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In recent decades, multispectral and hyperspectral remote sensing data provide unprecedented opportunities for the initial stages of mineral exploration and environmental hazard monitoring [...]

© 2020 by the authors. The exploration of carbonate-hosted Pb-Zn mineralization is challenging due to the complex structural-geological settings and costly using geophysical and geochemical techniques. Hydrothermal alteration minerals and structural features are typically associated with this type of mineralization. Application of multi-sensor remote sensing satellite imagery as a fast and inexpensive tool for mapping alteration zones and lithological units associated with carbonate-hosted Pb-Zn deposits is worthwhile. Multiple sources of spectral data derived fromdifferent remote sensing sensors can be utilized for detailed mapping a variety of hydrothermal alteration minerals in the visible near infrared (VNIR) and the shortwave infrared (SWIR) regions. In this research, Landsat-8, Sentinel-2, Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) and WorldView-3 (WV-3) satellite remote sensing sensors were used for prospecting Zn-Pb mineralization in the central part of the Kashmar-Kerman Tectonic Zone (KKTZ), the Central Iranian Terrane (CIT). The KKTZ has high potential for hosting Pb-Zn mineralization due to its specific geodynamic conditions (folded and thrust belt) and the occurrence of large carbonate platforms. For the processing of the satellite remote sensing datasets, band ratios and principal component analysis (PCA) techniques were adopted and implemented. Fuzzy logic modeling was applied to integrate the thematic layers produced by image processing techniques for generating mineral prospectivity maps of the study area. The spatial distribution of iron oxide/hydroxides, hydroxyl-bearing and carbonate minerals and dolomite were mapped using specialized band ratios and analyzing eigenvector loadings of the PC images. Subsequently, mineral prospectivity maps of the study area were generated by fusing the selected PC thematic layers using fuzzy logic modeling. The most favorable/prospective zones for hydrothermal ore mineralizations and ca

© 2019 by the authors. Listvenites normally form during hydrothermal/metasomatic alteration of mafic and ultramafic rocks and represent a key indicator for the occurrence of ore mineralizations in orogenic systems. Hydrothermal/metasomatic alteration mineral assemblages are one of the significant indicators for ore mineralizations in the damage zones of major tectonic boundaries, which can be detected using multispectral satellite remote sensing data. In this research, Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) multispectral remote sensing data were used to detect listvenite occurrences and alteration mineral assemblages in the poorly exposed damage zones of the boundaries between theWilson, Bowers and Robertson Bay terranes in Northern Victoria Land (NVL), Antarctica. Spectral information for detecting alteration mineral assemblages and listvenites were extracted at pixel and sub-pixel levels using the Principal Component Analysis (PCA)/Independent Component Analysis (ICA) fusion technique, Linear Spectral Unmixing (LSU) and Constrained Energy Minimization (CEM) algorithms. Mineralogical assemblages containing Fe2+, Fe3+, Fe-OH, Al-OH, Mg-OH and CO3 spectral absorption features were detected in the damage zones of the study area by implementing PCA/ICA fusion to visible and near infrared (VNIR) and shortwave infrared (SWIR) bands of ASTER. Silicate lithological groups were mapped and discriminated using PCA/ICA fusion to thermal infrared (TIR) bands of ASTER. Fraction images of prospective alteration minerals, including goethite, hematite, jarosite, biotite, kaolinite, muscovite, antigorite, serpentine, talc, actinolite, chlorite, epidote, calcite, dolomite and siderite and possible zones encompassing listvenite occurrences were produced using LSU and CEM algorithms to ASTER VNIR+SWIR spectral bands. Several potential zones for listvenite occurrences were identified, typically in association with mafic metavolcanic rocks (Glasgow Volcani

