Regional reflectivity analyses of the upper mantle using SS precursors and receiver functions

• Author / Creator

  Contenti, Sean M.

• SS precursor imaging and receiver function analysis allow for a detailed investigation
  of mantle structure of the Earth and subduction dynamics due to their sensitivities to the sharp velocity contrasts within the mantle. By investigating the lateral depth variability of mantle seismic interfaces, primarily the 410 and 660, this thesis explores the mantle structure beneath South and North America. In South America, we utilize over 5000 SS precursor waveforms to investigate the high-resolution reflectivity structure of the upper 1200 km of the mantle. In the vicinity of the subducting Nazca slab we observe a ~1500-km wide reflection gap on the 410, significant variability of the 660, and scattered lower mantle reflections. These observations support the existence of a slab-related compositional heterogeneity atop the 410, significant slab deformation with the transition zone, and combined Nazca slab stagnation and penetration at the base of the upper mantle. In North America, we compute over 1800 P-to-s receiver functions to investigate the local structure of the mantle beneath Alberta. We observe correlated depression of the 410 and 660 consistent with strong upper mantle heterogeneity. Thickened transition zone and increased P wave velocities in southernmost Alberta are potentially associated with a remnant of the Farallon-Kula plate near the base of the upper mantle.

• Subjects / Keywords

  • Singular spectrum analysis
  • Mantle transition zone
  • Receiver function
  • SS precursor
  • Radon transform

• Graduation date

  Fall 2012

• Type of Item

  Thesis

• Degree

  Master of Science

• DOI

  https://doi.org/10.7939/R3JW3X

• License

  This thesis is made available by the University of Alberta Libraries with permission of the copyright owner solely for non-commercial purposes. This thesis, or any portion thereof, may not otherwise be copied or reproduced without the written consent of the copyright owner, except to the extent permitted by Canadian copyright law.