²¹⁰Pb-based dating of recent sediments with the χ-mapping version of the Constant Sediment Accumulation Rate (CSAR)...

The ²¹⁰Pb-based method aims at determining the absolute age of recent sediments on the centennial scale. A family of models assumes that at the sediment-water interface the flux of unsupported ²¹⁰Pb (²¹⁰Pb_exc), F, relates to its initial activity concentration, A_o, and the mass sedimentation rate, w, as: F=A_ow. Additional specific assumptions that allow for analytical formulations of the models are: i) constant A_o (CIC), constant F (CF), and constant F with constant w (CFCS). A model with constant w (CSAR) was suggested for completeness but never used because of the lack of a suitable analytical formulation. The TERESA model assumes random and independent variability for A_o and w, described by normal distributions. It systematically generates a large number (∼10⁵) of potential solutions, whose performance for fitting the empirical ²¹⁰Pb_exc profile is quantified through the χ-function. This work aims to adapt the above methodology to formulate the χ-mapping version of the CSAR model. The performance of the model is evaluated with a set of synthetic and real cores for which an independent chronology is available. CSAR is able to capture the mean sedimentation rate from the ²¹⁰Pb_exc data and provides reliable chronologies and paleorecords of A_o, useful for tracking past changes in sedimentary conditions. CSAR provides an interesting different perspective for researchers working with ²¹⁰Pb-based dating of recent sediments.