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Lithologic map of the study area showing hydrothermal alteration zones. The map was constructed by the classification of a WorldView II image with the linear spectral unmixing technique
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Early investigators mentioned a potential resource of base metal sulfide mineralization associated with quartz diorites and the intermediate Rutig volcanic rocks in the area of Wadi Rofaiyed. The region’s complicated geological history and inaccessibility due to rugged topography makes it difficult to accurately map its lithology on field. A combin...
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... it identified those rocks altered by hydrothermal alteration using WorldView II. The only exception was the differentiation between weathered rhyolite and granite due to the similarity of their weathering products. The classes resulting from linear spectral unmixing classification for these two weathered rocks are combined together in one class (Fig. ...
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... Remote sensing theories in mineral exploration are well established and have been successfully applied to ore prospecting across numerous metallogenic belts around the world (Karimpour et al., 2008;Pour et al., 2013;Takodjou Wambo et al., 2020;Traore et al., 2020;Zoheir and Emam, 2012;Monsef et al., 2015;Zoheir et al., 2019;Bedini, 2017;Crósta et al., 2003;Anifadi et al., 2016). In most cases, evidence from field, geochemical and mineralogical studies have revealed the possible existence of ore deposits in close proximity to hydrothermal alterations (Suh et al., 2006;Vishiti et al., 2017;Yannah et al., 2015). ...
Remote sensing methods are a vital alternative for regional exploration surveys. Many ore deposits (e.g., epithermal, porphyry-related, volcanogenic massive sulphides, etc.) have distinct distribution patterns of alteration zones that can be used for recognizing this mineralization. Several known goldfields are distributed within the basement rocks of western Nigeria. The area of interest, Malumfashi Schist Belt, is located in NorthWestern Nigeria and is characterized by gneisses and metasediments that were intruded by Pan-African granitoids. Gold mineralization occurs as veins and veinlets that are associated with hydrothermal alteration zones (i.e., argillic, phyllic, and propylitic). Hence, the discrimination of these alteration zones is one of the key indicators for new prospective zones of gold mineralization in this met-allogenic belt. In the present study, Landsat Enhanced Thematic Mapper+ (Landsat-7 ETM+) and Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) data were processed and integrated with the aim to identify possible locations for gold mineralization within the Malumfashi Schist Belt. For this purpose, the band ratio techniques and Principal Component Analysis (PCA) were applied to identify, enhance and map the different alteration types, while fractal analysis was utilized to quantify the degree of alteration within each processed image. Using the multi-criteria evaluation method, the discretized images obtained from the fractal analysis were weighted and integrated into an enhanced possible location for gold occurrences. A receiver operating curve/Area under curve analysis was then used to evaluate the reliability of the predictive model. Both spatial and GIS analyses indicate that gold mineralization displays a proximal relationship to hydrothermal alteration data. We can map sets of alteration minerals which mainly represent new and good ore prospects for the investigated area. A sensitivity analysis points out a predictive accuracy of 78%, which suggests the model is capable of predicting gold occurrences within the study region. Besides, the results showed that the prospective zones of gold accumulations mainly occur within metasedimentary units. It is recommended that the studied dataset provide a potential tool for mapping alteration minerals related to gold deposits that can be applied in other regions with analogous geological setting. Ó 2020 National Authority for Remote Sensing and Space Sciences. Production and hosting by Elsevier B. V. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).
... However, the spatial resolution of these satellite remote sensed images is not satisfactory for small-scale applications. High spatial resolution datasets such as QuickBird [17], WorldView [18,19], Systeme Probatoire d'Observation de la Terre (SPOT) [20] and Chinese Gaofen (GF) [21] can be used to illustrate the boundaries of landmarks better, and their VNIR bands are sensitive to spectral characteristics related to electronic processes. However, such datasets mostly lack SWIR bands. ...
