P and S Body Wave Tomography of Southern Africa

Restricted (Penn State Only)
Author:
Ortiz, Kameron Jordan
Graduate Program:
Geosciences
Degree:
Master of Science
Document Type:
Master Thesis
Date of Defense:
January 15, 2018
Committee Members:
  • Andrew Arnold Nyblade, Thesis Advisor
  • Charles James Ammon, Committee Member
  • Sridhar Anandakrishnan, Committee Member
Keywords:
  • Seismology
  • Tomography
  • Crust
  • Mantle
  • Southern Africa
Abstract:
P- and S-wave seismic tomography was used to investigate the seismic velocity structure of the upper mantle beneath southern Africa using data from multiple seismic networks across the region. Tomographic images of upper mantle structures reflect the surface geology, and provide important constraints on subcrustal structure associated with Proterozoic mobile belts, Archean cratons and the Bushveld Complex. Fast velocities beneath the Kaapvaal and Zimbabwe cratons reveal a ~200 - 250 km thick cratonic lithosphere, while slow velocities reveal a ~100 – 150 km thick lithosphere beneath the Damara-Ghanzi-Chobe Belt. Low velocities beneath the Bushveld Complex extend into southern and central Botswana, and could be the result of compositional fertilization from the time of intrusion of Bushveld magmas. The tomographic images do not support the extension of the African Superplume anomaly from the lower mantle into the upper mantle beneath any part of the study region.