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"Perturbations in the carbon cycle are likely tied to major environmental and biotic changes on Earth."
PhD project title:
Understanding Earth’s carbon cycle through the Proterozoic.
Project description:
Past perturbations in the carbon cycle can be identified by changes in the carbon isotope composition (δ13C) of ancient seawater, preserved in marine carbonate rocks. The carbon cycle is central to investigating Earth’s past environment, particularly its oxygenation history. My project involves collating unpublished and published carbonate δ13C data from the Proterozoic (c. 2,500–540Ma) to develop the first comprehensive carbon isotope curve for this Eon. New data will also be gathered via fieldwork (e.g., the Scottish Hebrides), and international collaboration.
The carbon isotope curve will go on to be supplemented by other geochemical proxies, to investigate weathering rates (Sr-isotopes), seawater redox conditions (U-isotopes) and productivity levels (Cd-isotopes) across key intervals. The geochemical data will be integrated with a biogeochemical model to predict the controls and evolution of the biotic and abiotic components of Earth’s system throughout the Proterozoic, specifically across major perturbations in the carbon cycle.
The project will aim to address questions such as: 1) What were the dominant geological and/or biological drivers for the major carbon isotope excursions during the Proterozoic?; 2) Did environmental factors, such as oxygen levels, hinder the emergence and diversification of complex life?; and 3) Was the Mesoproterozoic a time of carbon isotope stability and thus Earth system stasis?. This research will result in a seawater carbon isotope curve for the Proterozoic that can be used for constraining ages for sedimentary successions that lack radiometric dating capabilities and/or age diagnostic fossils.