Development and application of oxygen and carbon isotopic measurements of biogenic carbonates by ion microprobe

The analytical capabilities of the ims 1270 ion microprobe (SIMS) in determining O and C isotope compositions in biogenic carbonate samples have been tested. Results indicated that, with a spot size of approximate to 30 mu m, the average reproducibility at the 1 s level was 0.3%0 for oxygen isotopes and 0.6%0 for carbon isotopes. Nevertheless, this reproducibility can reach 0.2%0 for oxygen isotope determinations during some sessions. These reproducibilities allowed us to perform analyses on biogenic carbonate samples for environmental studies. in this paper, examples of oxygen and carbon isotope measurements are presented for a modern coral and the Holocene scleractinian coral, Porites lutea.