However, in the case of google earth imagery, despite its meter- to cm-scale spatial resolution, which permits visualization of features and the wide variety of information obtained from it, it is generally undervalued for geological studies. Recognition and mapping of lineaments on open source and readily available data such as satellite or google earth images 6, 7, 33 are important in large sites that are partially accessible for conventional field mapping or better still for reconnaissance prior to detailed geologic field mapping. Today, knowledge of the occurrence and behavior of fractures is important in the assessment of subsurface geological units for their storage potentials e.g., CO 2 32. Fracture porosity, which increases in high fracture density zones, is also important for enhanced oil and gas recovery 31. Lineaments such as faults may function as migration pathways for hydrocarbon (and other fluids) in the subsurface 28, 29, and are therefore commonly considered during hydrocarbon exploration 30. Since seismic hazards commonly occur in or near zones of intense and active faulting or tectonic movements 25, 26, knowledge of the occurrence and behavior of lineaments may be important in choosing building, dams, and bridge construction sites 27. Understanding the occurrence and impact of lineaments is vital in groundwater and ore mineral exploration as lineaments are favorable zones for groundwater migration and storage 21, 22, hydrothermal fluid migration, and ore mineral emplacement 23, 24. ![]() Of greater significance is the integration of spatial data and GIS techniques for the analysis of topographic expressions such as lineaments, which are important for understanding tectonic evolution of the earth 7, 20. These properties are crucial for geomorphological studies of the earth’s topography. Moreover, integration of spatial data and geographic information system (GIS) techniques 2, 18 has aided the study of terrain properties such as slope, hillshade 18, and roughness 19. Lineaments can be mapped through conventional geological field mapping 10, which is generally laborious, costly and time-consuming, and via manual or automatic extraction from topographical maps, DEMs 11, geological maps 12, aeromagnetic data 13, seismic reflection data 14, 15, and satellite images 11, 16, 17. ![]() They are usually developed in areas of high stress or strain concentration following rifting or orogeny 8, 9. Lineaments are mappable linear geological features on earth’s surface and include faults, joints, shear zones, intrusions, and dykes. These DEMs come with improved ability to perform geospatial analysis 3 using tools such as ArcGIS and QGIS, and to virtually delineate geological features such as lineaments on a local to regional scale 6, 7. The availability of digital elevation models (DEMs) and digital surface models (DSMs) of almost all places on earth through platforms such as Google Earth, USGS earth explorer, and NASA’s world wind, and recent advances in geospatial technologies have enabled remote study of the earth’s geology and terrain properties 1, 2, 3, 4, 5. Importantly, our method is effective in remote mapping of lineaments and terrain attributes within the study area and has wider applications in other basement complex terrains. The high roughness indices observed have tectonic connotations and are related to the occurrence of lineaments, strain domains, and high degree of rock weathering. Streams in the area exhibit variable flow and partly align with the lineaments. Terrain roughness indices are high at the outcrops and lineament sites. Lineaments are widespread and dense around the batholith, occurring in areas of high elevation, and slope gradient. The case study area, the Idanre Hills in southwestern Nigeria, has a protracted history and is characterized by steep-sided outcrops of a granitic batholith and migmatite-gneiss. ![]() Our workflow is based on geographic information system tools and consists of stream network delineation, lineaments mapping, terrain roughness index calculation, and interpretation of structural fabrics from google earth aerial photographs. ![]() In this study, we use an integrated geologic mapping technique for remote mapping of lineaments and geologic terrain.
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