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How supercontinents and superoceans affect seafloor roughness
Citation
Whittaker, J and Muller, RD and Roest, WR and Wessel, P and Smith, WHF, How supercontinents and superoceans affect seafloor roughness, Nature, 456, (18/25 December 2008) pp. 938-942. ISSN 0028-0836 (2008) [Refereed Article]
Copyright Statement
Copyright 2008 Macmillan Publishers
Abstract
Seafloor roughness varies considerably across the world’s ocean
basins and is fundamental to controlling the circulation and mixing
of heat in the ocean1 and dissipating eddy kinetic energy2.
Models derived from analyses of active mid-ocean ridges suggest
that ocean floor roughness depends on seafloor spreading rates3,
with rougher basement forming below a half-spreading rate
threshold of 30–35mmyr21 (refs 4, 5), as well as on the local
interaction of mid-ocean ridges with mantle plumes or coldspots6.
Here we present a global analysis of marine gravity-derived
roughness, sediment thickness, seafloor isochrons and palaeospreading
rates7 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 palaeo-spreading directions and
isochron orientations7 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 (.456). Cretaceous Atlantic ocean floor, formed over mantle
previously overlain by the Pangaea supercontinent, displays
anomalously low roughness away from mantle plumes and is independent
of spreading rates. We attribute this observation to a sub-
Pangaean supercontinental mantle temperature anomaly8 leading
to slightly thicker than normal Late Jurassic and Cretaceous
Atlantic crust9, reduced brittle fracturing and smoother basement
relief. In contrast, ocean crust formed above Pacific superswells10,
probably reflecting metasomatized lithosphere underlain by mantle
at only slightly elevated temperatures11, 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.
Item Details
Item Type: | Refereed Article |
---|---|
Keywords: | seafloor, roughness, plate tectonics, mantle |
Research Division: | Earth Sciences |
Research Group: | Geology |
Research Field: | Marine geoscience |
Objective Division: | Expanding Knowledge |
Objective Group: | Expanding knowledge |
Objective Field: | Expanding knowledge in the earth sciences |
UTAS Author: | Whittaker, J (Associate Professor Jo Whittaker) |
ID Code: | 84439 |
Year Published: | 2008 |
Web of Science® Times Cited: | 23 |
Deposited By: | IMAS Research and Education Centre |
Deposited On: | 2013-05-14 |
Last Modified: | 2013-08-06 |
Downloads: | 0 |
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