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Journal articles
Carbonate slope morphology revealing sediment transfer from bank-to-slope (Little Bahama Bank, Bahamas)
Abstract : New high-quality multibeam and high-resolution seismic data reveal new observations on sediment
transfer and distribution and margin morphometrics in the uppermost slope of Northeastern Little
Bahama Bank between 20 and 300 m water depth. The echofacies/backscatter facies show an alongslope
sediment distribution forming successive strips. The upper part of the uppermost slope corresponds to
the alternation of several submerged coral terraces and escarpments that could be related to Late
Quaternary sea-level variations. The terraces could either be related to periods of stagnating sea-level or
slow-down in sea-level change and therefore increased erosion by waves, or periods of accelerated sealevel
rise since the Last Glacial Maximum. Terraces could therefore be related to coral construction and
drowing. The medium part corresponds to the marginal escarpment, a steep cemented area. The lower
part of the uppermost slope shows a discontinuous Holocene sediment wedge with varying thickness
between 0 and 35 m. It is separated from the upper part by a zone of well-cemented seafloor associated
with the marginal escarpment. Passing cold fronts result in sediment export caused by density cascading.
The associated sediment fall-out and convective sedimentation can generate density currents that form
this wedge and eventually flow through linear structures on the upper slope. The survey reveals the
presence of recently active channels that extend over the entire uppermost slope and interrupt the
wedge. The channels connect shallow tidal channels to submarine valleys connected to the proximal part
of canyons. They directly feed the canyons with platform-derived sediment forming low-density
turbidity currents and could supply the deepest part of the system with coarse-grained sediment
directly exported from the carbonate platform.
https://hal-ifp.archives-ouvertes.fr/hal-01566026
Contributor : Françoise Bertrand Connect in order to contact the contributor
Submitted on : Thursday, July 20, 2017 - 3:56:13 PM
Last modification on : Wednesday, November 17, 2021 - 12:27:14 PM
Contributor : Françoise Bertrand Connect in order to contact the contributor
Submitted on : Thursday, July 20, 2017 - 3:56:13 PM
Last modification on : Wednesday, November 17, 2021 - 12:27:14 PM