Lineament Directions Research Articles

Conjugate Riedel shears in a volcanic caldera: the case of the Laguna del Maule Volcanic Complex, Central Chile

The Andean intra-arc is characterized by large-scale continuous lineaments, often the direct surface expression of tectonic structures. In this study, we analyze the main lineaments around the Laguna del Maule Volcanic Complex, Central Chile (~36° S), to shed light on the main tectonic processes. We show that the lineament directions are consistent with structures based on a theoretical Riedel model and suggest the occurrence of two conjugate Riedel shears crossing Laguna del Maule. This structural arrangement can accommodate deformation related to either a transtensional regime, having a WNW-oriented master fault (Laguna Fea Fault), or a transpressional regime, characterized by NNE-oriented master faults (e.g., Melado Fault). In this context, the NE-striking Troncoso Fault would be a long-lived dextral fault compatible with both regimes. According to the Riedel model, ENE-oriented lineaments are predicted to be tensional structures, whilst NW-oriented structures (e.g., Los Cóndores Fault) would correspond to P-type structures accommodating compressional deformation. This tectonic architecture, characterized by the most intense deformation just at the intersection between shears, has likely promoted magma accumulation and would explain the compositional variability at Laguna del Maule. This study therefore demonstrates the usefulness of oriented lineament maps in interpreting regional tectonics for volcanically active areas.

Geological Structure Analysis Approach to Control The Distribution of Manganese in Gunungkasih Area, Tanggamus Regency, Lampung Province

Abstract Gunungkasih area has several lithologies that are generated by different processes. Based on The Geological Map of Kotaagung by Amin et. al. (1993) the oldest lithologies are composed of schist, phyllite, and marble from Paleozoic followed by shale, sandstone, chert from Menanga Formation (Km) and andesitic lava, tuff from Hulusimpang Formation (Tomh) with some complicated geological history. Variations of geological products triggered the possibility of the presence of a lot of natural resources, including manganese. Manganese had been exploited around 2003-2004 by two local companies, but because the manganese deposits had not been explored yet and for a few reasons the project had been discontinued. The structural analysis will be important to find out the presence of manganese because most manganese fills in fractures, so the pattern of these deposits would be solved by structural mapping and also treated by stereonet and rosette diagrams. The fracture planes have been found in more than 500 planes and showed several types of fractures such as shear fractures, joints, quartz veins, and manganese that fill fractures which have a few directions both fault and joint directions. The most dominant fractures that are filled by manganese have been found at 120 - 130 degrees, parallel with major fault and lineament directions. The direction could be parameters and help for continued exploration further.

Structure Analysis Gunung Benau Karst Area by Using mSTA and FFD, North Kalimantan, Indonesia

Abstract The formation of Gunung Benau is associated to the geological structural process. This study uses remote sensing using DEMNAS data resampled at 10 meters. The DEMNAS data will be modeled using the modified Segment Tracing Algorithm (mSTA) and Fault Fracture Density (FFD) approaches. Surface geological mapping methods involve observations, descriptions, direct measurements, and field data recording of data appearances and geological conditions on the Gunung Benau. The structure which found in Gunung Benau is a shear joint with syncline and anticline folds and nine faults identified. The mSTA’s main lineament directions, Northeast-Southwest and Southeast-Northwest, are consistent with the area’s geological structure. The FFD shows that the highest density values occur in the central region of Gunung Benau, where faults are extensively exposed.

