Molecular and isotopic composition of free hydrocarbon gases from Sicily, Italy
Molecular and isotopic composition of free hydrocarbon gases from Sicily, Italy
复制标题
意大利西西里岛游离烃气体的分子和同位素组成
DOI：
10.1029/2003gl019362
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发表时间：
2004
影响因子：
5.2
通讯作者：
M. Valenza
中科院分区：
文献类型：
--
作者：
F. Grassa;G. Capasso;R. Favara;S. Inguaggiato;E. Faber;M. Valenza
化学和同位素数据已被用作地球化学示踪剂的烃类气体的成因特性，从位于东部和中部-南部西西里（意大利）的11个表现。分子分析表明，几乎所有的样品都富含甲烷（高达93.2%体积），除了四个气体样本收集周围山。埃特纳显示出高地幔来源的二氧化碳含量。甲烷同位素特征表明，这些是热成因气体或热成因气体和微生物气体之间的混合物。虽然从南西西里（Macalube di Aragona）的一些泥火山中提取的样品显示出的同位素特征与热成因和微生物之间的混合模型一致，但通过结合分子组成（C1/（C2 + C3））和甲烷同位素比率（δ 13 C1），似乎排除了这种过程。因此，应援引继发性遗传后过程的发生。考虑了两个主要假设：第一个假设包括气体是由微生物活动产生的，并通过甲烷的微生物氧化进行了后遗传改变，而根据第二个假设，产热气体由于垂直迁移而改变了它们的分子比例。
Chemical and isotopic data have been used as geochemical tracers for a genetic characterization of hydrocarbon gases from a total of eleven manifestations located in Eastern and Central‐Southern Sicily (Italy). The molecular analysis shows that almost all the samples are enriched in methane (up to 93.2% Vol.), with the exception of four gas samples collected around Mt. Etna showing high mantle‐derived CO2 content. Methane isotope signatures suggest that these are thermogenic gases or a mixture between thermogenic gases and microbial gases. Although samples from some mud volcanoes in Southern Sicily (Macalube di Aragona) show isotope signatures consistent with a mixing model between thermogenic and microbial, by combining the molecular compositions (C1/(C2 + C3)) and the methane isotope ratios (δ13C1), such a process seems to be excluded. Therefore, the occurrence of secondary post‐genetic processes should be invoked. Two main hypotheses have been considered: the first hypothesis includes that the gas is produced by microbial activity and altered post‐genetically by microbial oxidation of methane, while according to the second hypothesis thermogenic gas have modified their molecular ratios due to vertical migration.