Dissertations / Theses on the topic 'Shortwave infrared'

The advent of relatively high spatial resolution hyperspectral imagery (HSI) provides a different perspective of the urban environment than lower spatial resolution hyperspectral data and either multispectral or panchromatic images. The objective of this thesis was to build and analyze a spectral library of urban materials and to understand how spectral variability affects the ability of classification algorithms to identify and discriminate various materials. The scope of the project was limited to non-vegetative impervious materials located on the Naval Postgraduate School campus. An airborne hyperspectral image, acquired September 30th 2011 was used for image-derived endmembers and a portable spectroradiometer was used to collect field spectra. Visual analysis of spectra was performed to assess intra- and inter-class variability and to identify spectral features and their causes. The spectral angle mapper (SAM) algorithm was used on the HSI data as a method to quantify intra-class spectral variability using a standard spectral angle. Classification maps were created with both SAM and mixture tuned matched filtering (MTMF) algorithms to determine how intra- and inter-class spectral variability affect the algorithms ability to classify urban materials. The spatially complex nature of the urban environment negatively affected the performance of the SAM algorithm, but the ability to increase the spectral angle to account for materials with high spectral variability allowed improved inter-class discrimination. The MTMF algorithm was better suited for intra-class discrimination of materials.

Thesis: Ph. D. in Physical Chemistry, Massachusetts Institute of Technology, Department of Chemistry, 2018.
This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.
Cataloged from student-submitted PDF version of thesis. Page 144 blank.
Includes bibliographical references (pages 127-143).
Visualizing structures deep within biological tissue is a central challenge in biomedical imaging, with both preclinical implications and clinical relevance. Using shortwave infrared (SWIR) light enables imaging with high resolution, high sensitivity, and sufficient penetration depth to noninvasively interrogate sub-surface tissue features. However, the clinical potential of this approach has been largely unexplored. Until recently, suitable detectors have been either unavailable or cost-prohibitive. Additionally, clinical adoption of SWIR imaging has been inhibited by a poor understanding of its advantages over conventional techniques. For fluorescence imaging in particular, there has further been a perceived need for clinically-approved contrast agents. Here, taking advantage of newly available detector technology, we investigate a variety of biomedical applications with SWIR-based imaging devices. We describe the development of a medical otoscope and our clinical observations using this device to evaluate middle ear pathologies in both adult and pediatric populations, showing that SWIR otoscopy could provide diagnostic information complementary to that provided by conventional visible otoscopy. We further describe fluorescence detection of an endogenous disease biomarker in animal models including nonalcoholic fatty liver disease and cirrhotic liver models and models of a neurodegenerative disease pathway. While this biomarker has been known for decades, we describe a method for its noninvasive detection in living animals using near infrared and SWIR light, as opposed to its conventional ex vivo detection. Furthermore, we show that SWIR image contrast and penetration depth are primarily mediated by the absorptivity of tissue, and can be tuned through deliberate selection of imaging wavelength. This understanding is crucial for rationally determining the optimal imaging window for a given application, and is a prerequisite for understanding which clinical applications could benefit from SWIR imaging. Finally, we show that commercially-available near infrared dyes, including the FDA-approved contrast agent indocyanine green, exhibit optical properties suitable for in vivo SWIR fluorescence imaging, including intravital microscopy, noninvasive, real-time imaging in blood and lymph vessels, and tumor-targeted imaging with IRDye 800CW, a dye being tested in clinical trials. Thus, we suggest that there is significant potential for SWIR imaging to be implemented alongside existing imaging modalities in the clinic.
by Jessica Ann Carr.
Ph. D. in Physical Chemistry

