Description:

The proposed TSRC workshop will bring together scientists from three diverse communities geosciences, atmospheric modeling, and quantum dynamics to examine recent progress into the molecular origins of sulfur mass-independent fractionation (S-MIF).

Approximately 2.4 billion years ago, the Earth underwent a cataclysmic "Great Oxygenation Event" (GOE) causing profound and permanent changes in its climate, geology, and chemistry, and giving rise to higher life forms. In recent years, geologists have developed the first proxy that may be directly tied to the GOE: isotopic fractionation of the element sulfur in the geological rock record. Specifically, "mass independence" characterizes the sulfur fractionation measured in rocks older than 2.4 billion years, but is absent in younger rocks. Most of the geochemistry community with an interest in Archean (early) earth geology has concluded that the disappearance of S-MIF can serve as a high-sensitivity tracer of the rise of atmospheric oxygen. This can thus provide a detailed characterization of the GOE, which is of great relevance to many scientific disciplines.

Efforts to understand the abrupt change in the relative sulfur isotopic abundances have to date been thwarted by a gap in knowledge of the underlying molecular processes. This understanding is necessary to interpret correctly the sources of the observed S-MIF signal. In a joint NASA-NSF workshop held in 2011, the geology, and atmospheric modeling S-MIF researchers engaged the chemical quantum dynamics community--whom, it was decided, already likely possessed the experimental and theoretical tools necessary to address open questions about S-MIF.

The 2011 NASA-NSF workshop served as a unique forum, bringing researchers together from diverse fields to share ideas and expertise, and leading to joint research ventures. Five years later, the proposed TSRC workshop will bring these communities together once more to assess the progress that has been made, to recalibrate priorities, and to foster new collaborative directions for profitably advancing forward this extremely important, but also very challenging, area of fundamental and interdisciplinary interest.