| 海底扇沉积相模式、沉积过程及其沉积记录的指示意义 |
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| 引用本文： | 谈明轩,吴峰,马皓然,付奕霖,张旭,崔浩楠.海底扇沉积相模式、沉积过程及其沉积记录的指示意义[J].沉积学报,2022,40(2):435-449. |
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| 作者姓名： | 谈明轩 吴峰 马皓然 付奕霖 张旭 崔浩楠 |
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| 作者单位： | 1.河海大学海岸灾害及防护教育部重点实验室, 南京 210098 |
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| 基金项目： | 国家自然科学基金（42002117）；;江苏省自然科学基金（BK20200529）；;中央高校基本业务费（2019B06314）~~； |
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| 摘 要： | 海底扇是由沉积物重力流形成的海底沉积体。其分类学和相模式研究表明，海底扇主要由海底水道、溢岸及朵叶体等沉积单元构成。然而古代和现代海底扇沉积均无法由单一的通用相模式进行解释。以粒度差异所建立的相模式类型涵盖了多方面信息，相对简单实用。海底扇的触发机制主要包括海底沉积物失稳、洪水型异重流、海洋动力过程及复合成因机制等类型。海底扇的主导流体类型（碎屑流与浊流）、海底地貌形态（限制性与非限制性）及海洋动力条件（底流作用）深刻影响了海底扇的沉积作用、平面形态及空间组合特征，整体上分为三类。其中，浊流沉积主导的海底扇在非限制性海底环境中主要表现为扇状或指状形态，在限制性海底环境中则直接受控于盆地的地貌形态；碎屑流沉积主导的海底扇以块体搬运为特征，平面上表现为舌状和叶状展布形态；底流与重力流共同作用形成的混合型海底扇朵叶体沿底流流向侧向偏转，部分受底流改造沉积形成孤立漂积丘状形态。海底扇沉积物记录了环境信号从“源”到“汇”传输效率和保存程度，对构造变形和古气候变化具有重要的指示作用。人类世以来的现代海底扇沉积物同时也是深海微塑料、陆源有机碳的重要储库，定量评估其丰度特征对于环境评价、污染治理与管控及全球碳循环均具有深远的现实意义。
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| 关 键 词： | 海底扇 相模式 触发机制 沉积过程 垂向组合 指示意义 |
| 收稿时间： | 2021-08-11 |
Facies Model,Sedimentary Process and Depositional Record of Submarine Fans,and Their Implications |
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| Institution: | 1.Key Laboratory of Ministry of Education for Coastal Disaster and Protection, Hohai University, Nanjing 210098, China2.College of Oceanography, Hohai University, Nanjing 210098, China3.Qingdao Institute of Marine Geology of China Geological Survey, Qingdao, Shandong 266071, China |
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| Abstract: | A submarine fan is a body of sediment on the sea floor deposited by sedimentary gravity flows. Taxonomy and facies models indicate that submarine fans mainly comprise submarine channel， overbank and lobe depositional elements. However， previous case studies on ancient and modern submarine fans show that they cannot be interpreted by one single facies model. Facies models based on different grain sizes contain a wide range of information， and are relatively straightforward and applicable. The triggering mechanisms of submarine fans include seafloor sediment failures， flood-related hyperpycnal flows， dynamic oceanographic processes， and several combinations of these. The predominant types of gravity flow （debris flow and turbidite flow）， submarine geomorphology （confined and unconfined） and oceanographic condition （e.g.， bottom current） strongly control sedimentary processes， planar geometry and spatial association. Briefly， these may be subdivided into three categories. （i） Turbidite-dominated submarine fans have a fan- or finger shape in unconfined submarine settings. These shapes are then largely modified by confined basin geomorphology. （ii） Debrites-dominated submarine fans are tongue-shaped and fringe-shaped due to freezing en masse. （iii） Hybrid （turbidite-contourite） submarine fans may be deflected laterally by bottom currents， with parts sometimes being reworked into isolated drift mounds. Submarine fan sediments record both source-to-sink propagation and degree of preservation， which are useful indicators of tectonic deformation and paleoclimate change. Modern submarine fans in the Anthropocene have also been found to be the major repository of microplastics and terrestrial organic carbon in deep-sea settings. Quantification of their content sheds a strong light on environmental evaluation， contamination treatment and management， as well as the global carbon cycle. |
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