Automatic Lineament Extraction Research Articles

Automatic extraction of non-bifurcated lunar lineaments from Lunar Reconnaissance Orbiter (LRO) monochromatic images based on a Markov chain method

ABSTRACT Lineaments play a critical role in the study of lunar geological evolution. However, lineaments still need to be extracted manually which constrains lunar research. To fill this gap, a Markov chain-based methodology is introduced for automatically extracting vector-based non-bifurcated lineaments from images. The extracted lineaments are formed by successive nodes and line segments, where nodes denote pixel positions and line segments represented connecting lines between nodes. A modified U-net with residual shortcut connections and dilated convolutions is proposed based on the elongated shapes of lineaments to evaluate the probability of nodes belonging to lineaments. Four connection shape features are proposed to describe the connection shapes of nodes and a Gaussian Mixture Model is used to evaluate the probability of line segments belonging to the lineaments based on the proposed features. In the final stage, the lineament probabilities of both nodes and line segments to extract lineaments are considered in the Markov chain. Our method has experimented on a dataset containing 220 samples and 10-fold cross-validation was used to evaluate the performance. Both qualitative and quantitative results indicated that our method can effectively extract non-bifurcated lunar lineaments with arbitrary bending. The method sheds useful light on automatic lineament extraction.

Automatic lineaments detection using radar and optical data with an emphasis on geologic and tectonic implications: a case study of Kabul Block, eastern Afghanistan

The earth’s surface linear features, expressing geological lineaments, play a key role in identifying hydrothermal alteration and mineralization zones, as well as in understanding tectonic settings of a region. The objective of this investigation is to utilize a method for extracting lineaments automatically, which will be integrated and applied to identify geological-based lineaments by making use of remote sensing data. The study will further examine the structural pattern and temporal-spatial evolution of the lineaments and establish their connection with the primary active faults present in the Kabul Block. Multi-sensor data from radar (DEM (Digital Elevation Model)-5m, Sentinel-1B GRD (Ground Range Detected)) and optical sensors (Sentinel-2 MSI (Multispectral Instrument) and ASTER) were processed using spatial and spectral filters before automatic lineament extraction. LINE-module algorithm was applied to various illuminated hill-shades of DEM-5m, filtered HH (Horizonal-Horizonal) and VH (Vertical-Horizontal) of Sentinel-1GRD and PC1 (Principle Component) of Sentinel-2A MSI, and ASTER data to detect linear surface features. Extensive testing was conducted to verify the accuracy of extracted lineaments and to exclude any artificial lineaments in the study area. The radar and optical data results were compared while taking into consideration the geological and tectonic settings of the study area to select the most appropriate extracted lineaments. The DEM-5m and Sentinel-1B GRD showed the best result for identifying lineaments, and these were found to be highly correlated with previously available data in the Kabul Block. The final results of DEM-5m and Sentinel-1B GRD were further analyzed. The extracted lineaments were found to trend predominantly in a NW-SE and NE-SW directions, which is consistent with the results of other data. Temporal evolution and spatial distribution reveal that a high density of the lineaments is associated with Paleogene and Quaternary formations, while a low density is observed in Proterozoic, Paleozoic, and Mesozoic formations. The west and southwest edges of the Kabul Block are controlled by compressive stress trending NNW-SSE, while the north and southeast margins are influenced by NE-SW and ∼ N-S trending compressive stress.

Identification of Fault Zone in Bali Using GGMPlus Gravity and Alos-2 Palsar-2 Data

