Radarsat-1 image processing for regional-scale geological mapping with mining vocation under dense vegetation and equatorial climate environment, Southwestern Cameroon

Fils, Salomon César Nguemhe; Mongo, Carrol Hedwige Bekele; Nkouathio, David Guimolaire; Mimba, Mumbfu Ernestine; Etouna, Joachim; Nouck, Philippe Njandjock; Nyeck, Brunot

doi:10.1016/j.ejrs.2018.05.005

Cited by 15 publications

(7 citation statements)

References 27 publications

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“…For the eight co-occurrence indices created, three indices highlighting the morphing structure of the study area and facilitating lithology discrimination were selected. This was based on their standard deviation value [23], [31] and their different functions (Table I): homogeneity, mean, and variance. This statistical method allows the identification and selection of the parameters that best define the elements from the measurement of grey tone distributions.…”

Section: ) Textural Analysis Results In Envi 47mentioning

confidence: 99%

“…This statistical method allows the identification and selection of the parameters that best define the elements from the measurement of grey tone distributions. 3) Colored compositions Variance, homogeneity and mean are the best indices used for lithological discrimination in radar images [31]. Through several combinations of these three textural parameters in colored composition (CC) for the RGB channels, two interesting images are obtained: Variance-Mean-Homogeneity (VMH) and Homogeneity-Mean-Variance (HMV).…”

Section: ) Textural Analysis Results In Envi 47mentioning

confidence: 99%

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Contribution of Remote Sensing for the Mapping of the Yaoundé Metadiorites

Metang

Brigitte²,

Myrianne³

et al. 2022

EJGEO

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Geologists face a number of problems, mainly related to the difficulty of covering the entire terrain, leading to various pieces of information collected and its extrapolation for drawing maps. To overcome these problems, we have proposed to use remote sensing which is a current tool for rock mapping. Remote sensing is a modern tool to highlight several information that conventional mapping methods do not allow. Thus, the objective of this work is to update the geological contours of the Yaoundé metadiorites by processing satellite images coupled with the classical approach. Sentinel 1-A radar images were used. A textural analysis of these images was carried out using the GLCM (Grey Level Co-occurrence Matrix) method, resulting in eight co-occurrence indices, among which three were chosen to perform colored compositions. The colored compositions obtained are VMH and HMV. And the contrasts obtained were compared with maps from previous work and also with field work. The metasedimentary rocks (kyanite - garnet migmatites and garnet micaschists) and metaigneous rocks (metadiorite) constitute the metamorphic complex distinctly mapped by exploiting remote sensing data, superposition maps from previous work and integrating the new sampling points. Remote sensing in geological mapping thus plays an important role mainly in the urbanized study area as it detects the metadiorites under the metasediments despite the existence of anthropogenic works and low vegetation cover.

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Section: ) Textural Analysis Results In Envi 47mentioning

confidence: 99%

Section: ) Textural Analysis Results In Envi 47mentioning

confidence: 99%

Contribution of Remote Sensing for the Mapping of the Yaoundé Metadiorites

Metang

Brigitte²,

Myrianne³

et al. 2022

EJGEO

View full text Add to dashboard Cite

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“…This method allows the identification and selection of the parameters that enable the best definition the elements from the measurement of the gray tone distributions. Numerous authors developed topics on the application of the GLCM technique in synthetic aperture space images in geological applications [7], [19]- [24]. Executed in ENVI software environment the implementation of GLCM, using a 5x5 window and Pixel offset 1 on the Landsat ETM+ monoband permitted the calculation and creation of normalized co-occurrence used for lineament investigations.…”

Section: Methodsmentioning

confidence: 99%

“…In geologic investigation, linear features on a satellite image regularly reflect the geological lineaments such as regional foliation, faults or fractures and hydrological structures such as river [25]. Several lineament detection algorithms exist in remote sensing, but those based on filtering techniques using directional filters (Sobel) show good results [7], [26]- [33]. The filtering methods principle' main goal is the detection of neighboring pixels which suddenly change in gray level by the use of a differential operation.…”

Section: Methodsmentioning

confidence: 99%

“…For regional mapping, structural interpretation and prospecting for ores and hydrocarbons, geologists have used space images [2]. Indeed, the advent of spatial technology, has greatly contributed to the improvement of the usual geological mapping methods, especially in developing countries where cartographic documents are incomplete or not updated due to some constraints [3] including the cost, accessibility to dangerous or previously inaccessible sites, the heterogeneity of the information and the interpolation methods of traditional field-based lithological mapping [4]- [7].…”