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Chemistry, 2013.
This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.
Cataloged from student-submitted PDF version of thesis.
Includes bibliographical references (pages 95-106).
Infrared-active nanostructures play an increasingly important role in the nanoscience toolbox, yet little is known about their optical properties at the single nanoparticle level. In this thesis, we detail efforts to extend the power of single-molecule spectroscopy into the shortwave-infrared (SWIR), marrying confocal microscopy with superconducting nanowire single photon detectors that operate very eciently in this portion of the spectrum. As a proof of principle, we interrogate single lead sulfide (PbS) nanocrystals emitting at 1100 nm and observe fluorescence intermittency (blinking) under continuous excitation. The extracted on/o waiting-time statistics were power-law distributed, with exponents nearly identical to those measured from visible NCs. In addition, we demonstrate the feasibility of performing sophisticated photon correlation experiments on weak SWIR emitters and confirm that the photoluminescence from single PbS NCs displays sub-Poissonian photon statistics, strong evidence for single-NC localization. Next, we use our unique apparatus to probe two key steps in the exciton lifecycle of single 1300-nm-emitting indium arsenide nanocrystals: the time evolution, and subsequent recombination, of single and multiple excitons. Upon correlating PL intensity with the lifetime decay, we discover that InAs/CdZnS nanocrystals blink in one of two ways, either with the PL decay rate fluctuating simultaneously or remaining constant for all PL intensities other than the o state. Surprisingly, we observe grey-state emission - commonly attributed to trion recombination - with a PL lifetime nearly equal to the bright state (attributed to neutral exciton recombination). For the 21 NCs studied, we observe signicant heterogeneity in single-NC radiative lifetimes (47 to 179 ns), while simultaneously measuring a near-zero biexciton quantum yield across the sample. Finally, we perform single-NC spectroscopy on a new generation of CdSe/CdS nanocrystals and extract kinetic rates of recombination for both neutral and charged excitons, which we assign to the bright and grey state respectively. By correlating the instantaneous PL lifetime with the PL intensity using fluorescence-lifetime-intensity-distribution (FLID) plots, we assess the prospects of alternative blinking mechanisms in 2-monolayer and 7-monolayer CdSe/CdS NCs, as well as QD Corp. NCs (QDC655), and nd little evidence for anomalous blinking (i.e. the recently proposed Type B blinking) for all three NC systems.
by Raoul Emile Correa.
Ph.D.

In California, natural vegetation is experiencing an increasing amount of stress due to prolonged droughts, wildfires, insect infestation, and disease. Remote sensing technologies provide a means for monitoring plant species presence and function temporally across landscapes. In this his dissertation, I used hyperspectral visible shortwave infrared (VSWIR), hyperspectral thermal (TIR), and hyperspectral VSWIR + broadband TIR imagery to derive key observations of plant species across a gradient of environmental conditions and time frames. In Chapter 2, I classified plant species using hyperspectral VSWIR imagery from 2013–2015 spring, summer, and fall. Plant species maps had the highest classification accuracy using spectra from a single date (mean kappa 0.80–0.86). The inclusion of spectra from other dates decreased accuracy (mean kappa 0.78–0.83). Leave-one-out analysis emphasized the need to have spectra from the image date in the classification training, otherwise classification accuracy dropped significantly (mean kappa 0.31–0.73). In Chapter 3, I used hyperspectral TIR imagery to determine the extent that high precision spectral emissivity and canopy temperature can be exploited for vegetation research at the canopy level. I found that plant species show distinct spectral separation at the leaf level, but separability among species is lost at the canopy level. However, species’ canopy temperatures exhibited different distributions among dates and species. Variability in canopy temperatures was largely explained by LiDAR derived canopy structural attributes (e.g. canopy density) and the surrounding environment (e.g. presence of pavement). In Chapter 4, I used combined hyperspectral VSWIR and broadband TIR imagery to monitor plant stress during California’s 2013–2015 severe drought. The temperature condition index (TCI) was calculated to measure plant stress by using plant species’ surface minus air temperature distributions across dates. Plant stress was not evenly distributed across the landscape or time with lower elevation open shrub/meadows, showing the largest amount of stress in June 2014, and August 2015 imagery. Plant stress spatial variability across the study area was related to a slope’s aspect with highly stressed plants located on south or south-southwest facing slopes. Overall, this dissertation quantifies the ability to temporally study plant species using hyperspectral VSWIR, hyperspectral TIR, and combined VSWIR+TIR imagery. This analysis supports a range of current and planned missions including Surface Biology and Geology (SBG), Environmental Mapping and Analysis Program (EnMAP), National Ecological Observatory Network (NEON), Hyperspectral Thermal Emission Spectrometer (HyTES), and ECOsystem Spaceborne Thermal Radiometer Experiment on Space Station (ECOSTRESS).

