The carbonate clumped isotope paleothermometer is becoming more widely used in the geosciences because it is less sensitive to solution δ18O and Mg/Ca than other carbonate-based temperature proxies. Here, we examine the impacts of dissolution on foraminiferal clumped isotope records (∆47). Dissolution is known to impact carbonate minerals in ocean sediments near and below the carbonate saturation horizon. The effects of dissolution on foraminiferal mass, δ18O, and Mg/Ca have been the subject of prior work but have not yet been reported for the carbonate clumped isotope paleothermometer. We examine six planktic foraminiferal species from core-tops collected at different water depths on the Ontong Java Plateau. Below the carbonate saturation horizon, multiple species exhibit higher ∆47 values, likely due to dissolution, biasing ∆47 to cooler temperatures. The largest effects are observed in G. siphonifera, P. obliquiloculata, and G. tumida with an ~0.01 ‰ difference from above to below the saturation horizon; p < 0.01 corresponding to a temperature bias of ~4 °C at a measured temperature of 28 °C and of ~3 °C at a measured temperature of 18 °C. Normalizing data for different species yields a pooled slope of -0.0006 ‰/µmol/kg ∆[CO32-] (p < 0.01). Dissolution experiments show that for two species, T. sacculifer and G. tumida, ∆47 increased with mass loss. We propose multiple mechanisms by which dissolution may impact ∆47 including intra-test heterogeneous dissolution, which provide context to enable corrections for the impacts of dissolution on clumped isotope-based paleo-records.
