North Atlantic Current variability through Marine Isotope Stage M2 (circa 3.3 Ma) during the mid-Pliocene

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doi: 10.1029/2008PA001725
Author(s): de Schepper, Stijn; Head, Martin J.; Groeneveld, Jeroen
Author Affiliation(s): Primary:
Universität Bremen, Fachbereich Geowissenschaften, Bremen, Federal Republic of Germany
Brock University, Canada
Volume Title: Paleoceanography
Source: Paleoceanography, 24(4). Publisher: American Geophysical Union, Washington, DC, United States. ISSN: 0883-8305 CODEN: POCGEP
Note: In English. 96 refs.; illus., incl. 2 tables, sketch maps
Summary: The mid-Pliocene was an episode of prolonged global warmth and strong North Atlantic thermohaline circulation, interrupted briefly at circa 3.30 Ma by a global cooling event corresponding to marine isotope stage (MIS) M2. Paleoceanographic changes in the eastern North Atlantic have been reconstructed between circa 3.35 and 3.24 Ma at Deep Sea Drilling Project Site 610 and Integrated Ocean Drilling Program Site 1308. Mg/Ca ratios and δ18O from Globigerina bulloides are used to reconstruct the temperature and relative salinity of surface waters, and dinoflagellate cyst assemblages are used to assess variability in the North Atlantic Current (NAC). Our sea surface temperature data indicate warm waters at both sites before and after MIS M2 but a cooling of ∼2-3°C during MIS M2. A dinoflagellate cyst assemblage overturn marked by a decline in Operculodinium centrocarpum reflects a southward shift or slowdown of the NAC between circa 3.330 and 3.283 Ma, reducing northward heat transport 23-35 ka before the global ice volume maximum of MIS M2. This will have established conditions that ultimately allowed the Greenland ice sheet to expand, leading to the global cooling event at MIS M2. Comparison with an ice-rafted debris record excludes fresh water input via icebergs in the northeast Atlantic as a cause of NAC decline. The mechanism causing the temporary disruption of the NAC may be related to a brief reopening of the Panamanian Gateway at about this time.
Year of Publication: 2009
Research Program: DSDP Deep Sea Drilling Project
IODP Integrated Ocean Drilling Program
IPOD International Phase of Ocean Drilling
Key Words: 12 Stratigraphy, Historical Geology and Paleoecology; Assemblages; Atlantic Ocean; Cenozoic; DSDP Site 610; Deep Sea Drilling Project; Dinoflagellata; Expeditions 303/306; Foraminifera; Globigerina; Globigerina bulloides; Globigerinacea; Globigerinidae; IODP Site U1308; IPOD; Integrated Ocean Drilling Program; Invertebrata; Isotope ratios; Isotopes; Leg 94; MIS 2; MIS M2; Microfossils; Middle Pliocene; Neogene; North Atlantic; O-18/O-16; Oxygen; Paleosalinity; Paleotemperature; Palynomorphs; Planktonic taxa; Pliocene; Protista; Quantitative analysis; Rockall Trough; Rotaliina; Stable isotopes; Tertiary
Coordinates: N495300 N495300 W0241400 W0241400
N531318 N531329 W0185312 W0185342
Record ID: 2010081931
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