Deep flow in the Madagascar–Mascarene Basin over the last 150000 years
The SW Indian Ocean contains at least four layers of water masses with different sources: deep Antarctic (Lower Circumpolar Deep Water) flow to the north, midwater North Indian Deep Water flow to the south and Upper Circumpolar Deep Water to the north, meridional convergence of intermediate waters a...
Published in: | Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences |
---|---|
Main Authors: | , , , |
Other Authors: | , , |
Format: | Article in Journal/Newspaper |
Language: | English |
Published: |
The Royal Society
2005
|
Subjects: | |
Online Access: | http://dx.doi.org/10.1098/rsta.2004.1480 https://royalsocietypublishing.org/doi/pdf/10.1098/rsta.2004.1480 |
id |
crroyalsociety:10.1098/rsta.2004.1480 |
---|---|
record_format |
openpolar |
spelling |
crroyalsociety:10.1098/rsta.2004.1480 2024-10-13T14:02:38+00:00 Deep flow in the Madagascar–Mascarene Basin over the last 150000 years McCave, I. N. Kiefer, T. Thornalley, D. J. R. Elderfield, H. Spencer, Tom Laughton, Anthony S. Flemming, Nic C. 2005 http://dx.doi.org/10.1098/rsta.2004.1480 https://royalsocietypublishing.org/doi/pdf/10.1098/rsta.2004.1480 en eng The Royal Society https://royalsociety.org/journals/ethics-policies/data-sharing-mining/ Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences volume 363, issue 1826, page 81-99 ISSN 1364-503X 1471-2962 journal-article 2005 crroyalsociety https://doi.org/10.1098/rsta.2004.1480 2024-09-23T04:22:18Z The SW Indian Ocean contains at least four layers of water masses with different sources: deep Antarctic (Lower Circumpolar Deep Water) flow to the north, midwater North Indian Deep Water flow to the south and Upper Circumpolar Deep Water to the north, meridional convergence of intermediate waters at 500–1500 m, and the shallow South Equatorial Current flowing west. Sedimentation rates in the area are rather low, being less than 1 cm ka −1 on Madagascar Ridge, but up to 4 cm ka −1 at Amirante Passage. Bottom flow through the Madagascar–Mascarene Basin into Amirante Passage varies slightly on glacial–interglacial time–scales, with faster flow in the warm periods of the last interglacial and minima in cold periods. Far more important are the particularly high flow rates, inferred from silt grain size, which occur at warm–to–cold transitions rather than extrema. This suggests the cause is changing density gradient driving a transiently fast flow. Corroboration is found in the glacial–interglacial range of benthic d 18 O which is ca. 2%, suggesting water close to freezing and at least 1.2 more saline and thus more dense glacial bottom waters than present. Significant density steps are inferred in isotope stage 6, the 5e–5d, and 5a–4 transitions. Oxygen isotope data suggest little change by mixing in glacial bottom water on their northward path. Benthic carbon isotope ratios at Amirante Passage differ from glacial Southern Ocean values, due possibly to absence of a local productivity effect present in the Southern Ocean. Article in Journal/Newspaper Antarc* Antarctic Southern Ocean The Royal Society Antarctic Southern Ocean Indian Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences 363 1826 81 99 |
institution |
Open Polar |
collection |
The Royal Society |
op_collection_id |
crroyalsociety |
language |
English |
description |
The SW Indian Ocean contains at least four layers of water masses with different sources: deep Antarctic (Lower Circumpolar Deep Water) flow to the north, midwater North Indian Deep Water flow to the south and Upper Circumpolar Deep Water to the north, meridional convergence of intermediate waters at 500–1500 m, and the shallow South Equatorial Current flowing west. Sedimentation rates in the area are rather low, being less than 1 cm ka −1 on Madagascar Ridge, but up to 4 cm ka −1 at Amirante Passage. Bottom flow through the Madagascar–Mascarene Basin into Amirante Passage varies slightly on glacial–interglacial time–scales, with faster flow in the warm periods of the last interglacial and minima in cold periods. Far more important are the particularly high flow rates, inferred from silt grain size, which occur at warm–to–cold transitions rather than extrema. This suggests the cause is changing density gradient driving a transiently fast flow. Corroboration is found in the glacial–interglacial range of benthic d 18 O which is ca. 2%, suggesting water close to freezing and at least 1.2 more saline and thus more dense glacial bottom waters than present. Significant density steps are inferred in isotope stage 6, the 5e–5d, and 5a–4 transitions. Oxygen isotope data suggest little change by mixing in glacial bottom water on their northward path. Benthic carbon isotope ratios at Amirante Passage differ from glacial Southern Ocean values, due possibly to absence of a local productivity effect present in the Southern Ocean. |
author2 |
Spencer, Tom Laughton, Anthony S. Flemming, Nic C. |
format |
Article in Journal/Newspaper |
author |
McCave, I. N. Kiefer, T. Thornalley, D. J. R. Elderfield, H. |
spellingShingle |
McCave, I. N. Kiefer, T. Thornalley, D. J. R. Elderfield, H. Deep flow in the Madagascar–Mascarene Basin over the last 150000 years |
author_facet |
McCave, I. N. Kiefer, T. Thornalley, D. J. R. Elderfield, H. |
author_sort |
McCave, I. N. |
title |
Deep flow in the Madagascar–Mascarene Basin over the last 150000 years |
title_short |
Deep flow in the Madagascar–Mascarene Basin over the last 150000 years |
title_full |
Deep flow in the Madagascar–Mascarene Basin over the last 150000 years |
title_fullStr |
Deep flow in the Madagascar–Mascarene Basin over the last 150000 years |
title_full_unstemmed |
Deep flow in the Madagascar–Mascarene Basin over the last 150000 years |
title_sort |
deep flow in the madagascar–mascarene basin over the last 150000 years |
publisher |
The Royal Society |
publishDate |
2005 |
url |
http://dx.doi.org/10.1098/rsta.2004.1480 https://royalsocietypublishing.org/doi/pdf/10.1098/rsta.2004.1480 |
geographic |
Antarctic Southern Ocean Indian |
geographic_facet |
Antarctic Southern Ocean Indian |
genre |
Antarc* Antarctic Southern Ocean |
genre_facet |
Antarc* Antarctic Southern Ocean |
op_source |
Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences volume 363, issue 1826, page 81-99 ISSN 1364-503X 1471-2962 |
op_rights |
https://royalsociety.org/journals/ethics-policies/data-sharing-mining/ |
op_doi |
https://doi.org/10.1098/rsta.2004.1480 |
container_title |
Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences |
container_volume |
363 |
container_issue |
1826 |
container_start_page |
81 |
op_container_end_page |
99 |
_version_ |
1812818959960899584 |