The aim of this dissertation, based on three papers, is to utilize novel analytical techniques to examine the potential of non-traditional geochemical proxies, such as calcium and boron isotopes, to address questions related to earth system science.
The first paper presents analytical protocols for high-precision calcium isotope measurements using thermal (TIMS) and plasma ionization mass spectrometry (MC-ICP-MS). These are applied to determine calcium isotope abundances of the Late Mesozoic belemnites that, in turn, are used to reconstruct the isotope composition of paleo-seawater and the evolution of the oceanic calcium cycle.
The second paper discusses in details the history of the oceanic calcium isotope budget during the Phanerozoic (last ∼500 Ma), which is based on the analysis of calcium isotope compositions of several hundred marine skeletal carbonates, mostly brachiopods, measured by the TIMS technique. The observed experimental record is simulated using a numerical model of coupled calcium/carbon/magnesium global cycles and the results are discussed in the context of changing fluxes of major cations to the oceans.
The third paper aims to utilize boron isotopes to constrain temporal changes in pH of the Jurassic surface oceans, with the ultimate goal to evaluate the effect of seawater pH on the oxygen isotope (delta18O) composition of coeval belemnites, hence on the delta18O-based paleo-temperature estimates.
Overall, the results of this thesis demonstrate the usefulness and limitations of calcium and boron isotope proxies for studies concerning the evolution of earth system, specifically oceans and the atmosphere, over geological time scales.
| Identifer | oai:union.ndltd.org:uottawa.ca/oai:ruor.uottawa.ca:10393/29644 |
| Date | January 2007 |
| Creators | Farkas, Juraj |
| Publisher | University of Ottawa (Canada) |
| Source Sets | Université d’Ottawa |
| Language | English |
| Detected Language | English |
| Type | Thesis |
| Format | 157 p. |
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