First detailed synchronous sediment-concentration and velocity data for submarine turbidity currents

第一个详细的海底浊流同步沉积物浓度和速度数据

• 批准号: NE/K013653/1
• 负责人: Daniel Parsons
• 金额: $ 37.35万
• 依托单位: University of Hull
• 依托单位国家: 英国
• 项目类别: Research Grant
• 财政年份: 2014
• 资助国家: 英国
• 起止时间: 2014 至 无数据
• 项目状态: 已结题
• 来源: https://gtr.ukri.org/projects?ref=NE%2FK013653%2F1
• 关键词: First; detailed; synchronous; sediment; concentration

Submarine sediment density flows ("turbidity currents") and rivers on land are volumetrically the most important processes for moving sediment across our planet. However, submarine flows are more episodic and are typically more violent (with speeds of up to 20m/s) than river floods. Moreover, a single submarine flow is capable of transporting ten times the annual sediment load from all of the world's rivers combined. Submarine flows are important because they produce many of the world's most extensive and voluminous sedimentary deposits, both on the modern sea floor and in the ancient rock record, but also because they can break seafloor cables that now carry over 95% of global data traffic (that underpin our daily lives through the internet and financial markets). Ancient submarine flows created subsurface rock sequences that contain many of our largest oil and gas reserves. Submarine flows carve canyons, which are deeper than the Grand Canyon, through processes that are still poorly understood, and flows within canyons play a key role in supplying organic carbon and nutrients to benthic ecosystem (that include important diversity hotspots) in the deep sea.The most remarkable aspect of submarine density flows is how difficult they are to monitor directly, and how few observations we presently have of such flows in action. This paucity of direct observation provides a stark contrast to the information available for other major sediment transport processes. Changes in the frontal speed of submarine flows have been measured in just five locations, mainly through indirect evidence provided by the timing of sequential underwater cable breaks. Their vertical velocity profile has only ever been measured in three locations and never with sampling rates more frequent than one per hour. No flow has been monitored along its full path, which is of key importance because flows evolve considerably in character along that path.To produce a fundamental step-change in our understanding of submarine flows we need to directly monitor active flows along their entire flow path. Until this is achieved, our understanding of the flow character and its spatial evolution will remain limited. This project will provide by far the most detailed monitoring data yet collected for submarine flows: be the first that places constraints on both dilute and dense near-bed flow components, be the first data set that spans the full flow path, and be the first data set to link measurements of flow processes and the resulting deposit character in such an environment. We aim to conduct a large-scale collaborative program to document and understand sediment transport processes occurring within Monterey Canyon offshore California during an 18-month period in 2014-16, in collaboration with the Monterey Bay Aquarium Research Institute (MBARI) and US Geological Survey (USGS). Such international collaboration is essential for spreading the cost of this ambitious work. MBARI are providing the project with access to a series of innovative tools for monitoring flows that MBARI have designed, built and field tested over the last decade; a contribution worth over $10 Million. This includes aBenthic Instrument Nodes for their Monterey Ocean Observing System that will provide the first high frequency (every 2 to 30 seconds rather than hourly) measurements of 3D velocity, temperature, salinity and density profiles from such flows. MBARI also provide access to the research vessels and ROVs necessary for equipment deployment and servicing during this 18 month period, as MBARI is located at the head of the canyon. MBARI and USGS will place further monitoring equipment in the canyon as part of the project that is worth a further $1.5 Million. Moreover, the MBARI and USGS bear the risk for the loss of all of their equipment. NERC bears a small fraction of the total cost and risk for this unique field experiment, which therefore represents exceptional value for money.

