Sorted bedforms over transgressive deposits along the continental shelf of western Sardinia (Mediterranean Sea)

Falco, Giovanni De; Budillon, Francesca; Conforti, Alessandro; Bitetto, Massimiliano Di; Martino, Gabriella Di; Innangi, Sara; Simeone, Simone; Tonielli, Renato

doi:10.1016/j.margeo.2014.11.008

Cited by 32 publications

(25 citation statements)

References 33 publications

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“…A typical Mistral wind storm with a return period of 1 y produces a JONSWAPtype spectrum characterized by a significant wave height (WHS) of 8 m, a peak period of 10 s and a peak wave direction of 308°(northwest). Storms with a return period of 10 y are characterized by a WHS of 10 m and a peak period of 11.5 s. The strong wave hydrodynamics were related to the presence of active sorted bedforms at a depth of 43-70 m along the shelf offshore the gulf (De Falco et al, 2015). The yearly tides are very weak and the maximum water displacement in the absence of wind and regular pressure is b0.2 m (Simeone et al, 2014).…”

Section: Regional Settingmentioning

confidence: 99%

Early cementation and accommodation space dictate the evolution of an overstepping barrier system during the Holocene

et al. 2015

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Section: Regional Settingmentioning

confidence: 99%

Early cementation and accommodation space dictate the evolution of an overstepping barrier system during the Holocene

et al. 2015

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“…Later investigations of sorted bedforms off Long Island, New York (Schwab et al, 2000;Goff et al, 2015a), Wrightsville Beach, North Carolina (Thieler et al, 2001;Murray & Thieler, 2004;Gutierrez et al, 2005) and the Martha's Vineyard coast, Massachusetts (Goff et al, 2005), USA, have revealed distinctive asymmetries of such bedforms, and linked them to the influence of directional (longshore) currents. Episodic storms or storm waves are also considered to be a major factor affecting the migration of sorted bedforms (Murray & Thieler, 2004;Diesing et al, 2006;De Falco et al, 2015;Goff et al, 2015a). Other important factors include: combined current and orbital forces (Black & Oldman, 1999;Green et al, 2004;Davis et al, 2013), subsurface stratigraphy (Gutierrez et al, 2005;Trembanis & Hume, 2011;Goff et al, 2015a) and sediment supply (Murray & Thieler, 2004).…”

Section: Introductionmentioning

confidence: 99%

Sorted bedforms off Western Long Island, New York, USA: Asymmetrical morphology and twelve‐year migration record

et al. 2018

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Sorted bedforms are widely present in sediment‐starved littoral and inner shelf settings; they are indicators for hydrodynamic conditions and a primary contributor for the subsurface structure. This study investigated the morphology and migration of sorted bedforms on the inner shelf of Long Beach Barrier Island, New York, USA, by repeat geophysical and geological surveys in 2001, 2005 and 2013 (following superstorm Sandy) involving swath bathymetry, backscatter, chirp seismic reflection data and grab sampling. Swath data revealed that the western sector, comprising the western 75% of the survey region, is dominated by NNE–SSW‐oriented, 0·5 to 1·0 km wide sorted bedforms with highly asymmetrical cross‐sections, with steeper slopes and coarser sands on the eastern (stoss) flanks. Many secondary bedforms were also observed (north–south to north‐east/south‐west oriented lineation structures) at the western edges of coarse sand zones. The eastern sector displays an unusual sorted bedform pattern that is dominated by coarse‐grained substrate, with isolated patches of fine‐grained sands oriented north‐east/south‐west which are 0·15 to 1·0 km in length and ca 30 to 200 m in width, similar in scale and orientation to the secondary bedforms in the western sector. Comparison analysis of the swath data sets indicates that the primary transverse sorted bedform morphology within the western sector was largely stable over this time frame, although the swales were deepened following the storms. The coarse/fine sand boundaries did migrate, however, moving ca 1 to 5 m eastward between 2001 and 2005, and ca 5 to 20 m westward between 2005 and 2013; the higher migration rates (up to 2·5 m year−1) in the latter time period may be attributable to large storm forcing (for example, hurricanes Irene and Sandy). Significant north‐westward migration of the secondary bedforms and coarse sand patches in the western sector, as well as fine sand patches in the eastern sector were also observed; these features are far more mobile than the primary sorted bedforms, possibly because they are fine sand drifts that do not erode into the coarse substrate. Seismic reflection data revealed a transgressive ravinement beneath sorted bedforms, merging with the sea floor at the bottom of swales. The authors hypothesize that long‐term topographic migration of transverse sorted bedforms contributes to the formation and evolution of the ravinement.

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“…Past experiments have demonstrated that an azimuth dependence of BS can be expected both for seabed with sand waves (Boehme et al 1985;Le Chenadec 2004;Richardson et al 2001) and seabed covered with shells (Stanic et al 1989); these case studies relied mainly on specific experimental configurations at low to medium sonar frequencies . In real survey conditions MBES-measured backscatter has been used to map and study large-scale seabed patterns (De Falco et al 2015;Schmitt and Mitchell 2014). On the contrary, smaller bedforms (e.g.…”

mentioning

confidence: 99%

Analysis of seafloor backscatter strength dependence on the survey azimuth using multibeam echosounder data

2017

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Sorted bedforms over transgressive deposits along the continental shelf of western Sardinia (Mediterranean Sea)

Cited by 32 publications

References 33 publications

Early cementation and accommodation space dictate the evolution of an overstepping barrier system during the Holocene

Early cementation and accommodation space dictate the evolution of an overstepping barrier system during the Holocene

Sorted bedforms off Western Long Island, New York, USA: Asymmetrical morphology and twelve‐year migration record

Analysis of seafloor backscatter strength dependence on the survey azimuth using multibeam echosounder data

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