Late Holocene Dust Deposition Fluxes Over the Entire South Atlantic Ocean

Michèlle van der Does*, Frank Lamy, Stephan Krätschmer, Jan Berend W. Stuut, Christoph Völker, Martin Werner, Roseanne Schwarz, Marty Fleisher, Gisela Winckler

*Corresponding author for this work

Research output: Contribution to JournalArticleAcademicpeer-review

Abstract

Mineral dust accumulated on the ocean floor is an important archive for reconstructing past atmospheric circulation changes and climatological conditions in the source areas. Dust emitted from Southern Hemisphere dust sources is widely deposited over the oceans. However, there are few records of dust deposition over the open ocean, and a large need for extended geographical coverage exists. We present a large data set (134 surface sediment samples) of Late Holocene dust deposition from seafloor surface sediments covering the entire South Atlantic Ocean. Polymodal grain-size distributions of the lithogenic fraction indicate that the sediments are composed of multiple sediment components. By using end-member modeling, we attempt to disentangle the dust signal from non-aeolian sediments. Combined with 230Th-normalized lithogenic fluxes, we quantified the specific deposition fluxes for mineral dust, crrent-sorted sediments and ice-rafted debris (IRD). Although the method could not completely separate the different components in every region, it shows that dust deposition off the most prominent dust source for the South Atlantic Ocean—southern South America—amounts up to approximately 0.7 g cm−2 Kyr−1 and decreases downwind. Bottom-current-sorted sediments and IRD are mostly concentrated around the continental margins. The ratio of the coarse to fine dust end members reveals input from north African dust sources to the South Atlantic. The majority of the observations are in good agreement with new model simulations. This extensive and relevant data set of dust grain size and deposition fluxes to the South Atlantic could be used to calibrate and validate further model simulations.

Original languageEnglish
Article numbere2023GC011105
Pages (from-to)1-17
Number of pages17
JournalGeochemistry, Geophysics, Geosystems
Volume25
Issue number1
Early online date27 Jan 2024
DOIs
Publication statusPublished - Jan 2024

Bibliographical note

Publisher Copyright:
© 2024 The Authors. Geochemistry, Geophysics, Geosystems published by Wiley Periodicals LLC on behalf of American Geophysical Union.

Funding

Funded by the Alfred Wegener Institute (AWI) Helmholtz Centre for Polar and Marine Research Strategy Fund Project DustIron. O. Esper is thanked for BSi data, V. Schumacher is thanked for help in the lab and in acquiring the samples. Vera Bender is thanked for the acquisition of GeoB samples from the MARUM core repository. We acknowledge the use of imagery from the NASA Worldview application (https://worldview.earthdata.nasa.gov), part of the NASA Earth Observing System Data and Information System (EOSDIS). Open Access funding enabled and organized by Projekt DEAL.

FundersFunder number
Helmholtz Centre for Polar and Marine Research Strategy Fund
National Aeronautics and Space Administration
MARUM – Zentrum für Marine Umweltwissenschaften
Alfred-Wegener-Institut, Helmholtz-Zentrum für Polar- und Meeresforschung

    Keywords

    • dust
    • end-member modeling
    • grain size
    • South Atlantic
    • Th-normalization

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