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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.
21

Petrological studies /

Alderman, A. R. January 1942 (has links) (PDF)
Thesis (Degree of D.Sc.] -- University of Adelaide, Geology Dept., 1942. / Includes previously published material, and material submitted for PhD (Cantab.).
22

Shock features of the Vargeão impact structure, Santa Catarina, Brazil

Poulos, Christina Maria. January 2007 (has links)
Thesis (M.S.)--State University of New York at Binghamton, Dept. of Geological Sciences and Environmental Studies, 2007. / Includes bibliographical references.
23

Carbon chemistry of giant impacts.

Abbott, Jennifer Ileana. January 1999 (has links)
Thesis (Ph. D.)--Open University. BLDSC no. DX227301.
24

Le lieu de mon sujet /

Després, Martial, January 2003 (has links)
Thèse (M.A.Plas.) -- Université du Québec à Chicoutimi, 2003. / Bibliogr.: f. 41. Document électronique également accessible en format PDF. CaQCU
25

Wellbore seismic and core sample measurement analysis integrated geophysical study of the Lake Bosumtwi impact structure /

Meillieux, Damien Yves Justin. January 2009 (has links)
Thesis (M. Sc.)--University of Alberta, 2009. / Title from pdf file main screen (viewed on July 16, 2009). "A thesis submitted to the Faculty of Graduate Studies and Research in partial fulfillment of the requirements for the degree of Master of Science in Geophysics, Department of Physics, University of Alberta." Includes bibliographical references.
26

Meteorites of Iran and hot deserts : classification and weathering / Météorites d'Iran et les autres déserts chauds : classification et altération

Pourkhorsandi Soufiani, Hamed 19 February 2018 (has links)
Les météorites sont parmi les sources d’information les plus importantes sur la structure et l’évolution du système solaire. Cette thèse présente une étude des météorites d’Iran, en particulier celles retrouvées dans le désert de Lut et leur comparaisons avec celles des autres déserts chauds du monde. Les météorites de Lut sont étudiées en détail en vu de comprendre le potentiel de ce désert dans l’accommodation et la classification des météorites, les âges terrestres, la météorisation, distribution spatiale et ‘pairing’. Nous démontrons la présence de deux champs de strewnfields de météorites et mettons en évidence les conditions favorables à la conservation, accumulation et collection des météorites. Nos données révèlent les différences entre les effets chimiques et minéralogiques de le météorisation (l’altération) sur les météorites en provenance de différents déserts. Parmi les centaines de météorites classifiées des déserts chauds, nous présentons notre étude détaillée sur un chondrite non-classifié (El Médano 301). Cette météorite, pourrait représenter un nouveau sous-groupe des chondrites ordinaire (OCs) avec une composition chimique moins réduite par rapport aux OCs standards. Famenin et Moshampa, deux météorites tombées en été 2015 dans le nord-ouest d’Iran, sont également étudiées en détail. Famenin est un chondrite ordinaire de type 3 qui présente des charactéristiques intermédiaires entre les chondrites H et L. Enfin, nous présentons les résultats de notre étude sur la météorite de Moshampa qui est une chondrite brecciated de type LL5. / Meteorites are amongst the most important sources of information about the structure, formation, and evolution of the solar system. This thesis reports studies on the meteorites from Iran, in particular the Lut desert and their comparison with the meteorites from other hot deserts. Lut desert meteorites are studied in detail to understand the potential of this desert for hosting meteorites, meteorite classification, terrestrial ages, terrestrial weathering, spatial distribution and pairing. We shows the presence of two main meteorite strewnfields and evidence suitable conditions for preservation, accumulation and finding of meteorites. Meteorites from different hot deserts are studied in order to document meteorite abundances, classification, and their terrestrial alteration. Our data reveal differences between the chemical and mineralogical effects of terrestrial weathering on meteorites from different deserts. Among the hundreds of classified hot desert meteorites, we present a detailed study on an ungrouped chondrite (El Médano 301). This meteorite might be representative of a new grouplet of ordinary chondrites (OCs) showing more reduced compositions than standard OCs. Famenin and Moshampa, two meteorites fallen during summer 2015 in NW Iran, are studied in detail. Famenin is a type 3 ordinary chondrite showing characteristics intermediate between H and L chondrites. Together with similar intermediate meteorites, we suggest the existence of a separate ordinary chondrite grouplet for which a different designation (H^L) is proposed. Classification results of Moshampa brecciated LL5 chondrite are reported.
27

On the origin of the Murchison meteorite phosphonates. Implications for pre-biotic chemistry.

