Variations of oxygen-minimum and primary productivity recorded in sediments of the Arabian Sea
Two deep-sea sediment cores from the northeastern and the southeastern Arabian Sea were studied in order to reconstruct the palaeoenvironments of the past glacial cycles. Core 136KL was recovered from the high-productivity area off Pakistan within the modern oxygen-minimum zone (OMZ). By contrast, m...
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ftunivbern:oai:boris.unibe.ch:158536 2023-08-20T04:08:30+02:00 Variations of oxygen-minimum and primary productivity recorded in sediments of the Arabian Sea Schulte, Sonja Rostek, Frauke Bard, Edouard Rullkötter, Jürgen Marchal, Olivier 1999 application/pdf https://boris.unibe.ch/158536/1/schulte99epsl.pdf https://boris.unibe.ch/158536/ eng eng Elsevier https://boris.unibe.ch/158536/ info:eu-repo/semantics/restrictedAccess Schulte, Sonja; Rostek, Frauke; Bard, Edouard; Rullkötter, Jürgen; Marchal, Olivier (1999). Variations of oxygen-minimum and primary productivity recorded in sediments of the Arabian Sea. Earth and planetary science letters, 173(3), pp. 205-221. Elsevier 10.1016/S0012-821X(99)00232-0 <http://dx.doi.org/10.1016/S0012-821X(99)00232-0> 530 Physics info:eu-repo/semantics/article info:eu-repo/semantics/publishedVersion PeerReviewed 1999 ftunivbern https://doi.org/10.1016/S0012-821X(99)00232-0 2023-07-31T22:08:11Z Two deep-sea sediment cores from the northeastern and the southeastern Arabian Sea were studied in order to reconstruct the palaeoenvironments of the past glacial cycles. Core 136KL was recovered from the high-productivity area off Pakistan within the modern oxygen-minimum zone (OMZ). By contrast, modern primary productivity at the site of MD900963 close to Maldives is moderate and bottom waters are today well oxygenated. For both cores, we reconstructed the changes in palaeoproductivity using a set of biomarkers (alkenones, dinosterol and brassicasterol); the main result is that primary productivity is enhanced during glacial stages and lowered during interstadials. The proxies associated with productivity show a 23 kyr cyclicity corresponding to the precession-related insolation cycle. Palaeoredox conditions were studied in both cores using a new organic geochemical parameter (C35/C31-n-alkane ratio) developed by analysing surface sediments from a transect across the OMZ off Pakistan. The value of this ratio in core 136KL shows many variations during the last 65 kyr, indicating that the OMZ was not stable during this time: it disappeared completely during Heinrich- and the Younger Dryas events, pointing to a connection between global oceanic circulation and the stability of the OMZ. The C35/C31 ratio determined in sediments of core MD900963 shows that bottom waters remained rather well oxygenated over the last 330 kyr, which is confirmed by comparison with authigenic metal concentrations in the same sediments. A zonally averaged, circulation–biogeochemical ocean model was used to explore how the intermediate Indian Ocean responds to a freshwater flux anomaly at the surface of the North Atlantic. As suggested by the geochemical time series, both the abundance of Southern Ocean Water and the oxygen concentration are significantly increased in response to this freshwater perturbation. Article in Journal/Newspaper North Atlantic Southern Ocean BORIS (Bern Open Repository and Information System, University of Bern) Indian Southern Ocean Earth and Planetary Science Letters 173 3 205 221 |
institution |
Open Polar |
collection |
BORIS (Bern Open Repository and Information System, University of Bern) |
op_collection_id |
ftunivbern |
language |
English |
topic |
530 Physics |
spellingShingle |
530 Physics Schulte, Sonja Rostek, Frauke Bard, Edouard Rullkötter, Jürgen Marchal, Olivier Variations of oxygen-minimum and primary productivity recorded in sediments of the Arabian Sea |