Approved for public release; distribution is unlimited
Visible to near-, shortwave-, and longwave-infrared (VNIR, SWIR, LWIR) remote sensing data are typically analyzed in their individual wavelength regions, even though theory suggests combined use would emphasize complementary features. This research explored the potential for improvements in material classification using integrated datasets. Hyperspectral (HSI) VNIR and SWIR data from the MaRSuper Sensor System (MSS-1) were analyzed with HSI LWIR data from the Spatially Enhanced Broadband Array Spectrograph System (SEBASS) to determine differences between individual (baseline) and combined analyses. The first integration approach applied separate minimum noise fraction (MNF) transforms to the three regions and combined only non-noise transformed bands from the individual regions during analysis. The second approach integrated over 470 hyperspectral bands covering the VNIR, SWIR, and LWIR wavelengths before using MNF analysis to isolate linear band combinations containing high signal to noise. Spectral endmembers isolated from data were unmixed using partial unmixing. The feasible and high abundance pixels were spatially mapped using a consistent feasibility ratio threshold. Both integration methods enabled straight-forward and effective identification, characterization, and mapping of the scene because higher variability existed between endmembers and background. Results were compared to the baseline analysis. Material identification was more conclusive when analyzing across the full spectrum.

Soil spectroscopy has experienced a tremendous increase in soil property characterisation, and can be used not only in the laboratory but also from the space (imaging spectroscopy). Partial least squares (PLS) regression is one of the most common approaches for the calibration of soil properties using soil spectra. Besides functioning as a calibration method, PLS can also be used as a dimension reduction tool, which has scarcely been studied in soil spectroscopy. PLS components retained from high-dimensional spectral data can further be explored with the gradient-boosted decision tree (GBDT) method. Three soil sample categories were extracted from the Land Use/Land Cover Area Frame Survey (LUCAS) soil library according to the type of land cover (woodland, grassland, and cropland). First, PLS regression and GBDT were separately applied to build the spectroscopic models for soil organic carbon (OC), total nitrogen content (N), and clay for each soil category. Then, PLS-derived components were used as input variables for the GBDT model. The results demonstrate that the combined PLS-GBDT approach has better performance than PLS or GBDT alone. The relative important variables for soil property estimation revealed by the proposed method demonstrated that the PLS method is a useful dimension reduction tool for soil spectra to retain target-related information.

Soil spectroscopy has experienced a tremendous increase in soil property characterisation, and can be used not only in the laboratory but also from the space (imaging spectroscopy). Partial least squares (PLS) regression is one of the most common approaches for the calibration of soil properties using soil spectra. Besides functioning as a calibration method, PLS can also be used as a dimension reduction tool, which has scarcely been studied in soil spectroscopy. PLS components retained from high-dimensional spectral data can further be explored with the gradient-boosted decision tree (GBDT) method. Three soil sample categories were extracted from the Land Use/Land Cover Area Frame Survey (LUCAS) soil library according to the type of land cover (woodland, grassland, and cropland). First, PLS regression and GBDT were separately applied to build the spectroscopic models for soil organic carbon (OC), total nitrogen content (N), and clay for each soil category. Then, PLS-derived components were used as input variables for the GBDT model. The results demonstrate that the combined PLS-GBDT approach has better performance than PLS or GBDT alone. The relative important variables for soil property estimation revealed by the proposed method demonstrated that the PLS method is a useful dimension reduction tool for soil spectra to retain target-related information.

