Uplift at lithospheric swells-I: seismic and gravity constraints on the crust and uppermost mantle structure of the Cape Verde mid-plate swell.

Wilson, D. J., Peirce, C., Watts, A. B., Grevemeyer, Ingo and Krabbenhöft, Anne (2010) Uplift at lithospheric swells-I: seismic and gravity constraints on the crust and uppermost mantle structure of the Cape Verde mid-plate swell. Open Access Geophysical Journal International, 182 (2). pp. 531-550. DOI 10.1111/j.1365-246X.2010.04641.x.

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Abstract

Wide-angle seismic data have been used to determine the velocity and density structure of the crust and uppermost mantle beneath the Cape Verdes mid-plate swell. Seismic modelling reveals a ‘standard’ oceanic crust, ∼8 km in thickness, with no direct evidence for low-density bodies at the base of the crust. Gravity anomaly modelling within the constraints and resolution provided by the seismic model, does not preclude, however, a layer of crustal underplate up to 3 km thick beneath the swell crest. The modelling shows that while the seismically constrained crustal structure accounts for the short-wavelength free-air gravity anomaly, it fails to fully explain the long-wavelength anomaly. The main discrepancy is over the swell crest where the gravity anomaly, after correcting for crustal structure, is higher by about 30 mGal than it is over its flanks. The higher gravity can be explained if the top 100 km of the mantle beneath the swell crest is less dense than its surroundings by 30 kg m−3. The lack of evidence for low densities and velocities in the uppermost mantle, and high densities and velocities in the lower crust, suggests that neither a depleted swell root or crustal underplate are the origin of the observed shallower-than-predicted bathymetry and that, instead, the swell is most likely supported by dynamic uplift associated with an anomalously low density asthenospheric mantle.

Document Type: Article
Additional Information: This article has been published in Geophysical Journal International ©2010 The Authors Published by Oxford University Press on behalf of the Royal Astronomical Society. All rights reserved.
Keywords: Geodynamics; Lithospheric Swell, Cape Verde, Seismic, Gravity, Crustal structure
Research affiliation: OceanRep > The Future Ocean - Cluster of Excellence
OceanRep > GEOMAR > FB4 Dynamics of the Ocean Floor > FB4-GDY Marine Geodynamics
Refereed: Yes
Open Access Journal?: No
DOI etc.: 10.1111/j.1365-246X.2010.04641.x
ISSN: 0956-540X
Projects: Future Ocean
Date Deposited: 13 Sep 2010 09:32
Last Modified: 10 Jul 2018 12:20
URI: http://oceanrep.geomar.de/id/eprint/8896

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