Radiogenic isotopic and clay mineralogical signatures of terrigenous particles as water-mass tracers: New insights into South Atlantic deep circulation during the last termination

F. Beny*, V. Bout-Roumazeilles, G. R. Davies, C. Waelbroeck, A. Bory, N. Tribovillard, M. Delattre, R. Abraham

*Corresponding author for this work

Research output: Contribution to JournalArticleAcademicpeer-review

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Abstract

The past evolution of the Southern Ocean, one of the major components of the climatic system, is still a matter of debate. This study provides new insights into the deep Southern Ocean circulation based on the radiogenic isotopes and clay mineralogical signature of the terrigenous fractions transported by the main deep water masses to sediments recovered in core MD07-3076Q from the central South Atlantic. This approach successfully permits: (1) provenance identification of the various grain-size fractions (clay, cohesive silt and sortable silt); (2) assignment of each grain-size fraction to a specific water-mass; (3) reconstruction of past changes in the main deep water-mass pathways. These data document the evolution of deep-water masses in the South Atlantic Ocean during the last deglaciation. The Antarctic Bottom Water (AABW) speed and northward extension were maximum at the end of the Last Glacial Maximum (LGM), associated with strong bottom water production in the Weddell Sea, together with a vigorous Lower Circumpolar Deep Water (LCDW). In contrast the North Atlantic Deep Water (NADW) circulation was weaker than today. The onset of the deglaciation (from 17.5 ka to 15 ka, ∼Heinrich Stadial 1, HS 1) was marked by weakening and southerly retreat of the AABW and by an increase of mixing between AABW and LCDW. The speed of the AABW remained at its lowest during the Bølling Allerød (B/A) and the Younger Dryas (YD), and the LCDW slowed and retreated to the south, while the NADW progressively migrated southward, deepened, and strengthened between the beginning of the Bølling Allerød and the Holocene (from ∼15 to 10 ka).

Original languageEnglish
Article number106089
Pages (from-to)1-19
Number of pages19
JournalQuaternary Science Reviews
Volume228
Early online date28 Nov 2019
DOIs
Publication statusPublished - 15 Jan 2020

Funding

We wish to thank Richard Smeets for his invaluable help in the clean lab, Emmeke Bos, Janne Koorneef, and Mathijs van de Ven for the help with TIMS Triton measurements, Bas van der Wagt and Kirsten van Zuilen for Neptune MC-ICPMS measurements. Tristan Lippens is thanked for computer support. We also wish to thank all organizations that provided financial support to the project: the “region Haut de France” and the Vrije Universiteit of Amsterdam. The research was supported by Europlanet 2020 RI, which received funding from the European Union’s Horizon 2020 research and innovation programme under grant agreement No 654208 . We also want to express our special thanks to the “flotte océanographique française” for retrieving the sediment core used in this study. FB and VBR thanks Monique Gentric for administrative support. CW acknowledges support from the European Research Council ERC grant ACCLIMATE/ n° 339108 . Appendix A

FundersFunder number
Europlanet 2020 RI
Horizon 2020 Framework Programme
Seventh Framework Programme339108, 871149, 654208
European Research Council
Horizon 2020

    Keywords

    • Clay mineralogy
    • Grain size distribution
    • Last deglaciation
    • Paleoceanography
    • Radiogenic isotopes
    • South Atlantic
    • Southern Ocean

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