topic_facet |
530 Physics |
description |
Two deep-sea sediment cores from the northeastern and the southeastern Arabian Sea were studied in order to reconstruct the palaeoenvironments of the past glacial cycles. Core 136KL was recovered from the high-productivity area off Pakistan within the modern oxygen-minimum zone (OMZ). By contrast, modern primary productivity at the site of MD900963 close to Maldives is moderate and bottom waters are today well oxygenated. For both cores, we reconstructed the changes in palaeoproductivity using a set of biomarkers (alkenones, dinosterol and brassicasterol); the main result is that primary productivity is enhanced during glacial stages and lowered during interstadials. The proxies associated with productivity show a 23 kyr cyclicity corresponding to the precession-related insolation cycle. Palaeoredox conditions were studied in both cores using a new organic geochemical parameter (C35/C31-n-alkane ratio) developed by analysing surface sediments from a transect across the OMZ off Pakistan. The value of this ratio in core 136KL shows many variations during the last 65 kyr, indicating that the OMZ was not stable during this time: it disappeared completely during Heinrich- and the Younger Dryas events, pointing to a connection between global oceanic circulation and the stability of the OMZ. The C35/C31 ratio determined in sediments of core MD900963 shows that bottom waters remained rather well oxygenated over the last 330 kyr, which is confirmed by comparison with authigenic metal concentrations in the same sediments. A zonally averaged, circulation–biogeochemical ocean model was used to explore how the intermediate Indian Ocean responds to a freshwater flux anomaly at the surface of the North Atlantic. As suggested by the geochemical time series, both the abundance of Southern Ocean Water and the oxygen concentration are significantly increased in response to this freshwater perturbation. |
format |
Article in Journal/Newspaper |
author |
Schulte, Sonja Rostek, Frauke Bard, Edouard Rullkötter, Jürgen Marchal, Olivier |
author_facet |
Schulte, Sonja Rostek, Frauke Bard, Edouard Rullkötter, Jürgen Marchal, Olivier |
author_sort |
Schulte, Sonja |
title |
Variations of oxygen-minimum and primary productivity recorded in sediments of the Arabian Sea |
title_short |
Variations of oxygen-minimum and primary productivity recorded in sediments of the Arabian Sea |
title_full |
Variations of oxygen-minimum and primary productivity recorded in sediments of the Arabian Sea |
title_fullStr |
Variations of oxygen-minimum and primary productivity recorded in sediments of the Arabian Sea |
title_full_unstemmed |
Variations of oxygen-minimum and primary productivity recorded in sediments of the Arabian Sea |
title_sort |
variations of oxygen-minimum and primary productivity recorded in sediments of the arabian sea |
publisher |
Elsevier |
publishDate |
1999 |
url |
https://boris.unibe.ch/158536/1/schulte99epsl.pdf https://boris.unibe.ch/158536/ |
geographic |
Indian Southern Ocean |
geographic_facet |
Indian Southern Ocean |
genre |
North Atlantic Southern Ocean |
genre_facet |
North Atlantic Southern Ocean |
op_source |
Schulte, Sonja; Rostek, Frauke; Bard, Edouard; Rullkötter, Jürgen; Marchal, Olivier (1999). Variations of oxygen-minimum and primary productivity recorded in sediments of the Arabian Sea. Earth and planetary science letters, 173(3), pp. 205-221. Elsevier 10.1016/S0012-821X(99)00232-0 <http://dx.doi.org/10.1016/S0012-821X(99)00232-0> |
op_relation |
https://boris.unibe.ch/158536/ |
op_rights |
info:eu-repo/semantics/restrictedAccess |
op_doi |
https://doi.org/10.1016/S0012-821X(99)00232-0 |
container_title |
Earth and Planetary Science Letters |
container_volume |
173 |
container_issue |
3 |
container_start_page |
205 |
op_container_end_page |
221 |
_version_ |
1774720787780993024 |