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Near steady denudation rates during the late Pleistocene in the tropics
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  • Etienne Large,
  • Julien Charreau,
  • Pierre-Henri Blard,
  • Germain Bayon,
  • Eduardo Garzanti,
  • Bernard Dennielou,
  • Gwenael Jouet,
  • Natalia Vazquez Riveiros,
  • Jacques Giraudeau,
  • Reisberg Laurie,
  • Aymeric Schumacher,
  • Alfred Andriamamonjy,
  • Michel Amos Fety Rakotondrazafy
Etienne Large
CRPG

Corresponding Author:[email protected]

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Julien Charreau
CRPG, CNRS, Université de Lorraine
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Pierre-Henri Blard
Centre de Recherches Pétrographiques et Géochimiques (CRPG)
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Germain Bayon
IFREMER
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Eduardo Garzanti
University of Milano Bicocca
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Bernard Dennielou
IFREMER Brest
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Gwenael Jouet
IFREMER, Centre de Brest, Institut CARNOT - EDROME
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Natalia Vazquez Riveiros
Ifremer
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Jacques Giraudeau
CNRS - University of Bordeaux
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Reisberg Laurie
CRPG
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Aymeric Schumacher
CRPG
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Alfred Andriamamonjy
Université d'Antananarivo
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Michel Amos Fety Rakotondrazafy
Université d'Antananarivo
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Abstract

Denudation is a key parameter controlling the evolution of the Earth’s surface, the production of soils, the stability of relief or the long-term evolution of climate. Climate fluctuations conversely have a strong impact on denudation, but these complex feedback mechanisms are still under-constrained. To better predict future changes that will affect our habitat, and understand links between climate and denudation, precise quantification of paleo-denudation rates is required. In this work, we measure cosmogenic radionuclides (10Be) in turbidites of a well-dated marine sedimentary core recovered in the Mozambique Channel to provide a 900 ka long near-continuous record of paleo-denudation rates over the 100 ka climatic cycles. Neodymium isotopes and heavy mineral analysis were used to provide constraints on the provenance of terrigenous sediments exported from Madagascar to the studied site and show that temporal variations in sediment provenance are limited and decoupled from climatic cyclicity. Our 10Be-based paleo-denudation rates are in the same order as modern rates, ranging from 17.4 ± 5.8 mm/ka to 73.9 ± 29.4 mm/ka, and do not show major variations through the Middle and Late Pleistocene. Importantly, we did not identify a systematic significant impact of glacial/interglacial cyclicity on denudation rates. Denudation of this subtropical island may instead have been controlled by variability of monsoon intensity associated with shifts in the Inter Tropical Convergence Zone, but this interpretation remains speculative at this stage as it cannot be recorded within the resolution of cosmogenic-derived denudation rates.
09 Nov 2024Submitted to ESS Open Archive
09 Nov 2024Published in ESS Open Archive