Depositional controls on a hypertidal barrier‐spit system architecture and evolution, Pointe du Banc spit, north‐western France

Abstract

Physical stratigraphy, architecture and evolution of barrier systems in hypertidal environments (tidal range above 6 m) are understudied, and depositional controls are poorly understood compared with wave-dominated barrier systems and barrier spits in microtidal, mesotidal and macrotidal settings. Based on vibracores, ground-penetrating radar, radiocarbon and optically stimulated luminescence age data, the formation and evolution of the hypertidal barrier system of Pointe du Banc, north-western France has been reconstructed. The study shows that the barrier spit has a complex composite sedimentary architecture consisting of wave-dominated and tide-dominated sedimentary bodies. A morpho-sedimentary model is presented that demonstrates how barrier-spit progradation resulting from littoral drift was the main manner of spit elongation, whereas sediment convergence caused by landward migration of swash bars and seaward migration of tidal dunes caused the spit terminus to grow in height and width. These results suggest that long-term accretion rates varied considerably in response to changes in sediment supply. Variations in storminess together with the large-scale topography of the coast controlled the sediment supply and thus the evolution of the barrier system during latest Holocene. Despite architectural complexity, hypertidal barrier systems preserve records of past climate changes.

Sand spit dynamics in a large tidal‐range environment: Insight from multiple LiDAR, UAV and hydrodynamic measurements on multiple spit hook development, breaching, reconstruction, and shoreline changes

“…(iv) Finally, breaching and destruction of the extremities of hooks are regularly observed in the evolution of spits with or without hooks (e.g. Sanchez‐Arcilla and Jimenez, 1994; Chaumillon et al ., 2014; Williams et al ., 2015; Safak et al ., 2016; Sadio et al ., 2017; Zainescu et al ., 2019; Fruergaard et al ., 2020). In addition to these points, the three stages of decadal evolution of the Agon spit, involving hook destruction followed by construction, also show that spit hooks can evince geomorphic resilience in the sense of Kombiadou et al .…”

“…The throat is located in an area of lower dune elevation, confirming that this parameter acts as a major morphological trigger on overwash occurrence (Sallenger, 2000). Concerning the partial destruction of a hook, the literature shows surface evolution patterns drawn from aerial or satellite photographs (Chaumillon et al ., 2014; Williams et al ., 2015; Fruergaard et al ., 2020), but quantification of sediment volumes involved has lagged behind. At the Agon spit, the total destruction of the tip of the spit that took place during winter 2015–2016 is estimated at about 109 300 m 3 (Table 2).…”

Characteristics and context of high-energy, tidally modulated, barred shoreface deposits: Kimmeridgian–Tithonian sandstones, Weald Basin, southern U.K. and northern France

“…12A; cf. Nielsen et al 1988;Fruergaard et al 2020). Stratal geometries consistent with stacking of dune cross-sets to form bar cosets are not noted at outcrop, implying that the stratal relationships resolved in thick shoreface clinoform sets (Fig.…”

The turnaround from transgression to regression of Holocene barrier systems in south‐eastern Australia: Geomorphology, geological framework and geochronology

“…Interest in these regressive coastal landforms has recently renewed, and is building on the legacy of pioneering work begun in the late 1970s (Thom, , 1983Thom et al, , 1981aRoy et al, 1980;Roy & Thom, 1981;Thom & Roy, 1985). In Australia and globally, this renewed interest is being driven by improvements in, and access to, remote sensing, geophysical and geochronological techniques, and the need to interpret palaeoenvironmental records and shoreline evolution in the context of observed and anticipated sea-level rise (Dougherty & Nichol, 2007;Timmons et al, 2010;Tamura, 2012;Dougherty et al, 2019b;Fruergaard et al, 2020). The ability to acquire high-resolution strandplain topography using airborne Light Detection and Ranging (LiDAR) has made possible the discrimination of successive shorelines (Fruergaard et al, 2015b;Oliver et al, 2017b).…”

“…Use of ground-penetrating radar (GPR) to image subsurface reflections within sandy coastal facies has enabled researchers to distinguish seaward-dipping from landward-dipping reflections (Neal, 2004;Dougherty et al, 2004;Buynevich et al, 2009;Tamura, 2012). Recent advances in geochronology, specifically the availability and use of optically stimulated luminescence (OSL) dating, have constrained the timing of landform deposition (Murray-Wallace et al, 2002;Tamura et al, 2019;Fruergaard et al, 2020).…”