Interpreting the stable carbon isotope record of both carbonate minerals and organic matter may provide clues into the carbon cycle, physiology of primary producers, and paleoecology of ancient oceans. However, the wide range of biological, ecological, sedimentological, and diagenetic factors that affect the isotopic distributions is reduced to just one value, the ratio of 13C and 12C. Thus, interpreting this single value is quite difficult.
Understanding the carbon isotopes becomes especially important when it comes to Neoproterozoic deposits (those that formed 1000 – 538 million years ago), which contain some of the largest 13C/12C deviations from standard values. These deviations are extremely well studied as they may reflect global processes linked to the rise of complex life and the appearance and diversification of animals. Yet, the origin of each of the Neoproterozoic isotope deviations remains argued.
I will discuss how combining the classical stable carbon isotope research with paleontology and with organic geochemistry may be a way forward to disentangle the multiple factors that affect the ancient carbon isotope record. This technique may help us to understand the factors that shaped the trajectory of the early evolution of complex life on our planet.