Project Team
Student
Victoria Froh
Environmental Chemistry, Astrobiology and Biogeosciences
Arizona State University
Mentor(s)
Department of Geosciences
Department of Geosciences
Project Video
Project Abstract
Tracking the stable carbon isotope (δ13C) composition of marine carbonate sediments provides a means of reconstructing past climate history, which has importance in predicting future climate change effects. Large shifts in the δ13C of marine carbonate records, known as primary carbon isotope excursions (pCIEs), reflect changes in the global carbon cycle driven by disruptions to the earth’s long-term climate. However, chemical and physical processes occurring during the burial of sediments (diagenesis) have the ability to alter those records, which can interfere with paleoclimate reconstructions. In order to better understand these effects, we used the reactive transport modeling software CrunchTope to simulate a marine carbonate sediment column. Within the modeled sediments, sedimentary organic carbon is respired by aerobic and sulfate reducing microbial communities, and authigenic carbonate minerals can precipitate as a by-product. By varying different controlling parameters, the effects on the rate of sulfate reduction, rate of authigenic carbonate precipitation, and therefore cumulative impact on the δ13C signal can be examined. Here, by modulating factors such as the sediment lithology, diagenetic carbon isotope excursions (dCIE) created similar peaks to those seen in climate events. These results demonstrate that carbonate diagenesis has the potential to significantly alter or amplify the primary δ13C signal in marine carbonates. In future studies, reactive transport models may be employed to identify diagenetic alteration and improve the accuracy of paleoclimate interpretations.