Thesis (M.Sc.)--York University, 2006. Graduate Programme in Earth and Space Science. / Typescript. Includes bibliographical references (leaves 97-101). Also available on the Internet. MODE OF ACCESS via web browser by entering the following URL: http://gateway.proquest.com/openurl?url_ver=Z39.88-2004&res_dat=xri:pqdiss&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&rft_dat=xri:pqdiss:MR19735

No description available.

No description available.

Thesis (M.S.)--University of Wisconsin--Madison. / Typescript. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaves 52-53).

No description available.

Gravity measurements made during 1979 and 1980, combined with existing gravity measurements, provide data for the interpretation of upper crustal structures relevant to the assessment of the geothermal potential of south-central Oregon. West of Upper Klamath Lake, free-air gravity anomalies trend north-south and average near 35 mgals. East of Upper Klamath Lake, free-air gravity anomalies trend west to northwest, and average near ten mgals. The complete Bouguer anomaly field exhibits a regional gradient of nearly .4 mgals/km, which is attributed to the existence of a low-density upper mantle layer beneath the Basin and Range province. The large northwest-trending negative anomaly associated with the Klamath graben suggests a depth of low-density fill of up to 2300 m (7500 feet). The regional gravity field exhibits a broad regional high over the area surrounding Klamath Falls which may be caused by a shallow mantle or a large intrusive body at depth, or may simply be due to intense silicification of the area by thermal waters. The residual anomaly field exhibits broad bands of positive anomalies which enclose the negative anomaly associated with the Klamath graben. The easternmost of these broad, positive trends may correspond to the eastern flank of an anticline which may have existed prior to graben faulting. Positive anomalies west of the graben coincide with the Mount McLoughlin lineament. A large positive anomaly located south of Sprague River is interpreted to be a volcanic center and the heat source for thermal waters found in the Sprague River Valley. A two-dimensional cross section near 42°26' N. latitude suggests that step-like faults form the west side of the Klamath graben. The model indicates the presence of a high density body south of Sprague River that is interpreted to be a buried volcanic source for local extrusive volcanic rocks. Northwest-trending gravity anomalies west of Upper Klamath Lake indicate that structural trends of the Basin and Range province extend into the Cascade Mountains, and suggest that a heat source for thermal waters may exist beneath the High Cascades, rather than beneath the areas which exhibit geothermal activity. / Graduation date: 1982

A free-air gravity anomaly map of the continental margin of Peru between 12° and 18° S. Lat. shows a -110 to -220 mgl anomaly associated with the Peru-Chile Trench, a -60 mgl anomaly over the Pisco Basin on the continental shelf, and -120 mgl anomaly over the Mollendo (or Arequipa) Basin on the upper continental slope. Anomalies observed over the continental slope and shelf consist of slope and basin anomalies superposed on a very large, broad regional anomaly. The approximately zero mgl anomaly observed in the region of the Nazca Ridge indicates the ridge is isostatically compensated. A structural model constrained by the observed gravity anomalies and seismic refraction data indicates that compensation is due to a crust approximately 8 km thicker and about 0. 04 g/cm³ less dense than the oceanic crust on either side of the Nazca Ridge. Gravity anomalies are consistent with mass distributions expected at the Peru-Chi1e Trench as a consequence of subduction of the Nazca Ridge and the Nazca Plate. Crustal and subcrustal cross sections constrained by free-air gravity anomalies, seismic refraction data, and geologic information indicate approximately 2 km of crustal thinning seaward of the trench on the southeast side of the Nazca Ridge but no crustal thinning on the northwest side of the ridge. Crustal thickness increases from approximately 10 km near the trench to about 25 to 30 km under the southwestern flank of the Andes and to approximately 70 km under the Andes. The crust is inferred to be 33 km thick under the Amazon Basin. A cross section north of the Nazca Ridge suggests a rupture of the crust at depth under the coast mountains, and earthquake hypo centers projected onto this cross section indicate a relatively shallow, nearly horizontal Benioff zone under the Andes and the Amazon Basin. A cross section south of the Nazca Ridge does not show these features, hence a different subduction process on each side of the Nazca Ridge is indicated. Free-air gravity anomalies indicate a structural high extending northwest from 17° S. Lat, along the coast, the Paracas Peninsula and nearly 100 km offshore along the edge of the continental shelf. Computations based on gravity data suggest the Pisco Basin immediately east of this structural high contains approximately 2. 2 km of sediment. A similar computation for the Mollendo Basin yields a sediment thickness of approximately 1.4 km. Gravity anomaly patterns are consistent with uplift beneath the continental shelf edge and upper slope and suggest a continental margin composed of compacted, dewatered sediments of both continental and oceanic origin. / Graduation date: 1976

Graduation date: 1981

Thesis (M.S.)--Virginia Polytechnic Institute and State University, 1983. / Vita. Abstract. Includes bibliographical references (leaves 35-38). Also available via the Internet.

No description available.