Post-Glacial and Holocene Migration of the Rhône Deltaic Complexes (NW Mediterranean)

Earth's climate oscillated during the Late Quaternary following the major glacial-interglacial cycles. The global climatic warming during the last deglaciation period is also affected by rapid global changes. Several fluctuations in the rate of the sea-level rise have been recognized from various proxy records and several melt water pulses have been identified at the transition of abrupt climate changes. These well-known variations influenced continental and marine sedimentary records worldwide. However, the associated changes of global sea-level and of environmental factors are not precisely documented, neither are their stratigraphic signatures. The extensive geophysical (swath bathymetric and high-resolution seismic data) and sedimentological investigations carried out in the Gulf of Lions (Western Mediterranean) since the early 90's allow us to explore the expanded sedimentary records preserved on this continental margin. The combination of high sediment supply (largely from Alpine glaciers) and significant subsidence favoured the preservation of high-resolution depositional sequences linked to post-glacial and Holocene climate and sea-level changes. The RHOSOS (RHOne SOurce to Sink) program provides new insight into the deglacial history of the Rhone system, within a broader source to sink approach. The detailed record for this period is mainly preserved along the Rhone depositional system as a set of shelf backstepping parasequences linked to the retreat path of the delta during the post-glacial sea-level rise and several eroded deltaic/prodeltaic lobes corresponding to the Late Holocene highstand period. This depositional system reveals the stratigraphic imprint of rapid events such as melt water pulses and climate driven sediment discharges. Our results demonstrate the influence of a very high sediment flux and of fluctuations of sea-level rise on the architecture of the Gulf of Lions deltaic system. It also supports the existence of several pulses of sea-level rise (MWPs) and their impact on shelf sedimentation worldwide.