Changes in deep ocean circulation inferred from depositional processes at the eastern Agulhas Ridge


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Jens.Gruetzner [ at ] awi.de

Abstract

The Agulhas Ridge forms an elongated part of the Agulhas-Falkland Fracture Zone (AFFZ) (43° S/9° E - 41° S/16° E) rising more than 2,000 m above the surrounding seafloor. Constituting a topographic barrier the ridge has a strong influence on the exchange of water masses between high and lower latitudes. While Antarctic Bottomwater (AABW) and Circumpolar Deepwater (CDW) originating in the Southern Ocean provide the inflow of cold water masses in larger water depths, the Agulhas leakage is the main source of warm and salty waters carried towards the Subpolar North Atlantic as the upper limb of the Meridional Overturning Circulation (MOC). In order to track past changes in this circulation pattern 5400 km of high-resolution multichannel seismic reflection data were acquired during RV Maria S. Merian cruise MSM 19/2 in the Agulhas Ridge area. Here we present processed profiles and a preliminary interpretation from the hitherto unexplored eastern plateau of the ridge and the area between the plateau and the Cape Rise Seamounts. Via crosscorrelation with ODP Leg 177 drillsites and a reconnaissance survey, prominent reflectors marking the early Oligocene, the middle Miocene and the base of the Pleistocene were identified. Sediment drifts deposited between these erosional surfaces indicate steady contour current acitivity at various depth levels. The chronological development of those drift structures studied both in 2d and 3d (depth to horizon and thickness maps) provide information on the displacement of depocenters and thus current pathways over time.



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Conference (Poster)
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Not peer-reviewed
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Published
Event Details
Gemeinsames Kolloquium - DFG-Schwerpunktprogramme ICDP (International Continental Scientific Drilling Program) und IODP (Integrated Ocean Drilling Program), 17 Mar 2014 - 19 Mar 2014, Erlangen.
Eprint ID
35289
Cite as
Gruetzner, J. and Uenzelmann-Neben, G. (2014): Changes in deep ocean circulation inferred from depositional processes at the eastern Agulhas Ridge , Gemeinsames Kolloquium - DFG-Schwerpunktprogramme ICDP (International Continental Scientific Drilling Program) und IODP (Integrated Ocean Drilling Program), Erlangen, 17 March 2014 - 19 March 2014 .


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