Cold seep deposits of Beauvoisin (Oxfordian; southeastern France) and Marmorito (Miocene; northern Italy): microbially induced authigenic carbonates
Cold seep deposits of Beauvoisin (Oxfordian; southeastern France) and Marmorito (Miocene; northern Italy): microbially induced authigenic carbonates
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DOI：
10.1007/s005310050246
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发表时间：
1999-05
影响因子：
2.3
通讯作者：
J. Peckmann;V. Thiel;W. Michaelis;P. Clari;C. Gaillard;L. Martire;J. Reitner
中科院分区：
文献类型：
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作者：
J. Peckmann;V. Thiel;W. Michaelis;P. Clari;C. Gaillard;L. Martire;J. Reitner
研究证实了两个著名的古碳酸盐岩沉积与油气渗漏的关系。这些化石被发现与Beauvoisin的Oxfordian渗漏碳酸盐和Marmorito的中新世石灰岩（“管虫石灰岩”）的形成有关。由古生菌介导形成的碳酸盐的δ ~（13）C值分别为极正或极负。高正值（+15‰）反映了甲烷生成产生的富含13 C的CO2的使用。Marmorito碳酸盐岩的低δ 13 C值（-30‰）表明渗漏源烃的氧化作用。同样，在这些样品中，发现特定的尾对尾连接的类异戊二烯（古生菌的生物标志物）的δ 13 C含量显著减少（低至-115‰）。同位素特征证实，古菌参与了在古老的地方渗漏源有机碳的循环。另一种中新世石灰岩（“Marmorito石灰岩”）显示出甲烷氧化细菌的强烈印记，如碳酸盐的δ 13 C值低至-40‰和生物标志物证据所示。落射荧光显微镜和场发射扫描电子显微镜显示，细菌生物膜参与碳酸盐聚集。除了透明双壳类以前报道的两个地方，我们推断，海绵Beauvoisin和管蠕虫Marmorito依赖于化学合成以及。与海绵埋藏有关的结核δ 13 C值较低（-27‰），表明海绵可能与烃氧化作用增强有关。Marmorito的管虫化石与现代冷泉中的化能合成的pogonophoran管蠕虫非常相似，并嵌入同位素轻碳酸盐（δ 13 C-30 ‰）中。
The relation of two well-known ancient carbonate deposits to hydrocarbon seepage was confirmed by this study. Archaea are found to be associated with the formation of Oxfordian seep carbonates from Beauvoisin and with a Miocene limestone from Marmorito ("tube-worm limestone"). Carbonates formed due to a mediation by archaea exhibit extremely positive or extremely negative δ13Ccarbonatevalues, respectively. Highly positive values (+15‰) reflect the use of13C-enriched CO2produced by methanogenesis. Low δ13C values of the Marmorito carbonates (–30‰) indicate the oxidation of seepage-derived hydrocarbons. Likewise, the δ13C content of specific tail-to-tail linked isoprenoids, biomarkers for archaea, was found to be strikingly depleted in these samples (as low as –115‰). The isotopic signatures corroborate that archaea were involved in the cycling of seepage-derived organic carbon at the ancient localities. Another Miocene limestone ("Marmorito limestone") shows a strong imprint of methanotrophic bacteria as indicated by δ13C values of carbonate as low as –40‰ and biomarker evidence. Epifluorescence microscopy and field-emission scanning electron microscopy revealed that bacterial biofilms were involved in carbonate aggregation. In addition to lucinid bivalves previously reported from both localities, we infer that sponges from Beauvoisin and tube worms from Marmorito depended on chemosynthesis as well. Low δ13C values of nodules related to sponge taphonomy (–27‰) indicate that sponges might have been linked to an enhanced hydrocarbon oxidation. Tube worm fossils from Marmorito closely resemble chemosynthetic pogonophoran tube worms from Recent cold seeps and are embedded in isotopically light carbonate (δ13C –30‰).