Researchers from Penn State University will test the hypothesis that recrystallization rates in "young" (i.e, less that one million years old) nannofossil ooze carbonates are significantly faster, and alteration of geochemical proxies much greater, than previously thought. This work will conduct calcium and strontium isotope measurements on marine carbonates and pore fluids and use a numerical diagenetic model to constrain carbonate recrystallization rates in marine systems. The work will extend such measurements from a few Ocean Drilling Program (ODP) sites previously measured, approximately doubling the number of sites examined. The goal is to ascertain if so-called rapid recrystallization extends to other locations in the ocean; if it does, rapid recrystallization may be considered to be a widespread effect of global significance. Researchers will collect archived ODP samples, measure their isotopic composition, and use numerical reactive transport models to interpret diagenetic rates of recrystallization and, critically, evaluate alternate hypotheses.
If rapid recrystallization is confirmed, the proposed work will create a framework for evaluating diagenetic alteration in a range of proxy systems (such as boron and magnesium), and suggest methods for correcting records used to study climate and geochemical evolution on Earth. This work has the potential to produce more accurate proxy records and increase our understanding of the uncertainty of geochemical proxy records, as well as to enable more accurate climate records with which to calibrate climate models used to predict future climate change. The funded research supports a recently-completed NSF-supported multiple-collector ICP-MS facility at Penn State University. Funding also supports education and training of a graduate student, research experiences for undergraduates, and the generation of outreach materials to be displayed at the Penn State Earth and Minerals Sciences Museum.
