Formation des gisements d'uranium de type roll : approche minéralogique et géochimique du gisement uranifère de Muyunkum (Bassin de Chu-Sarysu, Kazakhstan)

Abstract : Roll front ore U-ore deposits in the Chu-Sarysu basin (Kazakhstan) occur in paleogene, continental silicoclastic formations. Sedimentary sequences include unconsolidated arkosic sands and clay lenses, formed by detrital minerals issued from granites and calkalcaline volcanites but also from paleozoïc series from Karatau. All formations are characterized by a fine grain clay fraction dominated by smectites, associated with palygorskite which could be the result of alternated humid and dry periods. All series underwent a rather shallow burial which is indicated by the immature feature of the organic matter, the presence of newly formed unaltered smectites, and the presence of pyrite framboïds which are formed by bacterial sulphate reduction, indicated by the wide range of delta34S of pyrites. Sands are locally cemented by calcite which precipitated from meteoric fluids at low temperature. U-ores are spatially and genetically related to sulphides and organic matter, especially in levee facies at the top of the sedimentary sequence and in association with organic macro-clasts disseminated within the sand channels. Phospho-coffinites occur latter on. These deposits show similarities with those of Wyoming but differ by the size of the roll fronts front redox, the heterogeneity of the U-ores at small scale, and a probable significant pre-concentration associated with organic matter
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Theses
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http://docnum.univ-lorraine.fr/prive/DDOC_T_2012_0070_MUNARA.pdf
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https://hal.univ-lorraine.fr/tel-01749422
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Submitted on : Thursday, March 29, 2018 - 12:15:53 PM
Last modification on : Monday, April 16, 2018 - 10:41:30 AM

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  • HAL Id : tel-01749422, version 1

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Askar Munara. Formation des gisements d'uranium de type roll : approche minéralogique et géochimique du gisement uranifère de Muyunkum (Bassin de Chu-Sarysu, Kazakhstan). Sciences de la Terre. Université de Lorraine, 2012. Français. ⟨NNT : 2012LORR0070⟩. ⟨tel-01749422⟩

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