Multi-stage intrusive complex mapping plays an important role in regional mineralization research. The similarity of lithology characteristics between different stages of intrusions necessitates the use of richer spectral bands, while higher spatial resolution is also essential in small-scale research. In this paper, a multi-source remote sensing data application method was proposed. This method includes a spectral synergy process based on statistical regression and a fusion process using Gram–Schmidt (GS) spectral sharpening. We applied the method with Gaofen-2 (GF2), Sentinel-2, and Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) data to the mapping of the Mountain Sanfeng intrusive complex in northwest China in which Carboniferous intrusions have been proven to be directly related to the formation of Au deposits in the area. The band ratio (BR) and relative absorption band depth (RBD) were employed to enhance the spectral differences between two stage intrusions, and the Red-Green-Blue (RGB) false colour of the BR and RBD enhancement images performed well in the west and centre. Excellent enhancement results were obtained by making full use of all bands of the synergistic image and using the Band Ratio Matrix (BRM)-Principal Component Analysis (PCA) method in the northeast part of the study area. A crucial improvement in enhancement performance by the GS fusion process and spectral synergy process was thus shown. An accurate mapping result was obtained at the Mountain Sanfeng intrusive complex. This method could support small-scale regional geological survey and mineralization research in this region.
... In the area of southern Sinai in Egypt, the Cambrian clastic sedimentary rocks and the surrounding igneous rocks are an important poly-metallogenic belt. The polymetallic mineralization is associated with the Precambrian basement rocks and sedimentary cover; these mineralization have a great attention from many authors (El-Shazly et al. 1955;Hilmy and Mohsen 1963;Bogoch and Zilberfrab 1979;El-Ghawaby 1984;Hassan 1987;El Gaby et al. 1988;Soliman 1989;Soliman and Dardir 1990;Khalifa 1991;Khalid and Qweiss 1995;Soliman et al. 1998;Bekhit et al. 2000;EL-Ghawaby et al. 2000;Seleem and Khalifa 2006;Khalifa and Seleem 2007;Khalifa et al. 2011;Salem et al. 2013;Mamedov et al. 2014;Sallam 2015;Abd-El Monsef et al. 2015;Khalifa et al. 2016;Orabi et al. 2019). Manganese, copper, and uranium deposits are hosting in part in Cambrian sedimentary rocks (El Aassy et al. 1986Amer 1993), while gold-copper-sulfide mineralization is widely distributed in the ring structures of the Arabian-Nubian Shield in the southern Sinai (Mamedov et al. 2014). ...
Geological, mineralogical, and geochemical methods are utilized to discover new gold resources in the Cambrian clastic rocks in the area of southern Sinai. Relation between the Precambrian basement rocks and the overlying gold-bearing Cambrian sediments is also clarified. The Cambrian sediments are underlined by Precambrian basement rocks in which gold mineralization is closely related to intrusive granitic and volcanic rocks. The Cambrian clastic sediments are composed of basal conglomerate and thick sequence of sandstone and siltstone. The mineralogical studies revealed that the conglomerate and quartz-sandstone of the lower Cambrian platform are hosting zircon, monazite, uranophane, thoriante and xenotime, pyrite, and gold. The association of gold, rare earth element (REE)-bearing minerals, and sulfide suggested that these Cambrian sediments are the result weathering of former gold-enriched Precambrian hinterlands. Major and trace elements show the enrichment of silica, high field strength elements (Zr, Y, Nb, Hf, Th, and U), and depletion of all other major elements (Fe2O3, TiO2, MnO, MgO, K2O, Na2O, and CaO) and large-ion lithophile elements (Rb, Ba, and Sr); among the trace elements, gold shows high concentration range from 0.5 to 13 ppm. REE pattern shows enrichment in LREE and flat HREE with negative Eu anomalies, all of these indicate that the provenance of the present Cambrian sediments is a granitoid-greenstone located to the south. The geochemical parameters (Th/Co, Zr/Co, Th/La, and Th/Yb ratios) and the Paleo-weathering indices (CIA and ICV) for the Cambrian sediments indicate that they were derived from felsic source rocks which were subjected to high chemical weathering under humid climatic condition. The geochemical data and discrimination function plots indicate that the present Cambrian sediments deposited in a passive continental margin.
... Alteration zones are typically characterized by certain mineral associations (e.g., epidote, chlorite, kaolinite, alunite, illite, and many other minerals) which have significant specific spectral characteristics that enable their identification by spectral processing of the remotely sensed data (e.g., Crósta et al. 2003;Le et al. 2008;Abd-El Monsef et al. 2015;Gabr et al. 2015). ...
... The information of radio-senders collected from several references (e.g., McNeill and Labson 1991;Knödel et al. 1997;Bastani and Pedersen 2001;Klawitter 2004;Farag 2005) Crósta technique was originally developed by Crósta and Moore (1989) based on the concept of establishing a spectral relation behavior of the target and the numeric value of eigenvalue matrix used in the PCT calculations, such relation emphasize the PCs loaded and contain the most spectral information for the target material. Loughlin (1991) modified Crósta technique to be more like as object-oriented PC by applying PCA separately for bands that have the higher target spectral response (Crósta et al. 2003;Abd-El Monsef et al. 2015;Gabr et al. 2015). ...
