Abstract

The Mg/Ca in foraminifera shells is commonly used as a proxy to estimate ocean temperatures in Earth’s past. However, studies have shown that both dissolution and salinity influence the Mg/Ca in shells of tropical foraminifera, which can cause paleotemperature estimates to be inaccurate. We measured Mg/Ca in shells of Globigernoides ruber and Globigerinoides sacculifer from core tops in the eastern equatorial Pacific. We compared our results with global core top data, which paleotemperature equations have been calibrated and published. We find that Mg/Ca values range greatly at the same surface ocean temperature. We also find that salinity and dissolution do not affect the relationship between Mg/Ca and temperature. In analyzing the carbonate ion concentration of the water at 30m, we find that this might be affecting the relationship between Mg/Ca and temperature, which could be affecting the accuracy of the Mg/Ca proxy.