Sediment Imaging with Autonomous Underwater Vehicles: A Community Tool

使用自主水下航行器进行沉积物成像：社区工具

• 批准号: 1754419
• 负责人: Ross Parnell-Turner
• 金额: $ 9.89万
• 依托单位: University of California-San Diego Scripps Inst of Oceanography
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2018
• 资助国家: 美国
• 起止时间: 2018-08-01 至 2021-07-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1754419&HistoricalAwards=false
• 关键词: Sediment; Imaging; Autonomous; Underwater; Vehicles

The deepest parts of Earth's oceans are remote and difficult to explore. Thus, the geological, biological, and chemical processes taking place there remain poorly understood. Advances in autonomous underwater vehicle (AUV) technology in the past decade mean that we can now send these vehicles to the seabed in water depths of several miles where they collect data from just above the seafloor. AUVs are often equipped with a high-resolution compressed-high intensity pulse (CHIRP) sonar, which can capture centimeter-scale-resolution, cross-section images of the sediment that blankets the seafloor. These thicknesses can then be used as proxies for the length of time a feature has been exposed on the seafloor. Despite this potential, time constraints and a lack of an easily available sonar data processing scheme means that these CHIRP data are often under-utilized. This research develops a standard workflow and software for processing EdgeTech CHIRP sonar data, for use both at sea and on shore, using already existing AUV-acquired CHIRP surveys of sediment from a specific location on the Mid-Atlantic Ridge and other associated imaging data. Application of the processed data will be used to measure sediment thickness in an area where knowledge of this parameter advances our understanding of the interplay between the faulting and volcanism at mid-ocean ridge axes. Broader impacts of the research add value and capability to the existing US AUV fleet and advance our understanding of crustal formation at mid-ocean ridges. The methods and outcomes of the work will be incorporated into professional development workshops for in-service teachers in the highly diverse San Diego Unified School District, providing resources for lessons that can be widely used throughout the school system and support an early career investigator.In areas far from terrestrial sources, sediment thickness in deep sea marine environments is a rough proxy for the amount of time a feature has been exposed on the seabed. Thus, this provides a way to constrain the timing of geological events, such as volcanic eruptions and/or slip on faults. At young features, such as mid-ocean ridges axial valleys, sediment is typically only a few meters thick and so cannot be picked up by other shipboard geophysical/seismic imaging tools. These sediment thicknesses, at present, can only be imaged using near-bottom sonars such as those carried by AUVs. Use of these tools is particularly useful at slow-spreading mid-ocean ridges where the interplay between low-angle faults, know as detachments, and volcanism remains poorly understood. Although it is now clear that vast areas of seafloor are created under the influence of detachment faults, the relationships between detachments and magmatism and melt supply remain uncertain. This project uses already existing CHIRP data, acquired during fourteen dives of AUV Sentry at latitude 16.5°N on the Mid-Atlantic Ridge in 2013. Research goals are to provide new CHIRP processing protocols that can be used to more quickly process CHIRP sonar data and to use the existing data to quantitatively determine variations in sediment thickness and, thus, establish the relative timing of detachment fault slip and volcanism in the study area. The research adds significant value to an existing dataset that was acquired in an inaccessible part of the deep ocean and will deliver an open-source software tool to the scientific community and the public in a cost-effective way.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.

地球海洋的最深处是遥远的，难以探索。因此，对那里发生的地质、生物和化学过程仍然知之甚少。在过去的十年中，自主水下航行器（AUV）技术的进步意味着我们现在可以将这些航行器发送到水深数英里的海底，在那里它们可以从海底上方收集数据。AUV通常配备高分辨率压缩高强度脉冲（CHIRP）声纳，可以捕获覆盖海底的沉积物的厘米级分辨率横截面图像。然后，这些厚度可用作某一地物在海底暴露时间长度的代用指标。尽管有这种潜力，但时间限制和缺乏容易获得的声纳数据处理方案意味着这些CHIRP数据往往没有得到充分利用。 这项研究开发了一个标准的工作流程和软件，用于处理EdgeTech CHIRP声纳数据，在海上和海岸使用，使用现有的AUV获取CHIRP调查的沉积物从一个特定的位置在大西洋中脊和其他相关的成像数据。处理后的数据的应用将被用来测量沉积厚度的一个地区，这一参数的知识推进我们的理解之间的相互作用的断层和火山活动在洋中脊轴。 研究的更广泛影响增加了美国现有AUV舰队的价值和能力，并促进了我们对大洋中脊地壳形成的理解。 这项工作的方法和成果将被纳入高度多样化的圣地亚哥联合学区在职教师的专业发展研讨会，为可在整个学校系统广泛使用的课程提供资源，并支持一名早期职业调查员在远离陆地来源的地区深海海洋环境中的沉积厚度是一个地物暴露在海底的时间的粗略代用指标。因此，这提供了一种方法来限制地质事件的时间，如火山爆发和/或断层滑动。 在海洋中脊轴向山谷等新地貌上，沉积物通常只有几米厚，因此无法用其他船上地球物理/地震成像工具采集。目前，这些沉积厚度只能用水下机器人携带的近海底声纳成像。这些工具的使用在缓慢扩张的洋中脊特别有用，在那里，低角度断层（称为断层）和火山活动之间的相互作用仍然知之甚少。 虽然现在很清楚，大面积的海底是在拆离断层的影响下形成的，但拆离断层与岩浆作用和熔体供应之间的关系仍然不确定。 该项目使用现有的CHIRP数据，这些数据是2013年AUV Sentry在北纬16.5°的大西洋中脊进行14次潜水时获得的。研究目标是提供新的CHIRP处理协议，可用于更快地处理CHIRP声纳数据，并使用现有的数据，以定量确定沉积物厚度的变化，从而建立在研究区域的剥离断层滑动和火山活动的相对时间。 该研究为在深海难以进入的部分获得的现有数据集增加了重要价值，并将以具有成本效益的方式向科学界和公众提供开源软件工具。该奖项反映了NSF的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

项目成果

The Final Stages of Slip and Volcanism on an Oceanic Detachment Fault at 13°48′N, Mid-Atlantic Ridge

大西洋中脊北纬 13°48° 处海洋滑脱断层上滑动和火山活动的最后阶段

• DOI: 10.1029/2018gc007536
• 发表时间: 2018
• 期刊: Geosystems
• 作者: Parnell-Turner, R. E.;Mittelstaedt, E.;Kurz, M. D.;Jones, M. R.;Soule, S. A.;Klein, F.;Wanless, V. D.;Fornari, D. J.
• 通讯作者: Fornari, D. J.