© 2019 by the authors. Several regions in the High Arctic still lingered poorly explored for a variety of mineralization types because of harsh climate environments and remoteness. Inglefield Land is an ice-free region in northwest Greenland that contains copper-gold mineralization associated with hydrothermal alteration mineral assemblages. In this study, Landsat-8, Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER), and WorldView-3 multispectral remote sensing data were used for hydrothermal alteration mapping and mineral prospecting in the Inglefield Land at regional, local, and district scales. Directed principal components analysis (DPCA) technique was applied to map iron oxide/hydroxide, Al/Fe-OH, Mg-Fe-OH minerals, silicification (Si-OH), and SiO2 mineral groups using specialized band ratios of the multispectral datasets. For extracting reference spectra directly from the Landsat-8, ASTER, and WorldView-3 (WV-3) images to generate fraction images of end-member minerals, the automated spectral hourglass (ASH) approach was implemented. Linear spectral unmixing (LSU) algorithm was thereafter used to produce a mineral map of fractional images. Furthermore, adaptive coherence estimator (ACE) algorithm was applied to visible and near-infrared and shortwave infrared (VINR + SWIR) bands of ASTER using laboratory reflectance spectra extracted from the USGS spectral library for verifying the presence of mineral spectral signatures. Results indicate that the boundaries between the Franklinian sedimentary successions and the Etah metamorphic and meta-igneous complex, the orthogneiss in the northeastern part of the Cu-Au mineralization belt adjacent to Dallas Bugt, and the southern part of the Cu-Au mineralization belt nearby Marshall Bugt show high content of iron oxides/hydroxides and Si-OH/SiO2 mineral groups, which warrant high potential for Cu-Au prospecting. A high spatial distribution of hematite/jarosite, chalcedony/opal, and chlorite/epidote/b

© 2018 by the authors. Geological mapping and mineral exploration programs in the High Arctic have been naturally hindered by its remoteness and hostile climate conditions. The Franklinian Basin in North Greenland has a unique potential for exploration of world-class zinc deposits. In this research, multi-sensor remote sensing satellite data (e.g., Landsat-8, Phased Array L-band Synthetic Aperture Radar (PALSAR) and Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER)) were used for exploring zinc in the trough sequences and shelf-platform carbonate of the Franklinian Basin. A series of robust image processing algorithms was implemented for detecting spatial distribution of pixels/sub-pixels related to key alteration mineral assemblages and structural features that may represent potential undiscovered Zn-Pb deposits. Fusion of Directed Principal Component Analysis (DPCA) and Independent Component Analysis (ICA) was applied to some selected Landsat-8 mineral indices for mapping gossan, clay-rich zones and dolomitization. Major lineaments, intersections, curvilinear structures and sedimentary formations were traced by the application of Feature-oriented Principal Components Selection (FPCS) to cross-polarized backscatter PALSAR ratio images. Mixture Tuned Matched Filtering (MTMF) algorithm was applied to ASTER VNIR/SWIR bands for sub-pixel detection and classification of hematite, goethite, jarosite, alunite, gypsum, chalcedony, kaolinite, muscovite, chlorite, epidote, calcite and dolomite in the prospective targets. Using the remote sensing data and approaches, several high potential zones characterized by distinct alteration mineral assemblages and structural fabrics were identified that could represent undiscovered Zn-Pb sulfide deposits in the study area. This research establishes a straightforward/cost-effective multi-sensor satellite-based remote sensing approach for reconnaissance stages of mineral exploration in hardly accessible parts of the