Detection and characterization of lineaments using gravity data in the south-west Cameroon zone: Hydrogeological implications

Abstract In Cameroon, the drying up of wells and boreholes during the dry season is characterized by a lack of knowledge about the surface structures of the subsoil and the spatial distribution of groundwater. In this study, we propose to use gravity data to detect and characterize the surface structures of the south-west (SW) Cameroon and to analyze their hydrogeological implications. The application of the normalized standard deviation method on the data obtained from the stable downward continuation of the Bouguer anomalies led to the detection of 71 lineaments that characterize the tectonic events of the study area. The statistical analysis of the lineament directions shows that the near-surface structures were mainly affected by a tectonic of direction east–west followed by that oriented SW-north-west. These two directions are consistent with the megastructures in the region like the Ngoro-Belabo Shear Zone and the Sanaga Fault stretching from the Gulf of Guinea to the Central African Republic. In addition, the application of the Euler deconvolution method permits us to evaluate the interval in which lies the depth of each lineament hosting Euler solutions. The analyses showed that 12 lineaments, whose roof depths are between zero and 250 m, are very favorable for hydrogeological prospecting.

DEM-based directional statistical examination of linear features: the case study in Bükk Mountains (NE Hungary)

Analysis of linear features such as faults, valleys, interfluves, and escarpments is a commonly used method in structural morphologic and structural geologic research. The aim of our study was to investigate the relationship between the linear features by directional statistical analysis, and we also examined the applicability of this method in a research area with a complex geological structure. The study area was the Bükk Mountains (NE Hungary) and its two catchment areas. The analysed features (drainage network, lineaments and dominant aspect) were derived from a DEM. As a result of the research, we found that in the Sajó catchment, the direction of lineaments does not coincide with the direction of the valleys and structural elements, nor the dominant aspect, while in the Tisza watershed, the orientation of the main structural features notably differs from the direction of the other 3 feature sets. In our opinion, this finding can be explained in three possible ways. The first possibility is that the applied method does not provide reliable results in a geologically complex area. The second explanation is that regional structural processes may affect drainage network evolution and the dominant aspect. The other explanation is that there may have been unknown structural elements in the research area, which affect the recent geomorphological settings and processes. The results draw attention to the fact that besides the unmapped faults, there might be other factors affecting geomorphological processes (e.g., resistance to denudation of different rock types, microclimate), which have not been taken into account so far. The research was based only on directional statistical examinations; further geological and geophysical analyses are required to prove the existence of these hypothetical morphotectonic features.

Detection of Structural Control on Formation Water Quality, in Hemrin Oilfield, northern Iraq, Using Lineament Analysis and Hydrochemical Data

Formation water analyses of Tertiary reservoir (Euphrates, Jeribe, and Dhiban formations) in Hemrin oilfield reflect high salinity variation between Albufudhul, Nukhaila, and Allas domes. The present study suggests that this variation resulted by two reasons, (1) percolation of surface waters (rain water) which lead to devastation of oil type, (2) interaction between water and host rocks. Satellite image and DEM were used to detect the lineaments and morphometric analyses, which interpret the structural control on salinity variation. The main direction of lineaments are NE-SW, which prevailing with subsurface vertical faults between Albufudhul and Nukhaila domes that playing with SE limb of Albufudhul dome as conduits for percolation of surface water (rainwater), that lead to dilute the salinity and change the formation water properties from Albufudhul to Nukhaila domes, while the present of vertical fault between Nukhaila and Allas dome considered as semi impermeable according to geometry of domes, so Allas dome considered as semi closed system in comparison with Albufudhul and Nukhaila domes, that lead to increase in salinity and change of formation water properties. Formation water is classified as salinity variety water from medium salinity (TDS of 7430 mg/l), to brine, (TDS of 59118 mg/l), of mixed origin from meteoric water and connate water, of variety of pH value (6.75-8.89) from weak acidic to alkaline. Its type is Na-SO4-chloride and anions are ordered as rCl > SO4 > HCO3, whereas cations ordered as rNa > Ca > Mg. This type of water is associated with open system reservoir, influenced by percolation of surface water and consider as bad zone for preservation of hydrocarbon accumulations especially in Albufudhul and north east limb of Nukhaila domes, while Allas dome considered as closed system reservoir, which is a good zone for preservation of hydrocarbon accumulations.

