DC resistivity and seismic refraction survey across the SE margin of Lake Ngami, NW Botswana

Journal article

Authors/Editors

Shemang, Elisha

Research Areas

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Publication Details

Author list: Shemang EM, Molwalefhe LN

Publisher: Springer

Place: WARSAW 41

Publication year: 2009

Journal: Acta Geophysica (1895-6572)

Journal acronym: ACTA GEOPHYS

Volume number: 57

Issue number: 3

Start page: 728

End page: 742

Number of pages: 15

ISSN: 1895-6572

eISSN: 1895-7455

Languages: English-Great Britain (EN-GB)

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Abstract

Seismic refraction survey and DC resistivity measurements were made across the margin of the Lake Ngami. The structure and stratigraphy at the lake were determined. High resolution aeromagnetic data showed a prominent anomaly coinciding with the Kunyere Fault. Estimated depths to magnetic sources are increasing towards the lake. Two velocity layers were mapped. The top layer (500 m/s) is thin outside the lake and thicker inside the lake. The underlying layer (3125 m/s) has undeterminable thickness. Resistivity sounding results inside the lake showed that the low velocity layer has four sub-units: dry hard clays; diatomaceous earth; soft clays interlayered with silts; and wet whitish clays interlayered with silts. Normal faults were mapped along the profile with a total displacement up to 50 m. The results of the study indicate that the formation of the Lake Ngami basin was structurally controlled and probably initiated by the tectonics of the Okavango Rift Zone.

Keywords

Botswana, Lake Ngami, Okavango Rift Zone, resistivity, seismic refraction

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