The local active fault in Bali has a small magnitude (M<5) but has destructive potential because it is very close to residential areas. Mapping the fault area on Bali is needed to identify the parameters of faults. This study used gravity data from GGMplus, topographic data from DEMNAS, and lineaments using ALOS-2 PALSAR-2 data. Validation and interpretation using the geological map of Bali and seismicity data. We interpret the subsurface using the gravity derivative method to identify the type of fault movement. Identify fault locations using lineament extraction from SAR data processed by directional filters. The composite image red-green-blue (RGB) for HH, HV, and VV polarization was used for automatic lineament extraction and then corrected manually. The results of the gravity method succeeded in identifying 29 of the 30 faults from the geological map of the Bali sheet and a new spot from PALSAR-2. Bali land has 12 thrust faults, 11 strike-slip faults and six normal faults. The image of PALSAR-2 (L band) has succeeded in making a fault lineament map for the Bali region. The lineament extraction results from PALSAR-2 obtained four new faults (Pesanggaran, Sepang, Tegal Badeng, and Banyuwedang), while four faults were not identified (Tampaksiring Fault, Plaga, Mambal, and Munduk-Rajasa). NE-SW dominates the strike directions, and the dip angles are 45-80 degrees. We propose 30 faults in Bali, including 26 defects from geological maps with changes in length and location shift and four new marks extracted from automatic lineament.Keywords: Remote Sensing, Earthquake, Derivative Gravity, Lineament, SAR

Mapping of Geological Lineaments from Different Sun Elevation Angles Using Digital Elevation Model (DEM): A Case Study of Nigeria Geology Map Series Sheet 135 (Duhu Sheet)

The study focuses on the mapping of geological lineaments from the following different sun elevation angles: 0°, 45°, 90°, 135°, 180°, 225°, 270°, and 315° of the Digital Elevation Model (DEM). Four of the images with azimuth; 0°, 45°, 90° and 135° were combined to produce a single image with multi-illumination directions. The images with azimuth; 180°, 225°, 270°, and 315° were equally combined to produce another single shaded relief image with multi-illumination directions. The two multi-illumination direction images were used for the automatic lineament extraction using PCI Geomatica software. The extracted lineaments were overlaid, and duplicate lineaments were eliminated. The final lineaments of the study area were screened using high-resolution Google images for non-geological features. A total of 237 lineaments were extracted, with a total length of 649.77Km, a mean length of 2.742Km and standard deviation of 1.187. The dominant trending pattern in the final lineaments of the study area is NE-SW direction. The Lineament density for the study area ranges from 0 to 1.36 km/sqkm with about 69.1% of the study area being mapped as poor and low density while the high and very high densities area account for just about 30.9% of the study area.

Gold-related Alteration Zones Detection at the Um Balad Area, Egyptian Eastern Desert, using Remote Sensing, Geophysical, and GIS Data Analysis

The Um Balad area is a part of the Arabian Nubian Shield (ANS), which hosts various gold and base metal deposits. Gold can be prospected in the alterations and sheared zones in the widely exposed metagabbro-diorite rocks in the Um Balad area. In this regard, the image processing and analysis of the ASTER data is a rapid and efficient technique for such studies, where the structural pattern and associated lineaments are probable indicators of hydrothermal flow and activities developing in mineral-bearing alteration zones as targets for gold exploration. The Spectral Angle Mapper (SAM), Spectral Information Divergence (SID), and Mixture Tuned Matched Filtering (MTMF) techniques have identified the alteration zones and the characterized altered minerals of each alteration. The automatic lineament extraction method was used by ASTER's visible and near-infrared bands to produce a lineament density map. Using gamma-ray spectrometry data, the potassium percent (K %) and hydrothermal alteration parameters (F-parameter and Th-normalization) were calculated. As well as ratio maps (eTh/K and eU/K) were used to determine the potassic and phyllic hydrothermal alteration. The model of exploration for gold-related alterations was developed in the Um Balad area, using multiple layers derived from remote sensing and gamma-ray spectrometry data through a GIS (Weighted Sum Overlay) approach. The probability of gold-related alterations was graded as low, medium, good, and very good. A final map has been generated showing the gold-potential alteration zones in four localities (Area-1, Area-2, Area-3, and Area-4). In these altered zones, valuable minerals such as sulphides and gold may be precipitated, making them ideal gold exploration sites. The field observations and spectral signature analyses of the collected samples from the various identified alterations supported the results of the remote sensing and aero-spectrometry data analysis. Therefore, these techniques have been suggested for similar investigations in other areas.

