Late Archean rise of aerobic microbial ecosystems
Late Archean rise of aerobic microbial ecosystems
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DOI：
10.1073/pnas.0607540103
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发表时间：
2006-10-24
影响因子：
11.1
通讯作者：
Freeman, Katherine H.
中科院分区：
文献类型：
--
作者：
Eigenbrode, Jennifer L.;Freeman, Katherine H.
本文报道了西澳大利亚哈默斯利省1.5亿年前的晚太古代浅海和深水沉积物中保存的有机碳C-13含量。我们发现，相对于深水沉积物，27亿年后的浅水碳酸盐岩有机碳中C-13的富集量约为千分之十。浅水有机碳C-13的含量范围为29‰（-57‰至-28‰），与深水沉积物中变化较小但C-13消耗较强的有机碳（-40‰至-45‰）形成对比。C-13的富集可能表明微生物栖息地不受甲烷或其他C-13耗尽底物同化的强烈影响。我们认为，浅层环境的持续氧化有利于有氧生态系统和呼吸生物的扩展，因此，浅层环境中保存的有机碳同位素特征接近光合生物量的同位素特征。对已发表的碳同位素记录的相分析表明，哈默斯利浅水信号可能是太古宙晚期全球特征的代表，它先于类似的深海沉积物，但延迟了C-13富集。这些数据表明，在24.5亿年前的大气氧化之前，全球范围内含氧栖息地的扩张伴随着从厌氧生态系统向由含氧光合作用推动的呼吸微生物群落的进展。
We report the C-13 content of preserved organic carbon for a 150 million-year section of late Archean shallow and deepwater sediments of the Hamersley Province in Western Australia. We find a C-13 enrichment of approximate to 10 parts per thousand in organic carbon of post-2.7-billion-year-old shallow-water carbonate rocks relative to deepwater sediments. The shallow-water organic-carbon C-13 content has a 29 parts per thousand range in values (-57 to -28 parts per thousand), and it contrasts with the less variable but strongly C-13-depleted (-40 to -45 parts per thousand) organic carbon in deepwater sediments. The C-13 enrichment likely represents microbial habitats not as strongly influenced by assimilation of methane or other C-13-depleted substrates. We propose that continued oxidation of shallow settings favored the expansion of aerobic ecosystems and respiring organisms, and, as a result, isotopic signatures of preserved organic carbon in shallow settings approached that of photosynthetic biomass. Facies analysis of published carbon-isotopic records indicates that the Hamersley shallow-water signal may be representative of a late Archean global signature and that it preceded a similar, but delayed, C-13 enrichment of deepwater deposits. The data suggest that a global-scale expansion of oxygenated habitats accompanied the progression away from anaerobic ecosystems toward respiring microbial communities fueled by oxygenic photosynthesis before the oxygenation of the atmosphere after 2.45 billion years ago.