Abstract: The increment method is adapted to systematically evaluate oxygen isotope fractionations in carbonate minerals and the following sequence of 18O-enrichment is obtained: siderite>ankerite>magnesite> dolomite>calcite>aragonite>strontianite>cerussite≥witherlte．The internally consistent fractionation factors for the systems quartz carbonate and carbonate-water are acquired for a temperature range of 0 to 1200℃．There is good agreement between the present calculations and known experimental and/or empirical data．Therefore, this theoretical calibrations involving the carbonate minerals are applicable not only to determination of the formation temperature of mineral assemblages but also to tracing their formation mechanisms． The present calculations suggest that dolomite should behave isotopically like calcite, and the cauilibrium fractionation between dolomite and calcite is 0.56‰ at 25℃．Aragonite is predicted to be significantly depleted in 18O relative to calcite; equilibrium fractionation between calcite and aragonite is 4.47％ at 25℃．It is possible that polymorphic transition from aragonite to calcite could proceed through an essentially intact oxygen structure without isotopic resetting．In other words, the polymorphic transition involves only the breaking and rebinding of bonds between cation and carbonate complex rather than bonds between C and O inside the carbonate complex．It is hypothesized that the temperature dependence of oxygen isotope partitioning in aragonite could be conveyed to calcite in nature and in laboratory experiments．However, it remains to be tested whether oxygen isotope inheritance in calcite formation by the polymorphic transition is of critical importance in attempts to resolve dilemma involving fractionations in aragonite-calcite-dolomitewater systems.