Lineament Map Research Articles

Assessment of Hyperspectral, Multispectral, Radar, and Digital Elevation Model data in structural lineaments mapping: A case study from Ameln valley shear zone, Western Anti-Atlas Morocco

The analysis and the exploitation of remote sensing datasets have an effective contribution to geological studies, particularly the lineament extraction process could play an important role in tectonic features identification, well as new ore deposits, hydrogeological, and petroleum resources prospection. In this study, we applied an automatic approach to map structural lineaments in the Ameln valley area of the western Anti-Atlas province. The aim of this work is the mapping of structural lineaments in the region, then the comparison of the results of multi-source datasets in automatic lineaments extraction, where six images have been used including, HyMap, ASTER, ALOS PALSAR DEM, Sentinel-2A, and Sentinel-1A VH and VV polarizations. The principal component analysis was applied on optical images, a 7x7 Kernel matrix in four directions, N–S, NE-SW, E-W, and SE-NW for HyMap hyperspectral data image in order to achieve a clear and detailed contrast of structural features. ALOS PALSAR DEM was used for lineaments mapping after applying hill shading in the main four directions. Combined with the field investigations, the high resolution HyMap data image revealed relatively the highest number of lineaments (2091 lineaments), with lengths varying from a few hundred meters (100 m) to a kilometer wide (1.2 km). Additionally, the NNE–SSW, NE-SW, and ENE-WSW are the main obtained lineaments trends, where the NE-SW lineaments set highlights the main faults orientation in the study area. Whereas, a good number of lineaments was detected using elevation data of ALOS PALSAR and VH polarization data of Sentinel-1A that allowed the best discrimination of trending fracture system, leading to achieve a detailed map of the structural discontinuities in the study region. The lineaments mapping results highlight the significant contribution of the late Ediacaran extensional event in the actual tectonic structuration of the eastern Kerdous inlier.

Assessment of radarsat-1, ALOS PALSAR and sentinel-1 SAR satellite images for geological lineament mapping

Lineament mapping is a very important step in geological studies and mineral exploration, with the evolution of remote sensing, processing methods as well as the availability of several optical and radar satellite data, lineaments can be detected without using traditional methods. The objective of this work is to recommend the most suitable data for lineaments to be used in the field of geological science, by comparing the performance of three different RADAR data, namely ALOS PALSAR (The Advanced Land Observing Satellite Phased Array type L-band Synthetic Aperture Radar), Radarsat-1 and Sentinel-1 for automatic lineament extraction using a combination of edge detection and line linking algorithms. The methodology consists to link between the length, number, orientation and density of lineaments with surface characteristics such as the slope, faults, lithology, discontinuities and mineral veins. The results obtained show that the extracted lineaments from Sentinel-1 VH polarization have a better correlation with geological units, tectonic system direction, as well as shading and slope maps, which is due to the effectiveness of VH polarization, which is independent of soil properties compared to the other polarizations that have shown an overestimation of the lineaments.

Structural lineament mapping of Central-Eastern high atlas, Morocco, using ASAR/Envisat and SAR/sentinel 1B data

