Project: Collaborative Research: Unlocking the Cenozoic/Cretaceous seawater sulfate record via inclusion of 17O in marine barite

NSF Award Abstract:

The PIs will measure a never-before-analyzed chemical property of ocean sediments – variations in two trace isotopes of oxygen in barium sulfate particles. These data will provide a record of changes in ocean chemistry over the last 125 million years, changes that are driven by variations in the Earth’s carbon, oxygen and sulfur cycles. Understanding the history of the global cycles of these elements (carbon, oxygen, and sulfur) will help us understand the links between geological processes, natural climate change, and biological processes on land and in the ocean. Activities also include public outreach (via cartoon modules described the science), and the project will support training of a graduate student.

This project will build a record of the 17O in sulfate from marine barite over the last 125 million years, using a recently-developed method that enables high-precision analysis of 17O in barite. The chemistry of marine sediments stands as one of the central catalogs of climatic evolution and earth surface change on geological timescales. The sulfur and oxygen isotopic composition of marine sulfate (as captured in barite) are two key records ocean chemistry over the last 125 million years. They are important because sulfate serves as an energy source for microbial life that is roughly 10 times larger than atmospheric oxygen, and that integrates across a wide range of biogeochemical processes and cycles, including those of carbon and iron. Recently, a new hypothesis was generated involving the influence of large igneous province formation on the sulfur isotope record. The new data proposed here – 17O in barite – will be used to test this hypothesis, and more broadly, to better understand the C, S, and O cycles through the Cretaceous and Cenozoic.

This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.