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Surface and deep-water hydrography on Gardar Drift (Iceland Basin) during the last interglacial period

Surface and deep-water hydrography on Gardar Drift (Iceland Basin) during the last interglacial period
Surface and deep-water hydrography on Gardar Drift (Iceland Basin) during the last interglacial period
Changes in surface and deep-water hydrography were inferred from variations in stable isotopes and sortable silt mean grain size, respectively, on the southern Gardar Drift in the subpolar North Atlantic. The bathymetric ?13C gradient during the penultimate glaciation was similar to the last glaciation with high- ?13C Glacial North Atlantic Intermediate water above ? 2000 m, and low- ?13C water derived from the Southern Ocean below. During Termination II, low-?13C water was present throughout the water column with minimum values at intermediate depths (? 1500–2000 m) and below 3000 m. This pattern continued well into the early part of the Last Interglacial (LIG) period. Sortable silt mean size at 3275 m suggests that deep-water circulation on Gardar Drift was relatively weak during the earliest part of the LIG (128 to 124.5 ka) when planktonic ?18O was at a minimum, reflecting warming and/or reduced salinity. We suggest that low- ?13C water and slow current speed on Gardar Drift during the early part of the LIG was related to increased melt water fluxes to the Nordic Seas during peak boreal summer insolation, which decreased the flux and/or density of overflow to the North Atlantic. The resumption of the typical interglacial pattern of strong, well-ventilated Iceland Scotland Overflow Water was delayed until ? 124 ka. These changes may have affected Atlantic Meridional Overturning Circulation.
last interglacial, north atlantic, gardar drift, iceland–scotland overflow, thermohaline circulation, surface hydrography
0012-821X
10-19
Hodell, David A.
c9977ae9-d52c-4d74-8f01-08391ec61066
Minth, Emily Kay
a394a530-2e3a-48a0-89ab-d5b41d4ee382
Curtis, Jason H.
14c7bcf9-4bf1-4608-9d02-08e62cb916d4
McCave, I. Nicholas
2f082e65-9d43-49fa-ab55-c34b5813ef81
Hall, Ian R.
79d6c80f-11a9-4ffe-ba43-a20c5ee1c9de
Channell, James E.T.
55b6c1cc-76e7-4ca5-8186-d9111b9b5158
Xuan, Chuang
3f3cad12-b17b-46ae-957a-b362def5b837
Hodell, David A.
c9977ae9-d52c-4d74-8f01-08391ec61066
Minth, Emily Kay
a394a530-2e3a-48a0-89ab-d5b41d4ee382
Curtis, Jason H.
14c7bcf9-4bf1-4608-9d02-08e62cb916d4
McCave, I. Nicholas
2f082e65-9d43-49fa-ab55-c34b5813ef81
Hall, Ian R.
79d6c80f-11a9-4ffe-ba43-a20c5ee1c9de
Channell, James E.T.
55b6c1cc-76e7-4ca5-8186-d9111b9b5158
Xuan, Chuang
3f3cad12-b17b-46ae-957a-b362def5b837

Hodell, David A., Minth, Emily Kay, Curtis, Jason H., McCave, I. Nicholas, Hall, Ian R., Channell, James E.T. and Xuan, Chuang (2009) Surface and deep-water hydrography on Gardar Drift (Iceland Basin) during the last interglacial period Earth and Planetary Science Letters, 288, (1-2), pp. 10-19. (doi:10.1016/j.epsl.2009.08.040).

Record type: Article

Abstract

Changes in surface and deep-water hydrography were inferred from variations in stable isotopes and sortable silt mean grain size, respectively, on the southern Gardar Drift in the subpolar North Atlantic. The bathymetric ?13C gradient during the penultimate glaciation was similar to the last glaciation with high- ?13C Glacial North Atlantic Intermediate water above ? 2000 m, and low- ?13C water derived from the Southern Ocean below. During Termination II, low-?13C water was present throughout the water column with minimum values at intermediate depths (? 1500–2000 m) and below 3000 m. This pattern continued well into the early part of the Last Interglacial (LIG) period. Sortable silt mean size at 3275 m suggests that deep-water circulation on Gardar Drift was relatively weak during the earliest part of the LIG (128 to 124.5 ka) when planktonic ?18O was at a minimum, reflecting warming and/or reduced salinity. We suggest that low- ?13C water and slow current speed on Gardar Drift during the early part of the LIG was related to increased melt water fluxes to the Nordic Seas during peak boreal summer insolation, which decreased the flux and/or density of overflow to the North Atlantic. The resumption of the typical interglacial pattern of strong, well-ventilated Iceland Scotland Overflow Water was delayed until ? 124 ka. These changes may have affected Atlantic Meridional Overturning Circulation.

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More information

Published date: 30 October 2009
Keywords: last interglacial, north atlantic, gardar drift, iceland–scotland overflow, thermohaline circulation, surface hydrography
Organisations: Ocean and Earth Science

Identifiers

Local EPrints ID: 351184
URI: http://eprints.soton.ac.uk/id/eprint/351184
ISSN: 0012-821X
PURE UUID: 303c25b3-8855-432c-891c-f86885f74a2b
ORCID for Chuang Xuan: ORCID iD orcid.org/0000-0003-4043-3073

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Date deposited: 16 Apr 2013 09:06
Last modified: 18 Jul 2017 04:28

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Contributors

Author: David A. Hodell
Author: Emily Kay Minth
Author: Jason H. Curtis
Author: I. Nicholas McCave
Author: Ian R. Hall
Author: James E.T. Channell
Author: Chuang Xuan ORCID iD

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