Combining Mg/Ca and clumped isotope analyses for temperature estimation from foraminifera

Reconstructing past temperature beyond the instrumental record is challenging and paleotemperature proxies measured on different phases often disagree (e.g., alkenone SST and foraminifer Mg/Ca). We combined clumped isotopes and Mg/Ca thermometry on the same specimens of different Atlantic planktic foraminifera to provide independent estimates of temperature as well as the δO of the ambient seawater. The strength of the tandem approach is that unlike other palaeotemperature methods, Mg/Ca and Δ47 are measured on the exact same calcite phase, thereby eliminating differences in seasonality or depth habitat of proxies. This redundancy constitutes a rigorous test of individual methods with the advantage that the same approach can be applied to fossil specimens.