Climatically-driven impacts on sedimentation processes in the Bay of Quiberon (south Brittany, France) over the last 10,000 years

Abstract

The Bay of Quiberon (NW France), which is protected by the Quiberon Peninsula, provides well-preserved sedimentary archives for high-resolution reconstruction of Holocene climate variability. Very-high-resolution seismic profiles were obtained from two Seistec boomer seismic campaigns conducted in the bay. The seismic surveys reveal the deposition of five distinct sedimentary units. This succession is correlated with radiocarbon-dated sediments sampled in a long CASQ core (MD08-3204CQ). The analysis of the sediments shows significant changes in grain size, indicating a complex series of palaeo-climate events dated at 8800, 8600, 4270, 3860, 2470 and 1060 cal. yr BP. These may be correlated with millennial timescale climate variability corresponding to the phases of Holocene rapid climate changes (RCCs), associated with negative North Atlantic Oscillation (NAO) index and usually characterized by weaker winter storms. On the contrary, periods between RCCs are characterized by the predominance of westerly winds and stormy conditions for Brittany (i.e. positive NAO). However, only storm events occurring during the RCCs have been preserved in the Bay of Quiberon. This paper aims to reconstruct the Holocene sedimentary infill of the bay, highlighting the role of episodic acceleration phases of the sea-level rise on the preservation of sedimentary archives. Thus, the Bay of Quiberon provides substantially a complete sedimentation record of the last 10,000 years characterized by a series of complex palaeo-environmental changes.

Climate variability and storm impacts as major drivers for human coastal marsh withdrawal over the Neolithic period (Southern Brittany, NW France)

“…The GL marsh is therefore a perfect area to perform paleoenvironmental studies of the Holocene period using comprehensive sediment records. Additionally, several studies conducted around Brittany previously confirmed that coastal environments represent pertinent and key study areas to decipher Holocene climatic and/or anthropogenic changes (Sorrel et al, 2009(Sorrel et al, , 2012Baltzer et al, 2014;Fernane et al, 2014;Van Vliet-Lanoë et al, 2014).…”

Climate control on late Holocene high-energy sedimentation along coasts of the northeastern Atlantic Ocean

“…A dominant feature is the presence of discrete, millimetre to centimetre thick shelly sand to gravel layers embedded in back-barrier lagoonal successions (Degeai et al, 2015;Dezileau et al, 2011;Sabatier et al, 2008) or in marsh fine-grained sediments (Billeaud et al, 2009), interpreted as the imprint of barrier destruction and sand over wash . These discrete coarse layers are also recognised offshore, in the wave-influenced outer section of estuaries (Baltzer et al, 2014;Sorrel et al, 2009). Another dominant feature is the detection of discrete erosional discontinuities in estuaries (Billeaud et al, 2009;Tessier et al, 2010) and lagoons (Ferrer et al, 2010), indicative of prolonged phases of sediment remobilisation and/or erosion.…”

Temporal approaches of historical extreme storm events based on sedimentological archives

“…Fichaut and Suanez, 2011;Hall et al, 2006;Hansom et al, 2008;Hansom and Hall, 2009;Suanez et al, 2009;Williams and Hall, 2004), Mediterranean lagoonal sequences (e.g. Abad et al, 2019;Degeai et al, 2015;Kaniewski et al, 2016;Sabatier et al, 2012Sabatier et al, , 2010 and only few works have been conducted on the French Atlantic coast (Baltzer et al, 2014;Poirier et al, 2017;Sorrel et al, 2009;Van Vliet Lanoe et al, 2014). The British Isles (e.g.…”

“…Hall et al, 2006;Hansom and Hall, 2009;Williams and Hall, 2004), bay sedimentation (e.g. Baltzer et al, 2014;Poirier et al, 2017;Van Vliet Lanoe et al, 2014), dune evolution (e.g. Clarke and Rendell, 2006;Clemmensen et al, 2009;Jelgersma et al, 1995), beach ridges morphology (e.g.…”