Integrating remote sensing and aeromagnetic data for lithological and structural lineaments mapping in Abu Ghaylan - Kiklah - Tighrinna, northwest Libya

Abstract

Problems Statement and Purpose. Libya is the fourth-largest country in Africa and the seventeenth-largest country in the world with area of 1,759,540 sq. km. Most of Libya is located in the Sahara Desert and known for being the driest and most remote regions with limited accessibility. In the 1970s, the Industrial Research Center in Libya began to create geological maps of all Libyan lands derived from analog (hard-copy) aerial photographs and geological field trips to some accessible places. Recently, remote sensing and data integration techniques using GIS are crucial to geological survey and mapping, which provides a useful tool for studying and investigating the geology of remote regions without having to physically access them. The purpose of this study is mapping lithological unites and structural lineaments in the region of Abu Ghaylan - Kiklah - Tighrinna, northwest Libya, using integrated remote sensing data and spatial analysis. Data and Methods. Enhanced Thematic Mapper Plus (ETM+), Satellite Pour l'Observation de la Terre (SPOT 5), European Remote-Sensing Satellite-2 (ERS-2) Synthetic Aperture Radar (SAR) C-band, Digital Elevation Model (DEM), geologic maps, and aeromagnetic data were used to map and analyze the lithological and structural lineaments in the study area. Various fused images and IHS transformations were tested for lithological units recognizing. On the basis of spectral characteristics and topographic forms, lithological and structural lineaments were recognized and mapped. The extracted rasters and vectors data were integrated using remote sensing and GIS data integration techniques. Ground Truthing. The purpose of the ground truthing was to validate the DEM-based structural mapping and identify any landslides, streams, or valleys that may appear as edges in the DEM data. Also, determining the locations of the artificial lines, that appears in the processed images as geological lineaments and edges. Results and Discussion. The results indicate that remote sensing data were very useful in distinguishing between various rock units and recognizing geological lineaments in the study area. The generated lithologic map shows fifteen geological formations with apparent and accurate boundaries. The results exposed new geological lineaments in the study area. The direction of the extracted geological lineaments is dominantly NW-SE. The magnetic data reveal the boundary of sedimentary basin in the study area. The basement's depth within the basin varies from 122 meters to 4.5 kilometers. The extracted geological lineaments were analyzed and interpreted to provide more information about the main structural trends affecting the study area. The methods used in this study for remote sensing image analysis and field geological surveys can be used successfully in similar regions of Libya.