Publication Date

2014

Document Type

Dissertation/Thesis

First Advisor

Dodd, Justin P.

Degree Name

M.S. (Master of Science)

Legacy Department

Department of Geology and Environmental Geosciences

LCSH

Oxygen--Isotopes; Silica; Isotope geology; Geology; Geochemistry

Abstract

Oxygen isotope values of biogenic silica are increasingly used as proxies of paleoenvironmental conditions. A number of studies have demonstrated a strong relationship between the diatom silica and the temperature/oxygen isotope value of the formation water; however, some studies have indicated that early diagenesis of biogenic silica may alter the oxygen isotope values by several permil. Quantification of the maturation process has proven difficult since the mechanisms that drive post-mortem changes in the silica oxygen isotope values have not been well characterized. New silica maturation data from marine diatom, Stephanopyxis turris, cultured in a controlled laboratory experiment, demonstrate a rapid post-mortem decline in silica reactivity. A decrease in relative abundance of surface silanol groups coincides with a decrease in the surface charge density of freshly harvested frustules. These experiments demonstrate that rapid post-mortem alteration of biogenic silica provides a possible mechanism for alteration of oxygen isotope values in biogenic silica.

Comments

Advisors: Justin P. Dodd.||Committee members: Neil Blackstone; Reed Scherer.

Extent

71 pages

Language

eng

Publisher

Northern Illinois University

Rights Statement

In Copyright

Rights Statement 2

NIU theses are protected by copyright. They may be viewed from Huskie Commons for any purpose, but reproduction or distribution in any format is prohibited without the written permission of the authors.

Media Type

Text

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