Transport, Removal and Accumulation of sediments Numerically Simulated for Paleo-Oceans and Reconstructed from cores of The Eirik Drift (TRANSPORTED)


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Gabriele.Uenzelmann-Neben [ at ] awi.de

Abstract

The Wester Boundary Undercurrent (WBUC) flows around the Southern tip of Greenland and is a major contributor to the lower branch of the Atlantic Meridional Overturning Circulation (AMOC). It is mainly driven by deep water producing convection processes in the Nordic Seas and thus sensitive to atmospheric changes on a broad spectrum of time scales. A major presentconcern is the impact of long term climate change on both strength and flow path of the current. However, such time scales also include tectonic modifications as a contribution to alterations of the flow. The investigation of the state of the circulation in past geological epochs is feasible by means of sediment drift bodies which are plastered by the deep current along the lower shelf slope, e.g. the Eirik Drift on the Southern slope of Greenland. Seismic profiles (e.g., Müller-Michaels and Uenzelmann-Neben (2014, 2015)) and drill cores (Expedition 303 Scientists (2006), Shipboard Scientific Party (1987)) allow the determination of sedimentation rates and grain sizes since the late Miocene and the Pliocene. Such studies showed pronounced modifications during both the Miocene and the Pliocene which are especially geological epochs of interest to the climatological community due their resemblance to possible future anthropogenically modified climate states (Salzmann et al. (2009)). Several numerical climate and ocean studies have linked local temperature and precipitation proxies to global climate changes during the late Miocene and the Pliocene. In the project TRANSPORTED we aim to link tectonic events and climate change to alterations of the strength and flow paths of the WBUC and, hence, to sedimentation rates and grain sizes recorded in the cores from Sites 646 and U1305-1307 in the Eirik Drift.Density-driven deep currents in geostrophic balance show distinct features such as sustained widening while reducing velocity and pronounced narrow eddies at the bottom. These currents therefore produce an equally distinct sediment structure: a strong erosion channel and enhanced deposition downstream, as has been described by Rebesco et al. (2014)). We were able to reconstruct such currents successfully at a very high horizontal and vertical resolution along the southern slope of Greenland enabling us to drive our sediment module at most realistic conditions. Extracting grain sizes and densities of the main material deposited in the area of investigation from the previous sedimentological studies, we were able to conduct the first sensitivity studies altering tectonic and atmospheric parameters. These studies show a significant but moderate response to the modifications under present conditions but changes may be more pronounced for the conditions of past geological epochs when local deposition rates were peaking (Müller-Michaelis, Uenzelmann-Neben (2014)). Therefore, our next aim is to conduct paleological simulationsunder past climate forcing and crucial tectonic changes in order compare numerical results and sedimentological output



Item Type
Conference (Poster)
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Not peer-reviewed
Publication Status
Published
Event Details
IODP Kollquium, 18 Mar 2019 - 20 Mar 2019.
Eprint ID
49382
Cite as
Drinkorn, C. , Saynisch-Wagner, J. , Uenzelmann-Neben, G. and Thomas, M. (2019): Transport, Removal and Accumulation of sediments Numerically Simulated for Paleo-Oceans and Reconstructed from cores of The Eirik Drift (TRANSPORTED) , IODP Kollquium, 18 March 2019 - 20 March 2019 .


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