Doctoral Dissertations

Keywords and Phrases

Afar Depression; East African Rift System; Malawi Rift Zone; Receiver Functions; Shear Wave Splitting; Tectonophysics

Abstract

"Although a wealth of geophysical data sets have been acquired within the vicinity of continental rift zones, the mechanisms responsible for the breakup of stable continental lithosphere are ambiguous. Eastern Africa is host to the largest contemporary rift zone on Earth, and is thus the most prominent site with which to investigate the processes which govern the rupture of continental lithosphere. The studies herein represent teleseismic analyses of the velocity and thermomechanical structure of the crust and mantle beneath the Afar Depression and Malawi Rift Zone (MRZ) of the East African Rift System. Within the Afar Depression, the first densely-spaced receiver function investigation of crustal thickness and inferred velocity attenuation across the Tendaho Graben is conducted, and the largest to-date study of the topography of the mantle transition zone (MTZ) beneath NE Africa is provided, which reveals low upper-mantle velocities beneath the Afar concordant with a probable mantle plume traversing the MTZ beneath the western Ethiopian Plateau. In the vicinity of the MRZ, a data set comprised of 35 seismic stations is employed that was deployed over a two year period from mid-2012 to mid-2014, belonging to the SAFARI (Seismic Arrays For African Rift Initiation) experiment. Accordingly, the first MTZ topography and shear wave splitting analyses were conducted in the region. The latter reveals largely plate motion-parallel anisotropy that is locally modulated by lithospheric thickness abnormalities adjacent to the MRZ, while the former reveals normal MTZ thicknesses and shallow discontinuities that support the presence of a thick lithospheric keel within the MRZ region. These evidences strongly argue for the evolution of the MRZ via passive rifting mechanisms absent lower-mantle influences"--Abstract, page iv.

Advisor(s)

Gao, Stephen S.
Liu, Kelly H.

Committee Member(s)

Eckert, Andreas
Rogers, J. David
Mickus, Kevin

Department(s)

Geosciences and Geological and Petroleum Engineering

Degree Name

Ph. D. in Geology and Geophysics

Sponsor(s)

Statoil of Norway
National Science Foundation (U.S.)
University of Missouri Research Board

Comments

Partial funding was provided by the National Science Foundation of the United States (EAR grants 1009946 and 1460516).

Publisher

Missouri University of Science and Technology

Publication Date

Spring 2017

Journal article titles appearing in thesis/dissertation

  • Receiver function constraints on crustal seismic velocities and partial melting beneath the Red Sea Rift and adjacent regions, Afar Depression
  • The mantle transition zone beneath the Afar Depression and adjacent regions: Implications for mantle plumes and hydration
  • Passive rifting of thick lithosphere in the southern East African Rift: Evidence from mantle transition zone discontinuity topography
  • Seismic anisotropy and mantle dynamics beneath the Malawi Rift Zone, east Africa

Pagination

xiii, 215 pages

Note about bibliography

Includes bibliographic references.

Geographic Coverage

East Africa

Rights

© 2017 Cory Alexander Reed, All rights reserved.

Document Type

Dissertation - Open Access

File Type

text

Language

English

Thesis Number

T 11116

Electronic OCLC #

992174655

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Dissertation Location

 
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