The University of Southampton
University of Southampton Institutional Repository

Enhanced productivity on the Iberian margin during glacial/interglacial transitions revealed by barium and diatoms

Enhanced productivity on the Iberian margin during glacial/interglacial transitions revealed by barium and diatoms
Enhanced productivity on the Iberian margin during glacial/interglacial transitions revealed by barium and diatoms
The Portuguese margin is at a critical location for studies of the ocean's behaviour during glacial/interglacial climatic changes, and the rapid accumulation rates of the sediments enable high-resolution palaeoclimatic investigation. The sedimentary record of the past 350 ka has been investigated in a 35 m long core from 3.5 km water depth on the slope at 40°N by geochemical, isotopic and micropalaeontological techniques. The CaCO3 content of this core as a function of time contains significant Milankovitch orbital frequencies of 18.8, 23.7, 38.0 and 100.6 ka, but these are driven primarily by dilution by clay-flux variations rather than by CaCO3 productivity variations. The largest signals in the productivity indicators Corg, Ba/Al and diatom abundance are all observed as simultaneous peaks at the oxygen isotope stage boundaries 10/9 and 6/5, with the signal magnitude in the order 10/9>6/5 for all three indicators. Smaller coincident signals in Corg, Ba/Al but not diatoms are also observed at the oxygen isotope stage 2/1 boundary. Other less prominent peaks in the Corg and Ba/Al profiles occur elsewhere, including Heinrich Event horizons, but these are not always simultaneous and none contain evidence of the dissolution-prone diatom microfossils. The 10/9, 6/5 and 2/1 oxygen isotope stage transitions represent the three most extreme glacial/interglacial sea level rises in the past 350 ky, possibly in the same sequence of magnitude, when sea level rose rapidly by 120+m from glacial low stands to interglacial high stands. The productivity signals at these transitions are contained within <5 ka (including bioturbation).
IBERIAN MARGIN, PLEISTOCENE, CORES, PALAEOCLIMATE, BARIUM, DIATOMS, HEINRICH EVENTS, FORAMINIFERA, RADIOCARBON DATING, PALAEOPRODUCTIVITY, GEOLOGY, METEOROLOGY
0016-7649
667-677
Thomson, J.
3395054f-e507-4841-9758-a06ed37f7d6b
Nixon, S.
4f986947-9e12-4f2b-bc11-1d35b125d860
Summerhayes, C.P.
ef270d6d-fd3d-43ae-99c8-a423d9dad554
Rohling, E.J.
a2a27ef2-fcce-4c71-907b-e692b5ecc685
Schonfeld, J.
4de69a9a-517e-48cf-9441-4882d060971f
Zahn, R.
3d2ec2f1-5578-4d1c-bacb-d33014fe6831
Grootes, P.
1a16df67-2344-4ec1-8774-9de1092d1908
Abrantes, F.
6087b8bb-49c5-49f8-945b-9e1e1db48e14
Gaspar, L.
73f7fc7a-eca8-4ad5-9f6d-8883d4c8fd9d
Vaqueiro, S.
1cdbfd9b-759a-4000-8fe5-a3fc42522be5
Thomson, J.
3395054f-e507-4841-9758-a06ed37f7d6b
Nixon, S.
4f986947-9e12-4f2b-bc11-1d35b125d860
Summerhayes, C.P.
ef270d6d-fd3d-43ae-99c8-a423d9dad554
Rohling, E.J.
a2a27ef2-fcce-4c71-907b-e692b5ecc685
Schonfeld, J.
4de69a9a-517e-48cf-9441-4882d060971f
Zahn, R.
3d2ec2f1-5578-4d1c-bacb-d33014fe6831
Grootes, P.
1a16df67-2344-4ec1-8774-9de1092d1908
Abrantes, F.
6087b8bb-49c5-49f8-945b-9e1e1db48e14
Gaspar, L.
73f7fc7a-eca8-4ad5-9f6d-8883d4c8fd9d
Vaqueiro, S.
1cdbfd9b-759a-4000-8fe5-a3fc42522be5

Thomson, J., Nixon, S., Summerhayes, C.P., Rohling, E.J., Schonfeld, J., Zahn, R., Grootes, P., Abrantes, F., Gaspar, L. and Vaqueiro, S. (2000) Enhanced productivity on the Iberian margin during glacial/interglacial transitions revealed by barium and diatoms. Journal of the Geological Society, 157 (3), 667-677.

Record type: Article

Abstract

The Portuguese margin is at a critical location for studies of the ocean's behaviour during glacial/interglacial climatic changes, and the rapid accumulation rates of the sediments enable high-resolution palaeoclimatic investigation. The sedimentary record of the past 350 ka has been investigated in a 35 m long core from 3.5 km water depth on the slope at 40°N by geochemical, isotopic and micropalaeontological techniques. The CaCO3 content of this core as a function of time contains significant Milankovitch orbital frequencies of 18.8, 23.7, 38.0 and 100.6 ka, but these are driven primarily by dilution by clay-flux variations rather than by CaCO3 productivity variations. The largest signals in the productivity indicators Corg, Ba/Al and diatom abundance are all observed as simultaneous peaks at the oxygen isotope stage boundaries 10/9 and 6/5, with the signal magnitude in the order 10/9>6/5 for all three indicators. Smaller coincident signals in Corg, Ba/Al but not diatoms are also observed at the oxygen isotope stage 2/1 boundary. Other less prominent peaks in the Corg and Ba/Al profiles occur elsewhere, including Heinrich Event horizons, but these are not always simultaneous and none contain evidence of the dissolution-prone diatom microfossils. The 10/9, 6/5 and 2/1 oxygen isotope stage transitions represent the three most extreme glacial/interglacial sea level rises in the past 350 ky, possibly in the same sequence of magnitude, when sea level rose rapidly by 120+m from glacial low stands to interglacial high stands. The productivity signals at these transitions are contained within <5 ka (including bioturbation).

Full text not available from this repository.

More information

Published date: 2000
Keywords: IBERIAN MARGIN, PLEISTOCENE, CORES, PALAEOCLIMATE, BARIUM, DIATOMS, HEINRICH EVENTS, FORAMINIFERA, RADIOCARBON DATING, PALAEOPRODUCTIVITY, GEOLOGY, METEOROLOGY

Identifiers

Local EPrints ID: 8738
URI: https://eprints.soton.ac.uk/id/eprint/8738
ISSN: 0016-7649
PURE UUID: a45f0ff8-c9b5-459a-a5cc-31eba4500f30
ORCID for E.J. Rohling: ORCID iD orcid.org/0000-0001-5349-2158

Catalogue record

Date deposited: 25 Aug 2004
Last modified: 06 Jun 2018 13:06

Export record

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 https://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.

×