Seafloor gravity roughness

Full description

This data collection is associated with the publication: Whittaker, J. M., Müller, R. D., Roest, W. R., Wessel, P., & Smith, W. H. (2008). How supercontinents and superoceans affect seafloor roughness. Nature, 456(7224), 938-941. doi: 10.1038/nature07573

Publication Abstract

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 eddy 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. Here we present a global analysis of marine gravity-derived roughness, sediment thickness, seafloor isochrons and palaeospreading rates of Cretaceous to Cenozoic ridge flanks. Our 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. We 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). 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. We attribute this observation 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.

Authors and Institutions

Joanne M. Whittaker - EarthByte Research Group, School of Geosciences, The University of Sydney, Australia. ORCID: 0000-0002-3170-3935

R. Dietmar Müller - EarthByte Research Group, School of Geosciences, The University of Sydney, Australia. ORCID: 0000-0002-3334-5764

Walter R. Roest - Département des Géosciences Marines, Ifremer, France

Paul Wessel - Department of Geology and Geophysics (SOEST), University of Hawai'i at Mānoa, USA

Walter H. F. Smith - National Oceanic and Atmospheric Administration, USA

Overview of Resources Contained

This collection contains gridded gravity and gravity-derived seafloor roughness data. Predictions of seafloor gravity roughness that consider the influences of sediment thickness and spreading rate, and residual seafloor gravity roughness which are produced by removing the influences of sediment thickness and spreading rate from gravity-derived roughness are also provided.

List of Resources

Note: For details on the files included in this data collection, see “Description_of_Resources.txt”.

Note: For information on file formats and what programs to use to interact with various file formats, see “File_Formats_and_Recommended_Programs.txt”.

• Gravity anomalies (.txt, .nc, .cpt, .kmz, .jpg, .tif, total 2.89 GB)
• Gravity roughness 100 km (.txt, .nc, .cpt, .kmz, .jpg, .tif, total 2.9 GB)
• Masked gravity roughness 100 km (.txt, .nc, .cpt, .kmz, .jpg, .tif, total 2.46 GB)
• Gravity roughness 160 km (.txt, .nc, .cpt, .kmz, .jpg, .tif, total 2.88 GB)
• Masked gravity roughness 160 km (.txt, .nc, .cpt, .kmz, .jpg, .tif, total 2.45 GB)
• Residual gravity roughness (.txt, .nc, .cpt, .kmz, .jpg, .tif, total 2.55 GB)
• Predicted gravity roughness (.txt, .nc, .cpt, .kmz, .jpg, .tif, total 2.52 GB)

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