Holocene relative sea-level changes in western Brittany (France) between 7600 and 4000 cal. BP: Reconstitution from basal-peat deposits

Goslin, Jérôme; Vliët-Lanoé, Brigitte van; Stéphan, Pierre; Delacourt, Christophe; Fernane, Assia; Gandouin, Emmanuel; Hénaff, Alain; Penaud, Aurélie; Suanez, Serge

doi:10.4000/geomorphologie.10386

Cited by 22 publications

(62 citation statements)

References 51 publications

(120 reference statements)

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“…15). The Holocene sea-level change along the French Atlantic and southern English coast continues to be a matter of debate in regards to the response of the continental crust to glacio-and hydro-isostatic effects and regional subsidence, but also regarding the interpretation of coastal markers and palaeo-shorelines as storm deposits (Flemming, 1998;Goslin et al, 2013;Lambeck, 1997;Leorri et al, 2012;Wingfield, 1995). Nevertheless, the recent physical models (Flemming, 1998) do not indicate a significant difference with respect to global sea-level curves (Alley et al, 2005;Deschamps et al, 2012;Waelbroeck et al, 2002).…”

Section: Morphologic Controlmentioning

confidence: 90%

Long term evolution and internal architecture of a high-energy banner ridge from seismic survey of Banc du Four (Western Brittany, France)

et al. 2015

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International audienceThe recent completion of a coupled seismic and swath bathymetric survey, conducted across the sand ridge system of the Banc du Four located on the Atlantic continental shelf of Brittany (Mer d’Iroise, France), provided new data for the study of the long term evolution of deep tidal sand ridges. Five seismic units are distinguished within the ridge, separated by pronounced major bounding surfaces. The basal unit is interpreted to be shoreface deposits forming the core of the ridge. It is overlaid by a succession of marine sand dunes fields forming the upper units. Sandwave climbing, which combines progradation and accretion, is the major process controlling the growth of the ridge. The elevation of the preserved dune foresets reaches values of about 20–30 m within the ridge. The foresets indicate a combination of giant dunes characterized by numerous steep (up to 20°) clinoforms corresponding to a high-energy depositional environment. Moreover, the presence of scour pits linked to the 3D geometries of giant dunes allow the growth of bedforms migrating oblique to the orientation of giant dune crest lines. All of the radiocarbon ages of the biogenic surficial deposits of the Banc du Four range from 10,036 to 2748 cal years B.P. and suggest the Banc du Four has grown during the last sea-level rise. The apparent absence of recent surface deposits could be caused by a change in benthic biogenic productivity or the non-conservation of recent deposits. In contrast, the presence of relatively old sands at the top of the ridge could be explained by the reworking and leakage of the lower units that outcrop locally at the seabed across the ridge. Moreover, the long-term evolution of the ridge appears strongly controlled by the morphology of the igneous basement. The multiphase accretion of the ridge is closely linked to the presence of a residual tidal current eddy, consecutive with the progressive flooding of the coastal promontories and straits that structured the igneous basement.Therefore, the Banc du Four should be thought of as a representative example of a large-scale high-energy banner bank

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Section: Morphologic Controlmentioning

confidence: 90%

Long term evolution and internal architecture of a high-energy banner ridge from seismic survey of Banc du Four (Western Brittany, France)

et al. 2015

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“…Palaeo-storminess traces have already been discussed and events were extracted from the Holocene prism stratigraphy (Van Vliet-Lanoë et al, 2014b). The RSL curve for Brittany (Goslin, 2014;Goslin et al, 2013) was calibrated with the …”

Section: Methodsmentioning

confidence: 99%

“…The sedimentary record of RSL rise and particularly the High Stands (HS) were perturbed by the increased strength of storm surges, mostly after Roman times (Meurisse-Fort, 2009). Large-scale (pluridecimetric to metric) pseudo-oscillations observed in SL reconstructions (e.g., Morzadec-Kerfroun, 1974) are the expression of disturbances of the sedimentary record induced by storms (Goslin et al, 2013;Van Vliet-Lanoë et al, 2014a). Extreme storms or several-day gales could be responsible for major morphological changes in the former ridge and back-ridge zones.…”

Section: Sea Level and Storminess Morphological Impactmentioning

confidence: 98%

Holocene formation and evolution of coastal dunes ridges, Brittany (France)

Vliët-Lanoé

Goslin

Hénaff

et al. 2015

Comptes Rendus. Géoscience

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International audienceHolocene coastal dune formation under a continuously rising sea level (SL) is an abnormal response to increasing storm frequency. The aim of this work is to understand the coastal sedimentary budget and the present-day sand starvation, controlled by climate and man. Dating in Brittany shows that Aeolian deposition initiated from ca. 4000 cal BP, with the slowing down of the SL rise. Pre-historical dunes appeared here from ca. 3000 cal BP, without SL regression. After, further building phases recycled the same stock of sands. Historical dunes I developed from ca. 350 AD. Major storms between 900 and 1200 AD resulted in the construction of washover coastal ridges, the Historical dunes II. A part of the sand was evacuated offshore. From ca. 1350 AD, the pre-existing ridges are reworked forming the Historical dunes III, leading to rapid coastal erosion and inland drift. Holocene dunes with a rising SL constitute a temporary anomaly, mostly forced by man, soon erased by storms in Brittany

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“…At the Holocene's timescale, South Brittany is known to have been submitted to the competing effects of both post-glacial isostatic adjustments and regional stress field (Van Vliet-Lanoë et al, 1997). It is now well established from the recent Holocene relative sea-level curve that Brittany subsided at a rate of 0.3 mm/year during the last 2000 years (Goslin et al, 2013), whilst at a centennial timescale, levelling measurements indicate an uplift rate of 0.2-0.6 mm/year since about 70 years (Lenô tre et al, 1999).…”

Section: Coastal Erosion Processes At Penmarc'hmentioning

confidence: 97%

High-resolution onshore–offshore morpho-bathymetric records of modern chalk and granitic shore platforms in NW France

Duperret

Raimbault

Gall

et al. 2015

Comptes Rendus. Géoscience

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International audienceModern shore platforms developed on rocky coasts are key areas for understanding coastal erosion processes during the Holocene. This contribution offers a detailed picture of two contrasted shore-platform systems, based on new high-resolution shallow-water bathymetry, further coupled with aerial LiDAR topography. Merged land-sea digital elevation models were achieved on two distinct types of rocky coasts along the eastern English Channel in France (Picardy and Upper-Normandy: PUN) and in a NE Atlantic area (SW Brittany: SWB) in NW France. About the PUN case, submarine steps, identified as paleo-shorelines, parallel the actual coastline. Coastal erosive processes appear to be continuous and regular through time, since mid-Holocene at least. In SWB, there is a discrepancy between contemporary coastline orientation and a continuous step extending from inland to offshore, identified as a paleo-shoreline. This illustrates a polyphased and inherited shore platform edification, mainly controlled by tectonic processes

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Holocene relative sea-level changes in western Brittany (France) between 7600 and 4000 cal. BP: Reconstitution from basal-peat deposits

Cited by 22 publications

References 51 publications

Long term evolution and internal architecture of a high-energy banner ridge from seismic survey of Banc du Four (Western Brittany, France)

Long term evolution and internal architecture of a high-energy banner ridge from seismic survey of Banc du Four (Western Brittany, France)

Holocene formation and evolution of coastal dunes ridges, Brittany (France)

High-resolution onshore–offshore morpho-bathymetric records of modern chalk and granitic shore platforms in NW France

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