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Experimental Investigation of Calcium Carbonate Mineralogy in Past and Future Oceans

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Experimental Investigation of Calcium Carbonate Mineralogy in Past and Future Oceans - I - Experimental investigation of calcium carbonate mineralogy in past and future oceans Pieter Bots Submitted in accordance with the requirements for the degree of Doctor of Philosophy The University of Leeds School of Earth and Environment November, 2011 The candidate confirms that the work submitted is his own, except where work, which has formed part of jointly-authored publications, has been included. The contributions of the candidate and the other authors to this work have been explicitly indicated overleaf. The candidate confirms that appropriate credit has been given where reference has been made to the work of others. This copy has been supplied on the understanding that it is copyright material and that no quotation from the thesis may be published without proper acknowledgement. - II - Declaration Section 3.5 summarizes method development and the final methodologies for two analytical methods. The analyses described in section 3.5.2 were performed by the candidate, initially with the help of David Ashley. Chapter 4 is a reproduction of a peer-reviewed publication in Geology. Bots, P., Benning, L. G., Rickaby, R. E. M., and Shaw, S., 2011. The role of SO4 in the switch from calcite to aragonite seas. Geology 39, 331-334. All the experimental and modelling work for chapter 4 has been conducted by the candidate and the interpretation was performed by, and the manuscript was prepared by the candidate with the help of his supervisors: Liane G. Benning, Sam Shaw and Ros Rickaby. Chapter 5 is a reproduction of a final draft of a manuscript for publication, to be submitted to the Journal of the American Chemical Society. Bots, P., Benning, L.G., Rodriguez-Blanco, J.D., Roncal-Herrero, T., and Shaw, S., in prep. Mechanistic Insights into the Crystallization of Amorphous Calcium Carbonate (ACC). The experimental, analytical and modelling work for chapter 5 has been conducted by the candidate. During synchrotron beamtime at Diamond Light Source, the experimental work for chapter 5 was assisted by Juan-Diego Rodriguez- Blanco and Teresa Roncal-Herrero. The interpretation of the experimental and modelling data was performed by, and the manuscript was prepared by the candidate with the help of his supervisors: Liane G. Benning and Sam Shaw. Chapter 6 is a reproduction of a manuscript in preparation for publication. Bots, P., Benning, L.G., Rodriguez-Blanco, J.D., Roncal-Herrero, T., and Shaw, S., in prep. Using WAXS to study intricate crystallization pathways – gypsum and vaterite crystallization via rapidcreekite The experimental work for chapter 6 has been conducted by the candidate. During synchrotron beamtime at Diamond Light Source, the experimental work for - III - chapter 6 was assisted by Juan-Diego Rodriguez-Blanco and Teresa Roncal-Herrero. The interpretation of the experimental and modelling data was performed by, and the manuscript was prepared by the candidate with the help of his supervisors: Liane G. Benning and Sam Shaw. Chapter 7 is a reproduction of a manuscript in preparation for publication. Bots, P., Benning, L.G., Brinza, L., Lennie, A., and Shaw, S., in prep. Vaterite, formation and the effect of sulfate. All experiments, analyses and data processing described in chapter 7 were carried out by the candidate, except the analyses and interpretation of the vaterite XANES (by Loredana Brinza, Diamond Light Source) and the high-resolution XRD pattern by (Alistair Lennie, Diamond Light Source). These analyses were provided via a collaborative agreement with my supervisors. Collaborative publications Roncal-Herrero, T., Blanco, J. D. R., Bots, P., Shaw, S., and Benning, L. G., 2011. The role of Zn, Sr, Mg and PO4 in the interaction of carbonate-rich waters with sulphate minerals. Macla 15, 181-182. The candidate helped with the interpretations of the data and with the preparation of the draft. Rodriguez-Blanco, J. D., Bots, P., Roncal-Herrero, T., Shaw, S., and Benning, L. G., in press. The role of pH and Mg on the stability and crystallization of amorphous calcium carbonate. Journal of Alloys and Compounds. The candidate helped with the experimental part and the data analyses and with the preparation of the draft. Van Driessche, A. E. S., Benning, L. G., Rodriguez-Blanco, J. D., Ossorio, M., Bots, P., and García-Ruiz, J. M., in review. The role, and implications, of bassanite as a precursor phase to gypsum precipitation. Science The candidate helped with the experimental part and data analyses and with the preparation of the draft. - IV - Acknowledgements Even though it is my name on this thesis, I could not have done this work without the guidance and help of several people to whom I would