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 “"geochemical proxy"”.
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Gold mineralisation and mineral exploration within the Clogau mine, Dolgellau gold belt, N Wales
… being 0.81 Au g/t, 1.7 Au g/t and 2.15 Au g/t. Geochemical results where these gold grades were highest showed an increase in certain geochemical elements such as aluminium, copper, iron and sulphur. Using XRF elemental data, a partial correlation between an increase in sulphur (a geochemical …
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Jurassic limestone-marl sequences in northern spain: detecting diagenetic signals using rare earth and trace elements
… in NW Spain. Data from the application of this geochemical approach, in conjunction with stratigraphic analysis, provides insight into the distribution of elements that are facies-controlled, chemically-controlled, and elements that are independent of both. Results presented here for the use of …
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Controls on Carbonate Factory Distribution in a Restricted Intraplatform Basin: Upper Jurassic Smackover, Southwest Alabama
… cores and log data were analyzed, alongside geochemical proxy concentrations measured via X-ray Fluorescence (XRF) and Laser Induced Breakdown Spectroscopy (LIBS). These proxies were grouped into redox, terrestrial, and nutrient to assess how oceanographic conditions influence carbonate …
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Using the growth patterns and geochemistry of coralline red algae to develop proxies for paleoclimate reconstruction in tropical and subarctic environments
… of crustose coralline red algae (CCA) as geochemical proxy sources for paleoenvironmental and paleoclimate reconstructions. Rhodoliths (Lithothamnion sp.) from the Gulf of Panama (GOP), Panama were grown in a microcosm experiment to evaluate growth patterns and rates. Previous researchers …
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Methane cold seeps: Paleo proxies, modern measurements, and instrument development
… past. In this dissertation, I have developed a geochemical proxy to reconstruct AOM rates from methane-derived authigenic carbonates (MDACs) at cold seeps, applied this proxy to globally-distributed seeps, quantified CH4 emissions from seeps along the central Chilean Margin, and developed novel …
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Glacial-Interglacial Variability of Eastern Pacific Hydroclimate
… interactions is currently limited by sparse proxy data from the Eastern Pacific Warm Pool (EPWP) and the Gulf of California, specifically of reconstructions that extend beyond the Last Glacial Maximum (LGM; 19--23 ka). The work presented in this dissertation sheds new light onto the late …
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The importance of dissolved organic nutrients in the biogeochemistry of oligotrophic gyres
… has been investigated. The computation of a new geochemical proxy, TNex, for the determination of N to P anomalies suggests that N2 fixation is more important than previously thought. The spatial distribution of the isotopic composition of particulate organic matter shows a N2 fixation signal …
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Seasonality in a changing climate: Insights from the modern ocean with application to the Eocene Epoch
… reproduce with climate models. Likewise, multi-proxy studies from the same location frequently yield diverging SST estimates. </p> <p>These inconsistencies within the climate record inhibit our ability to identify the mechanisms responsible for late Eocene cooling, and call into question our …
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Climate proxies in planktic foraminifera: Environmental or biomineralisation controls?
… environments over geological time. However, the proxy-environment correlations often vary among species and individuals, indicating different degrees of biological control during calcification. This introduces significant uncertainties in their interpretation. To improve the reliability of …
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Geochemical Insights into Earth Materials from Quantum Mechanical Computation
… span from applications relevant to understanding geochemical proxies in biogenic carbonates, relevant to environments in past and present oceans at the Earth’s surface, through to volatile components in the Earth’s deeper interior, in particular a study of the nature of water in the silicate …
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PCO2 EFFECTS ON THE PRODUCTION OF PELAGIC BIOGENIC CARBONATE AND OCEAN CHEMISTRY: A CASE HISTORY FROM THE CRETACEOUS.
… (calcareous nannofossils) and geochemical (Re-Os isotopes, C and O stable isotopes) approach. Calcareous nannoplankton, responsible for primary productivity and effective producers of calcite, affect the C-cycle on both long- and short-term time scales. They are sensitive to …
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The Ups and Downs of the Holocene: Exploring Relationships between Global CO2 and Climate Variability in the North Atlantic Region
… radiocarbon dated, lake sediment geochemical proxies (magnetic susceptibility, loss-on-ignition, total carbon/nitrogen/sulphur determinations and biogenic silica), vegetational reconstruction (pollen analysis) and stomatal frequency based CO2 reconstructions. The stomatal frequency …