Doctoral Dissertations

Keywords and Phrases

East African Rift System; fault Growth; Fault Height/Length Profiles; Okavango Rift Zone; Pore Fluid Pressure; Tectonic Inheritance

Abstract

"Integrated geophysical, remote sensing, and field investigations of the Okavango Rift Zone (ORZ), Botswana indicate that a feedback between optimum-oriented basement structures and fluid flow influence the nucleation and growth of continental rifts in their incipient stages. The ORZ, the youngest rift of the East African Rift System, occurs within a Proterozoic inter-cratonic suture zone - the NE-trending Precambrian Damara/Ghanzi-Chobe orogenic belts. The Pleistocene to Holocene ORZ forms a ~450 km long and ~100 km wide half-graben bounded by NE-trending normal faults. Basement units within the Damara/Ghanzi-Chobe orogenic belts exhibit a well-developed NE-trending linear fabric (045-065) defined by parallel limbs of tight folds. The Tsau - Chobe fault system nucleated along the Proterozoic tectonic sutures defining the location of the embryonic ORZ. The initial length of the rift was established first by the Tsau-Chobe master-border fault as ORZ faults have abnormally low D/L relationships as a result of failure along favorably oriented preexisting mechanical strength anisotropies in the crust. Fluid circulation within fault zones reduces the shear stress necessary to reactivate these faults. Subsequent slip events trigger a pore fluid wave that promotes along strike propagation of the fault with low displacement. This creates a positive feedback in which fewer, longer, faults suppress nucleation of new faults. Eventually these faults develop strong cohesive fault rocks, and are abandoned in favor of forming new faults along planar strength anisotropies into the Ghanzi-Chobe basement, widening the ORZ in a southeast direction"--Abstract, page iv.

Advisor(s)

Hogan, John Patrick

Committee Member(s)

Abdel Salam, Mohamed G.
Eckert, Andreas
Gao, Stephen S.
Mickus, Kevin
Oboh-Ikuenobe, Francisca

Department(s)

Geosciences and Geological and Petroleum Engineering

Degree Name

Ph. D. in Geology and Geophysics

Sponsor(s)

National Science Foundation (U.S.)

Publisher

Missouri University of Science and Technology

Publication Date

Summer 2016

Journal article titles appearing in thesis/dissertation

  • The role of crustal strength anisotropies in strain localization during incipient continental rifting: An example from the Okavango Rift Zone, Botswana
  • The role of fluid-enhanced tectonic inheritance in continental rifting

Pagination

xvi, 122 pages

Note about bibliography

Includes bibliographic references.

Geographic Coverage

Botswana

Rights

© 2016 Angelica Alvarez Naranjo, All rights reserved.

Document Type

Dissertation - Open Access

File Type

text

Language

English

Thesis Number

T 11352

Electronic OCLC #

1041856035

Download

Share

 
COinS