Millennial-Scale Response of a Western Mediterranean River to Late Quaternary Climate Changes: A View from the Deep Sea

Type Article
Date 2014-11
Language English
Author(s) Bonneau Lucile1, 2, 3, Jorry Stephan J.ORCID3, Toucanne SamuelORCID3, Silva Jacinto Ricardo3, Emmanuel Laurent1, 2
Affiliation(s) 1 : Laboratoire Biominéralisations et Environnements Sédimentaires, Université Pierre et Marie Curie, Paris, France
2 : Institut des Sciences de la Terre de Paris, Paris, France
3 : Laboratoire Environnements Sédimentaires, Institut français de recherche pour l’exploitation de la mer, F-29280 Plouzané, France
Source Journal Of Geology (0022-1376) (University of Chicago), 2014-11 , Vol. 122 , N. 6 , P. 687-703
DOI 10.1086/677844
WOS© Times Cited 34
Abstract Although it is widely accepted that erosion and sediment transfer respond to millennial-scale climatic variability, these changes remain difficult to detect in marine sedimentary archives. In the Var sediment-routing system, northwestern Mediterranean Sea, the absence of a continental shelf results in a direct connection between the Var River mouth and the deep basin during both highstand and lowstand conditions. This makes the Var sediment-routing system an ideal target to test whether rivers can transmit climate-driven high-frequency changes in sediment flux to the ocean. On the basis of an unprecedented (centennial-to-millennial-scale) resolution in turbidite sequences, we reconstructed the activity of turbidity current overflows along the deep-sea Var Sedimentary Ridge over the past 75 kyr. The overflow activity is highest (one event every 10-30 yr) during maximum glacial conditions (30 kyr-16 kyr ago [ka]) and rapidly decreases (down to one event every 100-500 yr) during the last glacial-interglacial transition (Termination 1). During marine isotope stage (MIS)4 and MIS3 (75-30 ka), peaks in the overflow activity occurred synchronously with cold and arid Dansgaard-Oeschger stadials, while warmer and wetter interstadial conditions correspond to low overflow activity. We conclude that overflow activity on the Var Sedimentary Ridge mainly reflects changes in the magnitude of hyperpycnal currents flowing in the turbiditic channel-levee system in relation with variations in suspended-sediment concentration during Var River floods. We show that this signal is sensitive to changes in pure sediment flux induced by climatic perturbations occurring inland: (1) the decrease in glacier-derived sediment input after glacier retreat and (2) changes in erosion induced by shifts in the vegetation cover in response to Dansgaard-Oeschger climate swings.
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Bonneau Lucile, Jorry Stephan J., Toucanne Samuel, Silva Jacinto Ricardo, Emmanuel Laurent (2014). Millennial-Scale Response of a Western Mediterranean River to Late Quaternary Climate Changes: A View from the Deep Sea. Journal Of Geology, 122(6), 687-703. Publisher's official version : , Open Access version :