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首页> 外文期刊>Earth and Planetary Science Letters: A Letter Journal Devoted to the Development in Time of the Earth and Planetary System >Controls on the abundance, provenance and age of organic carbon buried in continental margin sediments
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Controls on the abundance, provenance and age of organic carbon buried in continental margin sediments

机译：对大陆边缘沉积物埋藏的有机碳的丰度，物质和年龄的控制

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摘要

Continental margins play a fundamental role in the carbon cycle as primary oceanic locations of organic carbon (OC) burial. However, gaps remain in our understanding of factors controlling the distribution and preservation of organic matter (OM) in these heterogeneous and dynamic systems. In particular, the impact of hydrodynamic processes on the age, abundance, and stable isotopic composition of sedimentary OC is poorly constrained. Here, we characterize the OC present in bulk and grain-size sediment fractions from seven continental margin settings. Our results reveal that hydrodynamic particle sorting processes exert a ubiquitous influence on the radiocarbon age of OC. Both, hydrodynamic characteristics of mineral particles and the nature of their interactions with OM influence sedimentary OC content, whereas no significant influence of either effect is manifested in corresponding delta(13) C values. Since OC preferentially resides within the fine silt fraction (2-8 mu m), and this fraction accounts for a substantial fraction of the bulk sediment mass, translocation and subsequent re-deposition of distant fine silt has the greatest potential to distort local OC signatures relative to those associated with clay or coarse silt fractions. We suggest that the magnitude of differences in C-14-age and OC content among grain-size fractions, determined by the interplay of hydrodynamic sorting and other site-specific processes, allow three different categories of depositional environment to be defined: initial, stable, and mature. Each domain is characterized by different degrees of vertical and lateral OC supply that reflect influences of local biological productivity and carbon export from overlying surface waters and physical forcing that drive hydrodynamic processes. This generic framework may serve as a guide to refine assessment of OC burial and to constrain the magnitude of potential aliasing among co-eval proxy signals in continental margin sedimentary sequences. (C) 2021 The Author(s). Published by Elsevier B.V.
机译：大陆边缘作为有机碳（OC）埋藏的主要海洋位置，在碳循环中发挥着重要作用。然而，在我们对这些异质和动态系统中控制有机物（OM）分布和保存的因素的理解上仍然存在差距。特别是，水动力过程对沉积有机碳的年龄、丰度和稳定同位素组成的影响很少受到限制。在这里，我们描述了来自七个大陆边缘环境的散装和粒度沉积物组分中的OC。我们的结果表明，流体动力颗粒分选过程对OC的放射性碳年龄具有普遍的影响。矿物颗粒的流体动力学特征及其与有机质相互作用的性质都会影响沉积有机碳含量，而相应的δ（13）C值并未表现出这两种影响的显著影响。由于OC优先存在于细粉砂组分（2-8μm）内，且该组分占大量沉积物质量的很大一部分，因此，与粘土或粗粉砂组分相关的OC特征相比，远距离细粉砂的迁移和随后的再沉积最有可能扭曲局部OC特征。我们认为，由流体动力分选和其他现场特定过程的相互作用决定的粒度组分之间的C-14年龄和OC含量差异的大小，允许定义三种不同类型的沉积环境：初始、稳定和成熟。每个区域的特点是垂直和横向OC供应的不同程度，反映了当地生物生产力和上覆地表水碳输出的影响，以及驱动水动力过程的物理强迫。该通用框架可作为完善OC埋藏评估的指南，并限制大陆边缘沉积层序中co eval代理信号之间潜在混叠的程度。（c）2021作者。由Elsevier B.V.出版。

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