The Central-Eastern part of the High Atlas is dominated by carbonate of Mesozoic age which is affected by the Alpine Orogeny. The deformation manifest in area by different geological structures. The analysis of these later lead to their classification in different category for understanding the geodynamic of the area. This study focuses to map structural lineaments in the Central-Eastern High Atlas using two types of Radar data: Synthetic Aperture Radar (SAR)/Sentinel 1B with polarization (VV + VH) and Advanced Synthetic Aperture Radar (ASAR)/Envisat with polarization (VV + HH). This research aims to demonstrate the utility of Radar data for extracting structural lineaments in carbonate deposits. In this work, two techniques of processing data are used: First, the automatic extraction technique, we are employing the Algorithm Line Module of PCI Geomatica program, after the enhancement of images by applying the mean Co-occurrence filter. Second, the manual extraction technique, it was accomplished by applying directional filters with four directions (N00°, N45°, N90° and N135°) in order to highlight linear structures, then trace the detected lineaments. The synthetic maps of structural lineaments are developed by the two techniques. They are validated by using the lithologic maps extracted from Landsat Operational Land Imager (OLI), the previous researches in the study area, shaded relief extracted from ASTER Global Digital Elevation Model (GDEM), and field investigation data. The results present a good correlation between the direction of structural lineaments extracted from the satellite images and the field measurements. Therefore, the directions of lineaments extracted are N-S and E-W, NE-SW and NW-SE, especially the abundance of the direction N-S. This last one is perpendicular with the major faults. The density of structural lineaments in the study area is controlled particularly by the lithological nature and dynamic evolution, where the concentration is high in the Liassic carbonates. The geostatistical and spatial distribution of the structural lineaments led us to conclude that different tectonic factors are responsible for the distribution of lineaments in the surface of the study area. The comparison of two types of radar data shows that Envisat data is more efficient in the manual extraction than Sentinel 1B data. However, Sentinel 1B data is more efficient in the automatic extraction than Envisat data. This work identifies several families of structural lineaments which can be determined the tectonic phases of the Alpine orogeny affected the intracontinental Atlas basin.

Lineament Mapping of Jabal Arkenu in Southern Libya

Remote sensing technology is an important technique in studying perilously and hard-to-reach places for investigating them in the field. Furthermore, it provides fast and accurate data to characterize natural features or physical objects on the ground. Remote sensing data could be used with other approaches to provide a more comprehensive overview of the feature of interest.
 Accordingly, in this study, the linear features of Jabal Arkenu, in the Kufrah Basin, south of Libya, were studied remotely. The main source data is a satellite image produced from the Alos Palsar satellite, which has a spatial resolution of 12.5 meters. The lineament features map of Jabal Arkenu was created by analyzing several shadow relief images. The length, density, direction and intersection of the lineaments have been extracted from the lineaments map and compared to provide clear maps for determining the type of faults, structural relationships and the geology in the study area. Additionally, the central part of Jabal Arkenu is dominated by high to very high lineament density, while the greater part of the study area is characterized by medium to low lineament density. The dominant direction of the analyzed lineaments is in the northeast direction, and they are concentrated in the north and south parts. Some linear features exist as a boundary between Nepheline syenite with Cambrian Sandstone and Phonolite with Syenite granite.

Towards Automated/Semiautomated Extraction of Faults from Lidar Data

The Pajarito fault system is a complex zone of deformation and a seismically active region nestled within the Rio Grande rift in north-central New Mexico. Numerous laterally discontinuous faults and associated folds and fractures interact in a manner that has important implications for seismic hazards and risk mitigation. Previous efforts have established a foundation for the location of lineaments and structures in the Pajarito fault system; however, ensuring the completeness of the current lineament mapping is required for identifying areas for field validation, evaluating the potential for future seismic activity, and better understanding fault interaction. Assistance with this fault-mapping task via automated or semiautomated techniques as applied to lidar data over a large area of interest is highly desirable. A proof-of-concept processing flow which transforms lidar point-cloud data into a raster of surficial fault candidates is described and illustrated herein. These initial results hold great promise toward achieving our ultimate goal.

Implications and interrelations of litho-boundaries and vicinity of lineaments for hydrothermal alteration zones under remote sensing and GIS environment

