The University of Southampton
University of Southampton Institutional Repository

Retreat of the Laurentide ice sheet tracked by the isotopic composition of Pb in western North Atlantic seawater during termination 1

Record type: Article

During the Last Glacial Maximum much of North America was covered by the Laurentide ice sheet. Its melting during termination 1 led to systematic changes in proglacial lake formation, continental runoff, and possibly North Atlantic Meridional Overturning Circulation. The accompanying change in chemical weathering rates in the interior of North America throughout the deglaciation resulted in a pronounced change in seawater Pb isotope composition in the western North Atlantic Ocean. Here we present the first high-resolution records of seawater Pb isotope variations of North Atlantic Deep Water extracted from authigenic Fe–Mn oxyhydroxides in three sediment cores (51GGC, 1790 m depth; 31GGC, 3410 m depth; 12JPC, 4250 m depth) from the Blake Ridge off Florida. These data reveal a striking excursion from relatively unradiogenic 206Pb/204Pb as low as 18.93 towards highly radiogenic Pb isotope compositions that was initiated during the Bølling–Allerød interstadial and was most pronounced in both intermediate and deep waters during and after the Younger Dryas (206Pb/204Pb as high as 19.38 at 8.8 ka in 4250 m). This pattern is interpreted to be a direct function of increased inflow of continent-derived radiogenic Pb into the western North Atlantic, supplied through chemical weathering of North American rocks that had been eroded and freshly exposed during the preceding glacial cycle. These sediment-derived data are complemented by new laser ablation Pb isotope data from a ferromanganese crust from the Blake Plateau at 850 m water depth, which show only small glacial–interglacial Pb isotope variations of the Florida Current (206Pb/204Pb between 19.07 and 19.16). The lack of change in the Blake Plateau record at the same time as the radiogenic excursion in the deeper sediments supports a northern origin of the pulse of radiogenic Pb. After the Younger Dryas, the deep western North Atlantic has experienced a persistent highly radiogenic Pb supply that was most pronounced during the first half of the Holocene and still lasts until today.

Full text not available from this repository.

Citation

Gutjahr, Marcus, Frank, Martin, Halliday, Alex N. and Keigwin, Lloyd D. (2009) Retreat of the Laurentide ice sheet tracked by the isotopic composition of Pb in western North Atlantic seawater during termination 1 Earth and Planetary Science Letters, 286, (3-4), pp. 546-555. (doi:10.1016/j.epsl.2009.07.020).

More information

Published date: 15 September 2009
Keywords: chemical weathering, authigenic, Fe–Mn oxyhydroxides, Pb isotopes, NADW, GNAIW, Laurentide ice sheet, continental runoff, incongruent weathering, deglaciation

Identifiers

Local EPrints ID: 191635
URI: http://eprints.soton.ac.uk/id/eprint/191635
ISSN: 0012-821X
PURE UUID: 8c3b2db9-5bf5-4c4a-9aec-e7780e89c0e8

Catalogue record

Date deposited: 23 Jun 2011 12:09
Last modified: 18 Jul 2017 11:35

Export record

Altmetrics

Contributors

Author: Marcus Gutjahr
Author: Martin Frank
Author: Alex N. Halliday
Author: Lloyd D. Keigwin

University divisions


Download statistics

Downloads from ePrints over the past year. Other digital versions may also be available to download e.g. from the publisher's website.

View more statistics

Atom RSS 1.0 RSS 2.0

Contact ePrints Soton: eprints@soton.ac.uk

ePrints Soton supports OAI 2.0 with a base URL of http://eprints.soton.ac.uk/cgi/oai2

This repository has been built using EPrints software, developed at the University of Southampton, but available to everyone to use.

We use cookies to ensure that we give you the best experience on our website. If you continue without changing your settings, we will assume that you are happy to receive cookies on the University of Southampton website.

×