GEOLOGICAL INTERPRETATION OF LANDSAT IMAGERY OF NIGERIA’S HAWAL PRECAMBRIAN BASEMENT COMPLEX TERRAIN

The Hawal Basement Complex is located in Nigeria’s NE region. Satellite imagery used in this study covers longitude 12º 00’ to 13º 30’E, and latitudes 9º 30’ to 11º 00’N. The aim of the study is to decipher the regional geologic structures based on analysis and to determine the mineralization implications from the landsat lineament data. The total land surface area covered is about 23,674.88 km2 and includes part of the north sector of Yola sedimentary Rift Basin. The data consists of LANDSAT TM and SPOT XS scenes collated as mosaics. The imagery was monoscopically studied. Classical aerial imagery interpretation techniques of mapping lineaments and tracing regional geological boundaries were used. A total of 368 lineaments were mapped and analyzed using multi-graphical analytical techniques. The results are presented as isolinear contour maps (isodensity and lineaments intersection maps). The isodensity lineament maps show two main areas of lineament concentrations, namely Shani area lying westward and Michika-Mubi area to the east. Reasons advanced for the preponderance of lineaments in parts of the study area are the combined effects of isostatic basement uplift and lithospheric stretching during the formation of Yola Rift and Chad Basin respectively, which caused large scale crustal deformations. Also, Precambrian and Cenozoic magmatic activities that caused emplacements of older granites and basaltic bodies respectively in the area contributed to fracturation of the crust. Fewer lineaments are observed over the sedimentary Rift zone and this is attributed to masking effect of the sediments on basement fractures. The lineament intersection map shows a prominent NE-SW zone of highest intersection which is parallel to the general flow direction of the Hawal River. Prominent lineament directions are N-S (0-20º), and NE-SW (40º- 60º), which are Pan African Orogenic directions. Aerogeological studies of this type are important in national economic development.

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.

Influence of geological discontinuities on the groundwater flow of the Serra Geral Fractured Aquifer System

Groundwater circulation in fractured aquifer systems is a topic of worldwide interest as they are heterogeneous and peculiar environments. In Brazil, little is known about the groundwater flow within fractured rocks. This knowledge gap motivated the investigation of (1) the statistical variance of the exploited discharges and their relationship with the directions of geological lineaments, (2) the analyzes of the relationship between of the groundwater flow with the different characteristics of the discontinuities and (3) the correlation between the acting stresses with the fracturing geometries that present groundwater flow. To reach these objectives, this paper is circumscribed within the following methods: frequency graphs, normality assumptions test, non-parametric homogeneity tests, multiple correspondence analysis, scanline profiles, and in situ stress analysis. This study was carried out in the Serra Geral Fractured Aquifer System, in Caxias do Sul, Rio Grande do Sul, Brazil. The results showed that most the exploited water wells are associated with the NW-SE and NE-SW lineament directions. There was a predominance of four sets of subvertical fractures (S1, S2, S3, and S4) and one sub-horizontal (S5). Sets of fractures S3, S4, and S5 showed the greatest persistence of fractures and presence of exudation. The tension axes σ1 and σ3 were identified in the (310°; 113°–141°) and (218°; 020°–051°) directions, respectively. The groundwater circulation in sets of fractures S3 and S4 is related to tensions σ1 and σ3 and the most exploited lineament directions NW-SE and NE-SW, while S5 is correlated to tension σ2 and behaves as a facilitator of the groundwater circulation in the underground flow network.

Thermal history along the Araçuaí Orogen and São Francisco Craton border, eastern Brazilian continental margin, based on low-temperature thermochronologic data

