Spätquartäre Sedimentation am Kontinentalhang nordwestlich Spitzbergens. Der letzte Glazial/Interglazial-Zyklus.


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Abstract

During the "RV Polarstem"-Expedition ARK VIII/2 sediment samples were obtained at the continentalslope of NW-Spitsbergen. Detailed sedimentological and geochemical analysis were carriedout at two undisturbed box cores (PS2122-1GKG, PS2123-2GKG) as well as two gravity cores(PS2122-1SL, PS2123-2SL). The following parameters were deterrnined: Organic carbon, nitrogenand carbonate contents, hydrogen index, stable isotopes, ice rafted debris, grain-size distribution andbiogenic opal. The main objective of this study was the reconstruction of paleoenvironmental changes off thenorthwest coast of Spitsbergen during the last glacial/interglacial-cycle, i.e., during the last about128.000 years.The results of the investigations can be summarized as follows:- During isotope stage 1 (Holocene) and 5.5 (Eemian Interglacial), light stable isotopes (8180: 3,4-2%0; 8BC: 0,26-0,5 %0), increased bioturbation, high content of planktonic foraminifera andbiogenic opal and low quantity of ice-rafted material, indicate seasonally ice-free conditions alongthe northwest coast due to the int1uence of the Westspitsbergen Current.- Additionally, the sediment characteristics of the middle of isotope stage 2 (Last Glacial Maximum)and at the end of stage 3 confirms an inflow of warmer Atlantic water. The highest production ofplanktonic and benthic foraminifera (N. pachyderma sin., Cassidulina teretis) (CaC03: 10 %) mayret1ect the expansion of the "Whalers Bay"-Polynya as a result of the int1uence of the WestspitsbergenCurrent. Presumably, occasionally open-ice conditions provide sufficient precipitation to buildupthe Svalbard/Barents Ice Sheet.- The time intervals for the glacier advances on Svalbard given by Mangerud et al. (1992), can becorrelated with increased accumulation of ice-rafted material in the sediments at the northwest coastof Spitsbergen. Especially during isotope stage 4 and at the beginning of the Last Glacial Maximum(isotope stage 2), a drastically increased supply of coarse terrigenous material occurs. The highaccumulation rate (0,18-0,21 g/cm2jky) of terrigenous organic carbon is indicated by high C/Nratios(until 16) and low hydrogen index (50 mg-HC/gC). In constrast to deep sea sediments in theFram-Strait (Hebbeln 1992), the glacier advance between 118.000 and 108.000 years B.P. ist documented in the continental slope sediments.- At the end of the Weichselian ice age, the deglaciation at the northwest coast starts with a typicalmelt-water signal in the stables isotope record (8180: 3,5 %0; 813C: -0,16 %0) and high contents ofgravel (6-13 %). The signal can be assigned to an event at the westcoast of Spitsbergen (core NP9039), dated to 14.500 years B.P. (Andersen et al. 1993).



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Thesis (Diplom)
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Eprint ID
20985
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Knies, J. (1994): Spätquartäre Sedimentation am Kontinentalhang nordwestlich Spitzbergens. Der letzte Glazial/Interglazial-Zyklus. , Diplom thesis, Justus-Liebig-Universität Giessen.


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