Abundance of calcareous nannofossils in sediments of the Fram Strait

Sediment cores from the Fram Strait are dated by means of calcareous nannofossil biostratigraphy and are shown to represent, at the most, the last 300 kyr (oxygen isotope stages 1-8). Differences in sedimentation rates are mainly controlled by the bottom topography and the intensity of ice-rafted deposition. Sedimentation rates are normally in the order of a few centimeters per kiloyear in the central Fram Strait but increase to over 10 cm/kyr in cores located on the continental slope. The highest sediment accumulation rates occurred on the shelf (several tens of centimeters per kiloyear).

Grain size and description on gravity core samples from ANT-IV/2 expedition to the Bransfield Strait

From the above and the grafical results it can be concluded that cores in the research area are locally dominated by turbiditic sequences, which can be observed by a strong increase in coarser sediment (>35 µm). These coarser intercalations are lacking in the vicinity of basaltic seamounts, probably due to a shadowing effect of the seamounts. The infill of the King George Basin might be dominated by a north eastern current. Sedimentary structures as observed in the cores are often lacking or vague due to hydrothermal effects (Suess, L, 1986).

Fluor and opal in surface sediment from the Bransfield Strait (Table 1)

The influence of biogenic opal sediment input (mainly diatom skeletons) on the fluorine budget of marine sediments will be shown for 24 sampling stations of the antarctic regions of Bransfield Strait, Powell Basin, South Orkney Plateau and northwestern Weddell Sea. 4 bulk samples, one from each sedimentation area, contain 9 to 28 wt.-% of biogenic opal , the clay fraction of the 24 samples investigated have 2 to 82 wt.-%. The fluorine concentration in the amorphous biogenic component is 15 ppm. 300 to 800 ppm of fluorine were measured in the clay fractions, 330 to 920 ppm in their lithogenic components. Biogenic opal causes a decrease in fluorine concentration of the sediment by a considerable amount: 6 to 56 % relative to the clay fraction, due to the proportions involved. Biogenic opal is therefore taken into account as a 'diluting' factor for the fluorine budget in marine sediments.

AWI Bathymetric Chart of the Fram Strait (BCFS) (Scale 1:100,000)

Based on data from R/V Polarstern multibeam sonar surveys between 1984 and 1997 a high resolution bathymetry has been generated for the central Fram Strait. The area ensonified covers approx. 36,500 sqkm between 78°N - 80°N and 0°E - 7.5°E. Basic outcome of the investigation is a Digital Terrain Model (DTM) with 100 m grid spacing which was utilized for contouring and generation of a new series of bathymetric charts at a scale of 1:100,000, the AWI Bathymetric Chart of the Fram Strait (AWI BCFS).

Age determinations, biomarker analyses, and accumulation rates of three sediment cores from the Fram Strait

A reconstruction of Holocene sea ice conditions in the Fram Strait provides insight into the palaeoenvironmental and palaeoceanographic development of this climate sensitive area during the past 8,500 years BP. Organic geochemical analyses of sediment cores from eastern and western Fram Strait enable the identification of variations in the ice coverage that can be linked to changes in the oceanic (and atmospheric) circulation system. By means of the sea ice proxy IP25, phytoplankton derived biomarkers and ice rafted detritus (IRD) increasing sea ice occurrences are traced along the western continental margin of Spitsbergen throughout the Holocene, which supports previous palaeoenvironmental reconstructions that document a general cooling. A further significant ice advance during the Neoglacial is accompanied by distinct sea ice fluctuations, which point to short-term perturbations in either the Atlantic Water advection or Arctic Water outflow at this site. At the continental shelf of East Greenland, the general Holocene cooling, however, seems to be less pronounced and sea ice conditions remained rather stable. Here, a major Neoglacial increase in sea ice coverage did not occur before 1,000 years BP. Phytoplankton-IP25 indices ("PIP25-Index") are used for more explicit sea ice estimates and display a Mid Holocene shift from a minor sea ice coverage to stable ice margin conditions in eastern Fram Strait, while the inner East Greenland shelf experienced less severe to marginal sea ice occurrences throughout the entire Holocene.

Clay minerals in the Norwegian Sea and Fram Strait, investigation from sediment traps and cores

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.