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.

Identification of hydrogeological features using remote sensing and electromagnetic methods in the hard- rock formations of the Cameroon coastal plain (Central Africa): implications for water borehole location

Sustainable access to groundwater in rural areas such as the coastal plain of Cameroon (Sub-Saharan Africa) is an ongoing challenge due to the lack of knowledge on hydrogeological features favorable to the identification of potential groundwater targets. In this study, remote sensing imagery and electromagnetic surveys were used to assess the hydrogeological potential of the Ngwei locality hard-rock. Automatic extraction of lineaments from Landsat-8 images indicated 200 lineaments with a total length of 293 km corresponding to 0.6 km of lineament per square km, suggesting a median groundwater potential. The main directions are NNW-SSE, N-S and NNE-SSW while the secondary directions are NW-SE; NE-SW and E-W. Surface geophysical investigations showed an electromagnetic field of 0 to 0.57 mV. These surface and borehole investigations confirmed basement fracturing and spatial variations in weathering profiles whose aquifer structure and yields (4.4 m3/h on average) are similar to what is commonly observed in the hard rock aquifer. The correlation between borehole productivity and the nearest lineament suggests that these lineaments are not (at least not all) surface traces of regional discontinuities that may act as major groundwater flow paths. This implies that the productivity of the Ngwei aquifers appears to be dependent on the fissured/fractured horizon, so exploration should be based on a contextual rather than general approach.Analysis of the consistency of the results with the field data allowed to propose a preliminary electromagnetic log model and also shows the value of using this approach to assess the availability of potential groundwater zones in hard rock areas. However, the methods used should be supported by further investigations to allow a better understanding of the hydrogeological characteristics of this part of the Central African basement so that no one is left behind in the achievement of the SDGs.

Determining the regional tectonic stress field by remote sensing in the Bou Azzer inlier, Central Anti-Atlas, Morocco

Purpose. This paper deals with the determination of the regional stress field direction of the Bou Azzer inlier using the remote sensing tool. Methods. CIn this study, we use an approach to digital mapping by remote sensing, including the steps of pre-processing and processing of Landsat-8 OLI images. Then, an automatic extraction of lineaments based on directional filtering has been performed. To determine the main directions of major mean fractures, these results have been supplemented and confirmed by an integrated model, including a synthesis of bibliographic works and field studies. Findings. The directional rosette analysis results show four systems of major directions namely, N0°, N45°, N90° and N135°. The regional stress field in the study area, according to tectonic history, is characterized by a horizontal compression tectonic regime, as indicated by several systems of strike-slip faults with a high tendency to deformation. Thus, the abundance of brittle and ductile microtectonic indicators confirms the direction of the main compressive stress N°30. The direction of the three-dimensional stress field: σ1: N°30, σ2: N°120, σ3: Vertical component. Originality. The present study allows to determine the regional stress field direction of the Bou Azzer inlier, in particular, in areas affected by complex tectonics of various scales, as well as in hard-to-reach areas. Practical implications. In mining practice, the study of stability using 2D and 3D geotechnical numerical modeling of underground mine workings is essential. The stress field direction is an important input parameter to develop more realistic decision support models, as well as to ensure the safety of people and materials at the Bou Azzer mine.

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.

Automatic detection of geological lineaments in central Turkey based on test image analysis using satellite data

The Hamurcu and Başdere study areas, part of the Central Anatolian Volcanic Provence (CAVP), are associated with metalliferous ore deposits. The assumption that hydrothermal alterations might be related to faults and fractures makes mapping the lineaments around the study areas vital. Accordingly, geological lineaments in the vicinity of the studied areas in Central Anatolia (Turkey) were delineated using Landsat-8 and Phased Array type L-band Synthetic Aperture Radar (PALSAR) data. We adopted a new methodology for determining the optimal values of six parameters used in a fully automated extraction of lineaments. The lineaments identified in the region including the study areas strike mainly the NW-SE direction in the PALSAR data. Moreover, hydrothermal alterations around the towns of Hamurcu and Başdere are directly related to the NW-SE oriented faults, indicating that the lineations in the region might be carefully scrutinized in the exploration of mineralization zones. As a result, it was demonstrated in this study that the most appropriate parameter values specified for automatic lineament extraction successfully map geological structures around both study areas and can confidently be employed in different geographical locations.

