Shorebased Analysis of Alvin and Sentry High-resolution Sidescan, Multibeam and Imagery Data from the 8 degree, 20' N latitude Seamounts

对来自北纬 8 度 20 英尺海山的 Alvin 和 Sentry 高分辨率侧扫、多波束和图像数据进行岸基分析

• 批准号: 1736544
• 负责人: Daniel Fornari
• 金额: $ 4.57万
• 依托单位: Woods Hole Oceanographic Institution
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2017
• 资助国家: 美国
• 起止时间: 2017-07-15 至 2020-06-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1736544&HistoricalAwards=false
• 关键词: Shorebased; Analysis; Alvin; Sentry; resolution

The ocean basins are underlain by mafic volcanic rocks that are erupted on the seafloor and originate at mid-ocean ridge spreading centers where upwelling of mantle material forms ocean crust and volcanic islands and seamounts. Presently, it is not known how much seafloor lava is erupted from fissures or other places in the ocean crust that are away from the spreading centers. In 2016, a major oceanographic expedition was sent out to an enigmatic seamount chain that extends to the west from the East Pacific Rise at 8° 20'N latitude in the eastern Pacific Ocean. To enhance the output of this expedition, two deep submergence platforms, the ALVIN, a human-occupied deep submergence vehicle, and SENTRY, an autonomous, robotic vehicle that is able to map deep ocean landscapes and operate independently from the ship and its operators, were added to the cruise and deployed. SENTRY provided high resolution mapping of the seafloor and the ALVIN allowed sampling of specific locations within the maps. This allowed targeted sample collection and selection of the most appropriate sites. It also provided important geologic context to where samples were taken. These two platforms returned a large volume (~20 terabytes) of near-bottom ALVIN and SENTRY data that now require processing. The dataset includes visual observations and high-resolution digital still and video imagery acquired using ALVIN, and near-bottom sonar data from SENTRY that provides ~1 m resolution of the volcanic terrain exposed on the seamount flanks and summits. This research involves the processing and partial analysis of this unique, high-resolution dataset in terms of extensive observational, sample and map coverage on volcanic seafloor away from the axis of a fast-spreading mid-ocean ridge out to seafloor ages of nearly 2 million years. The results of the processing and analysis is critical for enhancing the information collected on the expedition and its interpretation, especially with regard to evaluating relative age(s) of lava emplacement, quantitative measurement of seafloor topographic features, and illuminating the nature of seafloor volcanism along the seamount chain. Findings have important implications for our understanding of magmatic processes that occur significant distances (20-200 km) from a mid-ocean ridge spreading center axis where it is believe that most magmatism in the ocean occurs. Results of this work will also be key for constraining input parameters to geodynamic models that seek to describe melting processes in the upper mantle at fast-spreading ocean ridges. Broader impacts include providing important and complementary data for an major oceanographic expedition that will significantly enhance the research output, training of an early career scientist, processing a key dataset for understanding seafloor volcanic processes, and generating maps that could have importance for military submarine navigation. This research will process and provide preliminary analysis of the ALVIN and SENTRY data collected on the 2016, a major oceanographic expedition that explored the seamount chain that extends to the west of the East Pacific Rise at 8° 20'N latitude in the eastern Pacific Ocean. Data compilations and analyses that will be done include: georeferencing ~90,000 digital images acquired during 15 ALVIN dives and conducting quantitative analysis of the still- and video-imagery to help generate volcanic facies maps for each of the seamounts. These will be overlain on SENTRY multibeam and sidescan maps to produce geological maps of the surveyed areas and provide slope and seafloor textural analysis of SENTRY near-bottom sonar data. These will be correlated to volcanic feature morphology and sediment distribution that will be derived from digital still imagery analysis. The work will provide a morphological and slope analysis of EM122 multibeam data over the entire span of the 8° 20'N seamount area (~7000 km2) which will permit quantitative measurements of seamount basal diameters, height, morphology, presence of craters/calderas (and sizes), and seamount plan-view edifice shape characterization and aspect ratio. All of this will be done as a function of distance from the East Pacific Rise as well as the distance from each major edifice center and distance from adjacent abyssal hill faults. From this analysis, an estimation of the relative ages of features throughout the 8° 20'N seamount chain will be done, based on contact relationships with adjacent cones/edifices and faults at both regional and local scales. All processed data will be provided to a public data archive with all relevant metadata within two years. Publications from this work will be linked to data in the relevant data centers and archives.

洋盆下面是基性火山岩，这些火山岩在海底喷发，起源于洋中脊扩展中心，其中地幔物质的上涌形成洋壳、火山岛和海山，目前尚不清楚有多少海底熔岩喷发。 2016 年，一支大型海洋探险队被派往一个神秘的海山链。从东太平洋北纬8°20'的东太平洋隆起向西延伸，为了提高本次探险的输出，两个深潜平台，即载人深潜器ALVIN和SENTRY， SENTRY 号上添加了一种自主机器人车辆，能够绘制深海景观图并独立于船舶及其操作员进行操作，可提供高分辨率的海底测绘，而 ALVIN 则可对海底进行采样。这使得能够有针对性地采集样本并选择最合适的地点，这也为采集样本的地点提供了重要的地质背景。该数据集包括使用 ALVIN 获取的视觉观测数据和高分辨率数字静态和视频图像，以及来自 SENTRY 的近海底声纳数据，该数据提供了海山上暴露的火山地形的约 1 m 分辨率。这项研究涉及对这个独特的高分辨率数据集的处理和部分分析，包括对远离快速扩张的洋中脊轴至海底年龄的火山海底的广泛观测、样本和地图覆盖。近 200 万年的处理和分析结果对于增强探险队收集的信息及其解释至关重要，特别是在评估熔岩埋置的相对年龄、海底地形特征的定量测量以及阐明沿海山链的海底火山活动的性质对于我们理解距大洋中脊延伸中心轴很远（20-200公里）的岩浆过程具有重要意义，据信那里是海洋中大多数岩浆活动的中心。这项工作的结果对于限制地球动力学模型的输入参数也至关重要，这些模型试图描述快速扩张的洋脊上地幔的融化过程，包括提供重要和补充的数据。这项研究将显着提高研究成果，培训早期职业科学家，处理关键数据集以了解海底火山过程，并生成对军事潜艇导航具有重要意义的地图。 2016 年一次大型海洋考察收集的 ALVIN 和 SENTRY 数据，该考察对东太平洋北纬 8°20' 处延伸至东太平洋海隆以西的海山链进行了数据汇编和分析。将完成的工作包括：对 15 次 ALVIN 潜水期间获取的约 90,000 张数字图像进行地理配准，并对静态图像和视频图像进行定量分析，以帮助生成每个海山的火山相图，这些图像将覆盖在 SENTRY 多波束和侧扫地图上。生成勘测区域的地质图，并提供 SENTRY 近海底声纳数据的坡度和海底结构分析，这些数据将与火山特征形态相关。这项工作将对 8°20'N 海山区域（约 7000 平方公里）的整个跨度的 EM122 多波束数据进行形态和坡度分析，从而可以定量测量海山底部直径、高度、形态、陨石坑/破火山口的存在（和大小）以及海山平面视图建筑物的形状特征和纵横比，所有这些都将作为距离的函数来完成。东太平洋隆起以及距每个主要建筑物中心的距离以及距邻近深海山断层的距离，将根据接触情况估计整个 8°20'N 海山链中地物的相对年龄。区域和地方范围内与邻近锥体/建筑物和断层的关系将在两年内提供给公共数据档案，其中包含所有相关元数据。和档案。