Incised-valley morphologies and sedimentary-fills within the inner shelf of the Bay of Biscay (France): A synthesis

Abstract

This study is a first synthesis focused on incised-valleys located within the inner shelf of the Bay of Biscay. It is based on previously published results obtained during recent seismic surveys and coring campaigns. The morphology of the valleys appears to strongly controlled by tectonics and lithology. The Pleistocene sedimentary cover of the shelf is very thin and discontinuous with a maximum thickness ranging between 30 and 40 m in incised valley fills. Thus the incised bedrock morphology plays a key-role by controlling hydrodynamics and related sediment transport and deposition that explains some variations of those incisedvalley fills with respect to the previously published general models.Present-day seismic activity in the western part of France is moderate (Müller et al., 1992). It is possibly related to strain originating at the southern European plate boundary (Ziegler, 1992).Onland, rocky outcrops correspond to two main sets: (1) metamorphic and magmatic rocks related to the Hercynian orogen, north of the lay-Sèvre estuary (Pertuis breton, Fig. 1) and (2) Mesozoic and Cenozoic sedimentary rocks including, from north to south, early Jurassic to Pliocene strata in the Aquitanian basin, south of the Lay-Sèvre estuary. Southward of the Gironde estuary, Cenozoic strata are overlain by an extensive Quaternary sand cover including large eolian sand dunes.

Assessment of static flood modeling techniques: application to contrasting marshes flooded during Xynthia (western France)

“…In the past (from millenaries to centuries) the seaward parts of those onshore incised-valley segments were flooded by the sea (Allard et al, 2008;Billeaud et al, 2004;Chaumillon et al, 2008;Pawlowski, 1998). The rapid siltation and sedimentfill of those IV segments led to the development of extensive coastal marshes, one of them corresponding to the largest coastal marsh of France (the Poitevin Marsh, no.…”

Hydrodynamic controls of morpho-sedimentary evolution in a rock-bounded wave dominated estuary. Tina Menor (N Spain)

“…Other rock bounded estuaries have been described in the northwest of Iberian Península (Evans and Prego, 2003;Naughton et al, 2007), France (e.g. Menier, 2006;Chaumillon et al 2008;Sorrel et al, 2010;Tessier, 2012), United Kingdom and Ireland (Burningham and Cooper, 2004;Cooper, 2006) and South Africa (Cooper, 2001).…”

Depositional stages of the Eğribucak inner basin (terrestrial to marine evaporite and carbonate) from the Sivas Basin (Central Anatolia, Turkey)

“…Lagoon or bay environment occasionally fed by fluvial systems (Kangal and Varol, 1999;Chaumillon et al, 2008).…”

“…Interpretation: The sediments of this facies were deposited in the first stage of the marine input terminating terrestrial sedimentation. In particular, channel-fill deposits represented by cross-bedded pebbly sandstones are the typical examples of incised valleys developing in front of the progressing coastline (Chaumillon et al, 2008). The levels with evaporite transition indicate the restricted water circulation/closed environmental conditions together with climatic changes displaying short-term aridifications.…”