MANTLE FLOW AND TRANSITION ZONE DISCONTINUITIES BENEATH THE CARRIBEAN PLATE: CONSTRAINTS FROM SHEAR WAVE SPLITTING AND RECEIVER FUNCTION ANALYSES

<p>"Azimuthal anisotropy quantified by teleseismic SKS, SKKS, PKS (“XKS”) and local S wave splitting parameters is used to investigate lithospheric deformation and asthenospheric flow beneath the boundary zone of the North American and Caribbean plates and adjacent areas. A total of 4915 XKS and 1202 pairs of local S wave splitting parameters were obtained at 24 broad band seismic stations. The XKS observations can be divided into two groups based on the spatial distribution of the resulting fast polarization orientations. Those observed on the Caribbean Plate are mostly WNW-ESE which are roughly trench-parallel. In contrast, the fast orientations observed on the North American Plate are dominantly NNE-SSW which are approximately trench-orthogonal and are consistent with those previously observed in southern Mexico to the north of the area of the current study. At most of the stations at which XKS and local S wave splitting parameters are available, the fast orientations from the two types of shear waves are comparable, but the XKS splitting times are about twice of the local S wave splitting times, suggesting that the observed azimuthal anisotropy has contributions from both above and below the subducting oceanic slab. In the Lesser Antilles subduction zone, a thinner than normal transition zone thickness is revealed and is attributable to mantle upwelling along the edges of the slab and slab gaps beneath the area. The transition zone thinning is mostly caused by an uplifted 660 km discontinuity, suggesting that the thermal upwelling may be originated from the lower mantle of the Earth. The uplifted 410 km and depressed 660 km discontinuities in area south of the southern boundary of the Caribbean plate may indicate the existence of cold slab segments"--Abstract, p. iv</p>

Name thesis:degree_name

Ph. D. in Geology and Geophysics

Grantor

Missouri University of Science and Technology

Author dc:creator

• Xue, Tu

• Earth Sciences
• Geology
• Geophysics and Seismology
• Physical Sciences and Mathematics

Repository record dc:identifier

https://scholarsmine.mst.edu/doctoral_dissertations/3242

OAI identifier oai:identifier

oai:scholarsmine.mst.edu:doctoral_dissertations-4247