Geological mapping and mining prospecting in the Aouli inlier (Eastern Meseta, Morocco) based on remote sensing and geographic information systems (GIS)

Landsat 8 Oli, ASTER, and Sentinel 2A satellite images processing was used to map geological formations, lineaments and hydrothermal alteration minerals in the Aouli inlier, as a case study to illustrate the application of digital images processing and Geographic Information System (GIS) in geological mapping and mining prospecting. Principal Component Analysis (PCA) applied to the Landsat images allowed good lithological discrimination and contributed to the updating of available geological maps. The Automatic lineament extraction from Sentinel images revealed the main tectonic structures affecting Aouli inlier. The ratio bands (b5+b7)/b6 and the false color composite (b4/b6, b2/b1, b3/b2) allowed the hydrothermal alteration minerals mapping from Aster images. Combined with available geological data and field observations, the satellite derived data were integrated and analyzed in a GIS software to establish mining prospecting guides. The results showed that the anomaly zones are intimately linked to NNE –SSW and NW –SE oriented faults and to highly fractured areas developing argillic and Fe rich alterations. Verified via field survey, this approach was successfully applied to the Aouli inlier to rapidly target potential areas to be explored in the tactical phase. This provides a model for future prospecting efforts for similar mineral deposits in other areas.©2022 China Geology Editorial Office.

Automatic Lineaments Extraction using the Line Algorithm in the Denguélé District (North West of Ivory Coast)

The aim of this work was to apply the LINE Algorithm (Segment Extraction Algorithm) on Landsat 8 images for automatic lineament extraction in the Denguélé district. The Landsat 8 images had previously been subjected to the technique of Principal Component Analysis (PCA). After that, we implemented the LINE algorithm. Indeed, the LINE algorithm uses the following six (6) parameters : RADI (Radius of the filter) for improving the quality of the input image, GTHR (Threshold of the contour gradient), LTHR (Threshold of the contour length), FTHR (Threshold of mounting error), ATHR (Angular difference threshold between two contours ) and DTHR (Distance chaining threshold to link two contours ) for lineament discrimination. Analysis of the principal components PCA 1, PCA2 and PCA3 of bands 1, 2, 3, 4, 5 and 7 of the Landsat 8 images shows that they contain respectively 79.57; 15.88 and 2.15%, this represents overall 97.6% of all channels. 3468 lineaments were extracted. The minimum and maximum lengths of the lineaments extracted are respectively 4201.08 m and 16167.59 m and their cumulative length is 18 919 517.9 m. The lineaments average lengths are 5.55 km; 5.75 km; 5.6 km and 5.40 km respectively for NE-SW, NS, E-W and NW-SE directions. The analysis of the directions of the lineaments using a rose diagram with 10 ° of frequency, shows that the dominant directions are NE-SW (31.83% of the total lineaments), EW (28.71% of the total lineaments) and NS (27.91% of the total lineaments).

Rock discontinuities mapping with computer-based lineament extraction from satellite imagery

This study presents an approach for automatic lineaments analysis by using high-resolution digital images for mapping and delineating rock discontinuities. As a case study, we combine Landsat 8 images with 15 m resolution and shuttle radar topographic mission (SRTM) of a discovered gold mine in Nuba Mountains, Sudan. The satellite image contains band 7, band 4, and band 1 in red, blue, and green. In addition, band 5 is assigned to obtain the average of the three bands. The automatic extraction of lineaments approach was initially carried out with PCI Geomatica software, and then an accuracy assessment is performed to determine the most accurate parameters of extracted features. On the excellent reference of the output, the extracted lineaments are transferred to the Arc map software, and the coordinates of lines have been fixed. Finally, the attribute table of lineaments was imported to Rockware software to draw the rose diagram. Moreover, a manual lineament extraction process is carried out. For comparing automatic lineament extraction and manual lineament extraction, total length and number of lineaments and directional analyses are done by constructing the rose diagrams. Besides these two processes, field investigation in the study area is also applied to verify digitally extracted lineaments that the features represent true discontinuities. The final parameters of automatically extracted lineaments are determined. The produced lineament map in this study is proved to be very efficient in the discontinuities mapping for mining applications in terms of cost and time effectiveness.

