Seafloor roughness dataset: how supercontinents and superoceans affect seafloor roughness

Brief description

Seafloor roughness varies considerably across the world's ocean basins and is fundamental to controlling the circulation and mixing of heat in the ocean and dissipating kinetic energy. Models derived from analyses of active mid-ocean ridges suggest that ocean floor roughness depends on seafloor spreading rates, with rougher basement forming below a half-spreading rate threshold of 30-35 mm/yr, as well as on the local interaction of mid-ocean ridges with mantle plumes or cold-spots.

The investigators present a global analysis of marine gravity-derived roughness, sediment thickness, seafloor isochrons and palaeospreading rates of Cretaceous to Cenozoic ridge flanks. Analysis reveals that after eliminating effects related to spreading rate and sediment thickness, residual roughness anomalies of 5-20 mGal remain over large swaths of ocean floor. It was found that the roughness as a function of palaeospreading directions and isochron orientations indicates that most of the observed excess roughness is not related to spreading obliquity, as this effect is restricted to relatively rare occurrences of very high obliquity angles (> 45 degrees).

The Cretaceous Atlantic ocean floor, formed over mantle previously overlain by the Pangaea supercontinent, displays anomalously low roughness away from mantle plumes and independent of spreading rates. This observation is attributed to a sub-Pangaean supercontinental mantle temperature anomaly leading to slightly thicker than normal Late Jurassic and Cretaceous Atlantic crust, reduced brittle fracturing and smoother basement relief. In contrast, ocean crust formed above Pacific superswells, probably reflecting metasomatized lithosphere underlain by mantle at only slightly elevated temperatures, is not associated with basement roughness anomalies. These results highlight a fundamental difference in the nature of large-scale mantle upwellings below supercontinents and superoceans, and their impact on oceanic crustal accretion.

The seafloor roughness dataset contains five grid datasets and supporting images:

• Downward Continued Gravity
• Roughness 100 km
• Roughness 160 km
• Residual Roughness
• Predicted Roughness

The seafloor roughness dataset is available via the EarthByte website. For further information please refer to the associated publication below.