Indian Ocean circulation and productivity during the last glacial cycle

The Indian Ocean is an important part of the global thermohaline circulation system, receiving deep waters sourced from the Southern Ocean and being the location of upwelling and surface-ocean current flow which returns warm and salty waters to the Atlantic. It is also an ideal location to reconstru...

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Main Authors: Piotrowski, A.M., Banakar, V.K., Scrivner, A.E., Elderfield, H., Galy, A., Dennis, A.
Format: Article in Journal/Newspaper
Language:English
Published: Elsevier 2009
Subjects:
Online Access:http://drs.nio.org/drs/handle/2264/3372
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spelling ftnio:oai:dsr.nio.org:2264/3372 2023-05-15T17:13:56+02:00 Indian Ocean circulation and productivity during the last glacial cycle Piotrowski, A.M. Banakar, V.K. Scrivner, A.E. Elderfield, H. Galy, A. Dennis, A. 2009 http://drs.nio.org/drs/handle/2264/3372 en eng Elsevier An edited version of this paper was published by Elsevier. Copyright [2009] Elsevier palaeo studies ocean circulation glacial features thermohaline circulation neodymium isotopes foraminifera Journal Article 2009 ftnio 2012-08-25T20:09:08Z The Indian Ocean is an important part of the global thermohaline circulation system, receiving deep waters sourced from the Southern Ocean and being the location of upwelling and surface-ocean current flow which returns warm and salty waters to the Atlantic. It is also an ideal location to reconstruct the link between thermohaline circulation and deep-water nutrient contents. No mixing occurs between major deep-water masses along flow paths within the Indian Ocean, so changes in water-mass provenance reflect changes in deep-ocean circulation while nutrient contents reflect addition and dissolution of organic matter. Neodymium (Nd) and carbon (C) isotope records from an equatorial Indian Ocean core (SK129-CR2) spanning the last 150 kyr are presented. The Nd isotope record shows that an increased proportion of North Atlantic Deep Water (NADW) reached the Indian Ocean during interglacials (Marine Isotope Stages; MIS 1 and 5), and a reduced proportion during glacials (MIS 2, 4, and 6), and also that changes occurred during MIS 3. The magnitude and timing of deglacial and some MIS 3 variability is very similar to those in the RC11-83/TNO57-21 South Atlantic deep Cape Basin Nd isotope record. Since the deep Cape Basin is oceanographically upstream of the Indian Ocean from a deep water circulation perspective, the Nd isotopes suggest that Atlantic meridional overturning circulation changes were effectively propagated from the southeastern Atlantic into the central Indian Ocean via the Southern Ocean. Comparison of the Nd and C isotope records shows that deep-ocean circulation was decoupled from nutrient-content changes on glacial-interglacial timescales, in particular suggesting higher productivity during MIS 5. Increased equatorial productivity during MIS 5 is supported by benthic infaunal-epifaunal foraminiferal delta sup(13) C gradients, as well as benthic foraminiferal delta sup(13) C gradients along deep-water flow. Concurrent warming, indicated by planktonic foraminiferal Mg/Ca during MIS 5 at the site is consistent with changing thermocline temperature and may indicate a link to surface-ocean hydrographic changes. Article in Journal/Newspaper NADW North Atlantic Deep Water North Atlantic Southern Ocean National Institute of Oceanography, India: Digital Repository Service (DRS@nio) Indian Southern Ocean
institution Open Polar
collection National Institute of Oceanography, India: Digital Repository Service (DRS@nio)
op_collection_id ftnio
language English
topic palaeo studies
ocean circulation
glacial features
thermohaline circulation
neodymium isotopes
foraminifera
spellingShingle palaeo studies
ocean circulation
glacial features
thermohaline circulation
neodymium isotopes
foraminifera
Piotrowski, A.M.
Banakar, V.K.
Scrivner, A.E.
Elderfield, H.
Galy, A.
Dennis, A.
Indian Ocean circulation and productivity during the last glacial cycle
topic_facet palaeo studies
ocean circulation
glacial features
thermohaline circulation
neodymium isotopes
foraminifera
description The Indian Ocean is an important part of the global thermohaline circulation system, receiving deep waters sourced from the Southern Ocean and being the location of upwelling and surface-ocean current flow which returns warm and salty waters to the Atlantic. It is also an ideal location to reconstruct the link between thermohaline circulation and deep-water nutrient contents. No mixing occurs between major deep-water masses along flow paths within the Indian Ocean, so changes in water-mass provenance reflect changes in deep-ocean circulation while nutrient contents reflect addition and dissolution of organic matter. Neodymium (Nd) and carbon (C) isotope records from an equatorial Indian Ocean core (SK129-CR2) spanning the last 150 kyr are presented. The Nd isotope record shows that an increased proportion of North Atlantic Deep Water (NADW) reached the Indian Ocean during interglacials (Marine Isotope Stages; MIS 1 and 5), and a reduced proportion during glacials (MIS 2, 4, and 6), and also that changes occurred during MIS 3. The magnitude and timing of deglacial and some MIS 3 variability is very similar to those in the RC11-83/TNO57-21 South Atlantic deep Cape Basin Nd isotope record. Since the deep Cape Basin is oceanographically upstream of the Indian Ocean from a deep water circulation perspective, the Nd isotopes suggest that Atlantic meridional overturning circulation changes were effectively propagated from the southeastern Atlantic into the central Indian Ocean via the Southern Ocean. Comparison of the Nd and C isotope records shows that deep-ocean circulation was decoupled from nutrient-content changes on glacial-interglacial timescales, in particular suggesting higher productivity during MIS 5. Increased equatorial productivity during MIS 5 is supported by benthic infaunal-epifaunal foraminiferal delta sup(13) C gradients, as well as benthic foraminiferal delta sup(13) C gradients along deep-water flow. Concurrent warming, indicated by planktonic foraminiferal Mg/Ca during MIS 5 at the site is consistent with changing thermocline temperature and may indicate a link to surface-ocean hydrographic changes.
format Article in Journal/Newspaper
author Piotrowski, A.M.
Banakar, V.K.
Scrivner, A.E.
Elderfield, H.
Galy, A.
Dennis, A.
author_facet Piotrowski, A.M.
Banakar, V.K.
Scrivner, A.E.
Elderfield, H.
Galy, A.
Dennis, A.
author_sort Piotrowski, A.M.
title Indian Ocean circulation and productivity during the last glacial cycle
title_short Indian Ocean circulation and productivity during the last glacial cycle
title_full Indian Ocean circulation and productivity during the last glacial cycle
title_fullStr Indian Ocean circulation and productivity during the last glacial cycle
title_full_unstemmed Indian Ocean circulation and productivity during the last glacial cycle
title_sort indian ocean circulation and productivity during the last glacial cycle
publisher Elsevier
publishDate 2009
url http://drs.nio.org/drs/handle/2264/3372
geographic Indian
Southern Ocean
geographic_facet Indian
Southern Ocean
genre NADW
North Atlantic Deep Water
North Atlantic
Southern Ocean
genre_facet NADW
North Atlantic Deep Water
North Atlantic
Southern Ocean
op_rights An edited version of this paper was published by Elsevier. Copyright [2009] Elsevier
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