铁对有机碳的长期保存及古海洋极端事件响应

Long-term preservation of organic carbon by iron and its response to paleo-marine extreme events

  • 摘要: 海洋表层沉积物有机碳超20%以铁结合态有机碳(Fe-OC)的形式保存,深入分析Fe-OC的长期保存及其对古海洋极端事件的响应对理解全球碳循环和气候变化具有重要意义。本文梳理了海洋沉积物中Fe-OC的结合和释放机制及其导致的组成分异、区域分布特征及成岩作用对Fe-OC长期稳定性的影响,并探讨了古元古代大氧化事件、新元古代“雪球地球”事件、中生代海洋缺氧事件及第四纪冰期-间冰期旋回对Fe-OC形成与长期保存的潜在影响。研究发现,Fe-OC的富集受沉积环境诸多因素的控制,其中铁的氧化还原过程是关键因素,对Fe-OC具有保存和降解的双重作用。古海洋极端事件通过改变铁的氧化还原循环及其与有机碳的相互作用对Fe-OC形成及长期保存产生潜在影响。

     

    Abstract: Over 20% of organic carbon in marine surface sediments is preserved as iron-bound organic carbon (Fe-OC), and comprehensive analysis of its long-term preservation and responses to paleo-oceanic extreme events holds significant implications for understanding global carbon cycling and climate change. We reviewed the binding/release mechanisms of Fe-OC in marine sediments, compositional differentiation, regional distribution patterns, and the influence of diagenesis on the long-term stability of Fe-OC in marine sediments, and explored the potential influences of major geological events—the Great Oxidation Event of the Paleoproterozoic, the Neoproterozoic "Snowball Earth" event, Mesozoic oceanic anoxic events, and Quaternary glacial-interglacial cycles—on the formation and long-term preservation of Fe-OC. in addition, we revealed that the enrichment of Fe-OC was controlled by various factors in sedimentary environments, in which redox processes of iron played a critical role and had dual effects of preservation and degradation on Fe-OC. Paleo-oceanic extreme events likely modulated Fe-OC dynamics by altering iron redox cycling and its interactions with organic carbon.

     

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