The applicability and significance of remote sensing images varies according to capability of synoptic view. These synoptic views of satellite images have tremendous utility to solve many geological enigmas due to constraints of limitations of investigations (manual/ mapping error) in the field of geology. To prepare more accurate remote locations, structural maps such as lineament, fold, faults, shear zone, geomorphology, lithology and mineralogy of remote sensing image helps to solve these problems. In the research work of the hydrothermal alteration minerals zoning and identification completed through spectroscopic and advanced visible-infrared imaging spectroscopy new generation (AVIRIS-NG) hyperspectral remote sensing data. To establish intercorrelation and implications of lineaments with hydrothermal alteration zone of the study area prepared lineament map through manual and auto extraction using Landsat 7 ETM+ and ASTER digital elevation model (DEM) remote sensing data with the applications of algorithms such as Sobels filtering and “LINE” tool of PCI Geomatica. The networks of lineaments have a significant role in demarcation of potential mineral zones. To get vicinity of lineaments, prepared a lineament density map through extracted lineaments. In the final output the vicinity of lineaments density, mineral sample locations, mineral map and regolith zones have shown strong correlation among each other. So, the conclusion is that there is a strong significance in intercorrelation of hydrothermal alteration zones, lineaments and litho-boundaries.

Lineament mapping in the Central High Atlas using ASTER and ASTER-GDEM data, (Morocco)

The present work focuses on lineament mapping using new spatial remote sensing techniques in the central High Atlas (CHA) of Morocco. In this study, the automatic extraction of lineaments was based on using multispectral images type Advanced Spaceborne Thermal Emission Reflection Radiometer (ASTER, L1B) with high spatial resolution up to 15 m for the visible/near-infrared (VNIR) bands. Besides, a digital elevation model (DEM) type ASTER GDEM was used with a spatial resolution of 30 m. The satellite image was pre-processed before the automatic extraction of the lineaments using the mathematical algorithm Line Module of the PCI Geomatica software 2016. Then, multisource data, such as an extract of the Ouarzazate Alougoum geological map (1/100000) covering the entire study area and a calibrated field imaging background (source: Esri, Maxar, GeoEye, Earthstar Geographics, CNES/Airbus, DS, USDA, AeroGRID, IGN, and the GIS User Community), was used for validating the results. The extraction of the lineaments from the first principal component (PC1) image was derived from the satellite image and the DEM. These results proved that each produced map has a strong similarity in concentration and orientation with three major directions including NE-SW, E-W and ENE-WSW. We observed a high concentration of these lineaments in both the central and northern parts of the study area as well.

Mapping of major tectonic lineaments across Cameroon using potential field data

The cartography of lineaments across a territory can be optimized using geophysical potential field data. In this study, land gravity and EMAG2 (Earth Magnetic Anomaly Grid) data were simultaneously used to identify and characterize the major lineaments that spread across Cameroon. The data were filtered using a multi-scale approach including horizontal and vertical gradient analyses. The Euler Deconvolution method was later applied to the filtered data to estimate the extension and depth of the identified lineaments. Results show that the main lineaments across Cameroon are laterally extended with a dominant N45°E orientation. Some of these lineaments correlated well with the geographical location of some known major tectonic structures found across the country. The depth of these lineaments varies between 1 and 35 km. Some of the identified faults are still active as their location correlated with the location of some recent earthquakes that occurred in Cameroon. This work, therefore, highlights some hidden tectonic features which knowledge generally precedes exploration for subsurface resources.Graphical

Remote sensing and DC electrical investigations in the Figuil area (North-Cameroon): structural and geological implications

ABSTRACT This study is based on the analysis and interpretation of remote sensing and electrical data. This allows to characterise the geological formations in Figuil and to evaluate a basement-sediment contact or contact line (CL) of the Babouri-Figuil basin’s SE flank in the north Cameroon region. Manual and automatic extraction techniques applied on the Landsat 8 images brought out 130 lineaments following E – W (90°–100°N), N-S (0°- 10°N) and NNE-SSW (60–70°N) main directions. According to the lineaments map, the lineaments’ density map and the geological background mainly, the basement formations witness a high density of lineaments, while the low density of lineaments matches with the sedimentary formations. Meantime, in the western of Figuil, the geoelectrical surveys using DC electrical method was realised. The quantitative and qualitative interpretations of results revealed an electrical contrast between the basement characterised by high electrical gradients and the sedimentary formations characterised by low electrical gradients. This electrical contrast makes it possible an electrical discontinuity which materialises the real position of the basement–sediment contact or contact line of the SE flank of the Babouri-Figuil basin. The abovementioned information reveals proper electrical and reflection conditions for an efficient structural and geological evaluation.

