Arctic Ocean

Foraminifera were examined in recent (<100 years) fine-grained glaciomarine muds from surface sediments and cores from Nordensheld Bay, Novaja Zemlja, and Hornsund and Bellsund, Spitsbergen. This study presents the first data on modern foraminifera distribution for fjord environments in Novaja Zemlja, Russia. The data are interpreted with reference to the distribution of foraminiferal near Svalbard and the Barents Sea. In Nordensheld Bay, live and dead Nonionellina labradorica and Islandiella norcrossi are most abundant in the outer fjord. Cassidulina reniforme and Allogromiina spp.

The Palaeocene-Eocene Thermal Maximum (PETM; ~55.5 Ma) is a geologically relatively brief episode of extreme warmth. Both deep and surface ocean temperatures increased by up to 5 ?C in equatorial waters and up to 8 ?C in mid and high latitude waters. From the continents, the annual mean air temperature response during the PETM is still largely unknown, mainly due to a lack of quantitative temperature proxies and sufficient suitable, continuous high resolution records.

During the "Polarstern"-expeditions ARK-IX/4 (1993) and ARK-XI/1 (1995), organised by the Alfred Wegener Institute (AWI), acoustic subbottom profiles (Parasound) have been collected in the Laptev Sea Shelf, Siberia. These data have been interpreted as an indicator of ice scours frequency and off-shore permafrost patterns. An additional acoustic profile data-base was available by the results of the expedition of the Federal Institute for Geosciences and Natural Resources (BGR) of the year 1994.

The grain size distribution and clay mineral composition of lithogenic particles of ice-rafted material, sinking matter, surface sediments, as well as from deep-sea cores are analysed. The samples were collected in the Fram Strait, the Arctic Ocean, and the Norwegian Sea during several expeditions with the research vessels "Polarstern", "Meteor" and "Poseidon", and Norwegian rearch vessels. Sinking matter was caught with sediment traps, fitted with timer-controlled sample changers, which had been deployde in the sea for usually one year.

The deglaciation of the continental shelf to the west of Spitsbergen and the main fjord, Isfjorden, is discussed based on sub-bottom seismic records and sediment cores. The sea floor on the shelf to the west of Isfjorden is underlain by less than 2 m of glaciomarine sediments over a firm diamicton interpreted as till. In central Isfjorden up to 10 m of deglaciation sediments were recorded, whereas in cores from the innermost tributary, Billefjorden, less than a meter of ice proximal sediments was recognized between the till and the 'normal' Holocene marine sediments.

Marine sediments from the V?ring Plateau (Norwegian Sea) have been studied for their dinoflagellate cyst (dinocyst) and foraminiferal content in order to reconstruct sea-surface conditions in the eastern Norwegian Sea during Marine Isotope Stage (MIS) 5e. In combination with stable oxygen isotope and ice rafted detritus (IRD) data, the variations in foraminiferal and dinocyst assemblage composition reflect a stepwise transition from the final phase of deglaciation (Termination II) into typical interglacial conditions.

The distribution of temperature and salinity, current velocities, suspended particulate matter, bottom sediments, bottom morphology, and planktonic and benthic organisms during the summer period are studied in the estuary of the large Onega River and coastal areas of the Onega Bay (White Sea) influenced by interacting marine and riverine factors.

Ist die Tatsache ungew?hnlicher Temperaturzunahme im Nordpolarraum in den letzten Jahrzehnten durch zahlreiche Publikationen allgemein bekannt, so m?chte ich hier auf einige sehr bemerkenswerte, in j?ngster Zeit von mir aufgedeckte Erscheinungen und Beziehungen hinweisen. 1. Die Milderung der Wintertemperatur an der W-K?ste Gr?nlands. Bildet man die Wintertemperaturdifferenzen: Godthab minus Jakobshavn, so zeigt sich f?r die untersuchte Reihe 1876-1939: 2.

Stable isotope records, and sedimentological and organic-geochemical investigations of marine sediments from the east Greenland Sea at 70?N provide important information about glacial-interglacial variations of paleoenvironments through the last 225 kyr. The oxygen isotope records established on the planktonic foraminifer N. pachyderma sin. show some excursions from the global climate pattern, probably due to local/regional overprint by meltwater supply.

During the ARCTIC '91-Expedition with RV 'Polarstern', several Multicorer and Kastenlot-cores were recovered along a profile crossing the eastern part of the Arctic Ocean. The investigated cores consist mainly of clayey-silty sediments, and some units with a higher sand content. In this thesis, detailed sedimentological and organic-geochemical investigations were performed. In part, the near surface sediments were AMS-14C dated making it possible to Interpret the results of the organic-geochemical investigations in terms of climatic changes (isotopic stage 2 to the Holocene).