The stability fields of laumontite, prehnite, pumpellyite, zoisite, and tremolite-bearing assemblages were experimentally examined in the CaO–MgO–Al2O3–SiO2–H2O–CO2 system. The influence of the Fe content on the shift of the upper stability boundary towards both lower temperature and equilibrium values is shown for pumpellyite. The runs for some dehydration–carbonatization reactions in the complex H2O–CO2–NaCl fluid have revealed a decrease in the equilibrium values for even low salt content. The zeolite, prehnite–pumpellyite, and greenschist facies limits are plotted in the schematic diagram, and their possible Pfl limits are discussed. For examined P–T conditions of greenschist to amphibolite facies transition the absence of the compositional gap between tremolite and Ca-hornblende is found.