APPLICATION OF LANDSAT-8 OPERATIONAL LAND IMAGER AND SHUTTLE RADAR TOPOGRAPHY MISSION-DIGITAL ELEVATION MODEL IN THE STUDY OF IKARA AND ITS ENVIRONS, NORTHWESTERN NIGERIA

Images of the earth’s surface captured by radiometric detectors on air-borne (satellite) sensors were employed in geologic reconnaissance survey. They were used to study rock units, pattern and trends of geologic structures on the surface in 2D. Multispectral resolution Landsat-8 Operational Land Imager (Landsat-8 OLI), have nine spectral band with spatial resolution of 30 m (bands 1 to 7, and 9) and 15 m for band 8. The aim of this research is to discriminate lithological units/complexes and delineate fractures (lineaments), hence, only bands 2 to 7 were used for this study. This technique was used to discriminate existing lithological units and identify major and minor extensive geologic structures within the study area. These selected bands were selected, grouped and combined (Band Combination (BC)) and processed for interpretation using applicable Software Packages. Hence, for each procedure and maximum clarity in the output of results, three bands were combined for each analytical process. Bands 4,3,2; 6,5,4; 7,5,3 were combined for Natural Colour Composite (NCC), False Colour Composite (FCC) and Principle Component Analysis (PCA) respectively. The results revealed two distinct lithological Complexes due to their similarities in appearance and differences in mineralogical compositions. SRTM-DEM was used to highlight the topography showing the lowest relief at the northeast and the highest relief at the south east. More so, elongated ridges of intermediate-high reliefs were exposed at the southern part of the study area trending NW-SE. A lineament map and Rose plot shows dominant trend of fractures to be NNW-SSE, NW-SE, N-S, NNE-SSW and

Mapping of fracture zones and structural lineaments of the Gulf of Guinea passive margins using marine gravity data from CryoSat-2 and Jason-1 satellites

Satellite gravity datasets have been widely used in understanding of the Earth's internal structure and processes. These datasets are effective in providing insights into the lithospheric structure of the Earth. Gravity data from the satellite products CryoSat-2 and Jason-1 have been used to investigate the Gulf of Guinea sedimentary basins and structural lineaments in this under-explored marginal sea region through the application of various edge filters. Present-day filtering methods such as the analytical signal, tilt angle of the gradient amplitude, NTilt gradient amplitude and softsign function were evaluated for their performance on synthetic gravity anomalies with and without noise prior to their application to gravity data covering the Gulf of Guinea. The softsign filter outputs obtained from synthetic examples result in higher resolution and more explicit edges while preventing fictitious edges production in the findings. The results of the data interpretation disclosed deep-seated and shallow structural features within the Gulf of Guinea oriented mainly in the WNW-ESE, NW-SE, NE-SW and NNE-SSW directions and seen to be concentrated in the upper slope domain. This observation is in good agreement with the occurrence of drag folds and the apparent concentration of wrench faulting features across the ridge top and bordering the upper slope. These results bring new facts ruling our understanding of this atypical regional tectonic setting in close agreement with the NE–SW-striking Pelusium Megashear Zone.

