Biogenic spherical magnetite and coffinite from a sandstone-type uranium deposit in the Dongsheng area

H. Li*, C. Cai, K. Li, X. Luo

*Corresponding author for this work

    Research output: Chapter in Book/Report/Conference proceedingConference proceeding contribution

    Abstract

    Spherical magnetite and rod-shaped coffinite have been intergrown with pyrite and calcite cement in the Dongsheng sandstone-type uranium deposits. In order to assess the origin of magnetite and coffinite, the host sandstone has been analyzed for fluid inclusion oil biomarkers, pyrite δ 34S, calcite δ 13C and observed under microscope. The results show that fluid inclusion oils are characterized by "UCM" and significant amounts of 25-norhopanes, suggesting biodegradation of the oils. Sulfur in pyrite originated from bacterial sulfate reduction as indicated by low δ 34S values, and calcite cement has petroleum-derived CO 2. Coprecipitation of biogenic pyrite with calcite cement that has petroleum-derived carbon, suggests that petroleum was likely oxidized by sulfate-reducing bacteria (SRB). SRB could have depleted petroleum and reduced Fe(III) and U(VI) to Fe(II) and U(IV), respectively, by anaerobic respiration, resulting in magnetite and coffinite formation.

    Original languageEnglish
    Title of host publicationWater-Rock Interaction - Proceedings of the 12th International Symposium on Water-Rock Interaction, WRI-12
    Place of PublicationLondon
    PublisherTaylor & Francis
    Pages881-885
    Number of pages5
    Volume2
    ISBN (Print)9780415451383
    Publication statusPublished - 2007
    Event12th International Symposium on Water-Rock Interaction, WRI-12 - Kunming, China
    Duration: 31 Jul 20074 Aug 2007

    Other

    Other12th International Symposium on Water-Rock Interaction, WRI-12
    CountryChina
    CityKunming
    Period31/07/074/08/07

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