highlight linear features related to geomorphological data which are not identified in optical images. Multi-source data, such as Band Ratio image, geological map and fieldworks were used to verify and eliminate meaningless and non- geological lineaments extracted by applying line model tool of Geomatica software.The results indicate that automatic method was applied successfully for lineament mapping in the Telouet-Tighza area and showing improvement over previous techniques in detailing the main tectonic faults. Slope and lithological factor were recognized to understand their relation with spatial distribution of lineaments over the study area. Structural lineaments generated from PC1, selected Band composite images and shaded relief DEM data proved the coincidence of their direction, length, and density with the tectonic system of the study area. The resultant fracture network is oriented ENE-WSW and E-W with a predominance of the E-W direction. It showsgood correlation between the distribution and the orientation of the lineaments on updated lineament map in comparison with the localization and orientation of fault system pattern in the existing geological map. In addition, the new synthetic structural map shows more information and details compared with based geological map which reveals the performance of Landsat 8-oli bands and SRTM data in this kind of study.