PRELIMINARY EVIDENCE FOR LENA RIVER DISCHARGE EVENTS IN THE LAPTEV SEA, RUSSIAN ARCTIC

River discharge into the Arctic is known to cause changes in sea ice production and consecutively affect global climate. The Russian Lena River is one of the mayor contributors into the Arctic Ocean, delivering approximately 770 km3/year of freshwater and about 21 x106/year tons of suspended material. Here we present preliminary evidence of fresh water discharge events from the Lena River into the Laptev Sea, Russian Arctic.

During two separate coring-oceanographic expeditions in July and September, 2003, over 25 piston, gravity and vibro cores were collected from Neelov Bay and along a transect that extends from the delta floodplain onto the Laptev shelf. Preliminary results from our cores demonstrate that high magnetic susceptibility signals are a good indicator of river sediments deposition and provide an estimate of the number and magnitude of the river discharge. Sedigraph analyses in combination with Wet Sieving analysis (grain size > 3phi) reveal changes in grain size distributions and accurate grain size compositions along the core, which are well correlated with high magnetic susceptibility peaks. Based on lithostratigraphic interpretations and magnetic susceptibility correlations, at least 6 major sections are identified as possible discharge events in two transects that extends from the Lena River Delta into the Laptev Sea Shelf.

In Neelov Bay, cores in transect 2 show the possibility that terrestrial material may be from a different source than Bykovskaya channel in the south-east part of the bay. This terrestrial material may be transported from coastal sources by wave refraction or by wind, and/or submarine currents. Future work will help us to understand and reconstruct the chronology of observed sedimentological events.