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.