Visible and near-infrared diffuse reflectance spectroscopy has been demonstrated to be a fast and cheap tool for estimating a large number of chemical and physical soil properties, and effective features extracted from spectra are crucial to correlating with these properties. We adopt a novel methodology for feature extraction of soil spectroscopy based on fractal geometry. The spectrum can be divided into multiple segments with different step–window pairs. For each segmented spectral curve, the fractal dimension value was calculated using variation estimators with power indices 0.5, 1.0 and 2.0. Thus, the fractal feature can be generated by multiplying the fractal dimension value with spectral energy. To assess and compare the performance of new generated features, we took advantage of organic soil samples from the large-scale European Land Use/Land Cover Area Frame Survey (LUCAS). Gradient-boosting regression models built using XGBoost library with soil spectral library were developed to estimate N, pH and soil organic carbon (SOC) contents. Features generated by a variogram estimator performed better than two other estimators and the principal component analysis (PCA). The estimation results for SOC were coefficient of determination (R2) = 0.85, root mean square error (RMSE) = 56.7 g/kg, the ratio of percent deviation (RPD) = 2.59; for pH: R2 = 0.82, RMSE = 0.49 g/kg, RPD = 2.31; and for N: R2 = 0.77, RMSE = 3.01 g/kg, RPD = 2.09. Even better results could be achieved when fractal features were combined with PCA components. Fractal features generated by the proposed method can improve estimation accuracies of soil properties and simultaneously maintain the original spectral curve shape.

Visible and near-infrared diffuse reflectance spectroscopy has been demonstrated to be a fast and cheap tool for estimating a large number of chemical and physical soil properties, and effective features extracted from spectra are crucial to correlating with these properties. We adopt a novel methodology for feature extraction of soil spectroscopy based on fractal geometry. The spectrum can be divided into multiple segments with different step–window pairs. For each segmented spectral curve, the fractal dimension value was calculated using variation estimators with power indices 0.5, 1.0 and 2.0. Thus, the fractal feature can be generated by multiplying the fractal dimension value with spectral energy. To assess and compare the performance of new generated features, we took advantage of organic soil samples from the large-scale European Land Use/Land Cover Area Frame Survey (LUCAS). Gradient-boosting regression models built using XGBoost library with soil spectral library were developed to estimate N, pH and soil organic carbon (SOC) contents. Features generated by a variogram estimator performed better than two other estimators and the principal component analysis (PCA). The estimation results for SOC were coefficient of determination (R2) = 0.85, root mean square error (RMSE) = 56.7 g/kg, the ratio of percent deviation (RPD) = 2.59; for pH: R2 = 0.82, RMSE = 0.49 g/kg, RPD = 2.31; and for N: R2 = 0.77, RMSE = 3.01 g/kg, RPD = 2.09. Even better results could be achieved when fractal features were combined with PCA components. Fractal features generated by the proposed method can improve estimation accuracies of soil properties and simultaneously maintain the original spectral curve shape.

碩士
逢甲大學
電機工程所
99
This paper studies to design of shortwave infrared zoom lens, analyzes radiant intensity of image and the resolution of image by Non Sequential Ray Tracing. So, it could reduce the cost of development and also decrease the time of research. This research uses the U.S patent No.4854681 for the initial structure. The final design result is zoom lens with four groups where are positive, negative, positive, and positive power. The system is constituted with eleven lenses, it include three aspheric lenses. It focal length is from 24.619mm to 146.588mm, respond the wide-angle mode to the telephoto mode. On the axis, the modulation transfer function (MTF) at 20lp/mm is greater than 0.3. Off the axis, the MTF is greater than 0.2. The relative illumination is over 90%. The distortion is below 5%. And through the tolerance analysis, we verify the system’s production.

