Palynological counts (dinoflagellate cysts) and foraminiferal geochemistry (δ¹⁸O, d18C, Mg/Ca) of the Pliocene-Pleistocene transition in the North Atlantic

• Main Authors: Hennissen, Jan A I, Head, Martin J, De Schepper, Stijn, Groeneveld, Jeroen
• Format: Dataset
• Language: English
• Published: PANGAEA 2014
• Subjects: Deep Sea Drilling Project; DSDP; Integrated Ocean Drilling Program / International Ocean Discovery Program; IODP; Arctic; Foraminifera*; north atlantic current; North Atlantic
• Online Access: https://doi.pangaea.de/10.1594/PANGAEA.865415; https://doi.org/10.1594/PANGAEA.865415

The position of the North Atlantic Current (NAC) during the intensification of Northern Hemisphere glaciation (iNHG) has been evaluated using dinoflagellate cyst assemblages and foraminiferal geochemistry from a ~260 kyr interval straddling the base of the Quaternary System from two sites: eastern North Atlantic Deep Sea Drilling Project Site 610 in the path of the present NAC and central North Atlantic Integrated Ocean Drilling Program Site U1313 in the subtropical gyre. Stable isotope and foraminiferal Mg/Ca analyses confirm cooling near the marine isotope stage (MIS) G7-G6 transition (2.74 Ma). However, a continued dominance of the dinoflagellate cyst Operculodinium centrocarpum sensu Wall and Dale (1966) indicates an active NAC in the eastern North Atlantic for a further 140 kyr. At MIS 104 (~2.60 Ma), a profound dinoflagellate cyst assemblage turnover indicates NAC shutdown in the eastern North Atlantic, implying elevated atmospheric pressure over the Arctic and a resulting shift in the westerlies that would have driven the NAC. These findings challenge recent suggestions that there was no significant southward shift of the NAC or the Arctic Front during iNHG, and reveal a fundamental climatic reorganization near the base of the Quaternary.