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Type: Thesis
Title: Diagenetic effects on the molecular structure of biogenic silica: Implications for palaeoclimate research
Author: Petrinolis, Z.
Issue Date: 2016
School/Discipline: School of Physical Sciences
Abstract: Biogenic silica is abundantly preserved in sediment and is found in diatoms and many higher plants. The isotopic composition (δ18Osilica) of biogenic silica is used widely in paleoclimate research to infer conditions in which the organism grew. However, previous studies show that secondary alterations within the matrix of biogenic silica complicate the structural and geochemical analysis of silica. This study investigates how the hydrated structure of silica changes at different temperature with time. A statistical model is constructed that quantifies the degree of silica hydration (Q4/Q3) by calibrating Fourier transform infrared (FTIR) measurements against nuclear magnetic resonance. This study also conducts an investigation of various oxidation techniques to find an optimal method to be used to remove organics within biogenic silica, although residual contamination proved challenging to remove in most cases. These contaminants hinder the quantification of silica hydration using FTIR which is also used in the statistical modelling of Q4/Q3 measurements. The experimental results showed a relationship between time and the relative increase of the relative hydroxylation/dehydroxylation of biogenic silica. However, silica condensation is not a linear reaction, but reversible, potentially implying that the structure of silica readily undergoes temporary absorption/desorption at its surface in the presence of water.
Dissertation Note: Thesis (B.Sc.(Hons)) -- University of Adelaide, School of Physical Sciences, 2016
Keywords: Honours; Geology; biogenic silica; phytoliths; diatoms; degree of silica hydration; FTIR; 29Si NMR
Description: This item is only available electronically.
Provenance: This electronic version is made publicly available by the University of Adelaide in accordance with its open access policy for student theses. Copyright in this thesis remains with the author. This thesis may incorporate third party material which has been used by the author pursuant to Fair Dealing exceptions. If you are the author of this thesis and do not wish it to be made publicly available, or you are the owner of any included third party copyright material you wish to be removed from this electronic version, please complete the take down form located at:
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