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

洋盆的下面是在海底喷发的基性火山岩，这些火山岩起源于洋中脊扩张中心，在那里地幔物质上涌形成洋壳和火山岛及海山。 目前，尚不清楚有多少海底熔岩是从裂缝或海洋地壳中远离扩张中心的其他地方喷发出来的。 2016年，一个大型海洋学考察队被派往东太平洋北纬8° 20 '的东太平洋海隆向西延伸的神秘海山链。为了提高这次考察的产出，在巡航中增加并部署了两个深潜平台，一个是ALVIN，一个是载人深潜器，另一个是SENTRY，一个是能够绘制深海景观图并独立于船舶及其操作员操作的自主机器人潜水器。SENTRY提供了高分辨率的海底地图，ALVIN允许对地图内的特定位置进行采样。这使得有针对性的样本收集和选择最合适的网站。它还提供了重要的地质背景，采样。 这两个平台返回了大量（约20 TB）的近底部ALVIN和SENTRY数据，现在需要处理。该数据集包括使用ALVIN获得的视觉观测和高分辨率数字静止图像和视频图像，以及SENTRY提供的近海底声纳数据，该数据提供了海山侧翼和山顶火山地形的约1米分辨率。这项研究涉及对这一独特的高分辨率数据集进行处理和部分分析，涉及对远离快速扩张的大洋中脊轴的火山海底进行广泛的观测、采样和地图覆盖，直至近200万年的海底年龄。 处理和分析的结果对于加强考察期间收集的信息及其解释至关重要，特别是在评价熔岩就位的相对年龄、定量测量海底地形特征以及阐明沿着海山链海底火山活动的性质方面。这些发现对我们理解距大洋中脊扩张中心轴（据信海洋中大多数岩浆活动发生在此）有显著距离（20-200公里）的岩浆过程具有重要意义。这项工作的结果也将是限制地球动力学模型输入参数的关键，这些模型试图描述快速扩张的洋脊上地幔的熔融过程。更广泛的影响包括为一次重大的海洋学考察提供重要和补充的数据，这将大大提高研究成果，培训一名早期职业科学家，处理一个关键的数据集，以了解海底火山过程，并生成可能对军事潜艇导航具有重要意义的地图。这项研究将处理2016年收集的ALVIN和SENTRY数据并提供初步分析，这是一次大型海洋学考察，探索了东太平洋8° 20 'N纬度东太平洋海隆以西延伸的海山链。将进行的数据汇编和分析包括：对15次ALVIN潜水期间获得的约90 000幅数字图像进行地理参照，并对静止图像和视频图像进行定量分析，以帮助绘制每个海山的火山相图。这些数据将叠加在SENTRY多波束和侧扫地图上，以制作勘测区的地质图，并提供SENTRY近底声纳数据的坡度和海底结构分析。这些将与从数字静止图像分析中得出的火山特征形态和沉积物分布相关联。 这项工作将对整个北纬8° 20 '海山区域（~ 7 000平方公里）的EM 122多波束数据进行形态和坡度分析，从而能够定量测量海山底部直径、高度、形态、火山口/破火山口的存在（和大小）以及海山建筑物平面图形状特征和长宽比。所有这些都将作为与东太平洋隆起的距离以及与每个主要建筑物中心的距离和与相邻深海丘陵断层的距离的函数来完成。 通过这一分析，将根据区域和局部尺度上与相邻锥体/建筑物和断层的接触关系，估计整个北纬8° 20 '海山链各地貌的相对年龄。所有经过处理的数据将在两年内与所有相关元数据一起提供给公共数据档案。这项工作的出版物将链接到相关数据中心和档案中的数据。

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.