Abstract

Poster Presentations

Day 2, May 16（Tue.）　　Room P (Foyer, Room 1004-1007)

2P-38　　PDF

Raman mass spectroscopic evaluation of precision of oxygen isotope ratio of carbonate mineral

(Kyushu Univ.)
^oYuki Inoue, Junji Yamamoto

The oxygen isotope ratio of calcium carbonate varies with temperature. The δ18O of carbonates is often used to infer past climatic and hydrologic variability from a wide variety of materials and environments, including cave deposits (speleothems), corals, carbonate shells from marine and freshwater organisms, and inorganic and organic carbonates deposited in lake sediments and soils. Therefore, attention was focused on micro-Raman spectroscopy, which can be analysed with a spatial resolution of 1 µm. The precision of isotope ratio analysis using Raman spectroscopy has rarely been discussed. McKay et al. (2012) measured Raman spectra of calcite, which determined an error of 210‰ from the intensity ratio of the Raman spectra of calcite. However, the existence range of the natural oxygen isotope ratio is 166‰, which makes its application to natural samples difficult.
We measured with higher resolution and sensitivity than in previous studies. As a result, we were able to determine the oxygen isotope ratio of calcium carbonate from the Raman spectra with a precision of up to 9.7‰. This precision is two orders of magnitude lower than in previous studies.