Sediment transport and redeposition in the abyssal Weddell Sea (Antarctica)


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gerhard.kuhn [ at ] awi.de

Abstract

Glaciomarine sedimentation processes in the Weddell Sea are mainly influenced by interglacial-glacial inland ice sheet and ice shelf dynamics, and their impacts on thermohaline circulation, glacigenic sediment input and sediment redeposition. The different processes are documented by distinct sediment facies associations on the shelf, the continental slope, and in the abyssal plain.Especially during glacial times and advanced inland ice sheets, large amounts of sediments were transported to the shelf edge by ice and deposited on the continental slope by gravitational processes. This process contributed to the build-up of the large Crary Fan in the southeastern Weddell Sea. Lobes of debris-flow deposits dominate the upper slope. Canyons and associated levees are present on the lower slope and stretch out to the abyssal plain. Turbidity currents and contourites have shaped this channels and sediment ridges mainly during glacial times. High sedimentation rates, lamination, low dropstone content, and lacking bioturbation qualify these sediments for high-resolution studies of East Antarctic Ice Sheet variations and related environmental changes.We mapped large areas with sub-bottom echosounding (Parasound System) and together with data from high-resolution reflection seismics several large-scale sedimentary structures could be distinguished and their genesis studied. The Weddell Sea abyssal plain is filled up by well-sorted distal silty turbidites intercalated with hemipelagic fine-grained sediments. Meandering channels form the conduits for turbidity currents. Levees are low and more symmetrical than at the lower continental slope, because of lacking contour currents in the central basin. A up to 10m thick slurry-flow (megaturbidite) covering an area of more than 60.000km2 was mapped with the Parasound System and recognized in a sediment core on the abyssal plain of the central Weddell Sea more than 770km away from the continental slope. Approximately 500km3 material was deposited during this mass-flow event. Parasound data indicate that other slurry- or mass-flow deposits have filled up at least parts of the Weddell Sea abyssal plain.



Item Type
Conference (Poster)
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Peer revision
Not peer-reviewed
Publication Status
Published
Event Details
21. Internationale Polartagung der Deutschen Gesellschaft für Polarforschung, 17. - 22. März 2003 Kiel, Germany, Terra Nostra 2003/1.
Eprint ID
11024
Cite as
Kuhn, G. (2003): Sediment transport and redeposition in the abyssal Weddell Sea (Antarctica) , 21. Internationale Polartagung der Deutschen Gesellschaft für Polarforschung, 17. - 22. März 2003 Kiel, Germany, Terra Nostra 2003/1 .


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