Graduation date: 1981

Thesis (Ph. D.)--Carleton University, 2004. / Includes bibliographical references (p. 358-375). Also available in electronic format on the Internet.

Thesis (M.S.)--University of Wisconsin--Madison, 1969. / eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references.

Thesis (M.S.)--University of Wisconsin--Madison, 1983. / Typescript. 28 fold. maps in pocket. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaves 209-223).

Thesis (Ph. D.)--Ohio State University, 2005. / Title from first page of PDF file. Document formatted into pages; contains xv, 219 p.; also includes graphics. Includes bibliographical references (p. 112-114). Available online via OhioLINK's ETD Center

Typescript, etc. / Digitized by Kansas State University Libraries

published_or_final_version / Radioisotope / Master / Master of Philosophy

Shear wave attenuation measurements were made using ceramic bimorph transducers to excite transverse vibrations in a cylindrical column of unconsolidated sediment. Three different water-saturated sediments were used in an attempt to determine the effects of grain shape and sorting on the frequency dependence of attenuation. The mean grain size of the sediments was held constant while the grain shape and size distributions were varied. The sediment assemblages used in the attenuation measurements included a moderately-sorted angular quartz sand, a well-sorted angular quartz sand, and well-sorted spherical glass beads. The moderately-sorted sand showed the greatest attenuation over the measurement frequency range of 1 to 20 kHz. The well-sorted sand and the glass beads showed generally lower attenuation with the beads being the least lossy propagation medium. All three sediments showed evidence of viscous attenuation due to fluid-to-grain relative motion. This mechanism leads to a non-linear relationship between attenuation and frequency. Sediment physical properties were measured for use as inputs to a theoretical attenuation model based on the Biot theory of propagation of waves in porous media. The model allowed attenuation versus frequency predictions to be made for each of the three sediment assemblages. The resultant comparisons between the measured and predicted attenuations demonstrated the importance of using measured model inputs obtained under controlled laboratory conditions when theoretical model capabilities are being evaluated. The model comparison shed significant light on the ability of this particular model to predict shear wave attenuation in non-ideal sediments. / Graduation date: 1984

A compilation of high quality post-rift sediment isopach data has been used in conjunction with the observed free-air gravity anomaly to determine segmentation of the long term mechanical properties of the lithosphere at the Eastern USA passive margin. This segmentation is represented by a process-oriented analysis in which the flexural response of the margin to post-rift sediment loading is controlled by spatial variations in effective elastic thickness (T_e) of the underlying lithosphere. Existing Eastern USA margin T_e estimates range from less than 10km to more than 30km. In this study it is shown that high strengths of 10 - 40km T_e are confined to structural arches dividing the broadest marginal basins, while low strengths of less than 10km T_e are typically found in structural embayments and beneath the deep basins. The hinge zone, across which the degree of continental thinning increases rapidly, marks the transition between high and low strength. Yield strength envelope models support an argument that regions of low strength were created by lithospheric thinning during rifting, and sustained by thermal insulation and flexural curvature associated with voluminous post-rift sediment deposition. Along-strike T_e variations - reflected in the alternation of basement platforms and embayments - are attributed to inheritance of lithospheric segmentation from earlier tectonic events. Along-strike segmentation of the margin has previously been observed as a 300 - 500km wavelength spectral energy peak in the shelf break Airy isostatic gravity anomaly (IGA) high. That this segmentation is explained by variations in the underlying lithospheric strength is demonstrated by a flexural IGA high in which the equivalent spectral peak is absent. The spectral energy of the along-strike T_e distribution peaks in the same waveband. Removal of process-oriented components from the observed free-air gravity anomaly reveals other contributions that were not resolved in earlier studies. In particular, the (previously unknown) Carolina Trough Isostatic Gravity Anomaly, has been identified and attributed to an extrusive (syn-rift) volcanic source. Detailed study of this anomaly suggests that the margin is segmented in terms of its volcanic character, and argues against recent estimates of the volume of new igneous material emplaced during rifting.

Thesis (M.S.)--University of Delaware, 2006. / Principal faculty advisor: John Madsen, Dept. of Geological Sciences. Includes bibliographical references.