Global ETD Search
Search theses and dissertations gathered from participating repositories worldwide. Every result links back to the library that holds it. No account is needed.
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Showing 1 to 12 of 12 for “"meteorite impact"”.
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Structural observations and stratigraphic variability in Jurassic strata, Upheaval Dome, Canyonlands National Park, Utah, USA
… while the other proposes a catastrophic meteorite impact. (1) The seminal paper by Jackson et al. (1998) suggests that Upheaval Dome was created due to the growth and subsequent pinch-off of a salt diapir sourced from the Pennsylvanian Paradox Formation. Their conclusions were based on …
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A multi-proxy study of the Kalkkop impact Crater Lake deposits in south-central South Africa: implications for late neogene climate evolution
… Crater Lake deposit formed as a result of a meteorite impact, and is situated ~51 km southwest of Graaff-Reinet in the Southern part of South Africa. The structure is about 650 m wide, and contains 90 m of lake deposits that are mainly carbonate precipitates. A 90 m sediment core from the …
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Petrographic Analysis of an Early Cenozoic Breccia from the Tinton Area, Northern Black Hills, South Dakota
… intrusion breccia, pyroclastic volcanic breccia, meteorite impact breccia, and. breccia pipe. The presence of well mixed, rounded clasts of diverse lithology and size that are highly altered and fractured point to a probable breccia pipe origin. As an inferred stock of magma at depth cooled, it …
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Applied Geochemistry, Geochronology and Biostratigraphy: Case Studies from the 38th Parallel Structures in Missouri and Orange Basin, Offshore Western South Africa
… organic matter) and radiometric dating of impact spherules were used to constrain age and a relationship between these enigmatic structures and infer their paleoenvironmental conditions. Novel melting damages, unique to impact, were documented in the palynomorphs in all the three …
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Modern Pollen-Vegetation Relationships In Ghana, Tropical West Africa
… Lake Bosumtwi, Ghana, is a 1 million year old meteorite impact crater-lake, in which pollen has been deposited tracking vegetation change, including the expansion and contraction of grass dominated landscapes evidenced by very high proportions of Poaceae pollen. This thesis explores the modern …
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Raman Spectroscopy and Synchrotron X-ray Diffraction Study of Lunar and Terrestrial Plagioclase Feldspar at High-Pressure and High-Temperature Conditions
… the Moon and Mars, and is also commonly found in meteorites. This dissertation seeks to better understand the phase changes in plagioclase when subjected to meteorite impact and fundamental information about impact cratering process. Shock features in plagioclase from Mistastin Lake impact …
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High speed geological boundary layer flows
… geological flows. In particular, it focuses on meteorite impact structures of the Martian double-layer ejecta (DLE) type and the Mount St. Helens eruption of 1980 which was hypothesized to be an underexpanded jet originally by Kieffer. Key questions include: What causes the transition that can …
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Sotho/Tswana stone-wall settlements : investigating the nature of aggregation and variability in late iron age settlements in the Vredefort Dome : a geographic information systems application
The Vredefort Dome is a meteorite impact site (S26°51'36", E27°15'36") approximately 120km south-west of Johannesburg and about 300km north-east of Bloemfontein. It is one of South Africa's eight World Heritage Sites and straddles both North West and Free State provinces. Apart from its remarkable …
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Characterisation of air masses passing over the Vredefort Dome world heritage site
… site. It is the largest and second oldest meteorite impact structure in the world and is situated in the Witwatersrand basin (containing ~40% of the world's gold resources). In addition to the economic importance of the Vredefort Dome, it is of great geological (e.g. large meteorite crater …
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From phantom blocks to denudational noise
… deposits, tectonic fault-zone breccias, and impact breccias. This distinction is important to avoid erroneous or misleading deduction of paleoclimatic or tectonic implications. -> Grain size analysis shows that rockslide-derived micro-breccia closely resemble those from meteorite impact or …
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Diversity of compressional mechanisms among SiO2 polymorphs : case of coesite and cristobalite
… as a high-pressure mineral in rocks related to meteorite impact sites, in ultra-high pressure metamorphic rocks or in kimberlites (mantle derived rocks). Cristobalite is a high-temperature (> 1470 °C), low-pressure polymorph of silica that has a subordinate and rather exotic terrestrial …
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Diversity of compressional mechanisms among SiO<sub>2</sub> polymorphs : case of coesite and cristobalite.
… as a high-pressure mineral in rocks related to meteorite impact sites, in ultra-high pressure metamorphic rocks or in kimberlites (mantle derived rocks). Cristobalite is a high-temperature (> 1470 °C), low-pressure polymorph of silica that has a subordinate and rather exotic terrestrial …