Passive margins form in response to rifting affecting a continental area. Rifting evolution is dependent on structural and rheological inheritance, generally controlling differential denudation, and deposition. The Brazilian continental margin developed over a complex basement, composed of the orogenic lithosphere of the Brasiliano-Pan-African orogenic belts (e.g., the Araçuaí Orogen), and the cratonic lithosphere of the São Francisco Craton. In this work, we focus on the transitional zone between the warm and cold lithosphere of the northern segment of the Araçuaí Orogen to the São Francisco Craton. This study provides the first suite of two low-temperature thermochronometers, i.e., zircon and apatite (UTh)/He, for the region. Using this approach, we examine the main cooling events, the geodynamic forces acting upon the lithosphere, the denudation rates affecting this region since West Gondwana amalgamation, and the correlation between thermochronology and structural inheritance. Our results indicate that ZHe corrected ages range from 483.1 ± 38.6 to 93.8 ± 7.5 Ma and eU concentrations vary from 10.91 to 632.51 mg/g. AHe corrected ages span from 129.9 ± 7.79 to 32.7 ± 1.96 Ma and eU concentrations range from 5.6 to 62.8 mg/g. Both ZHe and AHe ages display a positive correlation with eU concentration. Based on this dataset, we identify three cooling episodes, constrained from Lower Devonian to Carboniferous, Triassic/Jurassic to the present day, and Late Cretaceous/Paleocene to the present day. Additionally, two reheating episodes are constrained from Middle Jurassic to Early Cretaceous and from Late Cretaceous to Paleocene. Furthermore, we analyzed lineament directions in the orogenic, cratonic, and Cenozoic sedimentary cover domains to understand how structural inheritance affects the thermochronological record. Our observations reveal that reactivation of the Brasiliano NW-SE inherited structures during continental breakup up until the Paleocene possibly kept the AHe system open, resulting in the youngest AHe ages of our data set.

Tele-Analytical Characterization of the Eburnean Tectonic Structures within the Birimian Formations of Mako Area, Eastern Senegal

The tectonic structures of the Mako area in the Kédougou-Kéniéba inlier (KKI) were mapped with tele-analytical investigation which is validated by field data. This study is based on different images processing in particular: 1) the colored combinations (1 to 5) and panchromatic (8) thematic mapping bands of the Landsat-8 (ETM+) satellite; 2) Digital Elevation Model (DEM) image of Space Shuttle Radar Topography Mission (SRTM); 3) airborne geophysics (aeromagnetic and radiometric) images. In these images, four major directions of lineaments NS, NNE-SSW, NW-SE and EW would be related to the tectonic structures, have been identified and mapped. Field data confirm these four structural directions and show that most of these lineaments are related to faults, shear and/or thrust zones, or even basic rock dykes. N-S to NE-SW oriented lineaments are more frequent followed by those NW-SE oriented. These two directions of lineaments are generally in correlation with trajectories of major sinistral shear zones in the Mako area. They would be associated with the S2a and S2b schistosities relative to the D2 Eburnean major deformation. They often intersect the E-W oriented lineaments which are less frequent and sometimes folded and crenulated. This E-W oriented lineament would be prior and are associated with the S1 schistosity of the D1 Eburnean thrust phase of deformation. At the scale of the studied area, these major linear structures (shear zones) are conjugated and create a partitioning of deformation through an anastomosed network of mylonitic shear zones which surround weakly deformed rock bodies. All these structures would be related to the Eburnean or post-Eburnean orogenic events in this Mako area.

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.

AUTOMATIC LINEAMENTS MAPPING AND EXTRACTION IN RELATIONSHIP TO NATURAL HYDROCARBON SEEPAGE IN UGWUEME, SOUTH-EASTERN NIGERIA

