Carbonate formation by anaerobic oxidation of methane : Evidence from lipid biomarker and fossil 16S rDNA
Carbonate formation by anaerobic oxidation of methane : Evidence from lipid biomarker and fossil 16S rDNA
复制标题
DOI：
10.1016/j.gca.2008.01.020
复制
发表时间：
2008-04
影响因子：
5
通讯作者：
A. Stadnitskaia;D. Nadezhkin;B. Abbas;V. Blinova;M. Ivanov;J. Damsté
中科院分区：
文献类型：
--
作者：
A. Stadnitskaia;D. Nadezhkin;B. Abbas;V. Blinova;M. Ivanov;J. Damsté
碳酸盐烟囱和其他碳酸盐结构在加迪斯湾广泛存在，可能反映了地质历史中存在的冷泉和相关的甲烷释放，可能是在早更新世，但目前还不清楚这些碳酸盐是在什么条件下形成的，是通过什么过程形成的。我们研究了从墨西哥湾基德泥火山收集的与甲烷有关的碳酸盐地壳化石。微生物脂质的浓度，其稳定的碳同位素组成，结合矿物学和碳酸盐的碳和氧同位素组成的厌氧甲烷古菌的化石16 S rRNA基因序列的地壳的7个不同的层位。有机和无机地球化学技术与分子生态学方法相结合，使人们对地壳的形成过程有了一致的看法，并表明地壳的形成分为两个阶段，而且是向下的。古生物脂类生物标志物和化石16 S rRNA基因序列数据揭示了古细菌ANME-2组的优势和地壳顶部形成过程中甲烷分压的升高。碳酸盐的下部可能是在甲烷通量减少的环境中形成的，这一点由ANME-1古菌化石遗骸的优势所揭示。这些方法的结合可以作为一个有效的工具，重建在前所未有的细节古地球化学过程导致的碳酸盐岩组构的形成。这种跨学科的策略也可以应用于其他化石甲烷衍生的碳酸盐，产生新的概念和知识，过去甲烷相关的碳酸盐系统。
Carbonate chimneys and other carbonate structures occur widespread in the Gulf of Cadiz and probably reflect the presence of cold seeps and associated release of methane in the geological past, possibly in the Early Pleistocene, but it is unclear under what conditions and by which processes these carbonates were formed. We studied a fossil methane-related carbonate crust collected from the Kidd mud volcano in the gulf. Concentrations of microbial lipids, their stable carbon isotope composition, sequences of fossil 16S rRNA genes of anaerobic methanotrophic archaea in combination with mineralogical and carbon and oxygen isotopic composition of carbonate were obtained for seven different horizons of the crust. This combination of organic and inorganic geochemical techniques with molecular ecological methods gave a consistent view on processes resulting in the formation of the crust and indicated that it took place in two phases and in a downward direction. Archaeal lipid biomarkers and fossil 16S rRNA gene sequence data revealed the dominance of archaeal ANME-2 group and elevated methane partial pressures during the formation of the top part of the crust. The lower part of the carbonate was likely formed in an environment with reduced methane fluxes as revealed by the dominance of fossil remains of ANME-1 archaea. The combination of these methods can be used as an effective tool to reconstruct in unprecedented detail the palaeo-biogeochemical processes resulting in the formation of carbonate fabrics. This interdisciplinary strategy may also be applied for other fossil methane-derived carbonates, generating new concepts and knowledge about past methane-related carbonate systems.