Bayesian Cyclostratigraphic Age-Depth Modelling: A Cambrian Case Study

Age-depth modelling and stratigraphic correlation are fundamental components of integrated geological time scale construction. This contribution illustrates a Bayesian statistical approach to both components using a Cambrian case study. A Bayesian framework is probabilistic in nature, integrating prior knowledge and observed data from one or multiple sources. Advantages of using a Bayesian approach to geological time scale construction include the explicit formulation of uncertainties and the consideration of different sources of stratigraphic information within a single analysis. The case study presented here focusses on the exceptional lower Cambrian strata of the Tiout section, southern Morocco. These strata are well studied in terms of biostratigraphy, chemostratigraphy, cyclostratigraphy and radio-isotopic dating. Firstly, we illustrate how individual astronomical cycles can explicitly be incorporated in a Bayesian age-depth model, while also considering radio-isotopic time constraints. Such approach is complementary to other cyclostratigraphic Bayesian approaches that consider total duration estimates for a section, or average sedimentation rates estimated based on a cyclostratigraphic interpretation. Secondly, we illustrate how cyclostratigraphic interpretations can be incorporated as prior information in the new “StratoBayes” model developed for Bayesian stratigraphic correlation. These innovative methods allow for the more accurate and precise age estimation of key geological events like the first occurrence of fossil taxa, or major carbon isotope excursions, including explicit uncertainty formulation.