The study focus on the integration of Remote Sensing and Geographic Information System for identification and delineation of lineaments in relation to natural hydrocarbon seepage, which occur in Ugwueme, South-Eastern Nigeria. To achieve this objective, remotely sensed data (ASTER Digital Elevation Model and Landsat 8 OLI/TIRS) were used to depict the surface expression of faults, folds and fractures which are expressed in the form of lineaments. The global positioning system (GPS) was also used for ground verification. The geology map of the study area, which is elucidated in the geology of Nigeria was used to show the distribution of rocks and other geologic structures. The delineation of lineament features was done automatically with the PCI Geomatica while the Rock ware was used to generate the Rose diagram for demonstration of the direction of the extracted lineaments. The classification of the lineaments density and the lineaments intersection analysis were categorized as very low, low, moderate, high and very high classes respectively. Areas classified as very high to high lineaments density are potential zone, which act as conduits for hydrocarbon seepage. The result shows that a total lineament frequency of 947 km and a total lineament length of 946 km were delineated from the satellite data. The result further shows that areas with high lineaments density are concentrated in the southwest, south, central and northern part of the study area while areas with low lineament density were found within the eastern part of Ugwueme. The Rose diagram highlight the major trend in the (NE-SW), (N-S) and (NW-SE) directions, and the minor trend in the (W-E) direction. These directional trends depict the directions of lineaments which act as conduits zones for hydrocarbon seepage in the region. The overall findings of the study shows that lineament density, lineament intersection and rose diagrams are concepts applicable in hydrocarbon oil and gas seepages.

Validation Approach of the Tectonic Lineament Extraction Enhancement Using Sentinel 2A Images and Modified 3 × 3 Bidirectional Prewitt Filters. Case Study: Grombalia, Tunisia

In this study, filters are used to extract directional tectonic lineaments and, thus, to reveal the presence of faults or fractures in the satellite images. The extraction process consists first in eliminating other different types of lineaments (e.g. the lithological limit, ridgelines, hydrographic network, roads, etc.). Besides, a comparative and quantitative approach is applied to show that when the directional Prewitt filter has a zero setting of the opposite of the assumed direction, as is the case of the N-S direction, the East-West direction is also set to zero. This research work, based on a bidirectional filter (N-S; E-W), shows satisfactory results especially concerning the quantitative fluctuation of lineament directions by interval. This fluctuation is in perfect agreement with the lineaments provided by the digitizing of the different tectonic accidents directions extracted in a GIS environment from the geological map of Grombalia. In this research work, a quantitative approach was used to evaluate the result of the lineament extraction methodology based on one direction analysis and by an interval of directions. Indeed, the N45 lineament direction, well documented in the geological study of the region, was more clearly distinguished by applying the Prewitt filter than by using the Sobel filter. The result was validated by comparison with the results obtained by the digitization of the tectonic accidents mapped on the geological map.

Remote Sensing (RS) and Geographical Information System (GIS) for Detecting Groundwater Potential Zones at Wadi Elmilk Area, North Kordofan State, Sudan

Remote sensing and GIS technology are great important for use in groundwater potential analysis. The current study has applied techniques to delineate the groundwater potential zones besides improving the allocation of drilled boreholes in order to integrate water resources development and management for Wadi Elmilk, Sodari, North Kordofan state, Sudan. Five thematic layers were prepared they are geology, structure, topography, drainage density and slope, extracted and then classified according to their importance with respect to ground water occurrence and weight are assigned through geographic information system. Landsat 8 ETM+ images and Digital Elevation Models (DEMs) were used in this study. The geology of the area is composed of basement complex followed by Nubian Sandstone covered by sand sheets. Mosaic of four landsat images ETM+8 were obtained for the geological features. Drainage and lineaments were studied to recognized groundwater occurrence. The slope amount map was derived from the DEM. In the study area, mainly 5 lineaments density categories have been identified and mapped. Reclassified amount of slope, lineaments density, drainage density account maps and in addition to Rose diagram of the lineament frequency were obtained. The conclusion that the groundwater potential zone in the area is related to deep basement, have certain geologic structure and presence of faults, cracks, joints and lineaments and the two prominent lineament directions: NE from SW are the major structural trends in the central Sudan and is most likely related to the Central African Shear Zone. It is recommended that more detailed studies should be conducted in order to check all the information extracted from remote sensing data and Radar.

