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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
81

Stratigraphic and structural development of the St. Vincent tertiary basin, South Australia

Stuart, William Joseph January 1969 (has links)
iii, 260 leaves : ill., charts & maps in back pocket / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / Thesis (Ph.D.1970) from the Dept. of Geology, University of Adelaide
82

The biostratigraphy and palaeoecology of South Australian Precambrian stromatolites

Preiss, Wolfgang Victor January 1971 (has links)
Precambrian stromatolites in South Australia are almost entirely restricted to the folded rock sequence of the Adelaide Geosyncline, a large, deeply subsiding basin with predominantly shallow - water sediments. The history of research into the age and fossils of the Precambrian rocks is reviewed, and a possible time - framework is suggested on the basis of available radiometric data. Stromatolites, laminated structures formed by trapping of detritus and precipitation of chemical sediment by algae and bacteria, have been studied by other workers from at least two points of views : most Western authors regard stromatolite morphology to be purely environmentally determined, while one Russian school maintains that it is largely controlled by the algae present, and that stromatolites evolve as a consequence of the evolution of the algae forming them. They concluded this from an empirical study of widespread stromatolites of different ages, which made possible the biostratigraphic subdivision and correlation of many Late Precambrian sections. The Russian methods of study and taxonomy have now been applied to South Australian stromatolites for the first time. Of the eighteen forms of columnar stromatolites described, five are identical or nearly identical to Russian forms. Nine forms are new, but sufficiently similar to Russia forms to allow inclusion in the same groups as these. Groups and forms must be defined on the basis of numerous characters, which may be given different relative weighting for different taxa. The taxa so defined have restricted ranges in geological time. Stromatolite correlation with the Russian sequence suggests that the Early Adelaidean ( i.e. pre - tillite ) beds are middle Riphean ; the Skillogalee Dolomite is youngest middle Riphean, i.e. older than the Late Riphean Bitter Springs Formation of Central Australia. The Late Adelaidean Umberatana Group assemblage, correlated with the youngest Late Riphean, has seven groups in common with the Bitter Springs Formation, but unlike the latter, it overlies the lower tillite. A comparison with available radiometric data shouts good agreement for the Umberatana Group, but some conflict with one recent age determination exists for the Early Adelaidean. A study of the environments of growth of South Australian stromatolites shows that at least three forms, of widespread distribution, grew under a variety of conditions of energy, oxidation, type of sediment influx, and possibly salinity. The taxa defined are stable under these varying conditions, but there are minor modifications due to differences in environmental energy. Skillogalee Dolomite stromatolites grew under varying energy conditions on a very extensive and level carbonate depositing platform, frequently under hypersaline conditions. Umberatana Group stromatolites inhabited a marine environment, either in marginal littoral zones in the south - western and north - eastern Flinders Ranges, or on off - shore carbonate banks interpreted to be related to rising diapirs. In both cases, stromatolites formed during episodes of shallowing water depth. / Thesis (Ph.D.)--Department of Geology and Mineralogy, 1971.
83

Mesozoic magmatic activity in Hong Kong

Wong, Po-wan, Kenny. January 2006 (has links)
Thesis (M. Phil.)--University of Hong Kong, 2006. / Title proper from title frame. Also available in printed format.
84

Paleo-oceanography of the subtropical southeastern Pacific during late Quaternary : a study of radiolaria, opal and quartz contents of deep-sea sediments

