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Hebert, B.; Baron, F.; Robin, V.; Lelievre, K.; Dacheux, N.; Szenknect, S.; Mesbah, A.; Pouradier, A.; Jikibayev, R.; Roy, R.; Beaufort, D. |
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Title |
Quantification of coffinite (USiO4) in roll-front uranium deposits using visible to near infrared (Vis-NIR) portable field spectroscopy |
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Journal Article |
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2019 |
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Journal of Geochemical Exploration |
Abbreviated Journal |
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199 |
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53-59 |
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Coffinite, Mineral quantification, Near infrared, Ore exploration, Portable field spectroscopy, Roll-front deposits |
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Abstract |
Coffinite (USiO4) is a common uranium-bearing mineral of roll-front uranium deposits. This mineral can be identified by the visible near infrared (Vis-NIR) portable field spectrometers used in mining exploration. However, due to the low detection limits and associated errors, the quantification of coffinite abundance in the mineralized sandstones or sandy sediments of roll-front uranium deposits using Vis-NIR spectrometry requires a specific methodological development. In this study, the 1135 nm absorption band area is used to quantify the abundance of coffinite. This absorption feature does not interfere with NIR absorption bands of any other minerals present in natural sands or sandstones of uranium roll-front deposits. The correlation between the 1135 nm band area and coffinite content was determined from a series of spectra measured from prepared mineral mixtures. The samples were prepared with a range of weighted amounts of arenitic sands and synthetic coffinite simulating the range of uranium concentration encountered in roll-front uranium deposits. The methodology presented in this study provides the quantification of the coffinite content present in sands between 0.03 wt% to 1 wt% coffinite with a detection limit as low as 0.005 wt%. The integrated area of the 1135 nm band is positively correlated with the coffinite content of the sand in this range, showing that the method is efficient to quantify coffinite concentrations typical of roll-front uranium deposits. The regression equation defined in this study was then used as a reference to predict the amount of natural coffinite in a set of mineralized samples from the Tortkuduk uranium roll-front deposit (South Kazakhstan). |
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0375-6742 |
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THL @ christoph.kuells @ hebert_quantification_2019 |
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184 |
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Bullock, L.A.; Parnell, J. |
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Selenium and molybdenum enrichment in uranium roll-front deposits of Wyoming and Colorado, USA |
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Journal Article |
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2017 |
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Journal of Geochemical Exploration |
Abbreviated Journal |
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180 |
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101-112 |
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Molybdenum, Roll-fronts, Selenium, Tellurium, Uranium, Wyoming |
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Sandstone uranium (U) roll-front deposits of Wyoming and Colorado (USA) are important U resources, and may provide a terrestrial source for critical accessory elements, such as selenium (Se), molybdenum (Mo), and tellurium (Te). Due to their associated toxicity, MoSeTe occurrences in roll-fronts should also be carefully monitored during U leaching and ore processing. While elevated MoSe concentrations in roll-fronts are well established, very little is known about Te occurrence in such deposits. This study aims to establish MoSeTe concentrations in Wyoming and Colorado roll-fronts, and assess the significance of these deposits in an environmental and mineral exploration context. Sampled roll-front deposits, produced by oxidized groundwater transportation through a sandstone, show high MoSe content in specific redox zones, and low Te, relative to crustal means. High Se concentrations (up to 168ppm) are restricted to a narrow band of alteration at the redox front. High Mo content (up to 115ppm) is typically associated with the reduced mineralized nose and seepage zones of the roll-front, ahead of the U orebody. Elevated trace element concentrations are likely sourced from proximal granitic intrusions, tuffaceous deposits, and local pyritic mudstones. Elevated MoSe content in the sampled roll fronts may be regarded as a contaminant in U in-situ recovery and leaching processing, and may pose an environmental threat in groundwaters and soils, so extraction should be carefully monitored. The identification of peak concentrations of MoSe can also act as a pathfinder for the redox front of a roll-front, and help to isolate the U orebody, particularly in the absence of gamma signatures. |
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THL @ christoph.kuells @ bullock_selenium_2017 |
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189 |
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Rubin, R. |
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Water conservation methods in Israel’s Negev desert in late antiquity |
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1988 |
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Journal of Historical Geography |
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14 |
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3 |
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229-244 |
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Settlement in Israel’s Negev desert historically has been dependent on water conservation techniques. Fieldwork carried out on settlement sites constructed during the Byzantine period, when agriculture and trade flourished, revealed a variety of water installations some of which are in use today. Perennial springs in the Negev are generally small and difficult of access. Cisterns were the most common conservation devices and came in both large, enclosed and single, open forms. Cisterns were common particularly in the towns, where they were usually built as part of house foundations. Dams were discovered at several sites but proved to be inefficient and easily abandoned because of evaporation and siltation problems. Public reservoirs were part of the structure of the largest towns and were open and among the larges structures uncovered at settlement sites. Wells were distributed widely throughout the desert and were part of the only conservation system that did not depend directly on surface rainfall. A qanat system was located in the eastern Negev dating from the late settlement period before the area was abandoned at the turn of the eighth century. These various water systems raise questions about their builders and their origins, and suggests that builders originating in more humid Mediterranean environments tended to produce less adaptable installations than builders derived from the south or the east. |
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0305-7488 |
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THL @ christoph.kuells @ Rubin1988229 |
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262 |
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Morin, E.; Grodek, T.; Dahan, O.; Benito, G.; Külls, C.; Jacoby, Y.; Van Langenhove, G.; Seely, M.; Enzel, Y. |
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Flood routing and alluvial aquifer recharge along the ephemeral arid Kuiseb River, Namibia |
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2009 |
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Journal of Hydrology |
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368 |
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1-4 |
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262-275 |
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THL @ christoph.kuells @ Morin2009flood |
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26 |
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Klaus, J.; Külls, C.; Dahan, O. |
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Evaluating the recharge mechanism of the Lower Kuiseb Dune area using mixing cell modeling and residence time data |
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2008 |
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Journal of Hydrology |
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358 |
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3-4 |
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304-316 |
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THL @ christoph.kuells @ Klaus2008evaluating |
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