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Title

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

Publication Year

2014

Author(s)
  • Bonneau, Lucile
  • Jorry, Stephan J.
  • Toucanne, Samuel
  • Jacinto, Ricardo Silva
  • Emmanuel, Laurent
Source
JOURNAL OF GEOLOGY Volume: 122 Issue: 6 Pages: 687-703 Published: 2014
ISSN
0022-1376 eISSN: 1537-5269
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.

Author Keyword(s)

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KeyWord(s) Plus
  • LAST GLACIAL MAXIMUM
  • VAR TURBIDITE SYSTEM
  • SOUTHERN CALIFORNIA
  • TEMPERATURE-CHANGES
  • SEDIMENT DELIVERY
  • ARMORICAN MARGIN
  • FRENCH RIVIERA
  • TIME SCALES
  • RECORD
  • CURRENTS
ESI Discipline(s)
  • Geosciences
Web of Science Category(ies)
  • Geology
Adress(es)

[Bonneau, Lucile; Emmanuel, Laurent] Univ Paris 04, Univ Paris 06, Lab Biomineralisat & Environm Sedimentaires, Paris, France; [Bonneau, Lucile; Emmanuel, Laurent] Inst Sci Terre Paris, CNRS, Unite Mixte Rech 7193, Paris, France; [Bonneau, Lucile; Jorry, Stephan J.; Toucanne, Samuel; Jacinto, Ricardo Silva] IFREMER, Lab Environm Sedimentaires, F-29280 Plouzane, France

Reprint Adress

Bonneau, L (reprint author), Univ Paris 04, Univ Paris 06, Lab Biomineralisat & Environm Sedimentaires, Paris, France.

Country(ies)
  • France
CNRS - Adress(es)
  • Institut des Sciences de la Terre Paris (iSTeP), UMR7193
Accession Number
WOS:000346125200004
uid:/KLVHNFWG
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