A Geophysical Investigation of the Structural Controls Along the Southern Margin of Lake Ngami, Northwestern Botswana Using Seismic Refraction and DC Resistivity

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PreviousNext No AccessSymposium on the Application of Geophysics to Engineering and Environmental Problems 2007A Geophysical Investigation of the Structural Controls Along the Southern Margin of Lake Ngami, Northwestern Botswana Using Seismic Refraction and DC ResistivityAuthors: Elisha M. ShemangLoago N. MolwalefheElvis MosweuElisha M. ShemangDepartment of Geology, University of Botswana, Private Bag UB 00704, Gaborone, BotswanaSearch for more papers by this author, Loago N. MolwalefheDepartment of Geology, University of Botswana, Private Bag UB 00704, Gaborone, BotswanaSearch for more papers by this author, and Elvis MosweuDepartment of Geology, University of Botswana, Private Bag UB 00704, Gaborone, BotswanaSearch for more papers by this authorhttps://doi.org/10.4133/1.2924707 SectionsAboutPDF/ePub ToolsAdd to favoritesDownload CitationsTrack CitationsPermissions ShareFacebookTwitterLinked InRedditEmail Abstract A shallow seismic refraction survey and DC Resistivity Soundings were undertaken at southeastern margin of the Palaeo Ngami Lake to determine the structure and shallow stratigraphy of the lake; determine the amount of fault displacement at the border fault of the lake. The results of the seismic refraction survey indicate that the there is a low velocity zone (∼500m/s) in the area which is thinner outside the lake (less than 10m) and much thicker toward the centre of the lake (more than 30m).This low velocity zone is underlain by a higher velocity (3125 m/s) layer. Augering results within the lake indicate that the low velocity zone consists of dry clays, diatomaceous earth/silts. The high velocity layer is believed to be made up of sandstone/siltstones. Fault displacement at the margin of the lake is about 21m of downthrow. Another downthrow (about 19m) occurs at a distance of about 1300m from the margin into the lake, thus resulting in a total throw of about 50m. The results of the DC resistivity sounding indicates that the low velocity zone within the lake is characterized by 3 distinct layers; the top layer which is less than 1 m thick, has a resistivity of about 1300 Ωm (dry hard clays), the second layer about 5 m thick and has a resistivity of 34 Ωm (diatomaceous earth) and the third layer has a resistivity of about 11 Ωm (whitish soft clays interlayered with silty units).Permalink: https://doi.org/10.4133/1.2924707FiguresReferencesRelatedDetails Symposium on the Application of Geophysics to Engineering and Environmental Problems 2007ISSN (online):1554-8015Copyright: 2007 Pages: 1557 publication data© 2007 Copyright © 2007 The Environmental and Engineering Geophysical SocietyPublisher:Environmental & Engineering Geophysical Society HistoryPublished: 30 Sep 2008 CITATION INFORMATION Elisha M. Shemang, Loago N. Molwalefhe, and Elvis Mosweu, (2007), "A Geophysical Investigation of the Structural Controls Along the Southern Margin of Lake Ngami, Northwestern Botswana Using Seismic Refraction and DC Resistivity," Symposium on the Application of Geophysics to Engineering and Environmental Problems Proceedings : 509-517. https://doi.org/10.4133/1.2924707 Plain-Language Summary PDF DownloadLoading ...