La vallée d'Ys : un paléoréseau hydrographique immergé en baie de Douarnenez (Finistère, France)

Jouet, Gwénaël; Augris, Claude; Hallégouët, Bernard; Roy, Pascal Le; Rolet, J.

doi:10.1016/s1631-0713(03)00066-x

Cited by 8 publications

(13 citation statements)

References 4 publications

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“…9). Previously observed in former studies, it was interpreted as fluvial buried deposits in the Bay of Brest (Baltzer et al, 2010) and in the paleo-valleys of Douarnenez (Jouet et al, 2003) and Vilaine (Menier et al, 2010;Traini et al, 2013). When this unit is preserved on terraces, it is often associated with periglacial heads (Babin et al, 1969, Morzadec-Kerfourne, 1974 (Fig.…”

Section: A From the Last Low Sea-level To 10000 Cal Yr Bpmentioning

confidence: 79%

“…The LST is bounded to the base by the first sequence boundary (SB1) and to the top by the erosive unconformity D1 corresponding to a second sequence boundary (SB2) (Fig. 11) (Jouet et al, 2003;Proust et al, 2010;Tessier et al, 2010). The SB2 surface also merged with the flooding surface (FS) marking the transition with the U1 unit.…”

Section: Chronostratigraphic Interpretationmentioning

confidence: 99%

“…The particularity of the site is the stepped geometry of the transgressive and highstand sedimentary deposits, wellpreserved in shallow environments and partly infilled in the paleo-network. Indeed, compared with other proximal systems (Jouet et al, 2003;Proust et al, 2010;Tessier et al, 2010;Tessier et al, 2012;Traini et al, 2013;Menier et al, 2016), the Bay of Brest has preserved a remarkable fluvial morphology maintained by strong tidal currents and low modern fluvial sedimentary inputs. Unlike, the other systems, the narrow entrance (Goulet) of the bay (1) induces a strong channelization and amplification of the tidal currents which preventing deposition along the channel axes and (2) limits significantly the action of waves on sediment transport.…”

Section: Accepted Manuscriptmentioning

confidence: 99%

“…These studies have highlighted the importance of the control of system parameters of the sedimentary deposits (Chaumillon et al, 2010). The case of the tide-dominated estuary, although less studied, is a good example of sedimentary preservation, partly because of its location at the land-sea transition (Dalrymple et al, 1990;Jouet et al, 2003;García-García et al, 2005;Billeaud et al, 2007;Menier et al, 2010;Proust et al, 2010;Dalrymple et al, 2012;Tessier et al, 2012;Traini et al, 2013;Green et al, 2013;Zhang et al, 2014).…”

Section: Introductionmentioning

confidence: 99%

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Control factors of Holocene sedimentary infilling in a semi-closed tidal estuarine-like system: the bay of Brest (France)

Gregoire

Roy²,

Ehrhold³

et al. 2017

Marine Geology

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This study details the sedimentary infilling of an original tidal-dominated estuary system during the final stage of the last marine transgression. The Bay of Brest is confined and connects the rivers Elorn and Aulne, to the sea of Iroise by a narrow strait encasing a well preserved paleo-channel. The compilation of high-and very-high-resolution bathymetric and seismic data, constrained by sediments datations, allows us to classify the paleo-morphology of the bay into three stepped domains: the paleo-valley floor surrounded by fluvial terraces, the central plateau, and the shallow embayments. Taking into account the main factors controlling the infilling, including sea-level rise, substratum morphology, and hydrodynamics, the stratigraphic scheme of the bay has been reconstructed. The lowstand system track (LST) is assumed to correspond to relict Pleistocene continental deposits associated with the last low sea level around 21,000 cal yr B.P. The transgressive phase, represented by the transgressive system track (TST), is divided into two parts. The lower part (TST1) constitutes the first stage of transgressive deposition in the bay. Starting around 9000 cal yr B.P. and currently conserved in the shallowest parts, it is characterized by tidal flats associated with deposits in the inner estuary. This stage ends at about 7000 cal yr B.P. and is separated from the upper part (TST2) by a tidal ravinement surface that occurs around 7700 cal yr B.P. at the foot slope. TST2 formed sand bodies in the central part of the bay between 6800 and 3000 cal yr B.P. These deposits, interpreted as tidal banks, are associated with the outer estuarine environment. The maximum flooding surface (MFS), dated around 3000 and 2000 cal yr B.P., marked the installation of a highstand system track (HST) under the combined influence of tidal currents, storms events, and anthropogenic activity. The geometry deposition of each system track is controlled at the first order by the combination of the irregular Holocene sea level rise and the inherited rocky substratum morphology. The retreat of the shoreline, and estuarine environments, is function of the successive flooding of stepped domains. The direct evolution of the volume of the assumed accumulated sea water in the bay favoured the gradual installation of the present-day hydrodynamic circulation. Highlights ► Sedimentary records retrace the landward retreat of tidal processes at the Holocene. ► The stepped bedrock allows unique preservation of depositional environments. ► The bed-rock morphology has a key-role on the conservation of sediment deposition.