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

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.

Lithological mapping and automatic lineament extraction using Aster and Gdem data in the Imini-Ounilla-Asfalou district, South High Atlas of Marrakech, Morocco

Lithological and lineament mapping using remote sensing is a fundamental step in various geological studies, as it forms the basis for the interpretation and validation of the results obtained. There were two objectives for this study, applied in the Imini-Ounilla-Asfalou district, South High Atlas of Marrakech region: first, lithological mapping by satellite image processing techniques such as ASTER L1B (hight spectral and spatial resolution), namely Principal Component Analysis (PCA), Minimum Noise Fraction (MNF), as well as the application of three types of supervised classification, namely Spectral Angle Mapper (SAM), Maximum Likelihood (ML) and Minimum Distance (MD), on the visible/near-infrared (VNIR) and short-wave infrared (SWIR) spectral bands of our ASTER image; second, an analysis of the distribution of lineaments by automatic extraction using a Global Digital Elevation Model (GDEM) and the PC1 image derived from the PCA transformation applied to the satellite image. The best results are highlighted by the delineation of new facies in relation to the existing map; after confirmation in the field, all of these facies, which include Eocene, Triassic and Jurassic formations, are represented on the new map. The results of lineaments showed that each of them systematically shows a similarity in terms of concentration and orientation, with four preferential oriented systems: NE-SW, E-W, NNE-SSW and NW-SE. The lineaments mainly follow those of the major fault zones, with high concentrations in the northeast and southwest parts of the study area.

Semi-Automatic Fracture Mapping Using Cellular Neural Networks Applied to ALOS PALSAR 2 Images of the Western Highlands of Cameroon

In Cameroon in general and in the Highlands of Cameroon in particular, there is no fracture map since its realization is not easy. The region’s harsh accessibility and climatic conditions make it difficult to carry out geological prospecting field missions that require large investments. This study proposes a semi-automatic lineament mapping approach to facilitate the elaboration of the fracture map in the West Cameroon Highlands. It uses neural networks in tandem with PCI Geomatica’s LINE algorithm to extract lineaments semi-automatically from an ALOS PALSAR 2 radar image. The cellular neural network algorithm of Lepage et al (2000) is implemented to enhance the pre-processed radar image. Then, the LINE module of Geomatica is applied to the enhanced image for the automatic extraction of lineaments. Finally, a control and a validation of the expert by spatial analysis allows elaborating the fracture map. The results obtained show that neural networks enhance and facilitate the identification of lineaments on the image. The resulting map contains more than 1800 fractures with major directions N20° - 30°, NS, N10° - 20°, N50° - 60°, N70° - 80°, N80° - 90°, N100° - 110°, N110° - 120° and N130° - 140° and N140° - 150°. It can be very useful for geological and hydrogeological studies, and especially to inform on the productivity of aquifers in this region of high agro-pastoral and mining interest for Cameroon and the Central African sub-region.

Automatic Extraction and Geospatial Analysis of Lineaments and their Tectonic Significance in South Cameroon Area using Remote Sensing Techniques and GIS

This study investigates the dominant orientations of lineament features and the relationship between these trends and the spatial orientation of tectonic structures in the transition zone of the Congo craton and the Pan African belt in South Cameroon area. Landsat 8 OLI/TIRS and hill-shaded images, constructed from 30 m-resolution SRTM-DEM data, were used for automatically extracting and mapping geological lineaments. Lineament features were analyzed by means of azimuth frequency and length density distributions. Three major sets of lineaments trending W–E, ENE-WSW and WNW-ESE are identified in the South Cameroon area. These trends are probably related to repeated reactivation of pre-existing crustal structures during Eburnean and Pan-African tectonic episodes. The lineaments were formed under the compressional tectonic stress regimes generated during these tectonic events.