从体积上来说，海底沉积物密度流（“浊流”）和陆地河流是在地球上移动沉积物的最重要过程。然而，海底水流比河流洪水更加间歇性并且通常更加猛烈（速度高达 20m/s）。此外，单一海底水流能够输送的泥沙量是世界上所有河流年泥沙量总和的十倍。海底流很重要，因为它们在现代海底和古代岩石记录中产生了许多世界上最广泛和数量最大的沉积矿床，而且还因为它们可以破坏目前承载全球 95% 以上数据流量的海底电缆（通过互联网和金融市场支撑我们的日常生活）。古代海底流形成了地下岩石层序，其中蕴藏着许多最大的石油和天然气储量。海底流通过我们仍知之甚少的过程形成了比大峡谷更深的峡谷，而峡谷内的流在向深海底栖生态系统（包括重要的多样性热点）提供有机碳和营养物方面发挥着关键作用。海底密度流最显着的方面是直接监测它们是多么困难，以及我们目前对这种流动的观测很少。这种直接观察的缺乏与其他主要沉积物输送过程的可用信息形成鲜明对比。仅在五个地点测量了海底水流锋面速度的变化，主要是通过水下电缆连续断裂的时间提供的间接证据。它们的垂直速度剖面仅在三个地点进行过测量，并且采样率从未超过每小时一次。没有任何流动沿着其整个路径进行监测，这一点至关重要，因为流动在沿着该路径的特征上发生了很大的变化。为了使我们对海底流动的理解发生根本性的改变，我们需要直接监测沿着整个流动路径的活跃流动。在实现这一目标之前，我们对流动特征及其空间演化的理解仍然有限。该项目将提供迄今为止收集到的海底流最详细的监测数据：成为第一个对稀流和稠密近床流成分施加约束的数据集，成为第一个跨越整个流动路径的数据集，并成为第一个将流动过程测量与此类环境中产生的沉积特征联系起来的数据集。我们的目标是与蒙特利湾水族馆研究所 (MBARI) 和美国地质调查局 (USGS) 合作，开展一项大规模合作计划，记录和了解 2014-16 年 18 个月期间加利福尼亚州近海蒙特利峡谷内发生的沉积物输送过程。这种国际合作对于分摊这项雄心勃勃的工作的成本至关重要。 MBARI 为该项目提供了一系列用于监控流程的创新工具，这些工具是 MBARI 在过去十年中设计、构建和现场测试的；价值超过 1000 万美元的捐款。其中包括蒙特利海洋观测系统的底栖仪器节点，该节点将首次高频（每 2 至 30 秒而不是每小时）测量此类流的 3D 速度、温度、盐度和密度剖面。由于 MBARI 位于峡谷顶端，因此 MBARI 还提供在这 18 个月期间使用设备部署和维修所需的研究船和 ROV 的权限。作为价值 150 万美元的项目的一部分，MBARI 和 USGS 将在峡谷放置更多监测设备。此外，MBARI 和 USGS 承担所有设备丢失的风险。 NERC 承担了这一独特现场实验的总成本和风险的一小部分，因此物有所值。

项目成果

A General Model for the Helical Structure of Geophysical Flows in Channel Bends

• DOI: 10.1002/2017gl075721
• 发表时间: 2017-12
• 期刊: Geophysical Research Letters
• 影响因子: 5.2
• 作者: M. Azpiroz-Zabala;M. Cartigny;E. Sumner;M. Clare;P. Talling;D. Parsons;C. Cooper

Newly recognized turbidity current structure can explain prolonged flushing of submarine canyons.

• DOI: 10.1126/sciadv.1700200
• 发表时间: 2017-10
• 期刊: Science advances
• 影响因子: 13.6
• 作者: Azpiroz-Zabala M;Cartigny MJB;Talling PJ;Parsons DR;Sumner EJ;Clare MA;Simmons SM;Cooper C;Pope EL
• 通讯作者: Pope EL

Autonomous Underwater Vehicles (AUVs): Their past, present and future contributions to the advancement of marine geoscience

• DOI: 10.1016/j.margeo.2014.03.012
• 发表时间: 2014-06-01
• 期刊: MARINE GEOLOGY
• 影响因子: 2.9
• 作者: Wynn, Russell B.;Huvenne, Veerle A. I.;Hunt, James E.
• 通讯作者: Hunt, James E.