The Characterization and Quantitative Analysis of Clay Minerals in the Athabasca Basin, Saskatchewan: Application of Shortwave Infrared Reflectance Spectroscopy

Abstract

The application of shortwave infrared (SWIR) reflectance spectroscopy to the characterization of clay minerals in the Athabasca Basin, in Saskatchewan, has been evaluated by detailed examination of 70 mineral separates (20 of kaolinite, 10 of dickite, 19 of illite, 16 of chlorites and 5 of magnesiofoitite). Clay minerals in the Athabasca Basin are widespread in the sandstones and are particularly abundant in alteration haloes associated with unconformity-type U deposits. SEM, TEM, XRD, EMPA, EPR and SWIR analyses confirm that dickite is a major clay mineral in the sandstones. Kaolinite from different geological settings has distinct values of crystallinity (i.e., Hinckley index in the range 0.84 to 1.61 in alteration haloes, 0.45 to 0.7 in the bleached zones of the paleoregolith, and 0.12 to 0.31 in late fractures and cavities). The SWIR reflectance spectroscopy is capable of quantitatively estimating the crystallinity of kaolinite by using a "14SP Index". Attempts to use SWIR reflectance spectroscopy for structural and compositional analysis of Athabasca illite and sudoite were complicated by the common occurrence of impurities in these minerals. Binary and ternary mixtures using well-characterized mineral standards reveal that SWIR reflectance spectroscopy is capable of identifying clay minerals at abundances as low as 1 wt%. Also, numerical relationships between spectral features and the abundances of clay minerals have been established from the muscovite -kaolinite, muscovite -dickite and muscovite -sudoite mixtures, and have been used to improve an empirical SWIR method for quantitative analysis of clay minerals in the Athabasca Basin. The estimated precision and accuracy of the improved empirical method are between 5 to 10%, comparable to those of conventional XRD methods. The detection limits of the SWIR method for samples containing multiple species of clay minerals are approximately 5 wt.% in relative abundance.Keywords: shortwave infrared reflectance spectroscopy, clay minerals, alteration assemblages, uranium deposits, Athabasca Basin, Saskatchewan. SOMMAIRENous avons évalué l'applicabilité de la spectroscopie par réflectance dans l'infra-rouge à ondes courtes (SWIR) pour caractériser les argiles du bassin d'Athabasca, au Saskatchewan, en utilisant soixante-dix concentrés (20 de kaolinite, 10 de dickite, 19 d'illite, 16 de chlorites et 5 de magnésiofoïtite). Les argiles sont répandues dans les grès du bassin d'Athabasca Basin, et surtout dans les auréoles d'altération associées aux gisements d'uranium localisés près d'une non-conformité. Les analyses par microscopie électronique à balayage et à transmission, par diffraction X, par microsonde électronique et par SWIR confirment que la dickite est une phase majeure dans les grès. La kaolinite provenant de divers contextes géologiques possède des valeurs distinctes de cristallinité (i.e., indice de Hinckley dans l'intervalle de 0.84 à 1.61 dans les auréoles d'altération, de 0.45 à 0.7 dans les zones lessivées du paléorégolithe, et de 0.12 à 0.31 ...

Characterization of sol–gel-derived nano-particles separated from oil sands fine tailings

“…The data for the finer solids obtained from the washing of bitumen do not appear to correlate with the data for other samples. The fact that the surface area increases with decrease in iron content suggests the agglomeration of finer particles by iron oxides thus supporting the theory of the cementation of clay particles by amorphous oxides [2,29]. Magnesium and potassium are significant components of both finer as well as coarser solids.…”

“…Elemental content of these solids suggests that compared with extracted residual coarser fraction, finer solids obtained by the sol Á/gel processing of the extracts and suspensions may be enriched with clay minerals as indicated from their Si and Al contents which fall in the range of clay minerals [29]. The presence of greater amounts of silica minerals, such as quartz in the extracted coarser solids fraction, accounts for higher levels of silica in these solids.…”

“…A sample of amorphous silica was prepared for comparison using a published procedure [17]. 29 Si NMR spectra were recorded at 40 MHz on a TecMag Apollo series spectrometer. Samples were spun at 4.5 kHz in zirconia rotors in a Doty 7 mm MASS probe.…”

“…Fig. 3 shows the 29 Si MAS NMR spectra of ultrafine solid samples listed in Table 1. Except sample F5, all the samples show a broad resonance at Â/(/98 ppm ( Fig.…”

Natural Radiation-Induced Damage in Quartz. I. Correlations Between Cathodoluminence Colors and Paramagnetic Defects

“…However, questions remain about the nature of alpha-particle-induced radiation damage in quartz and the origin of the characteristic CL in the radiation-damaged halos (and rims) in this mineral. The Mesoproterozoic Athabasca basin of northern Saskatchewan is home to several world-class uranium deposits (including the high-grade McArthur River deposit), which collectively represent approximately 30% of the global reserve of this strategic metal (Ramaekers 1981, Zhang et al 2001. As part of a broad study of cathodoluminescence (CL) in quartz from the Athabasca Basin, we noted that some samples of sandstone from the McArthur River deposit are characterized by well-developed radiation-damage-induced CL, which occurs not only as halos surrounding included U-and Th-bearing minerals (e.g., uraninite, zircon and fl uorapatite), but also as patches or a continuous rim along the grain boundaries and fractures (see also Meunier et al 1990;Götze et al 2001).…”