Gorrell, I.B., Wang, Liming, Marks, Alison J., Bryant, D.E., Bouillot, F, Goddard, A, Heard, D.E., Kee, T.P. January 2006 (has links)
No / Ab initio calculations, combined with experimental studies on the anaerobic hydrolysis of phosphaalkynes under thermal and photochemical conditions suggest a potential, exogenous source of reduced oxidation state phosphorus for the early Earth.
28

Determination of Nuclidic Ratios in Geological Samples with Neutron Capture Gamma Rays

Islam, M. A. 06 1900 (has links)
<p> This thesis is divided into two parts, the first part being devoted to the application of Neutron Capture Gamma Ray Analysis in determining S/Si and Fe/Si ratios in Allende meteorite and lunar samples and the second part, to evidence for a possible iron isotopic anomaly in the Allende meteorite obtained by the same method. The samples were irradiated in an in-core irradiation system in the McMaster swimming-pool nuclear reactor and the collimated beam of gamma rays was detected by a pair-spectrometer consisting of a Ge(Li) detector and NaI annulus. In the first part, besides the mainstream of the work, the basic principles of Neutron Capture Gamma Ray Analysis and Neutron Activation Analysis and the supremacy of the former over the latter for this particular problem has been discussed. In the second part, along with the implications and evidence of isotopic variations of other elements in the Allende meteorite, a brief description of the classification, structure and mineralogy of the Allende meteorite is given. The success and advantage of the method along with its limitations and further directions along these lines are also discussed.</p> / Thesis / Master of Science (MSc)
29

Origin of the circular silverpit structure, UK North Sea : meteorite impact or salt withdrawal?

Conway, Zana Kate January 2007 (has links)
The origin of the Silverpit structure, UK North Sea has been contested since its discovery on seismic data in 2002. The Silverpit structure consists of a 3 - 4km central zone of deformation, which includes a conical uplift. This is surrounded by a series of ring faults up to a maximum diameter of 20km. Meteorite impact, evaporite withdrawal, pull-apart basin tectonics and halokinesis tectonics have all been suggested as possible origins. This thesis uses a multi-discipline approach to test these hypotheses and determine with certainty the origin of the Silverpit structure. Seismic interpretation of the Silverpit structure has highlighted that deformation in the central deformation zone and beneath the structure is comparable with other meteorite craters. However, the ring faults are comparable with other structures formed by regional evaporite dissolution and movement. Seismic interpretation on a regional, 3500km2 scale proved that the structure is unique and that salt movement was taking place at the same time as the Silverpit structure was created. Unusual diagenesis in the chalk beneath the Silverpit structure was identified as a result of the presence of both unusual geophysical and geochemical signatures. An anomalous sonic log response is attributed to a significantly decreased porosity at the base of the chalk unit. Anomalously negative stable oxygen isotopes were also found in the chalk beneath the structure. Unusually elevated heat flow is the likely cause of these irregularities. The evidence presented in this thesis leads to the conclusion that the origin of the Silverpit structure is in fact two-phase. Meteorite impact has lead to the formation of the central zone of deformation and conical uplift. It has also influenced the diagenesis of the chalk beneath the crater and created a more brittle chalk unit. Regional salt withdrawal is responsible for the formation of the ring faults, which have only formed in the meteorite impact induced brittle chalk. In simple terms, a meteorite impact formed the 3km crater and then salt withdrawal produced the circular rings during several million years after the impact.
30

Schreibersite: Synthesis, Characterization and Corrosion and Possible Implications for Origin of Life

La Cruz, Nikita Latesha 01 January 2015 (has links)
We present study of the synthesis and reactions of an analog of the meteoritic mineral schreibersite with formula (Fe,Ni)3P, believed to be a prebiotic source of reactive phosphorus that may have prompted the formation of phosphorylated biomolecules near the time of the origin of life (Pasek and Lauretta, 2005). The mineral was synthesized by mixing stoichiometric proportions of elemental iron, nickel and phosphorus and heating in a tube furnace at 820°C for approximately 235 hours under argon or under vacuum, a modification of the method of Skála and Drábek (2002). The mineral was characterized using X-ray diffractometry (XRD), X-ray photoelectron spectroscopy (XPS), micro-raman spectroscopy and electron microprobe analysis (EMPA). Characterization indicates that both schreibersite, with approximate formula Fe2NiP and the mineral nickel-phosphide, FeNi2P were synthesized. In addition to characterization of the solid product, the reactions of the synthetic schreibersite were investigated to determine the similarity between these and prior work done with Fe3P. Synthetic schreibersite was corroded in several solutions: seawater and sulfidic water under both oxic and anoxic conditions. After corrosion, the solutions were analyzed using phosphorus nuclear magnetic resonance spectroscopy (31P NMR) and high performance liquid chromatography attached to an inductively coupled plasma mass spectrometer (HPLC-ICP-MS) to determine phosphorus speciation as well as concentrations of phosphorus present in solution. As expected from previous studies, the NMR and HPLC-ICP-MS results indicated the presence of orthophosphate, phosphite, pyrophosphate and hypophosphate in the corrosion solutions (Pasek and Lauretta, 2005). The HPLC-ICP-MS results indicate that the extent of corrosion of the mineral—measured by the concentration of phosphorus released—depends on the ionic strength of the solution, as well as the presence or absence of the chelating agent. Finally, we report the successful phosphorylation of a potentially prebiotic molecule—choline—using synthesized schreibersite.

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