Mud volcanoes and ice-keel ploughmarks, Beaufort Sea shelf, Arctic Canada

Abstract

The shallow shelf waters of the Beaufort Sea have experienced marine transgression during the Holocene (Hill et al. 1985; Taylor et al. 2013). This has led to a warming of what was terrestrial permafrost by water incursion, and to the dissociation of subsurface gas hydrates which now vent into marine waters. Accompanying this change is the development of conical submarine landforms produced through the extrusion of sediments, combined with the continuing reworking of the seafloor by the ploughing action of the keels of drifting ice (Fig. 1). Fig. 1. Multibeam swath bathymetry and bathymetric profiles of mud volcanoes and ice-keel ploughmarks on the Beaufort Sea shelf, Arctic Canada. ( a ) Sun-illuminated multibeam-bathymetric image showing mud volcanoes and ice-keel ploughmarks. Acquisition system Kongsberg EM302. Frequency 30 kHz. Grid-cell size 5 m. White arrows denote a curvilinear ploughmark cross-cutting its previous track. The image is a compilation of data from CCGS Amundsen -based surveys in 2009 and 2011. The NW–SE narrow, linear artefacts arise from instrumentation employed in the initial survey. Wide, curvilinear artefacts arise from different instrumentation employed in a subsequent survey. ( b ) Sun-illuminated multibeam-bathymetric image showing a swarm of mud volcanoes. Acquisition system Kongsberg EM3002. Frequency 300 kHz. …