Hyperspectral Remote Sensing for Mineral Exploration Research Papers (original) (raw)

Infrared (Visible-Near Infrared-Shortwave Infrared (VNIR-SWIR)) spectroscopy is a cost-effective technique for mineral identification in the field. Modern hand-held spectrometers are equipped with on-board spectral libraries that enable rapid, qualitative analysis of most minerals and facilitate recognition of key alteration minerals for exploration. Spectral libraries can be general or customized for specific mineral deposit environments. To this end, careful collection of spectra in a controlled environment on pure specimens of key minerals was completed using the National Mineral Reference Collection (NMC) of the Geological Survey of Canada. The spectra collected from specimens in the ‘Kodama Clay Collection’ were processed using spectral plotting software and each new example was validated before being added to a group of spectra considered for incorporation into the on-board library of the handheld ASD-TerraSpec Halo near-infrared (NIR) mineral identification instrument. Spectra from an additional suite of mineral samples of the NMC containing REE, U, Th, and/or Nb are being prepared for a new, publicly available spectral library. These minerals commonly occur in carbonatite or alkali intrusive deposits, and as such will assist in the exploration for critical metals.

- by and +2
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- Hyperspectral remote sensing, Hyperspectral Remote Sensing for Mineral Exploration

The Belessa kaolin deposit in the western margin of the Central Main Ethiopian Rift was studied using geological, mineralogical, chemical and physical methods to understand its genesis and evaluate its potential suitability for different industrial applications. X-ray diffraction and Scanning Electron Microscopy were used to establish the mineralogical composition. Bulk chemical compositions were determined using ICP-MS and ICP-AES. The geology of the kaolin district is comprised of Miocene to Quaternary age rhyolite and pyroclastic tuff. The kaolin occurrence is located in the central part of the study area and is associated with rhyolite. The host rock is composed of quartz and alkali feldspar phenocrsyts set in a groundmass of very fine grained quartz, alkali-feldspar and plagioclase. The rhyolite is partially to completely altered to kaolin. The kaolin deposit is composed predominantly of kaolinite and quartz. The kaolinite minerals of the deposit have high structural order. The geological, mineralogical and geochemical studies indicate that supergene alteration played a major role in the formation of the Belessa kaolin deposit. The absence of quartz veining and alteration zones containing high temperature minerals precludes significant hypogene alteration. The Chemical Index of Alteration (CIA) and Chemical Index of Weathering (CIW) also show that the host rock experienced strong alteration and weathering. Furthermore, high Ce+Y+La values correspond to supergene-type alteration. The low P and high Cr+Nb concentrations also support a supergene origin. The physical properties, chemistry, mineralogy and crystal morphology indicate that the Belessa kaolin has potential applications for paper coating, filler (in paper, rubber, plastic and paint), ceramics, pharmaceuticals and cosmetics.

Bulk geochemical data are routinely used in exploration and delineation of iron ore deposits. Increasingly, hyperspectral optical reflectance spectroscopic data are also used to offer complementary mineralogical and mineral chemical information. Herein we provide bulk geochemical and spectrally determined mineralogical data for several case examples of iron deposits, as well as high-resolution bulk geochemical data for Carlin-type Au and volcanogenic massive sulfide (VMS) deposits. These are used to illustrate the utility of linking disparate data sets through a downhole drill core protocol to allow for more effective analysis of these data sets. Such data integration should become routine in the future, in preparation for effective evaluation and interpretation of increasingly higher resolution data sets.

- by Jan Peter and +1
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- Hyperspectral remote sensing, Hyperspectral Remote Sensing for Mineral Exploration, Iron ore

The problem of recursively approximating motion resulting from the Optical Flow (OF) in video thru Total Least Squares (TLS) techniques is addressed. TLS method solves an inconsistent system Gu=z , with G and z in error due to temporal/spatial derivatives, and nonlinearity, while the Ordinary Least Squares (OLS) model has noise only in z. Sources of difficulty involve the non-stationarity of the field, the ill-posedness, and the existence of noise in the data. Three ways of applying the TLS with different noise conjectures to the end problem are observed. First, the classical TLS (cTLS) is introduced, where the entries of the error matrices of each row of the augmented matrix [G;z] have zero mean and the same standard deviation. Next, the Generalized Total Least Squares (GTLS) is defined to provide a more stable solution, but it still has some problems. The Generalized Scaled TLS (GSTLS) has G and z tainted by different sources of additive zero-mean Gaussian noise and scaling [G;z] by nonsingular D and E, that is, D[G;z]E makes the errors iid with zero mean and a diagonal covariance matrix. The scaling is computed from some knowledge on the error distribution to improve the GTLS estimate. For moderate levels of additive noise, GSTLS outperforms the OLS, and the GTLS approaches. Although any TLS variant requires more computations than the OLS, it is still applicable with proper scaling of the data matrix.