碩士
國立交通大學
理學院應用科技學程
100
ABSTRACT Shortwave infrared (Short Wave InfraRed, SWIR), its wavelength is 0.9 ~ 1.7um,the spectrum of this band in nature for the human eye can not seen, the heat sensor developed by the majority on the early military purposes in this range. Since the detection of the thermal sensor is not subjected to the limitations of weather conditions,we can get the accurate identification,rather the sensitivity of the sensor itself the target, The development of the thermal sensor technology becomes more sophisticated, and the cost is substantially reduced, so the product life has gradually diversified, in addition to military applications covered the manufacturing industry, food, medical and measurement, monitoring, development, etc.everywhere, the heat sensor on the circuit design and improved image quality requirements is also increasingly subject to considerable attention. In this thesis, One dimensional line sensing system with two-dimensional array sensor system studied by the methods of measurement of the thermal sensor and the target under test, analysis and resolution of the optical lens and a sense of temperature on thermal radiation measurement capability, individual analysis and assessment of the performance difference of the thermal sensor system.

This thesis presents results of a short-wave infrared (SWIR) reflectance spectroscopic study of clay minerals from the Athabasca Basin. Clay minerals (dickite, kaolinite, illite, and chlorite) are widespread in the Athabasca Basin and are particularly abundant in the alteration haloes associated with the unconformitytype uranium deposits. Many previous studies have emphasized a complex paragenesis of the Athabasca kaolinite-group minerals from detrital or early diagenetic origin in unaltered sandstones to occurrences in the alteration haloes associated with uranium mineralization and in the bleached zones and late fractures. SWIR reflectance spectroscopic analysis revealed that dickite is a characteristic phase in the unaltered sandstones, whereas kaolinite is a common clay mineral in the alteration haloes and also occurs in the bleached zones and late fractures. The presence of dickite has been confirmed by combined methods of XRD, EMPA, SEM, TEM and SWIR. Although the kaolinite-group minerals of the Athabasca sedimentary rocks do not exhibit any significant variation in composition, a wide range in crystallinity (Hinckley index of 0.12 to 1.61) has been revealed by XRD analysis. This variation in crystallinity of kaolinite is related to paragenesis. A linear relationship was established between the Hinckley index and the S WIR absorption feature at 1400 nm. Therefore, SWIR reflectance spectroscopy is a useful paragenetic indicator. All samples of illite examined in this study were collected from alteration haloes associated with uranium mineralization and belong to the 3T polytvpe or mixtures of 3T and 2M. XRD analysis revealed that these samples of illite vary in crystallinity from 1.39 to 4.0. Unfortunately, Pima II is incapable of distinguishing 3T and 2M polytypes of illite. Also no correlation was found between crystallinity and the SWIR spectra of illite. Two types of chlorite (clinochlore and sudoite) are present in the Athabasca Basin, although the latter is particularly common in the alteration haloes and has been studied in some details. Sudoite is almost invariably interlayered with illite and exhibits a wide range of compositional variation. Spectral study lias revealed that the intensities of the absorption near the 2200 nm region increase with the increase of relevant chemical compositions (AI and Fe). Artificial mixture experiments using well-characterized mineral Standards have revealed that the spectral features vary systematically with the change of the mineral abundances. Results of these artificial mixtures were used to modify an existing method for the quantitative analysis of clay minerals in the Athabasca Basin.

