Holocene evolution of a Languedocian lagoonal environment controlled by inherited coastal morphology (northern Gulf of Lions, France)

Abstract

The Maguelone shore extends along the northern coast of the Gulf of Lions margin, West of the Rhone delta and East of some high gradient coastal streams that have been providing most of the elastic sediments to the Gulf of Lions margin since the early Miocene. This 10 km wide area comprises an onshore small coastal watershed (15 km long) in low-lying carbonate hills, kilometer wide marshes, sandy beach and shoreface featuring local low sedimentation. Deposit architecture in such a coastal zone records dynamics of incised valley fill under the influence of rivers and wave/current hydrodynamics in a microtidal environment during an eustatic cycle.;A detailed analysis of about 250 km of very high resolution seismic profiles, tens of cores and outcrops data revealed the evolution of the Maguelone coastal system from Late-Quaternary to present-day. It highlighted also dominant denudation processes in the upstream catchments associated to the formation of incised valley seaward during Quaternary. Combination of this inherited morphology together with hydrodynamics controlled the lagoonal environment evolution since the last transgression. In particular, the Maguelone shore is characterized by the formation of built-over-rias lagoonal systems and records an evolution from partially protected lagoon to isolated lagoon environment. These two stages of lagoon evolution correspond to distinct deposit environments. Correlation of fauna contents with deposit geometry improves lagoonal environment models

Late-Holocene evolution of a coastal lagoon in the Gulf of Lions (South of France)

“…During the VI th century B.C., the development of Greco-Etruscan trade favours, in the western Mediterranean Sea, the development of a littoral harbour like at Agde, le Cailar and Lattara [Blanchemanche et al, 2003]. Raynal et al [2010] have estimated the beginning of construction of the actual barrier at 1800 ± 150 yr cal B.P. and was located on a small peninsula at the Lez mouth, on the northern border of the Palavasian lagoonal system [Chabal et al, 2008], thus facilitating economic shipping through permanent inlet ( fig.…”

Mapping past and recent landscape modifications in the Lagoon of Venice through geophysical surveys and historical maps

“…In the study area, however, the units H1 and H2b are not present: the lagoonal facies L ( i.e. the unit H3 of tidal channels and modern lagoon deposit in Zecchin et al (2009) 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 11 channel deposits and lagoonal deposits, respectively) in Raynal et al (2010), showing similar lagoon environmental behavior related to the sea-level rise during the Flandrian marine transgression (Storms et al, 2008, Antonioli et al, 2009. The micropalaeontological analyses (Albani et al, 2007) further characterize the facies L in different environments: salt-marsh facies Lsm, mudflat facies Lm, tidal channel laminated facies Lcl and tidal channel sandy facies Lcs.…”

SUBDUNE tool: quasi-explicit formulation of the water level along the shoreline

“…At the time scale of tens of years, many changes occur in the coastal environment. In particular, the mean shape of the shoreface may evolve depending upon the mean volume of sediment available (RAYNAL et al, 2009;2010). In the same way, mean forcings (wave height, wave angle, ...) may change after climate influence (JIMENEZ & SANCHEZ-ARCILLA, 2004).…”