Organic geochemistry of sediment cores from the Arbian 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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ftpangaea:oai:pangaea.de:doi:10.1594/PANGAEA.733514 2023-05-15T17:36:39+02:00 Organic geochemistry of sediment cores from the Arbian Sea Schulte, Sonja Rostek, Frauke Bard, Edouard Rullkötter, Jürgen Marchal, Olivier MEDIAN LATITUDE: 14.081000 * MEDIAN LONGITUDE: 70.013500 * SOUTH-BOUND LATITUDE: 5.040000 * WEST-BOUND LONGITUDE: 66.497000 * NORTH-BOUND LATITUDE: 23.122000 * EAST-BOUND LONGITUDE: 73.530000 * DATE/TIME START: 1990-09-12T00:00:00 * DATE/TIME END: 1993-09-22T00:00:00 1999-02-09 application/zip, 2 datasets https://doi.pangaea.de/10.1594/PANGAEA.733514 https://doi.org/10.1594/PANGAEA.733514 en eng PANGAEA https://doi.pangaea.de/10.1594/PANGAEA.733514 https://doi.org/10.1594/PANGAEA.733514 CC-BY-3.0: Creative Commons Attribution 3.0 Unported Access constraints: unrestricted info:eu-repo/semantics/openAccess CC-BY Supplement to: 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), 205-221, https://doi.org/10.1016/S0012-821X(99)00232-0 Arabian Sea GS900963 KL Marion Dufresne (1972) MD65 MD90-963 PAKOMIN PC Piston corer Piston corer (BGR type) SEYMAMA/SHIVA SO90 SO90_136KL Sonne Dataset 1999 ftpangaea https://doi.org/10.1594/PANGAEA.733514 https://doi.org/10.1016/S0012-821X(99)00232-0 2023-01-20T07:31:37Z 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. Dataset North Atlantic Southern Ocean PANGAEA - Data Publisher for Earth & Environmental Science Indian Southern Ocean ENVELOPE(66.497000,73.530000,23.122000,5.040000) |
institution |
Open Polar |
collection |
PANGAEA - Data Publisher for Earth & Environmental Science |
op_collection_id |
ftpangaea |
language |
English |
topic |
Arabian Sea GS900963 KL Marion Dufresne (1972) MD65 MD90-963 PAKOMIN PC Piston corer Piston corer (BGR type) SEYMAMA/SHIVA SO90 SO90_136KL Sonne |
spellingShingle |
Arabian Sea GS900963 KL Marion Dufresne (1972) MD65 MD90-963 PAKOMIN PC Piston corer Piston corer (BGR type) SEYMAMA/SHIVA SO90 SO90_136KL Sonne Schulte, Sonja Rostek, Frauke Bard, Edouard Rullkötter, Jürgen Marchal, Olivier Organic geochemistry of sediment cores from the Arbian Sea |
topic_facet |
Arabian Sea GS900963 KL Marion Dufresne (1972) MD65 MD90-963 PAKOMIN PC Piston corer Piston corer (BGR type) SEYMAMA/SHIVA SO90 SO90_136KL Sonne |
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 |
Dataset |
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 |
Organic geochemistry of sediment cores from the Arbian Sea |
title_short |
Organic geochemistry of sediment cores from the Arbian Sea |
title_full |
Organic geochemistry of sediment cores from the Arbian Sea |
title_fullStr |
Organic geochemistry of sediment cores from the Arbian Sea |
title_full_unstemmed |
Organic geochemistry of sediment cores from the Arbian Sea |
title_sort |
organic geochemistry of sediment cores from the arbian sea |
publisher |
PANGAEA |
publishDate |
1999 |
url |
https://doi.pangaea.de/10.1594/PANGAEA.733514 https://doi.org/10.1594/PANGAEA.733514 |
op_coverage |
MEDIAN LATITUDE: 14.081000 * MEDIAN LONGITUDE: 70.013500 * SOUTH-BOUND LATITUDE: 5.040000 * WEST-BOUND LONGITUDE: 66.497000 * NORTH-BOUND LATITUDE: 23.122000 * EAST-BOUND LONGITUDE: 73.530000 * DATE/TIME START: 1990-09-12T00:00:00 * DATE/TIME END: 1993-09-22T00:00:00 |
long_lat |
ENVELOPE(66.497000,73.530000,23.122000,5.040000) |
geographic |
Indian Southern Ocean |
geographic_facet |
Indian Southern Ocean |
genre |
North Atlantic Southern Ocean |
genre_facet |
North Atlantic Southern Ocean |
op_source |
Supplement to: 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), 205-221, https://doi.org/10.1016/S0012-821X(99)00232-0 |
op_relation |
https://doi.pangaea.de/10.1594/PANGAEA.733514 https://doi.org/10.1594/PANGAEA.733514 |
op_rights |
CC-BY-3.0: Creative Commons Attribution 3.0 Unported Access constraints: unrestricted info:eu-repo/semantics/openAccess |
op_rightsnorm |
CC-BY |
op_doi |
https://doi.org/10.1594/PANGAEA.733514 https://doi.org/10.1016/S0012-821X(99)00232-0 |
_version_ |
1766136209544839168 |