Temporal and spatial LGM variability of biomarker records in the Arctic Ocean

Using the sea ice proxy IP25 and phytoplankton-derived biomarkers (brassicasterol and dinosterol) Arctic sea-ice conditions were reconstructed for Marine Isotope Stage (MIS) 3 to 1 in sediment cores from the north of Barents Sea continental margin across the Central Arctic to the Southern Mendeleev Ridge. Our results suggest more extensive sea-ice cover than present-day during MIS 3, increasing sea-ice growth during MIS 2 and decreased sea-ice cover during the last deglacial. The summer ice edge sustained north of the Barents Sea even during extremely cold (i.e., Last Glacial Maximum (LGM)) as well as warm periods (i.e., Bølling-Allerød). During the LGM, the western Svalbard margin and the northern Barents Sea margin areas were characterized by high concentrations of both IP25 and phytoplankton biomarkers, interpreted as a productive ice-edge situation, caused by the inflow of warm Atlantic Water. In contrast, the LGM high Arctic proper (north of 84°N) was covered by thick permanent sea ice throughout the year with rare break up, indicated by zero or near-zero biomarker concentrations. The spring/summer sea-ice margin significantly extended southwards to the southern Lomonosov Ridge and Mendeleev Ridge during the LGM. Our proxy reconstructions are very consistent with published model results based on the North Atlantic/Arctic Ocean Sea Ice Model (NAOSIM).

Paleoelevations in the Pacific Ocean 35 million years ago

Data from deep sea drilling, linear magnetic anomalies and bathymetric measurements together with age and morphometric characteristics of seamounts have been used to construct a paleobathymetric map of the oceans 35 million years ago. A brief analysis of these results is presented.

Changes in dynamic viscosity of sea water with depth in the Pacific Ocean at Stations DM9-613W and DM9-618W

To check on the assumption that metabolic products of planktonic organisms can affect the coefficient of dynamic viscosity of seawater, viscosity was measured in water samples taken from depths of 0 to 1843 m, west of the Hawaiian Islands. Obtained results showed that plankton has no effect on viscosity of water in regions of low productivity and that viscosity can be determined with high degree of accuracy from the appropriate tables.