Activity diagrams for the MgO-Na2O-K2O-SiO2-AI2O3-H2O-HCI system in the temperature range 298 to 623 K and L bar pressure: application to the 1900 Ma phlogopite-Mg-chlorite-sericite schists of W. Bergslagen, Sweden

Abstract

Both 2- and 3-dimensional activity diagrams for the MgO-Na2O-K2O-SiO2-AI2O3-H2O-HCI system at temperatures of 298 to 623 K and 1 bar pressure are presented, showing the stability fields and volumes of phlogopite, Mg-chlorite, muscovite, paragonite, microcline, albite, kaolinite, and Mg-, Na-, and K-montmorillonite. Additionally, the expressions of reaction constants also contain the pressure term. The geological application of these diagrams to geochemical interpretation is briefly discussed in relation to the formation of 1900 Ma phlogopite-Mg-chlorite-sericite-quartz rocks in W. Bergslagen, Central Sweden.