Lineament mapping in the Ikniouen area (Eastern Anti-Atlas, Morocco) using Landsat-8 Oli and SRTM data

Abstract

The present work focuses on the use of remote sensing techniques and Geographical Information Systems (GIS), to Automatic extraction and geospatial analysis of lineaments, in the district of Ikniouen located in the eastern Moroccan Anti Atlas. To achieve this objective, we relied on the processing of Landsat-8 OLI spectral bands and SRTM data covering the study site. In the first instance, essential pre-processing was carried out on our spatial data for the automatic extraction of lineaments by applying the mathematical algorithm Line Module from PCI's Geomatica 2016 software. Some of the treatments used included Principal Component Analysis, Shaded relief of SRTM data from different angles, 7 × 7 matrix directional filters, and finally the automatic extraction of lineaments. The results obtained from lineament extraction from the PC1 image, the seven spectral bands with a spatial resolution of 30 m, and the digital elevation models (DEM) SRTM proved that each map produced had a strong similarity in terms of density and orientation with two major directions – NE-SW and E-W – with high densities in areas well known to be fractured, namely the Oussilkane granites in the northeast, the Ikniouen granites in the west, and the rhyolites and ignimbrites of the Amtatouch-Yadawdane formations in the south of the study area. The results from the automatic extraction of the lineaments revealed 2680 lineaments, whose size varied from a few metres to 3.4 km, with an average length of 534 m. The lineaments of small extensions were the most numerous, as they had an interval comprising almost between 30 and 1158 m. The projection of these lineaments on a Rose diagram showed a predominance of the NE-SW direction. Multi-source data, such as lithological factors, slope factors, and calibrated, high-resolution ESRI field imagery basemap, were used to validate potential results of this automatic lineament mapping. The automatic extraction allowed a better mapping of the structural lineaments; it add information to geological data, but the geological meaning of the linear feature have to be investigated. This technique is usefull to preliminary identify areas with a probable difference in potential lineament density together with their main directions.