In-situ sedimentary evidence of complex bottom currents at a modern deepwater seamount

Interactions between deep-ocean currents and seafloor sediments create bedforms that are important for paleoenvironment reconstructions, resource exploration, and mapping ecosystems. Oceanographers recognize complex flow dynamics where deep ocean currents interact with submarine topography (i.e. seamounts) however the effects on below-wave base seafloor sediment remain unquantified. Here we show complex, highly variable bedforms in the sediments around a seamount are linked to deep-ocean current and topographic interactions, using in-situ, high-resolution footage from a <10 year-old, 1-km water depth volcanic seafloor. Bedforms record sediment reworking, vary spatially and temporally at the scale of m – 100 s m and reflect changes in current velocity over hours to days. These observations provide insights into the complex sedimentology associated with current-topography interactions in mid- to deep-ocean settings and demonstrates the limitations of existing sedimentological models. This study highlights that primary seafloor data can be quickly obscured, impeding modern data collection, subsequent hazard modelling, and paleoenvironment reconstruction. Complex, reworked sediments on a young volcanic seafloor are closely linked to highly variable ocean currents around a seamount, according to in-situ, high-resolution footage collected at a 1-km water depth.