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陨石坑状凹陷。它们通常被解释为油气喷发的表面表现，但也可能是沿海地区的淡水流动、压实引起的沉积物脱水或天然或人为物体周围的底部冲刷所致。因此，它们可能与全球碳循环、近海基础设施、海底生命和斜坡稳定性有关。水柱中的麻点和相关气泡可以用现代舰载多波束系统来绘制。然而，为了了解它们与海洋地质和水动力过程的相关性，必须有重复和多学科的数据集来解决它们的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的存在，从最近在巴克利峡谷(加拿大)发现的一个巨大的凹坑区域可以获得丰富的多分辨率和多学科的海底数据。现有数据包括重复的多波束测量、海底录像、地震和EK60回声测深仪剖面、从凹坑挖出的巨石以及多波束水柱信息。这些数据集中的许多都是在过去10年里反复收集的。我将第一次使用这些数据来分析麻点领域的分布、形态和渗漏活动在十年的时间里是如何发展的。这一结果将有助于建立一个全面的模型，将巴克利峡谷麻点置于区域地质和水动力环境中，这将有助于更好地了解控制麻点形成和全球活动的过程。麻点油田，包括巴克利峡谷周围的麻点油田，通常会产生数百到数千个麻点。这种丰富性对他们的分析构成了挑战，但也是统计评估的一个很好的机会。为了支持对巴克利峡谷麻点区域的分析，我将创建能够在数字高程模型中绘制和表征大量地貌特征的自动化工作流。所有形态工作流程都将公开，用于数字高程模型中大量同心要素的自动制图和分类。

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.