Experimental diagenesis of organo-mineral structures formed by microaerophilic Fe(II)-oxidizing bacteria
Experimental diagenesis of organo-mineral structures formed by microaerophilic Fe(II)-oxidizing bacteria
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DOI：
10.1038/ncomms7277
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发表时间：
2015-02
影响因子：
16.6
通讯作者：
A. Picard;A. Kappler;Gregor Schmid;L. Quaroni;M. Obst
中科院分区：
文献类型：
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作者：
A. Picard;A. Kappler;Gregor Schmid;L. Quaroni;M. Obst
扭曲茎是某些嗜气Fe（II）氧化菌在低至3 μM的o2浓度下产生的有机矿物结构。这些结构在经历了成岩历史的岩石中的存在可以表明微生物的铁（II）氧化活性以及沉积物沉积时的局部氧丰度。在这里，我们使用光谱学和分析显微镜来评估是否以及什么样的转化发生在扭曲秸秆通过实验成岩作用。随着温度和压力条件的增加，秸秆上出现了独特的矿物纹理。赤铁矿和磁铁矿在170℃- 120 MPa下由铁水合矿形成。然而，在250℃- 140 MPa下，茎秆的扭曲形态和主要由长链饱和脂肪族化合物组成的有机基质得以保存。我们的研究结果表明，铁矿物可能在维持成岩条件下茎秆的结构和化学完整性方面发挥了作用，并为在岩石记录中寻找古代生命提供了光谱特征。
Twisted stalks are organo-mineral structures produced by some microaerophilic Fe(II)-oxidizing bacteria at O2concentrations as low as 3 μM. The presence of these structures in rocks having experienced a diagenetic history could indicate microbial Fe(II)-oxidizing activity as well as localized abundance of oxygen at the time of sediment deposition. Here we use spectroscopy and analytical microscopy to evaluate if—and what kind of—transformations occur in twisted stalks through experimental diagenesis. Unique mineral textures appear on stalks as temperature and pressure conditions increase. Haematite and magnetite form from ferrihydrite at 170 °C–120 MPa. Yet the twisted morphology of the stalks, and the organic matrix, mainly composed of long-chain saturated aliphatic compounds, are preserved at 250 °C–140 MPa. Our results suggest that iron minerals might play a role in maintaining the structural and chemical integrity of stalks under diagenetic conditions and provide spectroscopic signatures for the search of ancient life in the rock record.