Magma flow revealed by magnetic fabric in the Okavango giant dyke swarm, Karoo igneous province, northern Botswana | INSTITUT DE PHYSIQUE DU GLOBE DE PARIS

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  Magma flow revealed by magnetic fabric in the Okavango giant dyke swarm, Karoo igneous province, northern Botswana

Publication Type:

Journal Article

Source:

Journal of Volcanology and Geothermal Research, Volume 170, Issue 3-4, p.247-261 (2008)

ISBN:

0377-0273

Accession Number:

WOS:000255179900008

Keywords:

Géosciences marines, UMR 7154

Abstract:

To determine the magma flow direction of the giant, 179 Ma Okavango dyke swarm of northern Botswana, we measured the anisotropy of magnetic susceptibility (AMS) of 23 dykes. Dykes are located in two sections (Shashe and Thune Rivers), which are about 300 kin and 400 kin from the presumed magma source respectively; the Nuanetsi triple point. We collected samples from the margins of the dykes in order to use the imbrication of magnetic foliation to determine magma flow direction. About half of the magnetic fabric in the dykes is inverse, i.e. with the magnetic foliation perpendicular to the dyke plane. Lateral flow to the west and vertical flow is in evidence in the Shashe section. However, the overall analysis of normal and inverse magnetic fabric data supports that lateral flow to the west was dominant in the Shashe section. Across the Thune section, a poorly defined imbricated magnetic foliation also suggests lateral flow to the west. (C) 2007 Elsevier B.V. All rights reserved.