Morphology and sedimentation along the Kongsfjord Channel System, Svalbard continental margin, European Arctic
Abstract
The continental margin off northwestern Svalbard (between 79° and 80° N) has been affected by repeated mass wasting, as well as from northward-flowing contourite currents. One on the most striking morphological features is the approximately 120 km long, SE-NW oriented Kongsfjord Channel System (KCS) that can be traced from the shelf break at 250-300 m water depth to a maximum water depth of about 4000 m. Several channels/gullies starting at the shelf break merge into the main channel at around 1400 m. The main channel is at maximum 500 m wide and 80 m deep. Repeated interaction of the channel with contourite deposition has occurred. This includes relocation of the channel's axis related to the northward migration of the contourites, as well as renewed incision of contourites by activitiy within the channel. Two sediment cores were retrieved from either side of the main channel at 1430 m water depth, and two from about 1560 m water depth, respectively. The stratigraphy of these cores can easily be correlated to dated cores from the west Spitsbergen continental margin (Jessen et al., 2010). Preliminary results reveal that the sedimentation rates (SRs) at the shallower locations are generally higher than at the deeper stations during the past c. 30,000 years. At the sites from 1430 m water depth, the SRs were rather uniform during the past c. 10,000 years. However, prior to c. 10,000 cal. years BP, the SRs were significantly higher at the location of the core that was retrieved northeast of the channel. We assume that this is related to enhanced down-slope sediment transport within the channel and deposition to the right (northeast) of the transport direction - due to the Coriolis force and/or the northward-flowing contourite currents. The sources for sediment transport within the channel are most probably 1) enhanced sediment supply from the Kongsfjorden ice stream during the last glacial, and 2) winnowing of fine-grained material in the upper parts of the KCS and on the continental shelf following the retreat of the ice-stream front from the shelf break around 20,000 years ago. At the 1560 m water-depth sites, the SR was higher to the south of the channel prior to c. 14,000 cal. years BP, but higher to the north after c. 14,000 cal. years BP. This indicates that the northward migration of a contourite drift had the largest impact on the southern location prior to c. 14,000 cal. years BP. After c. 14,000 cal. years BP, down-slope sediment transport probably exceeded along-slope sediment transport, resulting in higher rates in the north. Reference: Jessen, S.P., Rasmussen, T.L., Nielsen, T. & Solheim, A., 2010. A new Late Weichselian and Holocene marine chronology for the westerns Svalbard slope 30,000-0 cal years BP. Quaternary Science Reviews 29, 1301-1312.
- Publication:
-
AGU Fall Meeting Abstracts
- Pub Date:
- December 2011
- Bibcode:
- 2011AGUFMEP33C0931F
- Keywords:
-
- 3002 MARINE GEOLOGY AND GEOPHYSICS / Continental shelf and slope processes;
- 3022 MARINE GEOLOGY AND GEOPHYSICS / Marine sediments: processes and transport;
- 3045 MARINE GEOLOGY AND GEOPHYSICS / Seafloor morphology;
- geology;
- and geophysics;
- 3070 MARINE GEOLOGY AND GEOPHYSICS / Submarine landslides