Sedimentological and clay mineralogical analysis of ODP sites in the central Fram Strait

This study presents the results of high-resolution sedimentological and clay mineralogical investigations on sediments from ODP Sites 908A and 909AlC located in the central Fram Strait. The objective was to reconstruct the paleoclimate and paleoceanography of the high northern latitudes since the middle Miocene. The sediments are characterised in particular by a distinctive input of ice-rafted material, which most probably occurs since 6 Ma and very likely since 15 Ma. A change in the source area at 1 1.2 Ma is clearly marked by variations within clay mineral composition and increasing accumulation rates. This is interpreted as a result of an increase in water mass exchange through the Fram Strait. A further period of increasing exchange between 4-3 Ma is identified by granulometric investigations and points to a synchronous intensification of deep water production in the North Atlantic during this time interval. A comparison of the components of coarse and clay fraction clearly shows that both are not delivered by the Same transport process. The input of the clay fraction can be related to transport mechanisms through sea ice and glaciers and very likely also through oceanic currents. A reconstruction of source areas for clay minerals is possible only with some restrictions. High smectite contents in middle and late Miocene sediments indicate a background signal produced by soil formation together with sediment input, possibly originating from the Greenland- Scotland Ridge. The applicability of clay mineral distribution as a climate proxy for the high northern latitudes can be confirmed. Based on a comparison of sediments from Site 909C, characterised by the smectite/illite and chlorite ratio, with regional and global climatic records (oxygen isotopes), a middle Miocene cooling phase between 14.8-14.6 Ma can be proposed. A further cooling phase between 10-9 Ma clearly shows similarities in its Progress toward drastic decrease in carbonate sedimentation and preservation in the eastern equatorial Pacific. The modification in sea water and atmosphere chemistry may represent a possible link due to the built-up of equatorial carbonate platforms. Between 4.8-4.6 Ma clay mineral distribution indicates a distinct cooling trend in the Fram Strait region. This is not accompanied by relevant glaciation, which would otherwise be indicated by the coarse fraction. The intensification of glaciation in the northern hemisphere is distinctly documented by a rapid increase of illite and chlorite starting from 3.3 Ma, which corresponds to oxygen isotope data trends from North Atlantic.

Vegetation in the coastal area of East Greenland

This paper deals with the syntaxonomy and ecology of debris, scree and alluvium vegetation of the Ammassalik district, Southeast Greenland, on more or less moist soil. The Oxyria digyna- and Chamaenerion latifoliumvegetation types are classified as Saxifrago-Oxyrietum digynae (Böcher 1933 ap. Nordh. 1943) Gjaerevoll 1950 respectively Chamaenerietum latifolii Böcher 1933 in the class Thlaspietea rotundifolii Br.-BI. ap. Br.-BI. et al. 1947. The chionophytic Saxifrago-Oxyrietum digynae and the Chamaenerietum latifolii occurring on river-banks are classified in the alliance Saxifrago stellaris-Oxyrion digynae Gjaerevoll 1950. This alliance belongs to the order Androsacetalia alpinae Br.-BI. ap. Br.-BI. & Jenny 1926, Thlaspietea rotundifolii Br.-BI. ap. Br.-BI. et al. 1947. The following syntaxa are described as new: Saxifrago-Oxyrietum digynae stellarietosum humifusae and typicum with two variants and one variant of the subassociation inops De Molenaar 1976, and the Chamaenerietum latifolii typicum with two variants and salicetosum herbaceae with three variants.

Investigation of Quaternary foraminifera in sediment core CRP-1 from the Ross Sea, Antarctica

Foraminifera are examined in twenty-six samples from a 44 metre succession of Quaternary glacial sediments recovered from the CRP-1 drillhole on Roberts Ridge, southwestern Ross Sea, Antarctica. In situ marine assemblages were documented in at least three of the six lithostratigraphic units, and it is likely that the remaining three interbedded diamicton units are also marine in origin. Peak foraminiferal diversities are documented in Unit 3.1 (73 species) and Unit 2.2 (32 species). Calcareous benthics dominate the assemblages, but may be accompanied by abundant occurrences of the planktonic Neogloboquadrina pachyderma. Low diversity agglutinated faunas appear in the uppermost strata of Units 4.1 and 2.2. A close relationship between lithofacics and foraminiferal biofacies points to marine environments that alternated between proximity to and distance from active glaciers and iceshelf fronts, with associated variations in salinity, sea-surface ice cover and the levels of rainout from debris-laden ice.