Publication Date:
2015-04-26
Description:
A seismological network was operated at the junction of the aseismic Walvis Ridge with the northwestern Namibian coast. We mapped crustal thickness and bulk Vp/Vs ratio by the H-k analysis of receiver functions. In the Damara Belt the crustal thickness is ~35 km with a Vp/Vs ratio of 〈1.75. The crust is ~30 km thick at the coast in the Kaoko Belt. Strong variations in crustal thickness and Vp/Vs ratios are found at the landfall of the Walvis Ridge. Here and at ~150 km northeast of the coast, the crustal thickness increases dramatically reaching 44 km and the Vp/Vs ratios are extremely high (~1.89). These anomalies are interpreted as magmatic underplating produced by the mantle-plume during the breakup of Gondwana. The area affected by the plume is smaller than 300 km in diameter, possibly ruling out the existence of a large plume head under the continent during the breakup.
Print ISSN:
0094-8276
Electronic ISSN:
1944-8007
Topics:
Geosciences
,
Physics
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