Economic mineralization and hydrothermally altered zones are areas of great economic interests. This study focusses on hydrothermal altered zones of high mineralization potentials in Wadi Al-Bana, in southern Yemen. An azimuthal very low frequency–electromagnetic (AVLF-EM) data acquisition was conducted in search for mineralization in the study area. The study integrated observations from geophysical field data with others extracted from object-oriented principal component analysis (PCA) to better map and understand mineralization in the investigated area. This technique was applied to two data sets, ASTER and Landsat 8 Operational Land Imager (OLI) imagery. The results of PCA revealed high accuracy in detecting alteration minerals and for mapping zones of high concentration of these minerals. The PCA-based distribution of selected alteration zones correlated spatially with high conductivity anomalies in the subsurface that were detected by VLF measurements. Finally, a GIS model was built and successfully utilized to categorize the resulted altered zones, into three levels.
... (i) Mineralogy mapping: WorldView data is widely used to extract mineral alteration information, evaluate lithologic mapping data, and map minerals because of its high spectral resolution [60][61][62][63] .In addition, Worldview-2 satellite imagery has been used to search for ancient gold mines in the Filippoi area of Macedonia, Greece 64 . ...
Geologists employ high-spatial-resolution (HR) remote sensing (RS) data for many diverse applications as they effectively reflect detailed geological information, enabling high-quality and efficient geological surveys. Applications of HR RS data to geological and related fields have grown recently. HR optical remote sensing data are widely used in geological hazard assessment, seismic monitoring, mineral exploitation, glacier monitoring, and mineral information extraction due to high accuracy and clear object features. By reviewing these applications, we can better understand the results of previous studies and more effectively use the latest data and methods to efficiently extract key geological information. Compared with optical satellite images, synthetic-aperture radar (SAR) images are stereoscopic and exhibit clear relief, strong performance, and good detection of terrain, landforms, and other information. SAR images have been applied to seismic mechanism research, volcanic monitoring, topographic deformation, and fault analysis. Furthermore, a multi-standard maturity analysis of the geological applications of HR images reveals that optical remote sensing data are superior to radar data for mining, geological disaster, lithologic, and volcanic applications, but inferior for earthquake, glacial, and fault applications. Therefore, it is necessary for geological remote sensing research to be truly multi-disciplinary or inter-disciplinary, ensuring more detailed and efficient surveys through cross-linking with other disciplines. Moreover, the recent application of deep learning technology to remote sensing data extraction has improved the capabilities of automatic processing and data analysis with HR images.
... (i) Mineralogy mapping: WorldView data is widely used to extract mineral alteration information, evaluate lithologic mapping data, and map minerals because of its high spectral resolution [60][61][62][63] .In addition, Worldview-2 satellite imagery has been used to search for ancient gold mines in the Filippoi area of Macedonia, Greece 64 . ...
Geologists employ high-spatial-resolution (HR) remote sensing (RS) data for many diverse applications as they effectively reflect detailed geological information, enabling high-quality and efficient geological surveys. Applications of HR RS data to geological and related fields have grown recently. By analyzing these applications, we can better understand the results of previous studies and more effectively use the latest data and methods to efficiently extract key geological information. HR optical remote sensing data are widely used in geological hazard assessment, seismic monitoring, mineral exploitation, glacier monitoring, and mineral information extraction due to high accuracy and clear object features. Compared with optical satellite images, synthetic-aperture radar (SAR) images are stereoscopic and exhibit clear relief, strong performance, and good detection of terrain, landforms, and other information. SAR images have been applied to seismic mechanism research, volcanic monitoring, topographic deformation, and fault analysis. Furthermore, a multi-standard maturity analysis of the geological applications of HR images using literature from the Science Citation Index reveals that optical remote sensing data are superior to radar data for mining, geological disaster, lithologic, and volcanic applications, but inferior for earthquake, glacial, and fault applications. Therefore, geological remote sensing research needs to be truly multidisciplinary or interdisciplinary, ensuring more detailed and efficient surveys through cross-linking with other disciplines. Moreover, the recent application of deep learning technology to remote sensing data extraction has improved automatic processing and data analysis capabilities.