Investigação geotécnica de taludes rochosos por meio da análise estrutural: estudo de caso da BR-116, Rio Grande do Sul

A BR-116, localizada no nordeste do estado do Rio Grande do Sul, atravessa a Escarpa da Serra Geral, composta de derrames ácidos e básicos da Formação Serra Geral. Diversos movimentos de massa são observados na rodovia, relacionados com a queda e os deslizamentos de blocos dos taludes rochosos. Como hipótese, pretendeu-se verificar se as famílias de fraturas tectônicas regionais causam os movimentos de massa nos taludes da BR-116. O objetivo desta pesquisa foi aperfeiçoar os métodos de investigação geotécnica, correlacionando a Geologia Estrutural com a estabilidade de taludes rochosos. Entre os métodos utilizados estão o sensoriamento remoto e a análise de lineamentos estruturais, a análise estrutural geométrica e a análise geotécnica dos maciços rochosos (identificação de possíveis planos de ruptura e cálculo de seus fatores de segurança). Os resultados dos lineamentos estruturais regionais indicam o predomínio da direção ENE, seguida pelas direções subordinadas NE e WNW. Em relação às fraturas de alto ângulo analisadas em campo, caracterizou-se um máximo com direção N50-70E, similar ao observado regionalmente. A interpretação do diagrama de movimentos de massa indica que 75% dos movimentos que podem ocorrer na BR-116 seriam causados por deslizamentos em cunha, e o restante são planares, com predomínio de descontinuidades de alto ângulo. A direção máxima dos lineamentos (N70-90E) pode causar movimentos em seis dos sete taludes estudados, e o segundo máximo (N60-80W) condiciona deslizamentos em quatro dos sete pontos. Essa evidência mostra que as estruturas provenientes dos lineamentos regionais são as que mais podem gerar movimentos de massa.

Characteristics of Geological Lineaments Along the Eastern Coast of the Korean Peninsula: A Statistical Approach

Kim, T.; Kim, Y.-S., and Lee, H.-J., 2020. Characteristics of geological lineaments along the eastern coast of the Korean Peninsula: A statistical approach. In: Jung, H.-S.; Lee, S.; Ryu, J.-H., and Cui, T. (eds.), Advances in Geospatial Research of Coastal Environments. Journal of Coastal Research, Special Issue No. 102, pp. 88-100. Coconut Creek (Florida), ISSN 0749-0208.Lineament analysis is an essential method for evaluation of site safety in important facilities such as nuclear power plant and nuclear waste disposal site. However, in the case of coastal areas, if the same criteria used for inland is applied, large-scale lineament could be underestimated. Therefore, a different classification criterion is necessary to evaluate the characteristics of lineament pattern along coastal areas. Thus, here, a new statistical method focusing on zonal analysis is proposed. This method is applied for evaluating the characteristics of lineaments developed within 5 km from the eastern coastline of the Korean Peninsula. The most dominant direction of lineaments along the eastern coast lies in the N–S direction, followed by the NE–SW, and the E–W directions. Since the length distribution of the lineament shows the characteristics of the lognormal distribution, statistical analysis was performed using probability density functions (PDFs). The results indicate that the mode value of the lineament length is about 2 km, and lineaments shorter than 6 km account for 90 % of the total. To confirm the validity of the statistical distribution features, re-analyzing the study area by progressively increasing its width to 10 km, 15 km, 20 km, and 30 km was done. The analysis showed that the distribution characteristics were similar to those of the area with a width of 5 km. The statistical analysis using PDFs improved the existing classification criteria based on lineament length and provided three new quantitative classes of lineaments within coastal regions.

