Doctoral Dissertations

Abstract

"In spite of numerous studies, the mechanisms for the rifting, uplifting, and volcanism on the African plate remain enigmatic. The most popular hypotheses proposed for explaining these tectonic phenomena involve edge-driven small-scale mantle convection and the thermal or dynamic effects of one or more mantle plumes. In this study we use continental scale shear-wave splitting (SWS) measurements to provide additional constraints on the various models of rifting, uplifting, and volcanism of the Cameroon Volcanic Line (CVL) and the Arabian plate. The splitting of P-to-S converted phases at the core-mantle boundary on the receiver side (XKS including PKS, SKKS, and SKS) is one of the most effective approaches to constrain convective mantle flow patterns. A robust procedure involving automatic and manual batch processing to reliably assess and objectively rank shear-wave splitting parameters were used. The resulting 1532 pairs of splitting parameters show a NNE dominated fast direction. Spatial distribution of the splitting parameters in the CVL and Arabia is not consistent with the edge-driven small-scale mantle convection hypothesis, the mantle plume hypothesis, fossil fabrics formed by past tectonic events, or the fabric-forming process due to the absolute plate motion relative to the deep mantle.

The research suggests that the progressive thinning of the lithosphere through basal erosion by the flow leads to decompression melting is responsible for the formation of the CVL, and olivine lattice preferred orientation in the upper asthenosphere associated with the northward motion of the African plate since 150 Ma, most likely causes the observed anisotropy across the Red Sea."--Abstract, page iv.

Advisor(s)

Gao, Stephen S.
Liu, Kelly H.
Abdel Salam, Mohamed G.

Committee Member(s)

Eckert, Andreas
Rogers, J. David

Department(s)

Geosciences and Geological and Petroleum Engineering

Degree Name

Ph. D. in Geology and Geophysics

Publisher

Missouri University of Science and Technology

Publication Date

Spring 2014

Journal article titles appearing in thesis/dissertation

  • Mantle seismic anisotropy and formation of the Cameroon volcanic line by lithospheric basal erosion
  • Seismic anisotropy and subduction-induced mantle fabrics beneath the Arabian and Nubian Plates adjacent to the Red Sea

Pagination

ix, 96 pages

Note about bibliography

Includes bibliographical references (pages 84-95).

Geographic Coverage

Africa, Eastern
Earth (Planet)--Mantle

Rights

© 2014 Ahmed Abdalla Elsheikh, All rights reserved.

Document Type

Dissertation - Open Access

File Type

text

Language

English

Subject Headings

Shear waves
Anisotropy
Volcanism -- Africa, Eastern

Thesis Number

T 10443

Electronic OCLC #

882476991

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Dissertation Location

 
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