Towards an understanding of the Proterozoic carbon isotope curve

碳循环是研究地球过去环境的核心，尤其是它的氧化史。过去碳循环的扰动可以通过保存在海相碳酸盐岩中的古海水碳同位素组成（δ c - 13）的变化来识别。我的项目将包括整理元古代（约2500 -539 Ma）未发表和已发表的碳酸盐三角洲c - 13数据，以开发该宙的第一个综合碳同位素曲线。新的数据也将通过实地考察（如苏格兰赫布里底群岛）、广泛的实验室工作和国际合作收集。碳同位素曲线将补充其他地球化学指标，使我能够研究风化速率（sr -同位素），海水氧化还原条件（u -同位素）和生产力水平（cd -同位素）在关键区间。地球化学数据将与生物地球化学模型相结合，以预测整个元古代地球系统的生物和非生物成分的控制和演化，特别是在碳循环的主要扰动中（例如Lomagundi和Shuram短途旅行）。该项目旨在解决以下关键问题：1)元古代主要碳同位素漂移的主要地质和/或生物驱动因素是什么？2)碳同位素漂移是否是氧合事件的良好指示？3)中元古代是否是碳同位素稳定的时期，从而导致地球系统停滞？

The carbon cycle is central to investigating Earth's past environment, particularly its oxygenation history. Past perturbations in the carbon cycle can be identified by changes in the carbon isotope composition (delta c thirteen) of ancient seawater, preserved in marine carbonate rocks. My project will involve collating unpublished and published carbonate delta c thirteen data from the Proterozoic (c. 2,500-539 Ma) to develop the first comprehensive carbon isotope curve for this Eon. New data will also be gathered via fieldwork (e.g., the Scottish Hebrides), extensive laboratory work and international collaboration. The carbon isotope curve will be supplemented with other geochemical proxies, allowing me 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 (e.g., the Lomagundi and Shuram Excursions). The project aims to address key questions such as: 1) What were the dominant geological and/or biological drivers of the major carbon isotope excursions during the Proterozoic?; 2) Are carbon isotope excursions good indications for oxygenation events?; and 3) Was the Mesoproterozoic a time of carbon isotope stability and thus Earth system stasis?