Section: Introductionmentioning

confidence: 99%

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Structural Interpretation of Lineament from Nlonako Area and Surroundings: Contribution to Pan-African Tectonic Reconstruction

Kamgang

Kouémo

Fozing

et al. 2020

EJGEO

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The Nlonako anorogenic complex (NAC) is located in the south western part of the Cameroon Line and is superposed on the N50E section of the central Cameroon shear zone. It is suggested to be a ring complex of 10 km diameter which was emplaced as sill intrusive body during the Tertiary. In order to do characterize the Nlonako complex shape and characterize the tectonic history in the study area and surrounding, spatial technology (Landsat 8 ETM+ and SRTM images) were used for geological mapping and structural reconstruction based on lineament analysis. Data extracted from Landsat 8 ETM and SRTM images show a sub-circular shape for the NAC and the superposition of field and petrographic data from our previous research works confirm the fact that the NAC is a ring or annular complex slightly elongated NNE-SSW, thus it is known as the Nlonako ring complex (NRC). Map of lineament synthesis and the SRTM image of the study area display NE-SW, NW-SE and N-S trend structures. (1) The dominant NE-SW trend mostly displayed by the NRC and its basement rock is parallel to (i) the main metamorphic foliation trend and (ii) to the central Cameroon shear zone regional fault, corresponds to the trending of the regional foliation, structures and the Ngondo pluton elongated shape. (2) The secondary N-S direction may correspond to the late deformational phase in the area because, the N-S-related structures transposing NE-SW structures towards a meridional direction in the NRC basement rock. (3) The NW-SE trend corresponds to the direction of NW-SE fault cross cutting the NRC. Field data and synthetic lineament map enable to identify: (1) a Compressive deformational phase D1 whose main markers are NNW-SSE to NW-SE S1 foliation; (2) an early left-lateral deformational phase D2 characterized by anticlockwise rotation of clasts and NE-SW sinistral transposition of early structures; (3) a NE-SW right-lateral deformational phase D3 marked by clockwise rotation and dextral transposition of preexisting structures as well as the NE-SW S3 foliation and (4) a late left-lateral deformational phase D4 marked by the N-S transposition of NE-SW dextral D3-related structures by late sinistral shear movement. This suggests a more complex tectonic history for the Pan-African Belt in Cameroon showing at least three shear phases, that is a right-lateral phase, sandwich by two left-lateral phases.

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Geological mapping and structural interpretation of the Dschang‐Santchou‐escarpment (West, Cameroon), using Landsat 8 OLI/TIRS sensors/SRTM and field observations

et al. 2022

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Geological mapping of the Dschang‐Santchou‐escarpment rocks in the Western Cameroon region was done using a combination of Landsat 8 OLI/TIRS, SRTM images acquired by satellites on January 21, 2021, and field observations. Lineaments were pre‐processing and processing, performed with Envi 5.1. The different methods of digital processing applied, such as the principal component analysis, the coloured compositions and the combination of bands, show a lithological differentiation of the geological formations of the study area. Lineament maps were obtained by applying Sobel directional filters where 496 lineaments were manually extracted. These lineaments display two main trending directions: the NW–SE trend corresponding to the S2 metamorphic foliation direction and the NE–SW trend corresponding to the S3 magmatic foliation direction. The set of these lineaments represents the fracture network in the area. The field observations as well as the lineaments mapping obtained, allowed us to confirm with the help of the fracture network that we are indeed in an escarped environment. Remote sensing data constitute thus a useful tool for geological mapping and structural reconstitutions in the escarped environment.

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Radarsat-1 image processing for regional-scale geological mapping with mining vocation under dense vegetation and equatorial climate environment, Southwestern Cameroon

Cited by 15 publications

References 27 publications

Contribution of Remote Sensing for the Mapping of the Yaoundé Metadiorites

Contribution of Remote Sensing for the Mapping of the Yaoundé Metadiorites

Structural Interpretation of Lineament from Nlonako Area and Surroundings: Contribution to Pan-African Tectonic Reconstruction

Geological mapping and structural interpretation of the Dschang‐Santchou‐escarpment (West, Cameroon), using Landsat 8 OLI/TIRS sensors/SRTM and field observations

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