Major perturbations in the Cretaceous global carbon cycle are reflected in long- and short-term fluctuations of δ13C and are commonly associated with the deposition of organic-rich sediments in the world oceans. The first major carbon cycle perturbation of the Cretaceous is within the Valanginian (the Weissert Event). This enigmatic event is proposed to have resulted from an increase in the rate of sedimentary burial of 13C-depleted organic carbon which has been tentatively related to oceanic anoxia. The enhanced burial rate should have led to a drop in the atmospheric pCO2 concentrations and the leak of O2 to the atmosphere. A means to evaluate the significance and potential impact of perturbations in the global carbon cycle and linked changes in atmospheric O2 is to examine the record of wildfires from a range of well-constrained Late Jurassic to Cretaceous marine sections in Europe as well as samples derived from the IODP. Assuming that oxygen is a dominant factor influencing fire during this time, estimates of atmospheric pO2 variability can be derived from wildfire proxies i.e. Polycyclic Aromatic Hydrocarbons and charcoal. Therefore, this project aims to determine trends in Polycyclic Aromatic Hydrocarbons, coupled with charcoal abundance and carbon isotopic analyses, through the latest Jurassic -Early Cretaceous (and across a major carbon cycle perturbation) in a number of key sections providing quantitative data on wildfire activity. As well as using these organic proxies to detect and quantify the wildfire this combined chemostratigraphic and organic-geochemical approach will provide further data regarding characterising the controls on one of the most significant paleoceanographic events of the Early Cretaceous. This research has significant in terms of understanding other Mesozoic events as deep time variation in atmospheric O2 has also played a key role in the evolution of life on Earth.
You will become an expert in cutting-edge techniques to sample and analyse Cretaceous marine sediments conducting geological fieldwork in Spain and France as well as sampling from the IODP core repository. You will receive training in advanced analytical techniques, including stable isotope mass spectrometry, isolation of PAHs from sediment samples and charcoal analysis.
This project will provide a first-class research experience for a student interested in Earth sciences. The scope of the research question will allow independent thinking and hypothesis testing, and result in a significant contribution to knowledge. This project will also allow the student to develop a broader methodological profile as well as develop research that has direct relevance to the petroleum field.