碩士
國立中正大學
資訊工程研究所
106
Short-wave infrared (SWIR) hyperspectral image (HSI) provides detailed spectral information regardless of target detection applications in military or search and rescue. While most HSI tasks image a static scene by a push-broom scanner, here a liquid crystal tunable filter (LCTF) is mounted in front of a broad-band SWIR camera to take snapshots of dynamic scenes. Due to the optical defects in LCTF, the collected images have pattern of interference fringes (PIF), which causes spatial and spectral distortion and interferes the target recognition tasks. Therefore, the purpose of this study is to develop a correction algorithm to eliminate PIF in the spectral images, and improve the recognition accuracy. We experimentally investigated the cause of PIF, and found the cost of hardware solution is very high. Therefore, we turned to develop algorithmic solutions. By collecting the reference images with PIF only, we examined three correction methods: (1) Template-based elimination, which directly subtracts the reference from the collected image; (2) Two-point correction, which uses two referenced intensities to derive a linear curve to predict the original pixel intensities; (3) Polynomial fitting, which uses multiple reference intensities to derive a nonlinear curve to predict the original pixel intensities. We found the third method is the most effective. Their technical details and corresponding experimental results are documented in the thesis.

A thesis submitted to the Faculty of Science, University of the Witwatersrand, Johannesburg, in the fulfilment of the requirements for the degree of Master of Science, 2020
Alteration within the Witwatersrand Basin has been of great interest and widely researched for many years with a focus on depositional and post-depositional processes that lead to the occurrence of the alteration. Numerous methodologies are used to investigate alteration of orebodies globally however hyperspectral scanning is a relatively new methodology that is gradually being introduced to determine the mineralogical characteristics of borehole core and hand specimens. Spectral scanning is quicker than using conventional and time-consuming methods such as petrological studies and geochemical analyses. A quantitative analysis of alteration within the Carbon Leader Reef in the AngloGold Ashanti West Wits Line Goldfield was carried out using several methodologies including macroscopic observations, petrology, geochemical analyses, gold assay as well as shortwave infrared reflectance spectroscopy (hyperspectral scanning). These methodologies were undertaken to better understand alteration and the associated gold grade across the West Wits Line (comprising Savuka Mine in the west, TauTona Mine in the east and Mponeng Mine south of Savuka and TauTona Mines). The immediate overlying hangingwall and underlying footwall units were also investigated. A comparison of the methodologies confirmed that more than one alteration event has occurred. This was noticeable in thin section and was verified by means of spectral scanning. A combination of rounded grains including gold, pyrite, chromite, uraninite and zircon were noted throughout the Carbon Leader Reef as well as within the hangingwall/footwall units and were suggestive of a detrital origin. Euhedral grains of tourmaline and pyrite were noted in a few of the reef samples representative of the north-east to central areas of the West Wits Line. Euhedral pyrite grains were seen in samples where pyrite had recrystallised and developed on the outer edges of a pre-existing detrital pyrite grain. Rounded to sub-rounded inclusions of gold and chalcopyrite within euhedral pyrite grains were also observed in thin section, suggestive of a secondary origin for the recrystallised pyrite, gold and chalcopyrite. Rutile that has undergone hydrothermal alteration results in the forming of leucoxene. Anhedral to euhedral grains of leucoxene were noted throughout the Carbon Leader Reef samples, further confirming that (secondary) hydrothermal alteration has taken place. Carbon (masses/flyspeck) was often noted to occur within the reef associated with leucoxene and rutile, and in a few samples associated with detrital gold and uraninite. Carbon was also noted to occur, infilling fractures or veinlets within uraninite grains. The close association of carbon with detrital uraninite grains suggests remobilisation of carbon has occurred. Carbon infilling fractures within uraninite grains suggests the carbon was introduced after the deposition of the uraninite grains. The spectral scanning data revealed variations in the alteration mineralogy. In most of the samples there was a dominant alteration mineral, with lesser amounts of different alteration products cross-cutting each facies type. This suggested that the alteration involved complex processes, possibly related to multiple injections of fluid phases during post-depositional fluid fluxes through the sedimentary package. This also suggested that several hydrothermal fluid (alteration) events