Landsat-7 and ASTER remote sensing satellite imagery for identification of iron skarn mineralization in metamorphic regions

The use of satellite remote sensing imagery for mineral exploration is a fast and low-cost approach for indicating high potential zones. Exploration of iron skarn mineralization in metamorphic regions is challenging during the fieldwork campaign. In this study, Landsat-7 and Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) satellite imagery were used for mapping alteration zones and geological structures associated with iron skarn mineralization in the Galali region, NW, Iran. Band ratio and Directed Principal Component Analysis (DPCA) and Automatic Lineament Extraction methods were applied to Landsat-7 data. Relative Absorption Band Depth (RBD) and Constrained Energy Minimization (CEM) algorithms were implemented to ASTER data. Fieldwork and laboratory analysis were conducted to verify the remote sensing results. Results indicate that propylitic alteration zone and intersection of N–S and NW–SE and curvilinear features are typically associated with iron skarn mineralization and some high potential zones are identified for future exploration projects.

Fracture network mapping using Landsat-8 OLI, Sentinel-2A, ASTER, and ASTER-GDEM data, in the Rich area (Central High Atlas, Morocco)

Geological mapping using remote sensing is one of the most important applied methods in natural resources exploration. The objectives of this study are mapping and analyzing of fractures distribution in the Rich area in order to understand the influence of lithology and geodynamics on fracture density. For this purpose, we relied on automatic lineament extraction using four types of satellite imagery: Landsat OLI, Sentinel 2A, ASTER L1B, and ASTER Global Digital Elevation Model (GDEM) in order to extract the maximum of lineaments affirmed significative in structural interpretations. After image corrections, the processing of these images is based on the highlighting of structural lineaments and their automatic extraction using the algorithm line of Geomatica software. The validation of linear structures was made based on existing data. The finding showed that each produced map shows systematically a similarity in terms of concentration and orientation with three preferential system-oriented NE-SW, NEE-SSW, E-W, and NNE-SSW. Lineaments mainly follow that of major fault zones, with a high concentration in the North-East part of the study area. This might be due to the importance of the Alpine orogeny deformation as well as the diapirism phenomenon of the Triassic formations in the hiner zone of the Atlas belt. However, the observation shows that the number and total length of structural lineaments could be extracted by using the sentinel 2A then Landsat OLI, ASTER-GDEM, and ASTER L1B set. The automatic extraction allows better mapping of structural lineaments. It shows a good agreement and more information compared with previous geological data, confirming the efficiency of applied techniques in geological studies.

Complementarity of Optical Remote Sensing and Geographic Information System for Detection and Mapping of Geological Lineaments: A Case Study in the Metlaoui Region in Southern Tunisia

This study focuses on the region of Metlaoui (Southern Tunisia) where the marks of a neotectonic activity are spectacular. The main objectives are the detection and the mapping of the network of fractures at this region. Different techniques of automatic extraction of lineaments based on remote sensing images acquired from Landsat-7 ETM and Aster satellites were applied. The results obtained from this satellite-based approach were compared with the results from two independent approaches based on the interpretation of aerial photographs and the exploitation of topographic maps. Major lineament groups were described based on the shapes, orientation and lengths. The most prevalent groups are those oriented along the following axes: NE-S; NW-SE; NNE-SSW; E-W; and N-S. The most common are the lineaments oriented following NW-SE and E-W directions, which reflect the passage of the wellknown directional fault of Metlaoui. Combining information from satellite images, aerial photographs, topographic and geologic maps, accompanied with in-depth validation from field campaigns allowed the accurate detection of the tectonic accidents at high spatial resolution over the whole studied region. A new map of lineaments has been established. Its use to update the geological map of the Metlaoui region is in progress.