Quantitative morphologic analysis of pockmarks around Barkley Canyon (NE Pacific): spatial and temporal evolution and formation mechanisms

麻点是海洋或湖泊沉积物中的火山口状凹陷。它们通常被解释为碳氢化合物排放的表面表现，但也可能是沿海地区淡水流动、压实引起的沉积物脱水或自然或人为物体周围的底部冲刷造成的。因此，它们可能与全球碳循环、近海基础设施、底栖生物和斜坡稳定性有关。水柱中的麻点和相关气泡可以用现代船基多波束系统绘制。然而，为了了解它们与海洋地质和水动力过程的相关性，需要重复的多学科数据集，以解决其形成机制和瞬时渗漏活动。由于有一个大型电缆水下观测站，最近在Barkley峡谷（加拿大）发现了一个巨大的麻点区，因此可以获得丰富的多分辨率和多学科海底数据。现有数据包括重复多波束勘测、海底录像、地震和EK60回声测深仪剖面、从凹坑中挖出的巨石和多波束水柱信息。其中许多数据集是在过去10年中反复收集的。我将首次利用这些数据来分析麻点田的分布、形态和渗流活动在十年内是如何发展的。研究结果将允许制定一个全面的模型，把巴克利峡谷麻点到区域地质和流体动力学的背景下，这将有助于更好地了解控制麻点的形成和活动的全球性的过程。麻点领域，包括周围的巴克利峡谷，通常会产生数百至数千个麻点。这种丰富性对它们的分析构成了挑战，但也为统计评价提供了巨大机会。为了支持巴克利峡谷麻点领域的分析，我将创建自动化的工作流程，能够映射和数字高程模型中的大量形态特征的特点。所有形态学工作流程都将公开，用于数字高程模型中大量同心特征的自动制图和分类。

Pockmarks are crater-like depressions in marine or lacustrine sediments. They are often interpreted as the surface manifestation of hydrocarbon venting but may also result from freshwater flow in coastal regions, compaction induced sediment dewatering, or bottom scouring around natural or anthropogenic objects. Hence, they can be of relevance for the global carbon cycle, offshore infrastructure, benthic life, and slope stability. Pockmarks and associated gas-bubbles in the water-column can be mapped with modern ship-based multibeam systems. However, to understand their relevance for geologic and hydrodynamic processes in the oceans, repeated and multi-disciplinary data sets are necessary that resolve their formation mechanism and transient seep activity. Owing to the presence of a large cabled underwater observatory, a wealth of multi-resolution and multi-disciplinary seafloor data is available from a recently discovered huge pockmark field at Barkley Canyon (Canada). Available data include repeated multibeam surveys, seafloor video footage, seismic and EK60 echo-sounder profiles, dredged boulders from the pockmarks, and multibeam water-column information. Many of these data sets have been collected repeatedly over the last 10 years. I will use this data to analyse, for the first time, how the distribution, morphology and seepage activity of a pockmark field has developed over a period of ten years. The results will allow formulating a comprehensive model that puts the Barkley Canyon pockmarks into the regional geological and hydrodynamical context and that will help to better understand the processes that control pockmark formation and activity globally.Pockmark fields, including the one around Barkley Canyon, typically yield several hundreds to thousands of pockmarks. This abundance constitutes a challenge for their analysis, but also a great opportunity for statistical evaluation. In order to support analyses of the Barkley Canyon pockmark field, I will create automated workflows that are able to map and characterize large numbers of morphologic features in digital elevation models. All morphologic workflows will be made publicly available for automated mapping and classification of large numbers of concentric features in digital elevation models.