Biogenic spherical magnetite and coffinite from a sandstone-type uranium deposit in the Dongsheng area
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 δ34S, calcite δ13C 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 δ34S values, and calcite cement has petroleum-derived CO2. 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.
H.Li C.Cai K.Li X.Luo
Key lab of Mineral Resources, Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing, PR China
国际会议
第十二届水-岩相互作用国际研讨会(P0roceedings of the 12th International Symposium on Water-Rock Interaction)
昆明
英文
881-885
2007-07-31（万方平台首次上网日期，不代表论文的发表时间）