碳酸盐中的Mg、Ca同位素平衡分馏系数对利用Mg、Ca同位素来进行地球内部碳循环示踪具有重要意义。我们通过第一性原理计算,在简谐近似(Urey H.C.,1947)的情况下,得到了不同Mg摩尔浓度的碳酸盐与白云石之间的Mg、Ca同位素平衡分馏系数,此方法已在Mg同位素(Wu et al.,2015)和Si同位素(Huang et al.,2014)应用。我们的结果显示,碳酸盐中的Mg摩尔浓度无论是高 Carbonate Mg, Ca isotope equilibrium fractionation factor is of great significance for the use of Mg and Ca isotopes for the internal carbon cycle tracing. We calculated the equilibrium fractionation coefficients of Mg and Ca isotopes between carbonate and dolomite at different Mg molar concentrations by simple first harmonic approximation (Urey HC, 1947) using the first-principles calculations Mg isotopes (Wu et al., 2015) and Si isotopes (Huang et al., 2014). Our results show that the carbonate Mg concentration is high