Abstract: The process of laser micro-sampling for analysis of C and O isotope in carbonate minerals is to focus a high-power laser beam on a carbonate sample to liberate CO2gas. Then the CO2gas is purified and sent into a mass spectrometer for isotope analysis of C and O, and its spatial resolution rate is more than 20μm. It is an effective way of separately producing CO2gas from all kinds of fine structure composition in carbonate to meet the need of isotope geology studies. Fractionation and reproducibility are characterized by analyzing carbonate standards: the optimal precision is approximately±0.22‰(σ) for bothδ¹³C and δ¹⁸O incarbonate standards, which is the same as what is gained in conventional acid dissolution method;δ13C is not evident in fractionation during laser micro-sampling, whileδ18O is. This
precision is constant (calcite,-1.72‰;dolomite,-1.59‰) for the same mineral and it can thus easily be corrected . The laser micro-sampling has been mainly used to analyze the isotopes of C and O in carbonate reservoir rocks and the isotope values. Meanwhile it can well explain the diagenesis process and porosity evolution of container rock.

Key words: laser micro-sampling, carbonate, isotope analysis