Masters Theses
Abstract
"Systematic spatial variations of mantle azimuthal anisotropy are revealed by over 3000 pairs of high-quality shear-wave splitting parameters (fast polarization orientations and splitting times) recorded at ~400 USArray and other network stations in the SE United States (75⁰-90⁰ W, and 24⁰-40⁰ N). The fast polarization orientations observed in the continental interior are subparallel to the absolute plate motion (APM) direction of the North American plate with apparent larger-than-normal splitting times, indicating a significant asthenospheric contribution. Fast orientations parallel to the edge of the North American craton are revealed along the southern and eastern margins of the continent. A portion of the eastern coastal area shows weak anisotropy, probably indicating the existence of vertical mantle flow. The majority of the splitting measurements can be satisfactorily explained by a model involving simple shear in the boundary layer between the lithosphere and asthenosphere. The model includes three flow systems. The first is related to the continental scale APM-parallel relative movement between the lithosphere and asthenosphere which creates the APM-parallel fast orientations observed in the continental interior. The second flow system is associated with the deflection of asthenospheric flow around the edges of the craton and is responsible for the edge-parallel fast orientations observed along the southern and eastern margins of the study area. The third system is sub-vertical, possibly caused by vertically deflected flow along the eastern root of the craton, similar to the mechanism proposed by Refayee et al. (2014, doi: 10.1016/j.epsl.2013.01.031) for the western edge. It could also be related to previously proposed upwelling or down-welling flow"--Abstract, page iii.
Advisor(s)
Gao, Stephen S.
Committee Member(s)
Liu, Kelly H.
Eckert, Andreas
Department(s)
Geosciences and Geological and Petroleum Engineering
Degree Name
M.S. in Geology and Geophysics
Sponsor(s)
Incorporated Research Institutions for Seismology. Data Management Center
Publisher
Missouri University of Science and Technology
Publication Date
Summer 2016
Pagination
viii, 59 pages
Note about bibliography
Includes bibliographical references (pages 55-58).
Rights
© 2016 Yunhua Liu, All rights reserved.
Document Type
Thesis - Open Access
File Type
text
Language
English
Subject Headings
Anisotropy
Shear waves -- Measurement
Orogenic belts
Thesis Number
T 10965
Electronic OCLC #
958293470
Recommended Citation
Liu, Yunhua, "Seismic anisotropy and mantle dynamics beneath the southeastern United States inferred from shear-wave splitting analysis" (2016). Masters Theses. 7559.
https://scholarsmine.mst.edu/masters_theses/7559