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

麻坑是海相或湖相沉积物中的坑状洼地。它们通常被解释为碳氢化合物排放的地表表现，但也可能是由沿海地区的淡水流动、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，它们可以与全球碳循环、海上基础设施、底栖生物和边坡稳定性相关。水柱上的麻点和相关气泡可以用现代舰载多波束系统进行测绘。然而，为了了解它们与海洋地质和水动力过程的相关性，需要重复和多学科的数据集来解决它们的形成机制和瞬态渗透活动。由于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）发现的巨大的坑洼区可以获得丰富的多分辨率和多学科海底数据。可用的数据包括重复多波束调查、海底视频片段、地震和EK60回声测深仪剖面、从凹坑中疏浚的巨石以及多波束水柱信息。在过去的10年里，很多数据集都是反复收集的。我将首次使用这些数据来分析十年来麻子场的分布、形态和渗流活动的发展情况。研究结果将有助于建立一个综合模型，将巴克利峡谷麻坑置于区域地质和水动力背景下，这将有助于更好地理解控制麻坑形成和全球活动的过程。麻坑田，包括巴克利峡谷周围的麻坑田，通常会产生数百到数千个麻坑。这种数量的丰富对他们的分析构成了挑战，但也为统计评估提供了很好的机会。为了支持对巴克利峡谷麻坑场的分析，我将创建能够在数字高程模型中绘制和表征大量形态特征的自动化工作流程。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.