Data from three refraction profiles of the 1993 LITHOPROBE refraction experiment were used to investigate the structure of the lithosphere of the Trans-Hudson Orogen. Novel digital processing of the wide-angle reflections arrivals with standard type reflection processing techniques revealed significant crustal thickness and Moho reflectivity variations within the orogenic belt. The obtained information was than complemented with the results of near-vertical incidence seismic sections to estimate the crustal thickness variations over the entire study area. The detected crustal thickness and Moho reflectivity changes could not be correlated to the location and extent of geological domains; they appear to reflect the complex deformation and metamorphic history of the orogen. The P-wave velocity image of the crust and upper mantle was established through ray-tracing and inverse modelling of the primary and secondary crustal and mantle arrivals. Successful modelling of the observation required the incorporation of non-standard inversion techniques into the processing sequence. Although the detected crustal velocity variations appear to correlate well with the changes of Moho reflectivity. These variations in the property of the crust are interpreted to be a consequence of differences between the tectonic evolution of orogenic units in the north-western and south-eastern parts of the study area. The transition belt separating these two areas appear to coincide with an anomalous zone located in the upper mantle. This mantle region exhibits strong P-wave velocity anisotropy, determined primarily from modelling of the mantle refraction arrivals. I interpret this anomalous mantle region as a highly deformed zone, a possibly suture, between the two collided Archean plates of the orogen. Additional information on the structure of the mantle was obtained by analyzing the secondary mantle phases, observed at offsets larger than 400 km on the shot records. The broad structure of this deeper mantle region was established by incorporating the results of regional teleseismic studies into the velocity models and refining the models with raytracing. Detailed acoustic properties of the mantle were investigated after introducing random perturbations into the models and comparing the computed finite-difference synthetic-seismic responses to the observations.

Thesis (M.Sc.)--Memorial University of Newfoundland, 2000. / Bibliography: leaves 114-119.

Thesis (Ph. D.)--University of California, Riverside, 2009. / Includes abstract. Available via ProQuest Digital Dissertations. Title from first page of PDF file (viewed March 20, 2010). Includes bibliographical references. Also issued in print.

Thesis (doctoral)--Universität Potsdam, 2002. / "April 2003"--P. [2] of cover. Lebenslauf. Includes bibliographical references (p. 93-101). Also available via the World Wide Web.

Thesis (M.S.)--West Virginia University, 2003. / Title from document title page. Document formatted into pages; contains vi, 21, [24] p. : ill. (some col.), maps (some col.). Includes abstract. Includes bibliographical references (p. 20-21).

Not available / text

This dissertation explores subduction zone-related deformation both on short time scales in the form of subduction zone earthquakes and over larger time and geographical scales in the form of subduction rollback or detachment of the subducting lithosphere. The study presented here is composed of two parts. First, we analyzed the source-rupture processes of the April 1, 2007 Solomon Islands Earthquake (Mw=8.1) using a body-wave inversion technique. Our analysis indicated that the earthquake ruptured approximately 240 km of the southeast Pacific subduction zone in two sub-events.In the second part of this study, we used shear-wave splitting analysis to investigate the effects of the subducting African lithosphere on the upper-mantle flow field beneath the Anatolian Plate in the Eastern Mediterranean region. Our shear-wave splitting results are consistent with relatively uniform southwest-directed flow towards the actively southwestward-retreating Aegean slab. Based on spatial variations in observed delay times we identified varying flow speeds beneath Anatolia and we attribute this variation to the differential retreat rates of the Aegean and the Cyprean trenches.Finally, we used teleseismic P-wave travel-time tomography to image the geometry of the subducting African lithosphere beneath the Anatolia region. Our tomograms show that the subducting African lithosphere is partitioned into at least two segments along the Cyprean and the Aegean trenches. We observed a gap between the two segments through which hot asthenosphere ascends beneath the volcanic fields of western Anatolia. Our results show that the Cyprean slab is steeper than the Aegean slab. We inferred that this steep geometry, in part, controls the flow regime of asthenosphere beneath Anatolia causing variations in flow speeds inferred from shear-wave splitting analysis.

No description available.

No description available.

No description available.