Enigmatic deep-water seafloor depressions east of Tortue Island, Northern Haiti margin

A widespread area of seafloor depressions—ranging from circular and arcuate to elongated in shape—has been identified along the northern coast of Haiti, at water depths of 600–2000 m. These features are characterized by wavelengths spanning several hundred meters and heights of tens of meters and are associated with a series of narrow ridges exhibiting varied morphologies. Our integrated analysis, utilizing multichannel seismic reflection, high-resolution bathymetry, and sedimentological and geochemical evaluations of surface sediment cores, indicates that along-slope bottom currents significantly influence sedimentary processes in the region. Sediment cores reveal deposits comprising hemipelagites, silty and sandy contourites, fine-grained turbidites, and reworked sand layers, indicative of sedimentation within a contourite drift system. This interpretation is further supported by seismic reflection data, which display wavy reflectors and aggradational stacking patterns typical of contourite drifts.

The seafloor depressions are likely erosional features that formed on the surface of a contourite drift, shaped by the interaction of bottom currents with irregular seafloor topography. Initial disturbance of the equilibrium seafloor appears to have been triggered by mass-wasting events. Subsequently, the quasi-steady flow of along-slope bottom currents influenced sediment distribution and played a critical role in the development and reshaping of the seafloor depressions through erosion along their flanks. The resulting rugged seafloor morphology likely facilitated the destabilization of bottom currents, leading to the formation of erosive eddies that further shaped the current configuration of the depressions. This study emphasizes the dynamic interplay between sedimentary processes and hydrodynamic activity, demonstrating how their combined effects govern slope sedimentation and seafloor geomorphology, producing distinctive erosional features.