Understanding the mechanisms behind high glacial productivity in the southern Brazilian margin
This study explores the mechanisms behind the high glacial productivity in the southern Brazilian margin (SBM) during the last 70 kyr using planktonic foraminifera assemblage and subsurface temperature information derived using the modern analogue technique. We show that enhanced glacial productivit...
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ftcopernicus:oai:publications.copernicus.org:cp70835 2023-05-15T18:00:55+02:00 Understanding the mechanisms behind high glacial productivity in the southern Brazilian margin Portilho-Ramos, Rodrigo da Costa Pinho, Tainã Marcos Lima Chiessi, Cristiano Mazur Barbosa, Cátia Fernandes 2019-05-27 application/pdf https://doi.org/10.5194/cp-15-943-2019 https://cp.copernicus.org/articles/15/943/2019/ eng eng doi:10.5194/cp-15-943-2019 https://cp.copernicus.org/articles/15/943/2019/ eISSN: 1814-9332 Text 2019 ftcopernicus https://doi.org/10.5194/cp-15-943-2019 2020-07-20T16:22:48Z This study explores the mechanisms behind the high glacial productivity in the southern Brazilian margin (SBM) during the last 70 kyr using planktonic foraminifera assemblage and subsurface temperature information derived using the modern analogue technique. We show that enhanced glacial productivity was driven by the synergy of two mechanisms operating in different seasons: (i) enhanced productivity in the upwelling region during short austral summer events; and (ii) the persistent presence of the Plata Plume Water (PPW) due to prolonged austral winter conditions. We suggest that the upwelling systems in the southern Brazilian margin were more productive during the last glacial period due to the enhanced Si supply for diatom production by high-Si thermocline waters preformed in the Southern Ocean. We hypothesize that orbital forcing did not have a major influence on changes in upwelling during the last glacial period. However, the more frequent northward intrusions of the Plata Plume Water were modulated by austral winter insolation at 60 ∘ S via changes in the strength of alongshore southwesterly winds. After the Last Glacial Maximum, the reduced Si content of thermocline waters decreased upwelling productivity, while lower austral winter insolation decreased the influence of the Plata Plume Water over the southern Brazilian margin, reducing regional productivity. Text Planktonic foraminifera Southern Ocean Copernicus Publications: E-Journals Austral Southern Ocean Climate of the Past 15 3 943 955 |
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Copernicus Publications: E-Journals |
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ftcopernicus |
language |
English |
description |
This study explores the mechanisms behind the high glacial productivity in the southern Brazilian margin (SBM) during the last 70 kyr using planktonic foraminifera assemblage and subsurface temperature information derived using the modern analogue technique. We show that enhanced glacial productivity was driven by the synergy of two mechanisms operating in different seasons: (i) enhanced productivity in the upwelling region during short austral summer events; and (ii) the persistent presence of the Plata Plume Water (PPW) due to prolonged austral winter conditions. We suggest that the upwelling systems in the southern Brazilian margin were more productive during the last glacial period due to the enhanced Si supply for diatom production by high-Si thermocline waters preformed in the Southern Ocean. We hypothesize that orbital forcing did not have a major influence on changes in upwelling during the last glacial period. However, the more frequent northward intrusions of the Plata Plume Water were modulated by austral winter insolation at 60 ∘ S via changes in the strength of alongshore southwesterly winds. After the Last Glacial Maximum, the reduced Si content of thermocline waters decreased upwelling productivity, while lower austral winter insolation decreased the influence of the Plata Plume Water over the southern Brazilian margin, reducing regional productivity. |
format |
Text |
author |
Portilho-Ramos, Rodrigo da Costa Pinho, Tainã Marcos Lima Chiessi, Cristiano Mazur Barbosa, Cátia Fernandes |
spellingShingle |
Portilho-Ramos, Rodrigo da Costa Pinho, Tainã Marcos Lima Chiessi, Cristiano Mazur Barbosa, Cátia Fernandes Understanding the mechanisms behind high glacial productivity in the southern Brazilian margin |
author_facet |
Portilho-Ramos, Rodrigo da Costa Pinho, Tainã Marcos Lima Chiessi, Cristiano Mazur Barbosa, Cátia Fernandes |
author_sort |
Portilho-Ramos, Rodrigo da Costa |
title |
Understanding the mechanisms behind high glacial productivity in the southern Brazilian margin |
title_short |
Understanding the mechanisms behind high glacial productivity in the southern Brazilian margin |
title_full |
Understanding the mechanisms behind high glacial productivity in the southern Brazilian margin |
title_fullStr |
Understanding the mechanisms behind high glacial productivity in the southern Brazilian margin |
title_full_unstemmed |
Understanding the mechanisms behind high glacial productivity in the southern Brazilian margin |
title_sort |
understanding the mechanisms behind high glacial productivity in the southern brazilian margin |
publishDate |
2019 |
url |
https://doi.org/10.5194/cp-15-943-2019 https://cp.copernicus.org/articles/15/943/2019/ |
geographic |
Austral Southern Ocean |
geographic_facet |
Austral Southern Ocean |
genre |
Planktonic foraminifera Southern Ocean |
genre_facet |
Planktonic foraminifera Southern Ocean |
op_source |
eISSN: 1814-9332 |
op_relation |
doi:10.5194/cp-15-943-2019 https://cp.copernicus.org/articles/15/943/2019/ |
op_doi |
https://doi.org/10.5194/cp-15-943-2019 |
container_title |
Climate of the Past |
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15 |
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3 |
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943 |
op_container_end_page |
955 |
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1766170195474251776 |