A new compilation of coral benchmarks: towards a consistent global repository of U-Th dated indicators of past sea levels

Abstract:

Coral benchmarks and speleothem records are valuable markers of past sea level. They are however, heterogeneous in both their geographic location and occurrence in time. Additionally, methodological (e.g. open system behaviour within ²³⁰Th/²³⁸U-series dating), local tectonic (i.e. site specific subsidence/uplift), and isostatic influences complicate their interpretation as markers of past sea level. Nonetheless, they remain a preeminent method for reconstructing and evaluating former sea levels during the Late Quaternary.

Our compilation is unique as we use modern ecological depth habitat constraints to refine our reconstructions. To support the growing awareness within the palaeoclimate community of the importance of coral habitat, we provide both global and regional depth habitat ranges for each species in our reconstruction of past sea levels.

As such we present an internally consistent global compilation of coral benchmarks (building on the compilations of Medina-Elizalde, 2012 and Dutton and Lambeck, 2012) containing >100 studies. We include a rigorous consideration of each error term associated with these records, such as: age, depth habitat, elevation measurement, and uplift correction. We apply commonly employed age screening methods (δ²³⁴U_initial and detrital ²³⁰Th concentrations) before undertaking a site specific assessment of each sea-level record. This includes consideration of stratigraphic integrity, replication (and any concordant age determinations) and validation of assumptions (e.g. uplift rates), where possible. Finally, we present a statistical assessment of the distribution of the data (where sufficient data density allows) within each site-specific sea-level record.

This presentation will show the dataset as currently compiled (>2,600 datapoints), and initial evaluations on a site-specific basis.