The "warm" Marine Isotope Stage 31 in the Labrador Sea; low surface salinities and cold subsurface waters prevented winter convection

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doi: 10.1002/2015PA002903
Author(s): Aubry, A. M. R.; Vernal, A.; Hillaire-Marcel, C.
Author Affiliation(s): Primary:
Université du Québec à Montréal, Geotop Research Center, Montreal, QC, Canada
Volume Title: Paleoceanography
Source: Paleoceanography, 31(9), p.1206-1224. Publisher: American Geophysical Union, Washington, DC, United States. ISSN: 0883-8305 CODEN: POCGEP
Note: In English. 97 refs.; illus., incl. 3 tables, sketch map
Summary: Surface and subsurface conditions in the Labrador Sea during Marine Isotope Stage (MIS) 31 at the Integrated Ocean Drilling Program Site U1305 off southwest Greenland are reconstructed based on dinocyst and foraminifer assemblages. Isotopic compositions of planktonic (Neogloboquadrina pachyderma, Np) and benthic (Cibicides wuellerstorfi, Cw, and Oridorsalis umbonatus, Ou) foraminifera provide further information about water properties in the mesopelagic layer as well as at the seafloor. Dinocyst proxy reconstructions indicate low salinities (32-34.5), cool winters (3-6°C), and mild summers (10-15°C) in the surface water layer during the MIS 31 "optimum". However, planktonic foraminifer assemblages largely dominated by Np suggest relatively cold subsurface conditions in winter and summer (<4°C). Lower δ13C values in Np versus Cw further suggest either a lesser-ventilated mesopelagic layer than the bottom one or high organic matter oxidation rates at Np habitat depth. The dinocyst and planktonic foraminifer records together suggest a strong stratification between the surface and subsurface water layers. Isotopic and micropaleontological data thus converge toward paleoceanographical conditions unsuitable for convection and intermediate or deep water formation in the Labrador Sea during the warm MIS 31 interglacial, a situation comparable to the one that prevailed during the warm MIS 5e. Abstract Copyright (2016), . American Geophysical Union. All Rights Reserved.
Year of Publication: 2016
Research Program: DSDP Deep Sea Drilling Project
IODP Integrated Ocean Drilling Program
IPOD International Phase of Ocean Drilling
ODP Ocean Drilling Program
Key Words: 02 Geochemistry; 24 Surficial Geology, Quaternary Geology; Anomalinidae; Assemblages; Atlantic Ocean; C-13/C-12; Carbon; Cassidulinacea; Cenozoic; Cibicidoides; Cibicidoides wuellerstorfi; DSDP Site 607; Deep Sea Drilling Project; Dinoflagellata; Expedition 303; Expedition 306; Expeditions 303/306; Foraminifera; Globigerinacea; IODP Site U1305; IODP Site U1314; IPOD; Integrated Ocean Drilling Program; Invertebrata; Isotope ratios; Isotopes; Labrador Sea; Leg 162; Leg 94; Lower Pleistocene; MIS 31; Marine environment; Microfossils; Mid-Atlantic Ridge; Neogloboquadrina; Neogloboquadrina pachyderma; North Atlantic; Northeast Atlantic; Northwest Atlantic; O-18/O-16; ODP Site 983; Ocean Drilling Program; Oridorsalis umbonatus; Oxygen; Paleoclimatology; Paleoecology; Paleoenvironment; Paleosalinity; Palynomorphs; Pleistocene; Productivity; Protista; Quaternary; Reykjanes Ridge; Rotaliina; Stable isotopes
Coordinates: N602412 N602412 W0233826 W0233826
N562200 N562200 W0275300 W0275300
N410004 N410005 W0325726 W0325727
N572800 N572900 W0483200 W0483200
Record ID: 2016094462
Copyright Information: GeoRef, Copyright 2017 American Geosciences Institute. Reference includes data from John Wiley & Sons, Chichester, United Kingdom