Fourth ESF SEDIFLUX Science Meeting and First Workshop of I.A.G./A.I.G. SEDIBUD Trondheim, Norway, October 29 th – November 02 nd , 2006 Sediment accumulation rates, geochemistry and provenance in complex High Arctic fjord, Hornsund, Svalbard Witold Szczuciński 1 , Georg Schettler 2 & Marek Zajączkowski 3 1 Institute of Geology, Adam Mickiewicz University, Poznań, Poland 2 GeoForschungsZentrum, Potsdam, Germany 3 Institute of Oceanology, Polish Academy of Sciences, Sopot, Poland Hornsund fjord, southern Spitsbergen, represents a complex fjord system with a catchment area of about 1200 km 2 . The catchment is glaciated in 73 %, which ranks it among the most glaciated fjord basins in Svalbard. It is supplied with sediments mainly from several tidewater glaciers, which retreated up to 16 km in the recent decades (Pälli et al. 2003). To determine fjord sediments accumulation rates and provenance a set of radiochemical and geochemical methods were applied for four short cores and fifty five surface sediment samples. Sediment accumulation rates in axial part of the fjord determined with 210 Pb and 137 Cs are in range of 0.5 to 0.7 cm yr -1 with slightly decreasing trend from the fjord head to the entrance. They are the highest modern sediment accumulation rates among those observed in central parts of the major Spitsbergen fjords (Sexton et al. 1992; Elverhøi et al. 1995; Hald et al. 2001; Svendsen et al. 2002; Szczuciński 2004). Fjord surface sediments were analyzed for their grain size composition, carbonate content, TC, TOC and thirty nine elements including REE. The sediments are composed of mud with common drop stones and are characterized by generally similar chemical composition. Only samples collected from shallow locations near sediment sources (river mouth or tidewater glacier front) draining basins of specific geology (e.g. limestone and marbles) differ remarkably. As revealed by statistical analysis (cluster analysis) the inner and central basin of the fjord may be clustered together in one group and the outer basin and shelf sediments in another. The results suggest that the sediments were deposited very close to the sources and there is little sediment flux from the inner basins, which are supplied by glaciers draining mainly clastic sedimentary rocks to the outer basin supplied from metamorphic rock dominated catchments. The geochemistry of the bottom sediments shows that they are transported in direction following the Coriolis force (to the east along the southern shoreline and to the west along the northern). No significant changes in geochemistry of the dated cores were detected. It proves that the provenance of those sediments was stable during the last decades. References Elverhøi, A., Svendsen, J.I., Solheim, A., Andersen, E.S., Milliman, J., Mangerud J. & Hooke, R.LeB., 1995: Late Quaternary Sediment Yield from the High Arctic Svalbard Area. Journal of Geology 103: 1-17. Hald, M., Dahlgren, T., Olsen, T.E. & Lebesbye, E., 2001: Late Holocene palaeoceanography in Van Mijenfjorden, Svalbard. Polar Research 20: 23-35. Pälli, A., Moore, J.C., Jania, J. & Głowacki, P. 2003. Glacier changes in southern Spitsbergen, Svalbard 1901-2000. Annals of Glaciology 37: 219-225. Sexton, D.J., Dowdeswell, J.A., Solheim, A. & Elverhøi, A., 1992: Seismic architecture and sedimentation in northwest Spitsbergen fjords. Marine Geology 103: 53- 68. Svendsen, H., Beszczynska-Møller, A., Hagen, J.O., Lefauconnier, B., Tverberg, V., Gerland, S., Ørbæk, J.B., Bischof, K., Papucci, C., Zajaczkowski, M., Azzolini, R., Bruland, O., Wiencke, C., Winther, J.-G. & Dallmann, W., 2002: The physical environment of Kongsfjorden-Krossfjorden, an Arctic fjord system in Svalbard. Polar Research 21: 133-166. Szczuciński, W., 2004. Late Holocene Sedimentation and Environmental Change Record in Billefjorden, Svalbard. PhD Thesis, A. Mickiewicz University, Poznań, 139 pp. 65 65 View publication stats View publication stats