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dc.contributor.authorLarson, Angela Marieen_US
dc.date.accessioned2014-03-14T20:42:03Z
dc.date.available2014-03-14T20:42:03Z
dc.date.issued2004-07-16en_US
dc.identifier.otheretd-07272004-145628en_US
dc.identifier.urihttp://hdl.handle.net/10919/34200
dc.description.abstractResults from two-station surface-wave inversions across the Archean Kaapvaal craton of southern Africa are compared with seismic velocities estimated from approximately 100 mantle xenoliths brought to the surface in kimberlite pipes. As the xenoliths represent a snapshot of the mantle at the time of their eruption, comparison with recently recorded seismic data provides an opportunity to compare and contrast the independently gained results. These cratonic xenoliths from the southern Kaapvaal, all less than 100Ma in age, have been analyzed geothermobarometrically to obtain the equilibrium P-T conditions of the cratonic mantle to about 180km depth [James et al 2004]. Seismic velocity-depth and density-depth profiles calculated on the basis of these P-T data and the mineral modes of the xenoliths are used to produce theoretical surface-wave dispersion curves and to generate roughly the upper 200km of a starting/reference model. A regionally-developed crustal structure [Niu and James 2002] was used for the crust and 300km of mantle values taken from PREM filled in down to 500km depth. This composite model was used as the starting/reference model for a Neighbourhood Algorithm surface-wave inversion using fundamental-mode Rayleigh-wave phase velocities for 16 paths within the Kaapvaal Craton from five events. The velocity structures found by that inversion are consistent with those derived from the xenolith data. Hence the velocity structure (i.e. thermal structure) of the mantle to a depth of 180km beneath the Kaapvaal craton is basically the same today as it was 80-90Ma. Further, synthetics runs show that for this surface-wave dataset, there is no strong low-velocity zone at depths shallower than at least 200km.en_US
dc.publisherVirginia Techen_US
dc.relation.haspartthesis-0729.pdfen_US
dc.rightsI hereby certify that, if appropriate, I have obtained and attached hereto a written permission statement from the owner(s) of each third party copyrighted matter to be included in my thesis, dissertation, or project report, allowing distribution as specified below. I certify that the version I submitted is the same as that approved by my advisory committee. I hereby grant to Virginia Tech or its agents the non-exclusive license to archive and make accessible, under the conditions specified below, my thesis, dissertation, or project report in whole or in part in all forms of media, now or hereafter known. I retain all other ownership rights to the copyright of the thesis, dissertation or project report. I also retain the right to use in future works (such as articles or books) all or part of this thesis, dissertation, or project report.en_US
dc.subjectvelocity structureen_US
dc.subjectupper mantleen_US
dc.subjectKaapvaal Cratonen_US
dc.titleS-wave velocity structure beneath the Kaapvaal Craton from surface-wave inversions compared with estimates from mantle xenolithsen_US
dc.typeThesisen_US
dc.contributor.departmentGeosciencesen_US
dc.description.degreeMaster of Scienceen_US
thesis.degree.nameMaster of Scienceen_US
thesis.degree.levelmastersen_US
thesis.degree.grantorVirginia Polytechnic Institute and State Universityen_US
thesis.degree.disciplineGeosciencesen_US
dc.contributor.committeechairSnoke, J. Arthuren_US
dc.contributor.committeememberJames, David E.en_US
dc.contributor.committeememberChapman, Martin C.en_US
dc.identifier.sourceurlhttp://scholar.lib.vt.edu/theses/available/etd-07272004-145628en_US
dc.date.sdate2004-07-27en_US
dc.date.rdate2006-07-30
dc.date.adate2004-07-30en_US


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