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 20 of 64 for “"Phanerozoic"”.
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Biogeochemical and phylogenetic signals of Proterozoic and Phanerozoic microbial metabolisms
… to terrestrial systems in the Proterozoic and Phanerozoic eons. Taken together, this thesis may be used to improve assessments of microbial activity in remote environments, and to enhance our understanding of the evolution of Earth’s carbon cycle.
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Biogeochemical and phylogenetic signals of Proterozoic and Phanerozoic microbial metabolisms
… to terrestrial systems in the Proterozoic and Phanerozoic eons. Taken together, this thesis may be used to improve assessments of microbial activity in remote environments, and to enhance our understanding of the evolution of Earth's carbon cycle.
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Contributions and New Methods in Paleontology: Geochemical, Ultrastructural, and Microstructural Characterization of Archean, Proterozoic, and Phanerozoic Fossils
Over the past decade, the study of organismal or systematic paleobiology has been progressing into a new age of digital paleobiology, in which advanced instrumentation is utilized for primary data collection and analyses. Having been progressing throughout this field of study, advanced …
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Earth’s oceanic oxygen history from Phanerozoic to Pleistocene glacial cycles: insights from the carbonate iodine-to-calcium proxy
… animals have diversified most dramatically in Phanerozoic (542 million years ago (Ma) to present day) and where geologists have the best fossil record for biology/environment comparison. I used a novel proxy, the iodine-to-calcium ratio (I/Ca) in carbonate rocks and planktic microfossils, which …
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Weathering Pathways and Limitations in Biogeochemical Models: Application to Earth System Evolution
Current biogeochemical box models for Phanerozoic climate are reviewed and reduced to a robust, modular system, allowing application to the Precambrian. It is shown that stabilisation of climate following a Neoproterozoic snowball Earth should take more than 10(7) years, due to long-term geological …
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Geochemical and isotopic constraints on the source regions of phanerozoic carbonatites and associated alkaline rocks from the Zandkopsdrift complex of Namaqualand, South Africa, and the Marinkas Quellen, and Dicker Willem complexes in Namibia
This is a study of Phanerozoic carbonatites and related alkaline silicate rocks from Zandkopsdrift in Namaqualand, South Africa (55 Ma), and Marinkas Quellen (529 Ma), and Dicker Willem (49 Ma) in southern Namibia, all emplaced within the Proterozoic Namaqua Natal province. The aims of this thesis …
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The Midcontinent exposed: Precambrian basement topography, and fault-and-fold zones, within the cratonic platform of the United States
… and exhumation. Marine transgressions during the Phanerozoic buried the region with sequences Phanerozoic sedimentary strata. The continent-wide contact between Precambrian crystalline rock and the overlying cover of Phanerozoic strata is known as the ""Great Unconformity."" Though the cratonic …
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High-precision U/Pb geochronology of large igneous provinces and mass extinctions : testing coincidence and causation
… mass extinction, which is the most severe in the Phanerozoic, and the Siberian Traps LIP, which is the largest continental magmatic event in the Phanerozoic, and (2) the Karoo-Ferrar LIP and the early-Jurassic biotic crisis and global ocean anoxia. With these datasets, age-models for both mass …
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HOW DO NOVICE AND EXPERT LEARNERS REPRESENT, UNDERSTAND, AND DISCUSS GEOLOGIC TIME?
… at ordering and discussing events before the Phanerozoic, but were challenged with events during the Phanerozoic. Novice learners had difficulty assigning values to events and establishing a scale for their models. Expert learners expressed difficulty with determining a scale because of the …
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NETWORK THEORY IN ICHNOLOGY: FROM BEHAVIOURAL TOPOLOGY TO THE DEPOSITIONAL ENVIRONMENT
… may have great potential for understanding Phanerozoic bioturbation patterns.
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Stratigraphic response to Cordilleran processes along the south central Andean margin
… deposition. This dissertation investigates the Phanerozoic to present sedimentary record to address the dynamic interactions among Earth-surface processes and lithospheric processes throughout a complex tectonic history along the Andean Cordilleran margin of Argentina. Chapter 1 applies detrital …
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The rheology and dynamics of the Precambrian lithosphere – insights from the British Isles
… crust proposed in Chapter Three. I then use the Phanerozoic deformation record to show that the microcraton has persisted as an (anisotropic) strong region throughout the Phanerozoic, and has exerted a strong influence on Britain’s geological evolution throughout this period. Although focused on …
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Compositional Diversity in Arcs: A Record of Magmatic Processes in the Peru Coastal Batholith, Ica
… crust made up of Precambrian lower crust and Phanerozoic upper crust consisting of volcanic, sedimentary, and earlier plutonic units at the emplacement level.</p>
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Geology of an Archean Greenstone Belt at Point Lake, Northwest Territories, Canada
… and structures at Point Lake resembles Phanerozoic collision zones where rocks of oceanic affinity have been emplaced upon continental crust.</p>
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Testing the ancient marine redox record from oxygenic photosynthesis to photic zone euxina
… the deep ocean became oxygenated in the early Phanerozoic, hydrogen sulfide, which is toxic to most aerobes, may have transiently accumulated in the marine photic zone (i.e. photic zone euxinia; PZE) during mass extinctions and oceanic anoxic events. Here, the molecular fossil evidence for …
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Testing the ancient marine redox record from oxygenic photosynthesis to photic zone euxina
… the deep ocean became oxygenated in the early Phanerozoic, hydrogen sulfide, which is toxic to most aerobes, may have transiently accumulated in the marine photic zone (i.e. photic zone euxinia; PZE) during mass extinctions and oceanic anoxic events. Here, the molecular fossil evidence for …
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Temperature trends of the Late Cambrian through the Middle Ordovician : implications for Ordovician climate and biodiversification
… the second-largest mass extinction of the Phanerozoic--the end Ordovician mass extinction. Climate change has been invoked as a contributing factor to both events. Much research has focused on the end Ordovician extinction and thus, paleotemperatures of the last 15 million years of the …
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Studies in biotic persistence and the taxonomic stability of traits over geological time
… tests its presence in marine animals over the Phanerozoic (Chapter 2); it also seeks to understand the interaction between some microbial traits and lineages over geological time as well as considering the implications of this interaction on the traits’ longevity. Chapter 3 considers the …
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Carbon and sulfur isotopic constraints on Ediacaran biogeochemical processes, Huqf supergroups, Sultanate of Oman
… which leads to a reinterpretation of existing Phanerozoic data. These strata contain sulfates in two forms (carbonate-associated sulfate: CAS, and anhydrite), providing an opportunity to investigate isotopic offsets reported between these seawater sulfate proxies. The results indicate that …
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