Holly Barnhart Rose Hills
Stable isotope analysis of travertine carbonates
For SURF 2017, I studied a travertine fissure ridge in Bridgeport, California to characterize trace element partitioning between thermal spring water and travertine carbonates. I will further analyze this system to establish an empirical temperature-oxygen isotope relationship for regional paleotemperature reconstruction. For use in paleoclimate reconstruction, temporal changes in carbonate precipitation conditions and their effect on carbonate trace element and isotopic composition must be characterized. In my earlier study, bulk solids were analyzed to capture overall travertine system dynamics. Analysis of travertine fluids and instantaneous precipitates can reflect present conditions of travertine formation and composition. A comparative analysis of the isotopic and trace element composition of the bulk and instantaneous carbonates can constrain conditions of past travertine deposition. This is important for isolating isotope and trace element partitioning effects in terrestrial carbonates due to climate signals like temperature, from other effects like biotic activity and evaporation. Changes in the deposition environment of Bridgeport travertine will be used to interpret measured isotopic and trace element compositions, furthering our understanding of terrestrial carbonates in continental paleoclimate reconstruction.