Conference:
ASSEMBLAGE European Project workshop, November 16-19, 2005, Hamburg (Germany).
Author:
Speranta-Maria Popescu, Stephan Klotz, Martin J. Head.
Abstract:
We have studied pollen grains, dinoflagellate cysts and palynofacies from the two cores BLKS 98-10 (Black Sea) and C10 (Marmara Sea). These cores have been drilled in upper continental slope, they cover the last 18 kyrs. Studies on the pollen transport and taphonomy show that the pollen concentration in surface sediment samples is linked to pollen density, climate and location of the studied core (i.e. proximal/ distal). Generally, high sea-levels correspond to warmer periods and the surface sediment samples are characterized by high percentages of mesophilous (i.e. warm-temperate) trees. On contrary, cooler periods (low sea-levels) are characterized by high percentages of herbs. Bisaccate pollen grains, more specially those of Pinus, have a high buoyancy and may be floating during some years and, as a consequence, go over long distances (resulting in their high-percentages in distal localities). The high-resolution in palynomorph analyses (pollen grains and dinocysts) ensures to identify the climate and sea-level changes during the last 18 kyrs. Three main pollen ratios can be used as climatic and eustatic indexes, respectively: “mesophilous trees / Artemisia”ratio, which well correlates with the GRIPP oxygen isotope curve (also in agreement with quantified climate parameters), “Pinus / halophytes” (i.e. coastal plants requiring salted conditions) ratio, which documents on the distal or proximal location of the core in accordance with sea-level changes, “halophytes / herbs” ratio has the same signification as the previous one, but it is continuously usable, even within sapropels where the signal is biased for Pinus. In cores BLKS98-10 and C10, these ratios are in good agreement and also consistent with palynofacies content (both indicating oxygenated vs. anoxic conditions and erosion on land) and dinoflagellate cyst assemblages, alternately characterized by relative importance of endemic species of the Black Sea and rare (core BLKS98-10) to abundant (core C10) invasive species from the Mediterranean Sea.