Constraining uplift and denudation of West African continental margin by inversion of stacking velocity data.

Walford, H. L. and White, N. J. (2005) Constraining uplift and denudation of West African continental margin by inversion of stacking velocity data. Journal of Geophysical Research-Solid Earth, 110,. B04403. ISSN 0148-0227 DOI

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An inverse model has been developed to determine the magnitude of denudation at seabed and subsurface unconformities by using root-mean-square (RMS) stacking velocity data derived from processing a set of seismic reflection profiles. This approach provides superior spatial coverage in comparison to other methods, such as vitrinite reflectance, apatite fission track, and sonic velocity modeling, which are restricted to borehole locations. The model assumes exponential porosity decay with depth and a standard velocity-porosity relationship in order to compute a synthetic RMS velocity profile. Denudation values at two levels in the stratigraphy are then adjusted until the fit between the model and the data is optimized. Successful modeling is dependent upon independent estimates of the initial porosity of sediment since significant trade-off occurs between initial porosity and denudation. Application to the west African shelf shows that 0.5–1 km of denudation occurred along the entire margin, probably during late Neogene times. The amount of denudation decreases oceanward and was probably triggered by regional tilting associated with initiation and/or regeneration of continent-wide mantle convective upwelling, which is thought to have affected much of subequatorial Africa. A subsurface Oligocene unconformity represents as much as 2.5 km of denudation and was probably produced by initiation of an oceanic current.

Item Type: Article
Additional Information: Copyright 2005 by the American Geophysical Union.
Uncontrolled Keywords: 2005 AREP; IA46; IA47; 2005 P
Subjects: 02 - Geodynamics, Geophysics and Tectonics
Divisions: 02 - Geodynamics, Geophysics and Tectonics
08 - Green Open Access
Journal or Publication Title: Journal of Geophysical Research-Solid Earth
Volume: 110,
Page Range: B04403
Identification Number:
Depositing User: Sarah Humbert
Date Deposited: 12 Aug 2010 14:34
Last Modified: 10 Jul 2014 12:03

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