Planktic Foraminifers to Reconstruct the Eastern Mediterranean Sea Paleoceanography at the Time of Sapropel S6 Deposition

Savannah Myers

Marine sapropels are dark-colored, organic-rich sediment layers occurring systematically in the Mediterranean Sea and the mechanisms of their formation come with great uncertainty. This study focuses on the “glacial” sapropel S6 layer dated at ~176 ka BP sampled from the Ionian Sea of the eastern Mediterranean and evaluates the corresponding fossilized planktic foraminifera samples through quantitative biostratigraphic analysis in order to interpret the mechanism of the sapropel’s deposition and reconstruct environmental, oceanographic, and climatic conditions during its deposition. This study compares the planktic foraminifera data to calcareous nannofossil, dinocyst, pollen, and stable isotope data from other studies. From this, it can be hypothesized that S6 deposition was formed by shared freshwater influx mechanisms: preconditioning by glacial meltwater and triggering by Nile River discharge; temperatures were mild rather than cold; Black Sea freshwater influx could have helped maintain deposition; the upper half of S6 had unstable stratification due to slight cooling and decline in Nile River discharge; and the climatic events leading to S6 deposition could have caused an increase of CO2. Our discoveries contribute to the archive of knowledge needed to understand how the Earth responds to climate changes and to foresee what changes can take place in the near future.