Submarine fans: A critical retrospective (1950–2015)

G. Shanmugam

摘要

Abstract When we look back the contributions on submarine fans during the past 65 years (1950–2015), the empirical data on 21 modern submarine fans and 10 ancient deep-water systems, published by the results of the First COMFAN (Committee on FANs) Meeting (Bouma et?al. , 1985a), have remained the single most significant compilation of data on submarine fans. The 1970s were the “heyday” of submarine fan models. In the 21st century, the general focus has shifted from submarine fans to submarine mass movements, internal waves and tides, and contourites. The purpose of this review is to illustrate the complexity of issues surrounding the origin and classification of submarine fans. The principal elements of submarine fans, composed of canyons, channels, and lobes, are discussed using nine modern case studies from the Mediterranean Sea, the Equatorial Atlantic, the Gulf of Mexico, the North Pacific, the NE Indian Ocean (Bay of Bengal), and the East Sea (Korea). The Annot Sandstone (Eocene–Oligocene), exposed at Peira-Cava area, SE France, which served as the type locality for the “Bouma Sequence”, was reexamined. The field details are documented in questioning the validity of the model, which was the basis for the turbidite-fan link. The 29 fan-related models that are of conceptual significance, developed during the period 1970–2015, are discussed using modern and ancient systems. They are: (1) the classic submarine fan model with attached lobes, (2) the detached-lobe model, (3) the channel-levee complex without lobes, (4) the delta-fed ramp model, (5) the gully-lobe model, (6) the suprafan lobe model, (7) the depositional lobe model, (8) the fan lobe model, (9) the ponded lobe model, (10) the nine models based on grain size and sediment source, (11) the four fan models based on tectonic settings, (12) the Jackfork debrite model, (13) the basin-floor fan model, (14) supercritical and subcritical fans, and (15) the three types of fan reservoirs. Each model is unique, and the long-standing belief that submarine fans are composed of turbidites, in particular, of gravelly and sandy high-density turbidites, is a myth. This is because there are no empirical data to validate the existence of gravelly and sandy high-density turbidity currents in the modern marine environments. Also, there are no experimental documentation of true turbidity currents that can transport gravels and coarse sands in turbulent suspension. Mass-transport processes, which include slides, slumps, and debris flows (but not turbidity currenrs), are the most viable mechanisms for transporting gravels and sands into the deep sea. The prevailing notion that submarine fans develop during periods of sea-level lowstands is also a myth. The geologic reality is that frequent short-term events that last for only a few minutes to several hours or days ( e.g. , earthquakes, meteorite impacts, tsunamis, tropical cyclones, etc. ) are more important in controlling deposition of deep-water sands than sporadic long-term events that last for thousands to millions of years ( e.g. , lowstand systems tract). Submarine fans are still in a stage of muddled turbidite paradigm because the concept of high-density turbidity currents is incommensurable. Keywords The Bouma Sequence ; High-density turbidity currents ; Sandy debris flows ; Turbidite facies models ; Submarine fans ; Submarine canyons ; Submarine channels ; Submarine lobes ; Lowstand systems tract prs.rt("abs_end"); 1. Introduction 1.1. The incentive The incentive for this review on submarine fans or deep-sea fans came from a startling comment on the irrelevance of submarine fans in a global geologic studies by Vérard et?al. (2015) published in the Journal of Palaeogeography . Vérard et?al. (2015) claim that their global geodynamic model allows one to reconstruct the surface features of topography on land and in adjacent oceans ( i.e ., paleobathymetry) anywhere on the globe and at any geological time during the past 600 million years (Ma). In their grand claim, Vérard et?al. (2015 , p. 72) state that “ Sedimentation does not reflect local climatic variations, nor does it account for local variations in detrital input. Lakes or rivers are not taken into account on continents, and deep sea fans are not modelled here. The amount of sediment in all major deep sea fans, however, is estimated to represent less than 0.01% (order of 10 14 to 10 15 m 3 ) of the total sediment volume in ocean. ” Without providing any empirical data or peer-reviewed references to substantiate their claim on submarine fans, the total exclusion of fan sedimentation from consideration is not only geologically unrealistic but deeply troubling. The fact is that during the past six decades, the importance of modern and ancient submarine fans have been excruciatingly well documented in the geologic record ( Menard, 1955 , Bouma, 1962 , McBride, 1962 , Klein, 1966 , Jacka et?al., 1968 , Enos, 1969 , Normark

