Equations for calculation of NaCl/( NaCl + CaCl2 ) ratios and salinities from hydrohalite-melting and ice-melting temperatures in the H2O-NaCl-CaCl2 system
利用H2O-NaCl-CaCl2体系水盐化合物和冰的融化温度计算NaCl/（NaCl＋CaCl2）比值和盐度的方程

The composition of fluid inclusions in the H2O-NaCl-CaCl2 system has been generally graphically estimated using the melting temperatures of hydrohalite （ Tm-HH ） and ice （ Tm-ice）. Here we present two equations that can be used to calculate the relative proportion of NaCl （ i. e. , NaCL/ NaCl ＋ CaC12 ] , or XNacl ） and the total salinity （ i. e. , NaCl ＋ CaCl2, wt% ） for fluid inclusions with ice as the last melting phase. XNacl can be calculated from Tm-HH using the following equation： y = （a＋bx）^-1/c where y is XNacl, x is Tm_HH , a =0. 33124402, b =-0. 031518028, and c =0. 22932736. In the cases where only Tm-ice is measured and Tm-HH is not known, Tm-ice can be used as the maximum possible Tm-HH to calculate the maximum value of XNacl using the above equation. In these cases, the following equation can be used to calculate the maximum total salinity： y=（a＋bx＋cx2） l where y is salinity, x is Tm-HH , a =0, 057184817, b =0. 00078565757, and c = 5. 7262766E-6. Because the isothems in the field of ice are sub-parallel to the NaCl-CaCl2 binary side in the H2O-NaCl-CaCl2 ternary system, the errors in salinity calculation introduced by the above approximation are small （ less than 2 wt% ）. A Windows program for calculation of XNacl and salinity is available at ： http ：//uregina. ca/-chiguox.