In situ carbon and oxygen isotopes measurements in carbonates by fiber coupled laser diode-induced calcination

Abstract

Stable isotopic compositions of carbon and oxygen (δ13C et δ18O) measured from carbonates are used in geology to reconstruct paleotemperatures and to learn about the evolution of the biogeochemical carbon cycle. The standard technique used since the middle of the XXth century [1] to measure isotopic ratios is based on a wet chemical protocol which CO2 is evolved from the acidic dissolution of carbonates followed by quantification of CO2 molecules isotopologues using mass spectrometer or infrared spectroscopy. This is a lengthy protocol that necessitate to manipulate acid solution and numerous gas phases purification steps before isotopic measurements. Our new preparation technique aims at offering an alternative to the wet chemical preparation of the samples by using a direct extraction of CO2 via a laser-induced calcination process. In addition to save time, this method allows to consider spatially resolved and automated in-situ measurements and does not necessitate further purification steps of the evolved CO2 during calcination.