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Section: A From the Last Low Sea-level To 10000 Cal Yr Bpmentioning

confidence: 79%

Section: Chronostratigraphic Interpretationmentioning

confidence: 99%

Section: Accepted Manuscriptmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Control factors of Holocene sedimentary infilling in a semi-closed tidal estuarine-like system: the bay of Brest (France)

Gregoire

Roy²,

Ehrhold³

et al. 2017

Marine Geology

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“…1b). These channels are connected to the main continental rivers surrounding the BD (Musset, 1934;Guilcher, 1948;Hallegouët, 1989;Jouet et al, 2003). The sedimentary infilling history of the BD is based on the analysis of seismic units (U1 to U6; Fig.…”

Section: The Bay Of Douarnenez (Bd)mentioning

confidence: 99%

Palaeoenvironmental reconstructions during the Meso- to Neolithic transition (9.2–5.3 cal. ka BP) in Northwestern France: Palynological evidences

et al. 2018

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Sedimentological, palynological, and micropalaeontological studies carried out throughout the first half of the Holocene, during the Mesolithic/Neolithic transition in the Bay of Brest (i.e. 9200-9000 and 6600-5300 cal. BP) and in the Bay of Douarnenez (i.e. 9200-8400 cal. BP), allowed characterizing coastal environmental changes under the increasing influence of the relative sea-level rise. The gradual flooding of the two studied sites implied a transition from river valleys to oceanic bays as revealed by the gradual retreat of salt marsh environments, as detected through palynological analysis. In addition, these high-resolution studies highlight the regional imprint of the North Atlantic millennial climate variability in northwestern coastal environments. Two cold climate events are indeed suggested to have been locally marked by a moisture increase, mainly detected by increases in Lingulodinium machaerophorum, Corylus, and Alnus percentages at 8550 cal. BP in the Bay of Douarnenez and at 6250 cal. BP in the Bay of Brest. Moreover, regarding the Neolithic transition timing in the Bay of Douarnenez, large pollen grains of Poaceae (i.e. Cerealia-type pollen grains) have been detected at around 8600 cal. BP, that is, 1500 years before the general accepted cereal cropping appearance in Western France. These results, consistent with other palynological studies conducted in the French Atlantic coast, could underline a Mesolithic 'proto-agriculture' in Brittany.

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Sedimentary infilling of bedrock-controlled palaeo-embayments off Cape Trafalgar, Strait of Gibraltar (Gulf of Cadiz)

Castro

Lobo

2017

Geo-Mar Lett

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La vallée d'Ys : un paléoréseau hydrographique immergé en baie de Douarnenez (Finistère, France)

Cited by 8 publications

References 4 publications

Control factors of Holocene sedimentary infilling in a semi-closed tidal estuarine-like system: the bay of Brest (France)

Control factors of Holocene sedimentary infilling in a semi-closed tidal estuarine-like system: the bay of Brest (France)

Palaeoenvironmental reconstructions during the Meso- to Neolithic transition (9.2–5.3 cal. ka BP) in Northwestern France: Palynological evidences

Sedimentary infilling of bedrock-controlled palaeo-embayments off Cape Trafalgar, Strait of Gibraltar (Gulf of Cadiz)

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