Crustal structure beneath Hudson Bay from ambient-noise tomography

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dc.contributor.advisorEaton, David
dc.contributor.authorPawlak, Agnieszka
dc.date.accessioned2017-12-18T22:31:25Z
dc.date.available2017-12-18T22:31:25Z
dc.date.issued2012
dc.descriptionBibliography: p. 168-190en
dc.descriptionSome pages are in colour.en
dc.description.abstractHudson Bay is a shallow inland sea located in north-central Canada. The underlying lithosphere preserves a complex deformational history that dates back to the Archean. The Hudson Bay Lithospheric Experiment, HuBLE, is a collaborative initiative aimed at understanding the lithospheric evolution beneath the Bay. The recent emergence of a methodology called ambient-noise tomography provides a tool to image the crust and upper mantle beneath the Bay with higher resolution than previously possible. Using ambient-noise generated by the Earth as a source, this technique requires continuous recordings of ground motion. The ambient­noise method is based on the cross-correlations of daily noise signals between station pairs to estimate empirical Green's Functions. This thesis is made up of there separate studies. The first is an isotropic application of the ambient-noise tomography method to image crustal structure beneath Hudson Bay. Results show crustal thinning beneath the Bay, allowing us to reject a hypothesis for eclogitization and crustal thickening, with support instead for an extensional hypothesis for the formation of the Hudson Bay basin. The next study focuses on anisotropic variations of velocity within the subsurface. Inversion results show a distinct outline of geologic boundaries in the upper to mid-crust that does not carry through into the lower crust. A significant change in anisotropic fabric is evident across the Trans-Hudson orogen (THO) suture zone, which allows us to establish that tectonic fabrics formed prior to collision. The third study employs joint inversion of ambient-noise data and teleseismic surface wave data for increasing resolution of the crust and upper mantle. Results show that the THO suture zone dips to the southeast within the crust and becomes vertical in the upper mantle. This feature is interpreted as a zone of weakness that extends through the lithosphere, providing a locus for initiation of localized lithospheric stretching.
dc.format.extentxiv, 219 leaves : ill. ; 30 cm.en
dc.identifier.citationPawlak, A. (2012). Crustal structure beneath Hudson Bay from ambient-noise tomography (Doctoral thesis, University of Calgary, Calgary, Canada). Retrieved from https://prism.ucalgary.ca. doi:10.11575/PRISM/4756en_US
dc.identifier.doihttp://dx.doi.org/10.11575/PRISM/4756
dc.identifier.urihttp://hdl.handle.net/1880/105757
dc.language.isoeng
dc.publisher.institutionUniversity of Calgaryen
dc.publisher.placeCalgaryen
dc.rightsUniversity of Calgary graduate students retain copyright ownership and moral rights for their thesis. You may use this material in any way that is permitted by the Copyright Act or through licensing that has been assigned to the document. For uses that are not allowable under copyright legislation or licensing, you are required to seek permission.
dc.titleCrustal structure beneath Hudson Bay from ambient-noise tomography
dc.typedoctoral thesis
thesis.degree.disciplineGeoscience
thesis.degree.grantorUniversity of Calgary
thesis.degree.nameDoctor of Philosophy (PhD)
ucalgary.item.requestcopytrue
ucalgary.thesis.accessionTheses Collection 58.002:Box 2093 627942965
ucalgary.thesis.notesUARCen
ucalgary.thesis.uarcreleaseyen
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