A centennial scale organic-walled dinoflagellate cyst record of the last deglaciation in the South Adriatic Sea (Central Mediterranean)

摘要

A high-resolution study of sea surface temperature (SST) and primary productivity changes during the last deglaciation in the South Adriatic Sea is presented on the basis of organic-walled dinoflagellate cysts (dinocysts), compared with stable oxygen and carbon isotope records derived from Globigerina bulloides. Two more defined warming phases between 14.75 and 14.10 cal kyr BP (GI-1e) and between 13.85 and 13.25 cal kyr BP (GI-1c), and perhaps a mild one between 12.95 and 12.60 cal kyr BP (GI-1a), interrupted by two cold events between 14.10 and 13.85 cal kyr BP (GI-1d) and between 13.25 and 12.95 cal kyr BP (GI-1b) are highlighted. Weaker SST oscillations occurred within the relatively stable periods GS-2a (17.00-14.75 cal kyr BP), GS-1 (or Younger Dryas, 12.60-11.60 cal kyr BP) and Early Holocene. Several dinocyst proxies used to evaluate surface primary productivity suggest that the cold events GI-1d and GI-1b are associated with episodes of both enhanced primary productivity and, perhaps, improved organic matter preservation due to reduced deep water formation. Phases of more pronounced increased surface primary productivity without stagnation in bottom waters are recorded during GI-1c and early GS-1. Freshwater (Po River) discharge seems to be the cause of enhanced productivity during event GI-1c (at 13.4 cal kyr BP) and, probably, during GI-1d.