Potential of ALOS-2 PALSAR-2 StripMap data for lithofacies identification and geological lineament mapping in vegetated fold-thrust belt of Nagaland, India

• Geological mapping of vegetation-covered NFTB is done with ALOS-2 SAR data. • Second order lithological variance could be discriminated by this process. • Meso-scaled geological lineaments has been mapped and analysed. In this study statics-based textural analysis GLCM (Grey Level Co-occurrence Matrix) of high resolution L band SAR data from ALOS-2 of JAXA has been used to discriminate between lithological facies of the fold-thrust belt of Nagaland, India. Sandstones, shales, siltstones and clays have been separated in the analysis. Importantly, the lithological facies with second-order compositional variance have been distinguished from each other. The study of 27 lithological pairs indicates a Transformed Divergence index greater than 1.7 except one pair which shows an index of 1.6. The average GLCM texture values of different stratigraphic units in VV and VH polarization shows appreciable differences. Coefficient of variation of the texture samples from each descriptor show uniform distribution around their mean. The mean has thus been used as a lithological index in this study. Further, the medium scaled geological lineaments have been extracted and mapped at 1: 25,000 scale. The Compass Edge Detector on the first Principal Component of full polarized ALOS-2 scene has been used for this purpose. Fracture network, outcrop length, density, and orientation have also been analyzed. The study is successful in rock characterization within vegetation-covered landscape, using L band SAR remote sensing. It may provide an important tool in geological mapping in inaccessible terrains with limited ground data control. The fracture map and its study can provide some useful insights about reservoir characterization and reduce exploration risk in this terrain that has a proven petroleum system.

Nickel Deposit Depth Estimation Using Source Parameter Imaging and Euler Deconvolution of Aeromagnetic Data of Bakin Kogi and its Environs in Jema’a Local Government Area of Kaduna state

This study aimed to estimate the depth of Nickel deposit in Bakin Kogi – Dangoma region, which lies between latitude 901''and 9027'N and longitude 8000' and 8017' E. The study area is located in Jema’a local government area of Kaduna state. The data was gridded using Oasis Montaj® to produce Total magnetic Intensity Map (TMI) of the area, and further subjected to some filtration processes in order to obtain regional and residual map of the study area. Enhancement methods such as first vertical derivative and analytic signal methods were applied to the residual map to delineate the area with potential Nickel deposit. The quantitativemethod applied were source Parameter Imaging and Euler Deconvolution to determine the various depths of Nickel deposit. From the results of the TMI map and the residual map, the magnetic intensity of the study area was between 32976.5 to 33093.3 nT and 32963.6 to 33072.9 nT respectively with Bakin kogi-Dangoma region, having the highest magnetic intensity of about 33093.3nT and 33072.9 nT respectively. The study area has a high magnetic intensity due to nickel deposit because Nickel ore environment are notable with recognizable “magnetic stratigraphy”, prospective mafic-ultramafic contact, typified by strong magnetic contrast. Abrupt changes in the magnetic intensity infer position of the outer contact of a Nickel bearing zone. The results on the superimposed analytic map on the lineament map showed regional lineaments in Bakin kogi-Dangoma region trending NE -SW, ENE – WSW and NNE – SSW directions. The fractures and faults seen around the study area were strongly associated with minerals deposit. The results of Source Parameter Imaging (SPI) gave a depth of shallower magnetic sources ranges from 92.7 to 116.0 m with an average depth value of 104.35 m while the depth of deeper magnetic sources ranges from 651.2 to 976.2 m with an average depth of 813.7 m. The results obtained from 3D Euler deconvolution which was associated with dykes (SI = 1) anomaly produced at a shallower depth range of 100 - 700 m. Results obtained, shows a correspondence between the depths results obtained from the SPI and that of the Euler Deconvolution methods, indicating correlation in the magnetic depth estimation.

LITHO-STRUCTURAL MAPPING USING REMOTE SENSING AND FIELD WORK TECHNIQUES: A CASE STUDY FROM CENTRAL SALT RANGE, DISTRICT KHUSHAB PUNJAB PAKISTAN