Numerous massive and sheared, milky quartz veins cut a sequence of Neoproterozoic island arc metavolcanic/volcaniclastic rocks and related banded iron formation (BIF) at Abu Marawat. Sulphide-bearing quartz veins and related hydrothermal breccia masses display a range of textures including sheared, boudinaged and recrystallised quartz, quartz with open space-filling, and microbreccia, implying a complex history of crack-seal processes characterising the relationship between mineral deposition and a major N-S-trending shear zone during a late brittle-ductile deformation event that affected the area at c.550 Ma. Gold-base metal mineralisation is associated with brecciation and fracturing of the iron ore bands close to silicified shears and related quartz veins. The auriferous quartz lodes are characterised by the occurrence of visible pyrite-chalcopyrite+/-pyrrhotite+/-sphalerite+/-galena mineralisation. Gold is refractory in pyrite and chalcopyrite, but rare visible gold/electrum and telluride specks were observed in a few samples. Hydrothermal alteration includes selectively pervasive silicification, pyritisation, sericitisation and carbonatisation confined to a delicate set of veins and altered shears and a more widespread propylitic alteration assemblage. The predominance of hydrated silicate phases (chlorite and sericite) within and adjacent to the shear zones points to fixation of H2O during shear-zone development, while CO2 was consumed to form carbonate in halos around the chlorite-dominated zones, leading to variations in the H2O/CO2 ratio of the ore fluid as hydrothermal alteration progressed. Ore textures, including hydrothermal quartz intimately associated with replacement of magnetite by pyrite, suggest the introduction of ore fluids via epigenetic conduits into the Fe-rich wallrocks. Fluid inclusion textural and microthermometric studies indicate heterogeneous trapping of a low-salinity aqueous solution that coexisted with a carbonic fluid; there is evid, Numerous massive and sheared, milky quartz veins cut a sequence of Neoproterozoic island arc metavolcanic/volcaniclastic rocks and related banded iron formation (BIF) at Abu Marawat. Sulphide-bearing quartz veins and related hydrothermal breccia masses display a range of textures including sheared, boudinaged and recrystallised quartz, quartz with open space-filling, and microbreccia, implying a complex history of crack-seal processes characterising the relationship between mineral deposition and a major N-S-trending shear zone during a late brittle-ductile deformation event that affected the area at c.550 Ma. Gold-base metal mineralisation is associated with brecciation and fracturing of the iron ore bands close to silicified shears and related quartz veins. The auriferous quartz lodes are characterised by the occurrence of visible pyrite-chalcopyrite+/-pyrrhotite+/-sphalerite+/-galena mineralisation. Gold is refractory in pyrite and chalcopyrite, but rare visible gold/electrum and telluride specks were observed in a few samples. Hydrothermal alteration includes selectively pervasive silicification, pyritisation, sericitisation and carbonatisation confined to a delicate set of veins and altered shears and a more widespread propylitic alteration assemblage. The predominance of hydrated silicate phases (chlorite and sericite) within and adjacent to the shear zones points to fixation of H2O during shear-zone development, while CO2 was consumed to form carbonate in halos around the chlorite-dominated zones, leading to variations in the H2O/CO2 ratio of the ore fluid as hydrothermal alteration progressed. Ore textures, including hydrothermal quartz intimately associated with replacement of magnetite by pyrite, suggest the introduction of ore fluids via epigenetic conduits into the Fe-rich wallrocks. Fluid inclusion textural and microthermometric studies indicate heterogeneous trapping of a low-salinity aqueous solution that coexisted with a carbonic fluid; there is evid

