Upper-mantle low-velocity zone structure beneath the Kaapvaal craton from S-wave receiver functions

Hansen, Samantha E., Nyblade, Andrew A., Julià, Jordi, Dirks, Paul H.G.M., and Durrheim, Raymond J. (2009) Upper-mantle low-velocity zone structure beneath the Kaapvaal craton from S-wave receiver functions. Geophysical Research Letters, 178 (2). pp. 1021-1027.

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Abstract

The southern African Plateau is marked by anomalously high elevations, reaching 1-2 km above sea level, and there is much debate as to whether this topography is compensated by a lower mantle source or by elevated temperatures in the upper mantle. In this study, we use S-wave receiver functions (SRFs) to estimate the lithospheric thickness and sublithospheric mantle velocity structure beneath the Kaapvaal craton, which forms the core of the Plateau. To fit the SRF data, a low-velocity zone (LVZ) is required below a ~160-km-thick lithospheric lid, but the LVZ is no thicker than ~90 km. Although the lid thickness obtained is thinner than that reported in previous SRF studies, neither the lid thickness nor the shear velocity decrease (~4.5%) associated with the LVZ is anomalous compared to other cratonic environments. Therefore, we conclude that elevated temperatures in the sublithospheric upper mantle contribute little support to the high elevations in this region of southern Africa.

Item ID: 18140
Item Type: Article (Research - C1)
ISSN: 1944-8007
Keywords: seismicity and tectonics, cratons, Africa
Date Deposited: 31 Aug 2011 01:21
FoR Codes: 04 EARTH SCIENCES > 0403 Geology > 040312 Structural Geology @ 50%
04 EARTH SCIENCES > 0403 Geology > 040313 Tectonics @ 50%
SEO Codes: 97 EXPANDING KNOWLEDGE > 970104 Expanding Knowledge in the Earth Sciences @ 100%
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