机译：摘要当我们回顾过去65年（1950-2015年）对潜艇爱好者的贡献时，第一位COMFAN（风机委员会）的结果发布了有关21艘现代潜艇风扇和10座古代深水系统的经验数据。会议（Bouma等人，1985a）仍然是海底风机数据的最重要的汇编。 1970年代是潜艇风机模型的“全盛时期”。在21世纪，一般的关注点已经从海底爱好者转移到海底群众运动，内部波浪和潮汐以及轮廓石上。这篇综述的目的是说明围绕潜艇爱好者的起源和分类问题的复杂性。利用来自地中海，赤道大西洋，墨西哥湾，北太平洋，东北印度洋（孟加拉湾）的九个现代案例研究，讨论了由峡谷，航道和波瓣组成的海底扇的主要要素。，以及东海（韩国）。重新检查了法国东南部Peira-Cava地区暴露的Annot砂岩（始新世-渐新世），该地区曾是“ Bouma层序”的类型所在地。在质疑该模型的有效性时记录了现场的详细信息，这是浊积-扇形连接的基础。使用现代和古代系统讨论了1970-2015年间开发的29个具有概念意义的风扇相关模型。它们是：（1）具有附加瓣的经典海底风扇模型;（2）分离瓣模型;（3）无瓣的河道堤坝群;（4）三角洲馈送坡道模型;（5）沟壑-波瓣模型，（6）上叶瓣模型，（7）沉积叶模型，（8）扇形叶模型，（9）池状叶模型，（10）基于晶粒大小和沉积物来源的九个模型，（11）基于构造设置的四种风机模型;（12）Jackfork残骸模型;（13）盆底风机模型;（14）超临界和亚临界风机;（15）三种类型的风机储层。每个模型都是独特的，长期以来人们一直认为潜艇迷是由浊石组成的，尤其是由砾石和沙质高密度浊石组成的神话。这是因为没有经验数据可以验证现代海洋环境中砾石和沙质高密度浊流的存在。另外，也没有实验性文献证明真正的浊流能够在湍流悬浮物中输送砾石和粗砂。包括滑坡，塌陷和泥石流（但不包括浊流）在内的大规模运输过程是将砾石和沙子运输到深海的最可行机制。潜艇爱好者在海平面低位时期发展的普遍观念也是一个神话。地质现实是，仅持续几分钟到几小时或几天的频繁短期事件（例如地震，陨石撞击，海啸，热带气旋等）比控制深水砂的沉积更为重要。持续数千到数百万年的零星长期事件（例如，低位系统域）。由于高密度浊流的概念是难以理解的，因此潜艇迷仍处于浑浊的范式阶段。关键词Bouma序列;高密度浊流沙质泥石流;浊积相模型;潜艇迷;海底峡谷;海底通道;水下裂片; Lowstand系统清单prs.rt（“ abs_end”）; 1.引言1.1。激励这次审查对海底风扇或深海风扇的动机来自于Vérard等人在全球地质研究中对海底风扇的无关性的惊人评论。（2015年）发表在《古地理》杂志上。维拉德（Vérard）等人。（2015年）声称，他们的全球地球动力学模型可以重建过去6亿年（Ma）内全球任何地方的陆地和邻近海洋地形的表面特征（即古生物学）。在他们的宏大主张中，Vérard等人。（2015年，第72页）指出：“泥沙没有反映当地的气候变化，也没有考虑到碎屑输入的当地变化。大洲未考虑湖泊或河流，此处未建模深海扇。但是，据估计，所有主要深海扇形体中的沉积物含量都不足0.01％（从10 14 到10 15 m 3 ）海洋中的总沉积物量。没有提供任何经验数据或同行评审的参考资料来证实他们对海底风扇的主张，完全排除风扇沉积物的考虑不仅在地质上不切实际，而且令人深感不安。事实是，在过去的六十年中，地质记录充分地记录了现代和古代海底风扇的重要性（Menard，1955年; Bouma，1962年; McBride，1962年; Klein，1966年; Jacka等， 1968年，埃诺斯，1969年，诺马克

Submarine fans: A critical retrospective (1950–2015)

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