Rapid changes in meridional advection of Southern Ocean intermediate waters to the tropical Pacific during the last 30 kyr

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doi: 10.1016/j.epsl.2013.02.028
Author(s): Pena, L. D.; Goldstein, S. L.; Hemming, S. R.; Jones, K. M.; Calvo, E.; Pelejero, C.; Cacho, I.
Author Affiliation(s): Primary:
Lamont-Doherty Earth Observatory, Palisades, NY, United States
Other:
Institut de Ciècies del Mar, Spain
Universitat de Barcelona, Spain
Volume Title: Earth and Planetary Science Letters
Source: Earth and Planetary Science Letters, Vol.368, p.20-32. Publisher: Elsevier, Amsterdam, Netherlands. ISSN: 0012-821X CODEN: EPSLA2
Note: In English. Supplemental information/data is available in the online version of this article. 121 refs.; illus., incl. 2 tables, sketch map
Summary: The Southern Ocean is increasingly recognized as a key player in the general ocean thermohaline circulation and the global climate system during glacial-interglacial transitions. In particular, the advection of Southern Ocean intermediate waters (SOIW), like Antarctic Intermediate Water and Sub-Antarctic Mode Water, to the Eastern Equatorial Pacific (EEP), through a so-called "oceanic tunnelling" mechanism, is an important means for rapid transfer of climatic signals (such as heat, fresh water, salt, and chemical species) from high-to-low latitudes. However, information on how intermediate water advection rates changed in the past, and particularly during deglaciations, is fragmentary. We present new results for Nd isotopes (εNd) in cleaned foraminifera shells (Neogloboquadrina dutertrei) for the last 30 kyr at ODP Site 1240 in the EEP. N. dutertrei preferentially dwells in the lower thermocline, at the core of the Equatorial Undercurrent (EUC), and the εNd variability over time provides a record of the changes in the εNd of the EUC. Through mixing models we show that the EUC record is primarily controlled by changes in the volume transport of intermediate waters and not by Southern Ocean εNd changes. Southern Ocean signals in the EUC are stronger during colder intervals (Younger Dryas, last glacial maximum and Heinrich stadials 1 and 2), in agreement with tropical Atlantic intermediate water records. In addition, covariations between N. dutertrei δ13C, molecular biomarkers, and diatom productivity at Site 1240 confirm the intermediate water route as an important mechanism for the transfer of climate signals from high-to-low latitudes. Changes in the SOIW chemistry during the deglaciation are likely linked to the upwelling of 'old' deep waters in the Southern Ocean and subsequent export as intermediate waters, which are coeval with the atmospheric CO2 rise. Moreover, a comparison of multiple proxy records for the last 30 kyr indicates a latitudinal shift and/or a change in the convection depth of intermediate waters in the Southern Ocean prior to the onset of the deglaciation. Abstract Copyright (2013) Elsevier, B.V.
Year of Publication: 2013
Research Program: ODP Ocean Drilling Program
Key Words: 24 Surficial Geology, Quaternary Geology; Advection; Antarctic Intermediate Water; Cenozoic; Climate change; Convection; Deglaciation; East Pacific; Equatorial Pacific; Foraminifera; Globigerinacea; Invertebrata; Isotopes; Leg 202; Metals; Microfossils; Mixing; Nd-144/Nd-143; Neodymium; Neogloboquadrina; Neogloboquadrina dutertrei; ODP Site 1240; Ocean Drilling Program; Ocean circulation; Pacific Ocean; Paleo-oceanography; Paleocirculation; Paleoclimatology; Paleocurrents; Panama Basin; Planktonic taxa; Protista; Quaternary; Rare earths; Rotaliina; Southern Ocean; Stable isotopes; Thermocline; Thermohaline circulation; Transport
Coordinates: N000100 N000100 W0822800 W0822800
Record ID: 2013063147
Copyright Information: GeoRef, Copyright 2019 American Geosciences Institute. Reference includes data from CAPCAS, Elsevier Scientific Publishers, Amsterdam, Netherlands