Planktonic foraminifera assemblage, MAT-derived sea surface temperature and Cibicides spp. oxygen isotopes, supplement to: Portilho-Ramos, Rodrigo Costa; Pinho, Tainã Marcos Lima; Chiessi, Cristiano Mazur; Barbosa, Catia Fernandes (2019): Understanding the mechanisms behind high glacial productivity in the southern Brazilian margin. Climate of the Past, 15(3), 943-955

This study explores the mechanisms behind the high glacial productivity in the southern Brazilian margin during the last 70 kyr. Therefore, we use planktonic foraminifera assemblage and subsurface temperatures derived through the Modern Analogue Technique. We show that enhanced glacial productivity...

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Bibliographic Details
Main Authors: Portilho-Ramos, Rodrigo Costa, Pinho, Tainã Marcos Lima, Chiessi, Cristiano Mazur, Barbosa, Catia F
Format: Article in Journal/Newspaper
Language:English
Published: PANGAEA - Data Publisher for Earth & Environmental Science 2019
Subjects:
Southern Ocean
Austral
Marcos
Ramos
Planktonic foraminifera
Online Access:https://dx.doi.org/10.1594/pangaea.902040
https://doi.pangaea.de/10.1594/PANGAEA.902040
Description
Summary:This study explores the mechanisms behind the high glacial productivity in the southern Brazilian margin during the last 70 kyr. Therefore, we use planktonic foraminifera assemblage and subsurface temperatures derived through the Modern Analogue Technique. We show that enhanced glacial productivity was driven by the synergy of two mechanisms operating in different seasons: (i) a high productivity upwelling during short austral summer events; and (ii) the persistent presence of the Plata Plume Water 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 through 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 65 °S through changes in the strength of alongshore SW-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.

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