Arctic front shifts in the subpolar North Atlantic during the mid-Pleistocene (800-400 ka) and their implications for ocean circulation

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doi: 10.1016/j.palaeo.2011.09.004
Author(s): Alonso-Garcia, Montserrat; Sierro, Francisco J.; Flores, José A.
Author Affiliation(s): Primary:
University of Salamanca, Department of Geology (Paleontology), Salamanca, Spain
Volume Title: Palaeogeography, Palaeoclimatology, Palaeoecology
Source: Palaeogeography, Palaeoclimatology, Palaeoecology, 311(3-4), p.268-280. Publisher: Elsevier, Amsterdam, Netherlands. ISSN: 0031-0182 CODEN: PPPYAB
Note: In English. Supplemental information/data is available in the online version of this article. 96 refs.; illus., incl. 1 table, sketch maps
Summary: Surface water conditions at the Integrated Ocean Drilling Program (IODP) Site U1314 (Southern Gardar Drift, 56° 21.8' N, 27°53.3' W, 2820 m depth) were inferred using planktic foraminifer assemblages between Marine Isotope Stage (MIS) 19 and 11 (ca. 800-400 ka). Factor analysis of the planktic foraminifer assemblages suggests that the assemblage was controlled by three factors. The first factor (which explained 49% of the variance) is dominated by transitional and subpolar species and points to warm and salty surface water conditions (Atlantic water). The second factor (37%) is dominated by Neogloboquadrina pachyderma sin and has been associated with the presence of cold and low saline surface waters (Arctic water). Finally, the third factor (9%), linked to a significant presence of Turborotalita quinqueloba, reflects the closeness of the Arctic front (the boundary between Atlantic and Arctic water). The position of the Arctic and Polar fronts has been estimated across the glacial-interglacial cycles studied according to planktic foraminifer abundances from Site U1314 (and their factor analysis) combined with a synthesis of planktic foraminifer and diatom data from other North Atlantic sites. Regarding at the migrations of the Arctic front and the surface water masses distribution across each climatic cycle we determined five phases of development. Furthermore, deep ocean circulation changes observed in glacial-interglacial cycles have been associated with each phase. The high abundance of transitional-subpolar foraminifers (above 65% at Site U1314) during the early interglacial phase indicated that the Arctic front position and surface water masses distribution were similar to present conditions. During the late interglacial phase, N. pachyderma sin and T. quinqueloba slightly increased indicating that winter sea ice slightly expanded southwestwards whereas the ice volume remained stable or was still decreasing. N. pachyderma sin increased rapidly (above 65% at Site U1314) at the first phase of glacial periods indicating the expansion of the Arctic waters in the western subpolar North Atlantic. During the second phase of glacial periods the transitional-subpolar assemblage throve again in the central subpolar North Atlantic associated with strong warming events that followed ice-rafting events. The third phase of glacial periods corresponds to full glacial conditions in which N. pachyderma sin dominated the assemblage for the whole subpolar North Atlantic. This division in phases may be applied to the last four climatic cycles. Abstract Copyright (2011) Elsevier, B.V.
Year of Publication: 2011
Research Program: IODP Integrated Ocean Drilling Program
Key Words: 24 Surficial Geology, Quaternary Geology; Algae; Arctic front; Atlantic Ocean; Atmospheric circulation; C-13/C-12; Carbon; Cenozoic; Climate change; Cycles; Expedition 306; Expeditions 303/306; Factor analysis; Foraminifera; Gardar Drift; Glacial environment; Glaciomarine environment; Globigerinacea; IODP Site U1314; Ice; Ice rafting; Integrated Ocean Drilling Program; Interglacial environment; Invertebrata; Isotope ratios; Isotopes; Marine environment; Marine sediments; Microfossils; Middle Pleistocene; Nannofossils; Neogloboquadrina; Neogloboquadrina pachyderma; North Atlantic; Northeast Atlantic; O-18/O-16; Ocean circulation; Oxygen; Paleo-oceanography; Paleoecology; Planktonic taxa; Plantae; Pleistocene; Polar regions; Protista; Quaternary; Rotaliina; Sea ice; Sediments; Stable isotopes; Statistical analysis; Subpolar regions; Turborotalia quinqueloba
Coordinates: N562200 N562200 W0275300 W0275300
Record ID: 2012016250
Copyright Information: GeoRef, Copyright 2019 American Geosciences Institute. Reference includes data from CAPCAS, Elsevier Scientific Publishers, Amsterdam, Netherlands