HR: 13:55h
AN: U52B-02    [PDF]
TI: The use of mass-independent and mass-dependent isotope fractionations to study the sulfur cycle
AU: * Farquhar, J
EM: jfarquha@essic.umd.edu
AF: ESSIC and Department of Geology, University of Maryland, College Park, MD 20742 United States
AU: Johnston, D T
EM: dtj@geol.umd.edu
AF: ESSIC and Department of Geology, University of Maryland, College Park, MD 20742 United States
AU: Wing, B A
EM: wing@essic.umd.edu
AF: ESSIC and Department of Geology, University of Maryland, College Park, MD 20742 United States
AB: The inclusion of $\delta$$^{33}$S and $\delta$$^{36}$S data with $\delta$$^{34}$S data is providing a new perspective on the evolution of Earth's sulfur cycle. Two types of sulfur isotope fractionations have been observed in the geologic record, mass-independent isotope fractionations and mass-dependent isotope fractionations. Mass-independent isotope effects have been reported in some of Earth's oldest rocks, present-day atmospheric aerosol samples, and in some volcanic ash layers in ice cores (c.f., Savarino et al. year, 2002 AGU Fall meeting). These mass-independent isotope signatures have been used both to provide insight into the atmospheric sub-cycle and also as a tool to trace the movement of sulfur through other parts of the global sulfur cycle. Mass-dependent isotope effects are responsible for most of the very large range of $\delta$$^{34}$S fractionations that are observed in the geologic record. The ability to identify different types of mass-dependent isotopic fractionations by using $\delta$$^{33}$S and $\delta$$^{36}$S data can provide a means of differentiating between different types of biological and abiological signatures in the geologic record. We will discuss the developing framework for evaluating these mass-dependent isotopic fractionations and their range of potential applications (see also Johnston et al. 2003 AGU Fall meeting).
DE: 0400 Biogeosciences
DE: 1030 Geochemical cycles (0330)
DE: 1040 Isotopic composition/chemistry
SC: U
MN: 2003 Fall Meeting