Orientation and Frequency Analysis of Topographic Lineaments in the Miringa Volcanic Zone of the Biu Plateau Region, Borno State, Nigeria

The aim of present study is to spatially analyze the topographic lineaments of tectonic origin in the Miringa Volcanic Zone located in the northwestern part of the Biu Plateau. To achieve such aim, SRTM of spatial resolution 12.5 m was utilized. The lineaments were automatically extracted by using PCI GEOMARTICA software version 10. This was followed by field work for ground thruting and to establish field relationships. ArcGis 10.5 software version was used for spatial analysis of lineaments while Rockworks version 16 was used in creating the Rossace used in lineament trend analysis and other related statistical variables associated with the lineaments of the study area. 2036 linear structures were identified in the area with a total length of 30,193.85 m. The maximum length of lineament recorded in the study area is 150 m while the minimum is 3.68 m. Field work revealed that most of the lineaments in the area developed from the weathering of contacts between successive volcanic beds in areas overlaid by the highly dissected plateaus, escarpment slopes and denudation hills. Trend analysis of lineaments of the study area indicates that the direction of lineaments tend to lie in the North-east to southwest direction (Azimuth 45°-225°) which has same direction with major drainage system and most of the volcanoes of the area. This signifies the presence of a major fissure trending in the north-east to south-west direction as the primary tectonic structure of the area. Subsequent exogenic processes exploited this structure leading to the formation of other micro-lineaments that trend along the same direction.

Iranian regional l ament zones and the location of Cu, Pb, Zn and Fe deposits

Background. Large-scale geological structures, such as lineaments, are of great research interest due to their potential to mark the presence of ore fields.Aim. To determine the relationship between ore deposits, lineaments and large-scale faults in Iran using satellite imagery, digital relief modelling and structural mapping.Materials and methods. In this study, we compiled a map of lineaments in the Iran, which were determined both automatically and manually. A database of the distribution of ore deposits and lineaments was compiled from available maps, publications and reports on ore deposits in Iran. These maps were overlaid to study the relationship between the locations of the lineaments, faults and ore deposits.Results. An analysis of the lineaments revealed on geological maps indicates the presence of four dominant strike directions of large and small lineaments. The developed lineament map shows the main northwest trending longitudinal faults, which are parallel to the main strike of the Zagros orogenic belt; sublatitudinal and submeridional trending oblique faults; northeast trending transverse faults. A “Combined map of lineaments and deposits of copper, lead, zinc and iron in Iran” was compiled by the ArcGis software using maps of lineaments and mineral deposits. The ore deposits identified were analysed to determine the distribution of the distances between each deposit using the counting and cumulative methods the ArcGis software.Conclusions. About 90% and 50% of ore deposits are located at a distance of less than 15 km and 5 km, respectively, from the centre line of the associated lineament. A direct relationship between the density of lineaments and the presence of deposits was observed. The obtained results demonstrate the potential of this method for assessing the prospects of ore fields in hard-to-reach and poorly studied regions.

The influence of geological fractures on karstic sinkhole development in eastern areas of Centurion, South Africa

Centurion is a fast developing area facing severe karstic sinkhole development. The area is predominantly underlain by fractured dolomite formations that include Oaktree, Monte Christo, Lyttelton, and Eccles of the Malmani Dolomite Group (~ 2600 and ~ 2500 Ma). Fractures of the underlying dolomite formations were investigated as one of the most influencing factors in karstic sinkhole formation using fieldwork mapping, petrology, and remote-sensing techniques (automated lineament extraction methods). Fieldwork results indicate that the study area has two prevalent fracture orientations trending N–S and ENE–WSW with average orientations of 178°/86° E and 073°/67° N. The fieldwork mapping results coincide with those acquired using remote-sensing techniques by automated extraction of lineaments from colour-shaded image and from four Sobel directional filtered images. Remote-sensing techniques indicate that there are extra two prevalent lineament directions; NE–SW and E–W in the study area and majority of the sinkholes develop in areas with high lineament density. Eccles, Monte Christo, and Oaktree dolomite formations exhibit a unidirectional fracture system while Lyttelton dolomite formation exhibit bidirectional fracture system. It is, therefore, concluded that (1) geological lineaments extracted using remote sensing and fractures present in the underlying dolomite formations play a significant role in controlling fluid circulation and thus influencing karstic processes such as dissolution, and therefore, (2) sinkhole development is primarily structurally controlled; however, it is exacerbated by anthropogenic activities due to the influence of water ingress.