δ18O analysis of diatom silica via laser ablation -IRMS and associated methods for removing exchangeable oxygen

Oxygen in silica that forms the skeletons of oce

anic organisms takes a value of δ18O that depends

on the ocean temperature. When an organ

ism dies and its skeleton is buried in the ocean

floor, it preserves the value for later analysis.

Hence the δ18O in diatom silica found in deep

sea cores is a surrogate for past ocean tem

perature. A method for accurately determin

ing δ18O via laser-fluorination IRMS is reported