ALBERT

Description: Accurate reconstruction of past ocean temperatures is of critical importance to paleoclimatology. Carbonate clumped isotope thermometry ("L'l47") is a relatively recent technique based on the strong relationship between calcification temperature and the statistical excess of 13C- 180 bonds in carbonates. Its application to foraminifera holds great scientific potential, particularly because Ll47 paleotemperature reconstructions do not require assumptions regarding the 180 composition of seawater. However there are still relatively few published observations investigating the potential influence of parameters such as salinity or foraminiferal size and species. We present a new calibration data set based on 234 replicate analyses of9 planktonic and 2 benthic species of foraminifera collected from recent core-top sediments, with calcification temperatures ranging from -2 to 25 °C. We observe a strong relationship between Ll47 values and independent, oxygen-IS estimates of calcification temperatures: L'l47 = 41.63 x 103 /T2 + 0.2056 The formal precision of this regression(± 0.7-1.0 °C at 95 % confidence level) is much smaller than typical analytical errors. Our observations confirm the absence of significant species-specific biases or salinity effects. We also investigate potential foraminifer size effects between 200 and 〉560 μm in 6 species, and conclude that all size fractions from a given core-top location and species display statistically undistinguishable L'l47 values. These findings provide a robust foundation for future interlaboratories comparisons and paleoceanographic applications.