Stable isotope ratios of planktonic foraminifera from LGM sediments of the Pacific Ocean

By analyzing the oxygen isotopes of surface dwelling (G. sacculifer, G. ruber), thermocline dwelling (N. dutertrei, G. menardii, P. obliquiloculata) and sub-thermocline dwelling (G. inflata) planktonic foraminifera, both relative and absolute estimates of the changes in the temperature gradient over this depth interval have been made.

Owing to poor carbonate preservation in the Holocene section of both cores, relative temperature estimates suggest only a slight glacial cooling (~2°C) at these locations, similar to that reported by CLIMAP [1976, 1981]. However, absolute temperature estimates determined from calcite-seawater paleothermometry indicate the eastern equatorial Pacific (EEP) was ~3°C cooler during the last glacial maximum (LGM), while the western equatorial Pacific (WEP) was ~4°C cooler.