Exploring the contributions of liquid-phase sulfur chemistry to the mass-independent sulfur fractionation of the Archean rock record
Name
671398853-MIT.pdf
Description
Full printable version
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2.99 MB
Format
Adobe PDF
Checksum (MD5)
6e1df8761cd19009adb75daf048a44f6
Author(s)
Kopf, Sebastian Hermann
Advisor(s)
Shuhei Ono.
Date Issued
2010
Publisher
Massachusetts Institute of Technology
Abstract
Archean sulfur mass-independent fractionation (S-MIF) has been widely recognized as one of the strongest indicators for the rise of atmospheric oxygen in the Early Proterozoic. A decade after its discovery, the wide-ranging implications of Archean sulfur MIF have been discussed extensively and despite a number of recent studies on the gas-phase chemistry of sulfur, no definite overall picture has emerged to date as to the precise origin and preservation of the Archean mass-independent sulfur signal. The interpretation of the Archean sulfur MIF as a strong constraint for atmospheric oxygen levels, however, requires a dominant atmospheric source of sulfur MIF. This study was aimed at investigating the potential contribution of the poorly explored mass-independent effects from liquid-phase sulfur chemistry and focused on sulfur isotope fractionation during liquid-phase photolytic breakdown of phenacylphenylsulfone (PPS) as a model system for initial investigation. Results confirm that MIF in this system is caused by the magnetic 33S isotope and excludes other mechanisms such as nuclear volume effects or vibronic coupling that would produce concomitant MIF in the 32S-34_3-3S triad. This provides a starting point for discussing the implications of magnetic isotope effects as a mechanism for mass-independent isotope fractionation in the chemical evolution of the sulfur cycle and suggests that liquid-phase processes such as the photolysis of PPS cannot constitute the principal source of mass-independent sulfur fractionation in the Archean.
Description
Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Earth, Atmospheric, and Planetary Sciences, 2010.
Cataloged from PDF version of thesis.
Includes bibliographical references (p. 30-32).
Subjects
Earth, Atmospheric, and Planetary Sciences.
MIT Department
Massachusetts Institute of Technology. Department of Earth, Atmospheric, and Planetary Sciences
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