This proposal requests funds to support analysis of four sulfur isotopes in 70 bulk samples from three cores collected as part of recent ICDP drilling in the Barberton Mountain Land, South Africa. Samples include black shales, disseminated sulfide and sulfide layers in chert and barite. The proposed analyses will provide a first glimpse into the sulfur isotope geochemistry of these Palaeoarchean era (3600 to 3200 million years ago) sedimentary sequences with an excellent state of preservation. One goal of this work will be to evaluate the possibility that evidence exists supporting microbial reworking of sulfur, and if so, what information it provides for understanding sources of sulfur to and controls on sulfate concentrations in the oceans. A second aim of this work will be to evaluate whether variations in the relationship between Δ36S and Δ33S that are seen in other successions are present in the Paleoarchean.
Project is part of a broad international collaboration on sulfur isotopes on these core materials involving the PI, and scientists at University of Utrecht, Westfälische Wilhelms University (Muenster, Germany), the Swedish Museum of Natural History (Stockholm, Sweden) and the Institute de Physique du Globe (Paris, France). All of these groups are currently either involved in existing collaborations or are planning to work together under the umbrella of the Barberton Drilling project. This is seen as a unique opportunity to study a large number of samples using shared techniques at a high level of detail from the approximately 2 km of sedimentary drill core, providing ample room for joint studies and coordination between sub-projects to yield a more significant and comprehensive dataset. At minimum, one joint overview publication in a major international journal will results from this work.
