Controlled-source, azimuthal, time-domain, electromagnetic (TDEM) surveys were conducted over a schist formation with uniformly striking, nearly vertical foliation. Direct current electrical resistivity and seismic refraction surveys provided additional independent assessment of the field site. Quantitative interpretation of the TDEM survey used a theoretical electromagnetic model of a vertical transverse anisotropic conducting half-space. The combination of forward modeling and azimuthal acquisition geometry provides an innovative geophysical technique useful for mapping poorly exposed metamorphic terrains, and possibly determining fracture system orientations and assessing anisotropic hydraulic conductivity. Metamorphic rocks may exhibit transverse electrical anisotropy detectable by time-domain electromagnetics due to the characteristics of foliated rocks. For this reason, the field site was chosen within the Packsaddle Schist exposed in Mason County, Texas. Foliation of the Packsaddle Schist at the survey site strikes 146? and dips 82? NE. Polar plots of early-time, TDEM voltages, measured at large transmitter-receiver separations (> 40m) exhibit a symmetric two-lobed curve that agrees with theoretical model responses calculated for a vertical transverse anisotropic half space. The long axis of the symmetric two lobe response function is oriented 137?, which is nearly parallel to schist foliation of 146?. A best-fit forward model to the data indicates the electrical conductivity parallel and perpendicular to foliation are 0.015 S/m and 0.0012 S/m, respectively. Small transmitter-receiver separations (< 40m) exhibit azimuthal responses typical of an isotropic half space, which indicates the presence of a layer overlying the schist probably produced by weathering. An additional independent azimuthal Wenner resistivity survey exhibits apparent resistivity in the form of an ellipse with the major axis (direction of maximum conductivity) oriented 149?, which is nearly parallel to schist foliation of 146?. Analysis of data indicates the apparent electrical conductivity parallel and perpendicular to foliation are 0.0163 S/m and 0.0094 S/m, respectively. Results of TDEM and direct current resistivity closely match in both orientation and electrical conductivity values. Preliminary seismic refraction data were compatible with the TDEM data and also indicated anisotropy, but were not as conclusive.

The backlimb trishear velocity field is compared to that of mechanical models of fault-bend folds in an incompressible anisotropic viscous media to determine the relationship between the magnitude and orientation of mechanical anisotropy and the kinematic parameters of the trishear model. The trishear model can describe the velocity field of the mechanical model, at least to first order approximation for some cases. We find that the apical angle, asymmetry angle and overall geometry of the hanging-wall syncline above the ramp depend on the magnitude and orientation of the planar anisotropy inherent in stratigraphic sequences. The asymmetry of trishear zone in the backlimb region mimics that of the planar anisotropy. In general, as the magnitude and inclination of the anisotropy increase, the trishear apical angle decreases. The trishear parameters that describe physical models of fault-bend folds with different magnitudes of anisotropy also show a decrease in apical angle with an increase in magnitude of anisotropy. Yet the apical angles of the backlimb of physical models generally are less than these predicted by the mechanical model for the same magnitude of anisotropy. In addition, the physical models display significantly more negative asymmetry than predicted by the mechanical model. The results of this study may be used to determine the conditions under which the trishear model is an acceptable approximation to natural formation and help guide the selection of trishear parameters for subsurface structural interpretations in fault-fold terrains.

The problem of evaluating permeability anisotropy in the Tilje Formation, Heidrum field, offshore mid-Norway, has been investigated by the Statoil Research Centre by a detailed combination of the geological and petrophysical data. The large diversity and contrasting levels of heterogeneity within depositional facies observed in the Tilje Formation reflect complicated patterns of deposition along deltaic shorelines and the adjunct shelf of a tidally influenced, narrow seaway. Permeability anisotropy can alter the directionality of the fluid flow in the reservoir, and thereby affect the most important exploration procedures: perforation, water and gas injection, production, and estimation of the field resource. This thesis presents a simplified method of modeling permeability anisotropy in the Tilje Formation.

Magnetism is one of material essential attributes, the different material¡¦s magnetic has been studied for many years as well as the application.The processing is smaller with recent years, and the submicro physical phenomenon adapt to more and more important. Microscopically, ferromagnetic material tend to reduce the total energy of the system, and the sample interior will response to devide several magnetic domains, however, from the article by G. Leaf et al[34], we saw the final domain structure at remanence of cobalt bar, which is not the configuration with lowest energy, is predicted from a high-field analysis of the frequencies of the standing spin waves. To further discuss this interesting phenomenon, we use the computer simulation method, and make a series of computation of cobalt disc with the various sizes and thickness. From this research, we will propose that the magnetic domain reverse process and mechanism, and also give showing relations to between the energy and the magnetic domain.

Thesis (Ph. D.)--University of Washington, 2000. / Vita. Includes bibliographical references (p. 161-173).

Thesis (M.S.)--West Virginia University, 2001. / Title from document title page. Document formatted into pages; contains iv, 76 p. : ill. (some col.). Includes abstract. Includes bibliographical references (p. 47-51).

Thesis (Ph. D.)--Lehigh University, 2001. / Includes vita. Includes bibliographical references (leaves 175-193).

Thesis (Ph. D.)--University of Oregon, 2000. / Typescript. Includes vita and abstract. Includes bibliographical references (leaves 139-151). Also available for download via the World Wide Web; free to University of Oregon users.

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