Litho-structural mapping in an inaccessible rugged and mountainous region like the Central Salt range has frequently been a great challenge and importance for geologists. For this purpose, in the present study, litho-structural mapping was carried out based on enhancement and interpretation of Landsat 8 USGS data by the application of remote sensing and GIS technology and further verified by the data which was collected in field work to the study area. Different band combinations of the image are applied for visual image interpretation to digitize the rock boundaries while as Sobel and Laplacian filtering techniques are utilized for lineament mapping. The purpose of our field work was a comprehensive mapping of Geology and related structural aspects of Kufri, Jhalar, Chamnaki, Surraki, Khura and Naushehra area, Central Salt Range, district Khushab Punjab Pakistan in the Central Salt Range Pakistan. It includes Litho-structural Mapping at scale of 1:10,000. The results and conclusion of this study demonstrate that the processing and interpretation of Satellite data set can be employed as a powerful tool to improve lithological discrimination and enhance the overall mapping performance in the rugged and hilly terrain like Salt range.

The contribution of GIS and remote Sensing for mapping fracture networks in the northern border western High Atlas Mafrrakech (Morocco)

The main objective of this work is to test the use of Landsat Oli Tirs imagery for structural identification in the region of the Aït Ourir basins (High Western Atlas). Different processing techniques were used (color composites, band ratios, principal component analysis and directional filters) which provide an excellent discrimination between the different lithological formations and helped us to establish lineament mapping. The results were validated with the fieldwork and bibliography that are essential in any study based on remote sensing. Finally, a lithostructural map of the study area was established on the basis of the results obtained in this work.

Lineaments analysis of Bafoussam (West-Cameroon) using remote sensing and vertical electrical sounding: Hydrogeological implication

The study proposes to map the tectonic accidents existing in Bafoussam locality using the remote sensing and vertical electrical sounding methods. The principal component analysis and directional filtering applied respectively to Landsat8 and SRTM images allowed to extract remote sensing lineament map. The interpretative rose diagram shows a distribution of lineaments following four directions: NE-SW, NW-SE, N-S and E-W. The main directions are from N30°E to N80°E; these are those of large strike-slip of the Central Pan-African Fold Belt (CAFB) in Cameroon and from the extension of the Central Cameroonian Shear Zone (CCSZ) in the studied area. The superimposition of these lineaments on the hydrographic network map enabled establishing genetic links because rivers flow following the main N30°E and the secondary N120°E lineament directions. The superimposition of the iso-resistivity maps resulting allowed to extract the geophysical lineament map which has been confirmed by achieving resistivity sections in depth. These lineaments are N40°E to N60°E directed comparable to the network fracture and foliation direction on orthogneiss flagstones within the area. These lineaments superimposed on those automatically extracted by remote sensing show a good correlation following the two methods used. The both mapping methods therefore allowed to extract the fracturing map zone. As groundwater is generally stored in the fracture network of hard rocks, the results of this study will thus provide progress in the course of wells and boreholes implantation. The second generation of fractures with a N140°E striking direction is the most appropriate for the hydrogeological studies in Bafoussam.

ANALYSIS OF LINEAMENT MAP OF PART OF MARU SCHIST BELT, NORTHWEST, NIGERIA AND ITS IMPLICATION FOR MINERAL EXPLORATION

Lineament are extended mappable linear or curvilinear feature of a surface which can be utilized in mineral, oil, gas, and underground water studies. They are obvious in satellite images, aerial images or aerial photographs. The aim of this study is to analyse an automatically generated lineament from part of the Maru schist belt using a combination of Digital Elevation Model (DEM) data and Aeromagnetic data. The area of study is within the Maru schist belt in Zamfara State. A shaded relief map was produced from the two data sources and the lineament was extracted automatically from them. The extracted lineament was combined to obtain a final lineament map of the area. Trends such as N-S, NW–SE, ENE–WSW and NW–SE, with very little E-W were all present. The areas of very high, high, moderate and low population of lineaments was delineated. Regions with very high lineament intersections and lineament concentration, covers an area of 153.6 km2 and accounts for 16.1% of the study area, these regions are known to harbour gold and iron ores from literature reviews. These target regions are located at the Northern and South part of the study area. Also, the gold artisan miners have dominated these same regions and they have only started from exposed vein of gold mineralization. With this rather fast and easier approach of obtaining such a map, it could be used as a start point for planning a more detailed geophysical or geological survey

