The University of Southampton
University of Southampton Institutional Repository

A saltier glacial Mediterranean outflow

A saltier glacial Mediterranean outflow
A saltier glacial Mediterranean outflow
©2018. American Geophysical Union. The state of Atlantic Meridional Overturning Circulation (AMOC) is influenced by both the strength and the location of the Mediterranean Outflow Water (MOW) plume in the Gulf of Cadiz. To evaluate the influence of MOW on AMOC over deglaciations, precise and accurate salinity and temperature reconstructions are needed. For this purpose, we measured Mg/Ca and clumped isotopes of several benthic foraminiferal species at Integrated Ocean Drilling Program Site U1390 in the Gulf of Cadiz. The clumped isotope results of Cibicidoides pachyderma, Uvigerina mediterranea, and Pyrgo spp. are consistent between species and record no significant difference in Last Glacial Maximum to Holocene deep water temperature. Over the deglaciation, the Mg/Ca-based temperatures derived from U. mediterranea indicate three periods of MOW absence at Site U1390. Mg/Ca-based temperatures of Hoeglundina elegans and C. pachyderma are on average 6°C too cold when compared to the present core-top temperature, which we explain by a carbonate ion effect on these epibenthic species related to the high alkalinity of the MOW. Combining deep water temperature estimates with the benthic oxygen isotope data and considering different relationships between seawater oxygen isotopes and salinity, we infer a salinity decrease of MOW by three to eight units over the deglaciation and four units during Sapropel 1, accounting for the global δ 18 O depletion due to the decrease in ice volume. Our findings confirm that the Mediterranean Sea accumulates excess salt during a glacial low stand and suggest that this salt surged into the Atlantic over the deglaciation, presumably during Heinrich Stadial 1.
Gibraltar buoyancy exchange, Heinrich events, Mediterranean salinity
179-197
van Dijk, J.
f05f1de9-1157-4aea-9d15-56be79468946
Ziegler, M.
803ba330-20ad-426a-9f0d-c3164f927812
de Nooijer, L.J.
ff491e03-c179-4239-94a9-e30016f31cba
Reichart, G.J.
dd155475-f861-47d6-9a00-d1a927bb4d08
Xuan, C.
3f3cad12-b17b-46ae-957a-b362def5b837
Ducassou, E.
b92cc04f-1c63-47c6-b1a8-d3ea9d12f1d4
Bernasconi, S.M.
d60685c9-9440-45e1-a27e-9e9e1c872082
Lourens, L.J.
d3c5b95b-b14d-4f5f-8ec1-f3f517335ca1
van Dijk, J.
f05f1de9-1157-4aea-9d15-56be79468946
Ziegler, M.
803ba330-20ad-426a-9f0d-c3164f927812
de Nooijer, L.J.
ff491e03-c179-4239-94a9-e30016f31cba
Reichart, G.J.
dd155475-f861-47d6-9a00-d1a927bb4d08
Xuan, C.
3f3cad12-b17b-46ae-957a-b362def5b837
Ducassou, E.
b92cc04f-1c63-47c6-b1a8-d3ea9d12f1d4
Bernasconi, S.M.
d60685c9-9440-45e1-a27e-9e9e1c872082
Lourens, L.J.
d3c5b95b-b14d-4f5f-8ec1-f3f517335ca1

van Dijk, J., Ziegler, M., de Nooijer, L.J., Reichart, G.J., Xuan, C., Ducassou, E., Bernasconi, S.M. and Lourens, L.J. (2018) A saltier glacial Mediterranean outflow. Paleoceanography and Paleoclimatology, 33 (2), 179-197. (doi:10.1002/2017PA003228).

Record type: Article

Abstract

©2018. American Geophysical Union. The state of Atlantic Meridional Overturning Circulation (AMOC) is influenced by both the strength and the location of the Mediterranean Outflow Water (MOW) plume in the Gulf of Cadiz. To evaluate the influence of MOW on AMOC over deglaciations, precise and accurate salinity and temperature reconstructions are needed. For this purpose, we measured Mg/Ca and clumped isotopes of several benthic foraminiferal species at Integrated Ocean Drilling Program Site U1390 in the Gulf of Cadiz. The clumped isotope results of Cibicidoides pachyderma, Uvigerina mediterranea, and Pyrgo spp. are consistent between species and record no significant difference in Last Glacial Maximum to Holocene deep water temperature. Over the deglaciation, the Mg/Ca-based temperatures derived from U. mediterranea indicate three periods of MOW absence at Site U1390. Mg/Ca-based temperatures of Hoeglundina elegans and C. pachyderma are on average 6°C too cold when compared to the present core-top temperature, which we explain by a carbonate ion effect on these epibenthic species related to the high alkalinity of the MOW. Combining deep water temperature estimates with the benthic oxygen isotope data and considering different relationships between seawater oxygen isotopes and salinity, we infer a salinity decrease of MOW by three to eight units over the deglaciation and four units during Sapropel 1, accounting for the global δ 18 O depletion due to the decrease in ice volume. Our findings confirm that the Mediterranean Sea accumulates excess salt during a glacial low stand and suggest that this salt surged into the Atlantic over the deglaciation, presumably during Heinrich Stadial 1.

Text
4_reviewer_attachment_1_1511194127_convrt - Accepted Manuscript
Restricted to Repository staff only
Request a copy
Text
2017PA003228 - Version of Record
Download (2MB)

More information

Accepted/In Press date: 1 January 2018
e-pub ahead of print date: 10 February 2018
Published date: February 2018
Keywords: Gibraltar buoyancy exchange, Heinrich events, Mediterranean salinity

Identifiers

Local EPrints ID: 418705
URI: http://eprints.soton.ac.uk/id/eprint/418705
PURE UUID: 69cd1d35-5e0d-4199-a854-8c59d4bd61a1
ORCID for C. Xuan: ORCID iD orcid.org/0000-0003-4043-3073

Catalogue record

Date deposited: 19 Mar 2018 17:30
Last modified: 18 Feb 2021 17:22

Export record

Altmetrics

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.

×