Listvenite or listwaenite is an uncommon rusty-red-weathering quartz-fuchsite-carbonate rock formed by the metasomatic transformation of mafic and ultramafic rocks, typically at the margins of fault-bound ophiolitic blocks. In highly deformed orogenic belts, listwaenites are commonly associated with metal enrichment and auriferous quartz veins. Electron microprobe measurements are used to study the mobility and dispersion of Cr, Au and other elements in listwaenite associated with the Haimur gold deposit. Positive correlations between Ni, As, Cu and Au in the late pyrite-arsenopyrite-chalcopyrite association and various contents of Cr2O3 in chlorite and fuchsite reflect mobilisation of Au and other elements. Textural relationships of fuchsite, Cr-chlorite and relicts of Cr-spinel crystals indicate Cr mobilisation from primary Cr-spinels through metasomatism. Temperature estimates based on the composition of gersdorffite, arsenopyrite and hydrothermal chlorite reflect the development of the observed mineral association as the system cooled down from 450 to 250 degrees C. The oxygen and sulphur fugacity corresponds to the low-sulphidisation and oxidising environment typical for orogenic, silica-rich ore-bearing listwaenite., Listvenite or listwaenite is an uncommon rusty-red-weathering quartz-fuchsite-carbonate rock formed by the metasomatic transformation of mafic and ultramafic rocks, typically at the margins of fault-bound ophiolitic blocks. In highly deformed orogenic belts, listwaenites are commonly associated with metal enrichment and auriferous quartz veins. Electron microprobe measurements are used to study the mobility and dispersion of Cr, Au and other elements in listwaenite associated with the Haimur gold deposit. Positive correlations between Ni, As, Cu and Au in the late pyrite-arsenopyrite-chalcopyrite association and various contents of Cr2O3 in chlorite and fuchsite reflect mobilisation of Au and other elements. Textural relationships of fuchsite, Cr-chlorite and relicts of Cr-spinel crystals indicate Cr mobilisation from primary Cr-spinels through metasomatism. Temperature estimates based on the composition of gersdorffite, arsenopyrite and hydrothermal chlorite reflect the development of the observed mineral association as the system cooled down from 450 to 250 degrees C. The oxygen and sulphur fugacity corresponds to the low-sulphidisation and oxidising environment typical for orogenic, silica-rich ore-bearing listwaenite.

Au-bearing quartz +/-carbonate veins in the area of the El-Anbat mine are associated with pervasively silicified, highly sheared ophiolitic and island-arc rocks. Structural analysis of the shear fabrics along the ore zones indicates that the geometry of the mineralised quartz veins and alteration patterns are controlled by the regional NNW-trending transpression zone known as the Wadi-Kharit-Wadi Hodein shear system. Au is chemically bound in As-pyrite, arsenopyrite and gersdorffite, while free-milling Au is rarely observed in the quartz veins and silicified host rocks. Hydrothermal alteration may have liberated additional traces of Au from early pyrrhotite disseminated in listvenite. Geochemical studies showed that shear zones associated with lenticular masses of porphyritic granite in the middle of the transpression zone are heavily mineralised at ppm levels compared with other parts of the alteration zone. Where no granite is observed low-grade ppb level zones of Au mineralisation occur in the highly deformed serpentinite and metavolcanoclastic rocks. Mass balance calculations indicated that hydrothermal fluids which infiltrated under brittle-ductile shear conditions led to addition of Au, As, Cu, Rb and Sb concurrent with silicification, carbonatisation and seriticisation of the host rocks. Dispersion of Au and associated pathfinder elements occurs in altered rocks beyond the lode zone, indicating the potential for extensive low- grade zones outside the El-Anbat mine location., Au-bearing quartz +/-carbonate veins in the area of the El-Anbat mine are associated with pervasively silicified, highly sheared ophiolitic and island-arc rocks. Structural analysis of the shear fabrics along the ore zones indicates that the geometry of the mineralised quartz veins and alteration patterns are controlled by the regional NNW-trending transpression zone known as the Wadi-Kharit-Wadi Hodein shear system. Au is chemically bound in As-pyrite, arsenopyrite and gersdorffite, while free-milling Au is rarely observed in the quartz veins and silicified host rocks. Hydrothermal alteration may have liberated additional traces of Au from early pyrrhotite disseminated in listvenite. Geochemical studies showed that shear zones associated with lenticular masses of porphyritic granite in the middle of the transpression zone are heavily mineralised at ppm levels compared with other parts of the alteration zone. Where no granite is observed low-grade ppb level zones of Au mineralisation occur in the highly deformed serpentinite and metavolcanoclastic rocks. Mass balance calculations indicated that hydrothermal fluids which infiltrated under brittle-ductile shear conditions led to addition of Au, As, Cu, Rb and Sb concurrent with silicification, carbonatisation and seriticisation of the host rocks. Dispersion of Au and associated pathfinder elements occurs in altered rocks beyond the lode zone, indicating the potential for extensive low- grade zones outside the El-Anbat mine location.