like to express my eternal gratitude. My supervisors: Liane Benning and Sam Shaw for their brilliant guidance and trusting me with the science, for allowing me to come along to Diamond and sending me to several major conferences and making my aware of all the Pieterisms and Pieterites I use when writing, and Ros Rickaby for her guidance and ideas during the preparation of my Geology paper. Rob Newton for being part of my research support group and the discussions about the applications of my work for the paleoceanography world. Juan Diego Rodriguez-Blanco and Teresa Roncal-Herrero for the countless discussions on the work we have done and for their assistance with my experiments at Diamond. David Ashley for his enthusiastic assistance during the method development and for the training on Ion Chromatography, Lesley Neve for training me on XRD and Eric Condliffe for training my on SEM. The Marie Curie Research Training Network: Min-Gro for the funding for my PhD and all the fancy network meetings I was allowed to go to, the School of Earth and Environment at the University of Leeds for their travel bursary and their students‘ publication prize 2010-2011, the Mineralogical Society of Great Britain and Ireland for their travel bursary to attend Goldschmidt 2009 and Diamond Light Source for beamtime at station I22 (SAXS/WAXS). All the people from the Cohen group and the other parts of the School of Earth and Environment for discussions and drinks after work. I would also like to thank my friends for making my time in Leeds very enjoyable and the LGBT society at Leeds University Union for all the friends I made and the experience I had during my time on the committee. Finally, I would like to thank my family for supporting me all the way. - V - Abstract Inorganic marine calcium carbonate formation and mineralogy varies significantly concurrent with the solution composition. During the Phanerozoic, due to oscillations in the seawater composition, this resulted in the formation of either dominantly calcite or aragonite. Variations in seawater composition also appear to have influenced the evolution of biomineralizing organisms. Additionally, many organisms utilize amorphous calcium carbonate (ACC) during biomineralization. The occurrence of calcite and aragonite throughout the Phanerozoic and calcium carbonate biomineralization were investigated. This was done by determining the influence of solution chemistry (SO4 and Mg) on calcium carbonate formation, mineralogy and stability via a variety of laboratory and synchrotron based synthesis experiments. During the formation of aragonite and calcite, aqueous SO4 and the Mg/Ca ratio both affect the formation of calcite and aragonite. An increase in aqueous SO4 decreases the Mg/Ca ratio at which calcite is destabilized and aragonite becomes dominant. These results suggest that the models relating seawater chemistry to calcium carbonate formation needs re-evaluation. Abiotic ACC crystallization to vaterite occurs in three stages. In the first stage, ACC crystallizes to vaterite via a spherulitic growth mechanism. The second stage is characterized by surface particle growth at the expense of ACC. Finally, particle growth via Ostwald ripening is the only remaining process. This process can be described as the inorganic analogue to biological ACC crystallization, which is adjusted by organisms to produce their preferred calcium carbonate polymorph and morphology. An increase in SO4 concentration only decreases the spherulitic growth rate and Ostwald ripening, even when rapidcreekite (as an intermediate) and gypsum crystallizes. Finally, SO4 promotes the formation of vaterite. Depending on the formation process this is caused by either the stabilization of vaterite and destabilization of calcite (slow heterogeneous formation), or by the destabilization and inhibition of calcite formation (spherulitic growth). - VI - Contents Declaration ................................................................................................................ II Acknowledgements .................................................................................................. IV Abstract ..................................................................................................................... V Contents ................................................................................................................... VI Figures ....................................................................................................................... X Tables .................................................................................................................. XVII Chapter 1 Introduction ............................................................................................. 1 1.1 Background information ............................................................................
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