may have taken place to alter the mineralogy of the host rock over a period of time. The rounded clasts within the samples suggest transportation from a source area has occurred. Following deposition, several pulses of hydrothermal fluids through time altered the mineralogy of the host rock, allowing for the formation of secondary mineral phases such as rutile, tourmaline and recrystallised pyrite. At the AngloGold Ashanti West Wits Line, a Carbon Leader Reef facies model based on three facies types (the No. 1 Facies, No. 2 Facies and No. 3 Facies) is used to differentiate between sedimentological variations as well as the occurrence of carbon within the Carbon Leader Reef. The facies model however does not provide much information on the mineralisation within the Carbon Leader Reef. As a result, the Carbon Leader Reef estimation domain model was developed and implemented by AngloGold Ashanti at its West Wits Line. The estimation domain model encompasses Carbon Leader Reef mineralogical characteristics, alteration mineralogy, sedimentology facies, structural influences as well as trend analyses with the variations of grade and channel width. The estimation domain model however does not account for the occurrence or absence of carbon within the Carbon Leader Reef. The current research findings suggest that variations in the mineralogy of the Carbon Leader Reef do not align fully with the Carbon Leader Reef facies model nor with the Carbon Leader Reef estimation domain model. A new Carbon Leader Reef facies model, specific to the West Wits Line, has been proposed to include a No. 3 Facies sub-type. The No. 3 Facies sub-type was based on samples that did not align fully with the No. 3 Facies definitions (i.e. samples with a thin basal carbon seam and/or higher than average gold grades of the No. 3 Facies). The samples used within this research also indicated that the TauTona, Driefontein and Peggy estimation domains need to be re-evaluated and revised on a continuous basis as more information becomes available. Using the results from the various methodologies applied in this research, three major alteration zones have been identified based on alteration styles including: pyrophyllitic alteration, chloritisation and sericitic alteration. The pyrophyllitic alteration zone was based on pyrophyllite as a major alteration mineral and extended from the north-eastern to the southern portion of TauTona Mine. The chloritisation zone, based on a combination of chlorite and chloritoid as the major alteration minerals, extended across the West Wits Line from east to west. The sericitic alteration zone, based on sericitic muscovite as a major alteration mineral, exhibited was similar distribution range to that covered to the chloritisation zone, however, it extended further north-east and further south than the chloritisation zone. The pyrophyllitic alteration zone was noted to coincide with the Pretorius Fault Zone. The zone of chloritisation was noted to coincide with frequent, smaller faults and fewer intrusions, and the sericitic alteration zone was noted to coincide with a frequent occurrence of intrusions with lesser faults. Based on geothermometric techniques, an estimated timeline for alteration was proposed. It was suggested that the Pretorius Fault Zone pre-dates the occurrence of the smaller and more frequent faulting events with fewer intrusions. The youngest events correspond to abundant intrusions associated with lesser faulting. Overall, this suggested that the intrusions are younger than the faults across the West Wits Line, with the Pretorius Fault Zone having occurred before the smaller faults and associated intrusions. Spectral scanning was able to assist in determining alteration within the host rock as reliably as petrological and geochemical analyses. However, spectral scanning could not accurately predict gold grade within the Carbon Leader Reef or the hangingwall and footwall units. Spectral scanning presents accurate results, and this contributes to the easy identification of sedimentological contacts where macroscopic observations are not as obvious. Analysis of the alteration within the Carbon Leader Reef, as well as the hangingwall and footwall units, showed that there was very little correlation between alteration type and the associated gold grade. The presence of organic matter (i.e. carbon) in samples is commonly noted to affect the spectral scanning outcomes. Additional research should be carried out using a reef, such as the Ventersdorp Contact Reef, that is non-carbon bearing to determine if there is a correlation between alteration type and associated gold, where the presence of carbon cannot influence the alteration readings of the spectral scans. The presence of carbon and/or uraninite within the host rock, however, was a consistent indicator for the presence of gold grade. Based on these results, it could be concluded that favourable gold grade is independent of the type of alteration and is more dependent on the presence of carbon and/or uraninite within the host rock
CK2021