Molina-Cruz, Adolfo 28 May 1975 (has links)
Micropaleontological data have been analyzed through mathematical and statistical procedures, in order to: (1) establish the distribution pattern of radiolarian assemblages in the surface sediments, (2) establish the relationship of these assemblages with oceanographic variables, (3) determine the faunal composition down-core with respect to the faunal surface pattern, and (4) estimate water temperatures and 1OO M PO₄ within the geological past. This, together with the analysis of opal and quartz content of the sediments, has permitted the inference of the paleo-oceanography of the subtropical southeastern Pacific during the last 75,000 years. Factor analysis shows that five major radiolarian assemblages (factors), accounting for 93.6% of the variance, reflect the mixed layer circulation and its associated water masses. According to their position in the area, these factors are called: (1) the Subtropical factor, (2) the Equatorial factor, (3) the Peru (current) factor, (4) the Chile (current) factor, and (5) the Backwater factor. The subtropical factor is correlated with "warm" water temperatures, the Equatorial factor with opal production, the Peru factor with coastal upwelling, the Chile factor with "cool" water temperatures, and the Backwater factor with mixing of water masses. The distribution pattern of quartz reflects the position of the southeast trade winds which largely control the oceanographic conditions of the subtropical southeastern Pacific. The opal distribution resembles the patterns of surface primary productivity. Opal content is "high" below the Equatorial Undercurrent. However, it is "low" along the South American coast probably due to dilution by terrigenous input. Cores RC11-230 (8°48'S-110°48'W), V19-29 (3°35'S-83°56'W), and Y71-6-12 (16°26'S-77°23'W) were used in the stratigraphic study. Their stratigraphic control (correlation) is made through their δ ¹⁸O records. The changes of quartz, opal and radiolarian assemblages contents down-core are considered to be the result of shifts or changes in intensity of the atmospheric and oceanic circulation. Oceanographic changes have occurred in the subtropical southeastern Pacific during the last 75,000 years, but they are not manifested at each location in the same form. These changes have not been synchronous with changes of global ice volume; rather, during pronounced climatic changes, a sequence which is initiated by changes in the wind circulation is observed. The oxygen isotope stage 4 is characterized by mixing of water masses, "deep" thermocline and low concentration of nutrients. The lower interval of isotope stage 3 is characterized by weakened wind-driven circulation and "high" water temperatures. The middle of isotope stage 3 is a time in which wind-driven conditions become dominant in the region. Oxygen isotope stage 2 is "cool" and has strong wind-driven conditions. The shift to the present oceanographic conditions in the subtropical southeastern Pacific occurred 11,000 years ago. / Graduation date: 1976
85

Geology of the Buster Creek-Nehalem Valley area, Clatsop County, northwest Oregon /

Olbinski, James Steven. January 1983 (has links)
Thesis (M.S.)--Oregon State University, 1983. / Typescript (photocopy). Some col. ill. and col. maps folded in pocket. Includes bibliographical references (leaves 168-178). Also available via the World Wide Web.
86

The Middle Paleozoic stratigraphy of the central Rocky Mountain region ... /

Tomlinson, Charles Weldon. January 1900 (has links)
Thesis (Ph. D.)--University of Chicago, 1916. / "Private edition distributed by the University of Chicago Libraries, Chicago, Illinois." "Reprinted from the Journal of geology, Vol. XXV, Nos. 2-4, 1917."
87

The Middle Devonian of Ohio ... /

Stauffer, Clinton R. January 1909 (has links)
Thesis (Ph. D.)--University of Chicago, 1909. / Published also as Bulletin no. 10. Geological survey of Ohio. Includes bibliographical references and index. Also available on the Internet.
88

Geochemical and isotopic study of a core of the Tipton shale member of the Green River Formation, Wyoming /

Rao, Pejavar Lata. January 1900 (has links)
Thesis (M.S.)--Ohio State University, 1984. / Includes bibliographical references (leaves 134-138). Available online via OhioLINK's ETD Center
89

Structural geology and tectonics of the paleoproterozoic rocks of the Mount Rushmore Quadangle, Black Hills, Souh Dakota

Hill, Joseph Christopher, January 2006 (has links)
Thesis (Ph.D.)--University of Missouri-Columbia, 2006. / The entire dissertation/thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file (which also appears in the research.pdf); a non-technical general description, or public abstract, appears in the public.pdf file. Title from title screen of research.pdf file viewed on (April 26, 2007) Vita. Includes bibliographical references.
90

Late Cenozoic stratigraphy and landscape dynamics in the unglaciated central Appalachians a case study from the Northern Blue Ridge, south-central Pennsylvania, USA /

Grote, Todd D. January 1900 (has links)
Thesis (Ph. D.)--West Virginia University, 2006. / Title from document title page. Document formatted into pages; contains viii, 118 p. : ill. (some col.), maps (some col.). Vita. Includes abstract. Includes bibliographical references (p. 80-88).

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