ANAEROBIC OXIDATION OF PETROLEUM COUPLED WITH REDUCTION OF URANIUM MINERALIZATION -CASES FROM DONGSHENG AND QIANJIADIAN URANIUM DEPOSITS
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摘要: 鄂尔多斯盆地东胜和开鲁盆地钱家店铀矿床砂岩主岩中包裹体和吸附的石油烃含有丰富的25-降藿烷和去甲基三环萜烷系列,为生物所降解的产物;主岩具有黄铁矿、碳酸盐胶结物与铀石或沥青铀矿紧密共生的现象;黄铁矿为生物成因,其δ34S分别为-39‰~17‰和-44.5‰~-31.40‰;碳酸盐胶结物含有来自油气碳的特征,其δ13C分别为-27.5‰~0.3‰和-21‰~-4‰;而铀石具有微化石结构。于是,提出了硫酸盐还原菌或与其它微生物共同将油气厌氧氧化的同时,将硫酸盐、六价铀还原,形成黄铁矿和四价铀矿床。Abstract: Host sandstones in Dongsheng and Qianjiadian deposits contain hydrocarbons inclusions and absorbed oils.The oils contain abundant 25-norhopanes and tricyclic terpanes,indicating that oils were heavily biodegraded.The host sandstones show intimate intergrowth of coffinite or pitchblende with secondary pyrite and carbonate cement.The pyrite is biogenic,as defined by low δ34S values from -39‰ to 17‰,and from -44.5‰ to -31.40‰ in the Dongsheng and Qiajiandian deposit,respectively.The carbonate cement has carbon derived from petroleum oxidation as indicated by its δ13C values from -27.5‰ to 0.3‰,and from -21‰ to -4‰,respectively.The coffinite shows microorganism-like structure.Based on the data,we proposed that sulphate reducing bacteria alone or using other kinds of bacteria oxidized petroleum simultaneously and reducd sulphates and U(Ⅵ) to generate pyrite and uranium U(Ⅳ) deposits.
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