Pelagic sedimentation on rough seafloor topography 2. Inversion results from the North Atlantic Acoustic Reverberation Corridor

Abstract

Seafloor slope distributions are sensitive to basement topography, the surface shape of sediment distributions, and the average thickness of sediment within a region. By comparing slope distributions computed from bathymetric data to distributions from realistic models of sedimented topography, we determine how characteristic values of average sediment thickness (L), RMS basement variability (H), and apparent diffusivity (κ) vary throughout the Office of Naval Research Acoustic Reverberation Corridor, located on the western flank of the Mid‐Atlantic Ridge north of the Kane Fracture Zone (25.5°–27.25°N, 44.5°–49°W). Values of L from basin‐centered subregions show thinner sediments near the axis, thickening westward with maximum values found on 10–20 Ma seafloor. Lower values of L are found for older (late Oligocene/early Miocene) seafloor. Values of L on young seafloor suggest a sediment accumulation rate of 6.5±2.3 m/m.y. since ∼10 Ma. Values of H computed from hill‐centered regions range from 217 to 306 m, with an average of 267±27 m. Hills are generally larger to the north of a low running through the study area. Values of κ range from 0.12 to 0.77 m2/yr, with an average of 0.32±0.19 m2/yr. Lower values of Kbetter describe the surface shapes of individual high‐standing ponds, while higher values are needed to model the surface shapes of thick deposits in regional lows. This difference in κ with geological setting is probably due to variations in sediment transport mechanisms.