Pockmarks and ploughmarks are observed to coexist on the floor of some high-latitude continental shelves (Fig. 1). Pockmarks are rounded to oval-shaped depressions up to few 100 m in diameter and few metres in depth and are often related to subsurface fluid-flow (King & MacLean 1970). They may appear as single features, in groups or as long chains (Hovland 1981). Ploughmarks are linear to curvilinear depressions in shallow seas and shelves, formed by iceberg keels impinging on the sedimentary seafloor (e.g. Woodworth-Lynas et al. 1991).
Fig. 1.
( a ) Multibeam image of pockmarks and ploughmarks from the SW Barents Sea collected during the 2009 HU Sverdrup II cruise (funded by Lundin Norge AS). Acquisition system Kongsberg EM710. Frequency 70–100 kHz. Grid-cell size 5 m. ( b ) Enlarged image of pockmarks, some aligned along a ploughmark. ( c ) Backscatter image of the area shown in (b). ( d ) Sub-bottom profiler data of a pockmark showing stratified marine (above yellow line) and glacimarine sediments (above green line). Blue line is modern seafloor. Acquisition system HUGIN HUS AUV. Frequency 4–24 kHz. ( e ) Location of study area (red box; map from IBCAO v. 3.0).
Many crater-like features are observed on the seafloor in the SW Barents Sea along the NW boundary of the Ingoydjupet depression …
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