The wavelength dependence of the dominant directional reflective properties of beach sands was demonstrated using principal component analysis and the related correlation matrix. In general, we found that the hyperspectral bidirectional reflectance distribution function (BRDF) of beach sands has weak wavelength dependence. Its BRDF varies slightly in three broad wavelength regions. The variations are more evident in surfaces of greater visual roughness than in smooth surfaces. The weak wavelength dependence of the BRDF of beach sand can be captured using three broad wavelength regions instead of hundreds of individual wavelengths.

- by Charles Bachmann and +3
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- Optical Spectroscopy, Hyperspectral remote sensing, Surface Roughness, Dimensionality Reduction

The Geochemical characteristics of geophagic clays from Calabar and Okon-Eket were evaluated to determine their quality and the possible health effects of their consumption. The study involved questionnaire administration to geophagic adults to determine justification and clay preferences, determination of physico-chemical properties, geochemical analysis of major and trace elements using ICP-MS technique and XRD aided mineralogical determination. Twenty geophagic clay samples were randomly obtained from markets and clay mines within the study areas and were air-dried and pulverized prior to analyses. Medical Records from clinics in the areas were also mined to ascertain the prevailing medical conditions in the study areas. Geophagic clays consumed are mined from riverbeds and valleys, mainly by digging. Sun-drying, baking and burning are the heat treatments applied to the clays and they are often consumed without further processing. The geophagic individuals propose relief from gastrointestinal problems, topical application to cure skin infections and cultural justifications as reasons for the practice. Results of analyses revealed a pH range of 6.5-7.0 for consumed clays, relatively high concentrations of Fe2O3 (0.64-7.74%), Al2O3 (14.32-27.31%) and SiO2[calculated] (65.77-78.89%); and concentrations of Cu (9.1-23ppm), Pb (16.7-55.6ppm), Zn (13-148ppm), Ni (11.1-46.4ppm), Co (1.8-21.7ppm), Mn (16-338ppm), As (BDL-15ppm) and Cd (BDL-0.2ppm) exceeding the recommended dietary intake by humans. XRD revealed major mineral phases as quartz and kaolinite, and minor phases as montmorillonite and muscovite. The toxic concentrations of the trace elements are probably responsible for or contribute to the prevalence of hypertension, cardiac failures and gastrointestinal problems within the study areas. The kaolinite present in the geophagic clays make them suitable for use as traditional antacids but the toxic trace element concentrations and significant quartz content will mask the beneficial effects of kaolinite and hence, the clays would cause more harm than benefit to the consumer.
Keywords: Geophagy - Geochemical evaluation - Trace elements - Mineralogy

- by E. Ben-dor
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- Cartography, Remote Sensing, Photosynthesis, Environmental Remote Sensing

It is so important to be aware of quantitative and qualitative characteristics of changes for the environment, land use planning and sustainable development. Detecting the changes in the condition of an issue is done by time difference observations. Change detection refers to the process of detecting time changes of an object through different time observations. The detection of changes by satellite imageries has come recently to the focus of attention due to their comprehensive and integrated characteristics and their ability to monitor changes during long periods as well as their application to monitoring and controlling changes in the forest ecosystems. The vegetation maps are now used to generate required information for macro and micro planning. This study was done to monitor the changes in the forest of Golestan province in the past and also to investigate the possibility of its future forecast using the Land Change Modeler (LMC). A forest type map was first prepared to monitor changes in forests of Golestan province from 2000 to 2015. The images taken in 12 months during 2000 and 2015 were collected form MODIS satellite imageries to monitor the forest. After pre-processing and preparing the time series in two sections, the forest changes were considered using the Normalized Difference Vegetation Index and Moisture Stress Index (NDVI and MSI). The changes were then classified by indices, including the lands with excellent, very good, medium and poor coverage and compared together. The accuracy of the classification results was assessed using the field maps. The best result was found in the average time series data and the use of the NDVI index was prioritized over other indices. The forecast of changes by 2030 as 0.8629 Kappa and the model results for 2030 indicated a decline of 70000 in the land with high and very high capacities and a further increase in land with a low capacity.

PRISMA is a hyperspectral mission launched by the Italian Space Agency on 21 March 2019. PRISMA is the spaceborne hyperspectral sensor which provides imageries of the Earth's surface with (i) global coverage of 30 km x 30 km with a total acquisition capacity of 1800 km in a continuous strip, and (ii) spectral resolution of 12 nm for the contiguous bands (400-2500 nm wavelength). This study presents a review of the hyperspectral datasets from PRISMA for geological applications. A few geological regions from India are selected to check the capability of the PRISMA datasets. Dimensionality reduction and spectral analysis were performed and narrowband indices were generated. Few constraints with the previous hyper-spectral sensors, i.e. large swath with a medium resolution camera on-board, are now covered in the PRISMA mission. This study is focused on the characteristics and compatibilities of the PRISMA hyper-spectral sensor and will be beneficial to the scientific and users community.