APPLICATION OF LANDSAT-8 OPERATIONAL LAND IMAGER AND SHUTTLE RADAR TOPOGRAPHY MISSION-DIGITAL ELEVATION MODEL IN THE STUDY OF IKARA AND ITS ENVIRONS, NORTHWESTERN NIGERIA

Images of the earth’s surface captured by radiometric detectors on air-borne (satellite) sensors were employed in geologic reconnaissance survey. They were used to study rock units, pattern and trends of geologic structures on the surface in 2D. Multispectral resolution Landsat-8 Operational Land Imager (Landsat-8 OLI), have nine spectral band with spatial resolution of 30 m (bands 1 to 7, and 9) and 15 m for band 8. The aim of this research is to discriminate lithological units/complexes and delineate fractures (lineaments), hence, only bands 2 to 7 were used for this study. This technique was used to discriminate existing lithological units and identify major and minor extensive geologic structures within the study area. These selected bands were selected, grouped and combined (Band Combination (BC)) and processed for interpretation using applicable Software Packages. Hence, for each procedure and maximum clarity in the output of results, three bands were combined for each analytical process. Bands 4,3,2; 6,5,4; 7,5,3 were combined for Natural Colour Composite (NCC), False Colour Composite (FCC) and Principle Component Analysis (PCA) respectively. The results revealed two distinct lithological Complexes due to their similarities in appearance and differences in mineralogical compositions. SRTM-DEM was used to highlight the topography showing the lowest relief at the northeast and the highest relief at the south east. More so, elongated ridges of intermediate-high reliefs were exposed at the southern part of the study area trending NW-SE. A lineament map and Rose plot shows dominant trend of fractures to be NNW-SSE, NW-SE, N-S,

Lithological, structural and hydrothermal alteration mapping utilizing remote sensing datasets: a case study around Um Salim area, Egypt

Remote sensing datasets have introduced remarkable advancements in mapping rock units, structural elements, and hydrothermal alteration zones. This study applied Landsat Operational Land Imager (OLI) multispectral dataset in discriminating the intricate basement of Um Salim area, Central Eastern Desert (CED), Egypt. Moreover, a panchromatic 15m pixel size band is implemented to extract the study area’s linear structural features. Several image processing methods including False Color Combination (FCC), Band Ratio (BR), Optimum Index Factor (OIF), and Density slicing were utilized in lithological and alteration mapping. The widely used, LINE module of the PCI Geomatica is applied for lineament extraction. Results reasonably discriminate the complicated rock units using selected composites depending on OIF results. A photo-geological map is constructed and shows greater coincidence with recently published maps. Lineaments map and its density revealed the preponderance of NE-SW and WNW-ESE structural trends. The spatial relationship between the resultant hydrothermally-altered zones and the detected structural features strongly recommends further detailed examination for ore deposits within the study area besides manifesting the efficiency of the utilized data and methods.

Interpretation of Aeromagnetic Data of Part of Gwagwalada Abuja Nigeria for Potential Mineral Targets

This study analyzes aeromagnetic data over a section of Gwagwalada in Abuja. The data were obtained from the Nigerian Geological Survey Agency acquired at 100 m terrain clearance. The study area spans longitudes 7.0875 E to 7.1458 E and latitude 8.9625 N to 9.0 N (about 27 km2). The dataset was reduced to the equator (RTE) and downward continued by 50 m. Analytic signal filter was applied on TMI-RTE grid to detect the edges of the magnetic bodies present. The structure was observed to trend NE-SW. The CET lineament map reveals intersections such as junctions and corners on the map. This revealed structure liable for potential mineralization zone. Euler deconvolution technique applied over the transformed dataset ascertain the location and depth of the structure,having a maximum depth of about 421 m and a minimum of about 59 m.Variation in magnetic depth and susceptibility contrast is specified by the gridded SPI depth map.