Lipids of sulfate-reducing bacteria and sulfur-oxidizing bacteria found in the Dongsheng uranium deposit  

作　　者：JIANG Lei CAI ChunFang ZHANG YongDong MAO ShengYi SUN YongGet LI KaiKai XIANG Lei ZHANG ChunMing 

机构地区：[1]Key Laboratory of Petroleum Resources Research,Institute of Geology and Geophysics,Chinese Academy of Sciences,Beijing 100029,China [2]Graduate University of Chinese Academy of Sciences,Beijing 100049,China [3]State Key Laboratory of Organic Geochemistry,Guangzhou Institute of Geochemistry,Chinese Academy of Sciences,Guangzhou 510640,China [4]Department of Earth Science,Zhejiang University,Hangzhou 310027,China [5]Department of Geochemistry,Yangtze University,Jingzhou 434023,China

出　　处：《Chinese Science Bulletin》2012年第11期1311-1319,共9页

基　　金：supported by the Knowledge Innovation Program of the Chinese Academy of Sciences (KZCX2-YW-JC102);National Basic Research Program of China (2011CB808800)

摘　　要：U-bearing sandstones from the Dongsheng deposit in Ordos Basin contain abundant C15-C18 fatty acids. The fatty acids may have been derived from modern and ancient organisms including organisms from the intervals of U mineralization. A certain amount of i15:0, a15:0, a17:0 fatty acids coexist with small amounts of i17:1ω7c and 10me16:0, characteristic biomarkers of Desulfovibrio and Desulfobacter sp., respectively. This indicates the existence of sulfate-reducing bacteria (SRB) in the sandstones. The presence of sulfur-oxidizing bacteria (SOB), such as Beggiatoa and Thioploca, is indicated by significant amounts of 16:1ω7c and 18:1ω7c fatty acids. The existence of the SRB in the deposit, as inferred from the fatty acids, is consistent with results from fossilized microorganisms and isotopic compositions of ore-stage pyrite. This suggests that the environment may have been favorable for the SRB to grow since ore formation (9.8-22 Ma). The bacteria may have degraded hydrocarbons directly, or indirectly utilized hydrocarbons degraded by oxic microbes in the deposits. This process may have produced 12C-rich calcite and prominent baseline humps of unresolved complex mixtures (UCM), and 25-demethylated hopanes and tricyclic terpanes. The existence of sulfur-oxidizing bacteria and sulfate-reducing bacteria in the deposit may have resulted in bacterial sulfate reduction to sulfide, re-oxidization of the sulfide to sulfate and subsequent reduction of the sulfate to sulfide. This assertion is supported by ore-stage pyrite with δ34S values as low as-39.2‰, and the lightest sulfate (about 11‰) measured during the Phanerozoic, a difference of more than 46‰.U-bearing sandstones from the Dongsheng deposit in Ordos Basin contain abundant C15-C18 fatty acids. The fatty acids may have been derived from modem and ancient organisms including organisms from the intervals of U mineralization. A certain amount of i15：0, a15：0, a17：0 fatty acids coexist with small amounts of i17：1o37c and 10reel6：0, characteristic biomarkers of Desulfovibrio and Desulfobacter sp., respectively. This indicates the existence of sulfate-reducing bacteria （SRB） in the sandstones. The pres- ence of sulfur-oxidizing bacteria （SOB）, such as Beggiatoa and Thioploca, is indicated by significant amounts of 16：1co7c and 18：1co7c fatty acids. The existence of the SRB in the deposit, as inferred from the fatty acids, is consistent with results from fos- silized microorganisms and isotopic compositions of ore-stage pyrite. This suggests that the environment may have been favora- ble for the SRB to grow since ore formation （9.8-22 Ma）. The bacteria may have degraded hydrocarbons directly, or indirectly utilized hydrocarbons degraded by oxic microbes in the deposits. This process may have produced 12C-rich calcite and prominent baseline humps of unresolved complex mixtures （UCM）, and 25-demethylated hopanes and tricyclic terpanes. The existence of sulfur-oxidizing bacteria and sulfate-reducing bacteria in the deposit may have resulted in bacterial sulfate reduction to sulfide, re-oxidization of the sulfide to sulfate and subsequent reduction of the sulfate to sulfide. This assertion is supported by ore-stage pyrite with δ^34S ValUeS as low as -39.2%, and the lightest sulfate （about 11%） measured during the Phanerozoic, a difference of more than 46%.

关 键 词：硫酸盐还原菌 硫氧化细菌 铀矿床 不饱和脂肪酸 微生物降解 碳氢化合物 脂类 鄂尔多斯盆地 

分 类 号：P619.14[天文地球—矿床学]