Steatite with wide diversified applications and varied compositions is one of the most important industrial materials. In
2013, India ranked 2nd position in terms of quantum production of Steatite and talc mineral. Each steatite deposit being unique
needs to be characterized in terms of its genesis and more so in respect of ultramafic-derived steatite deposits which although
minor account for the best in terms of quality and application. Steatite is a massive variety of talc (hydrothermally altered
ultramafic rock) occurs associated with ultramafic rocks of the Sargur Group and Bababudan Group. Steatite is a soft talcose rock
that is easily carved even with stone, bone or metal tools. In the Bronze Age, steatite vessels seemed to become more common. The
present study demonstrates the geochemical and hyperspectral characterization of steatite deposits in Bhahaddurghatta-Hosahatty
village. This deposit occurs to be linear shaped with almost NNW-SSE direction. Transmitted light microscope, SEM-EDX and
Spectro-Radiometer instruments were actively utilized as methodology on economic deposits of steatite in the study area. The
spectral signatures of the collected samples were derived in laboratory environment to achieve better accuracy based on their
physico-chemical and optical properties. The lab spectral absorptions were studied with the spectra of USGS and JPL mineral
library. The final results highlight the characterization of industrial steatite deposits for its effective mapping and utilization.

The most intense hydrothermally altered rocks in volcanogenic massive sulfide (VMS) deposit systems occur in the stratigraphically underlying feeder zone and rocks immediately adjacent to mineralization. This alteration zone is typically much larger than the mineralization itself, and hence the ability to detect such alteration by optical remote sensing can be invaluable for mineral exploration. Our investigation focuses on assessing the applicability of hyperspectral data to determine trends in hydrothermal alteration intensity in and around the Izok Lake VMS deposit in northern Canada. To this end, we linked hydrothermal alteration intensity information based on two indices, the Ishikawa (AI) and chlorite-carbonate-pyrite (CCPI), to hyperspectral field and laboratory data in three dimensions. Our results suggest that chlorite group minerals display variable chemical composition across the study area that broadly correlates with hydrothermal alteration intensity.

- by Kati Laakso and +1
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- Hyperspectral remote sensing, Hyperspectral Remote Sensing for Mineral Exploration, Volcanogenic Massive Sulfide
- by Giora Kidron and +1
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- Remote Sensing, Environmental Remote Sensing, Clay Minerals, Iron Oxide

Direct measurement of depth of the ~1900 nm feature (F 1900) caused by molecular water is not possible from hyperspectral data acquired under natural illumination. Proxy measures for depth were evaluated to estimate the true depth of F 1900 from such data. Suitable proxy measures were identified using data acquired by a high-resolution spectrometer (under artificial and natural illumination) and by a hyperspectral imaging sensor (under artificial illumination), with different amounts of simulated atmospheric noise. The best performing proxy measures were used to estimate depth from hyperspectral imagery acquired in the field under natural illumination. Proxy measures comprised a ratio of reflectance, continuum-removed depth at a single wavelength and continuum-removed depth integrated over several wavelengths. For high resolution spectra, a ratio of reflectance at 2017 nm and 1967 nm (Ratio 2017/1967) and the continuum-removed depth at 1967 nm (CRD 1967) were strongly correlated with depth R 2 = 0.98–0.99 and R 2 = 0.95–0.96, respectively. For hyperspectral imagery acquired in the laboratory, Ratio 2017/1967 and CRD 1967 were strongly correlated with depth across all levels of atmospheric noise (R 2 = 0.94–0.98 and 0.94–0.97, respectively). Proxy measures using integrated depth performed relatively poorly (R 2 = 0.65–0.86). In independent tests, depth of F 1900 was consistently overestimated by CRD 1967 but not by Ratio 2017/1967. Validation of field imagery was done by comparing depth predicted by the proxy measures with depth measured from laboratory imagery of collocated samples from the field. Ratio 2017/1967 derived from a polynomial fit to the data between 1961 and 2134 nm (RatioP 2017/1967) most closely approximated measured depth. Ratio 2017/1967 , derived from the original data either under or overestimated depth. Measures of continuum-removed depth generated from the original data (CRD 1967) and from a polynomial fit to the original data (CRDP 1967) overestimated the depth of F 1900. This study showed that the depth of F 1900 can be predicted from data acquired under natural illumination however, the choice of proxy measure can have a significant impact upon quantitative estimates.

- by Jan Peter
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- Geology, Computer Science, Hyperspectral remote sensing, IEEE